Patent Application
20100295833
The present invention relates to a display device including a photosensor in its display panel.
There has been known a liquid crystal display device including a photosensor in its pixel circuit.
Patent Literature 1 discloses such a display device.
A pixel in each display region 10 includes a display pixel 26 and a photosensor pixel 27.
The display pixel 26 is provided at or near each of intersections of source signal lines 23 and gate signal lines 22a, which extend in a column direction and a row direction, respectively. The display pixel 26 includes (i) a TFT 32, (ii) a liquid crystal capacitance defined by a pixel electrode 61, which is provided at an end of the TFT 32, and a common electrode and (iii) a storage capacitor 35 formed between the display pixel 26 and a common signal line 31.
The photosensor pixel 27 includes (i) a TFT 64 serving as a photo diode, (ii) a storage capacitor 63 for storing a pre-charge voltage, (iii) a TFT 62b serving as a source follower, (iv) a TFT 62a serving as a switching element for applying the pre-charge voltage to the storage capacitor 63, and (v) a TFT 62c for selectively supplying, to corresponding one of photosensor output signal lines 25, a source follower output supplied from the TFT 62b. The TFT 62a has (i) a terminal which is connected to corresponding one of pre-charge voltage signal lines 24 and (ii) a gate which is connected to corresponding one of gate signal lines 22c. The TFT 64 (serving as a photosensor element), the TFT 62b, and the storage capacitor 63 each have a terminal which is connected to the common signal line 31. The TFT 64 and the storage capacitor 63 each have another terminal which is connected to a gate of the TFT 62b. The TFT 62c has a gate which is connected to corresponding one of gate signal lines 22b.
The gate signal lines 22a are driven by a gate driver circuit 12a. The gate signal lines 22b and the gate signal lines 22c are driven by a gate driver circuit 12b. The pre-charge voltage signal lines 24 and the photosensor output signal lines 25 are driven by a photosensor processing circuit 18. The source signal lines 23 are driven by a source driver 14.
The TFT 62a applies, to the another terminal of the TFT 64, a pre-charge voltage supplied from the photosensor processing circuit 18 via corresponding one of the pre-charge voltage signal lines 24. The TFT 62a is turned ON upon application of an ON voltage to the gate signal line 22c connected thereto. The pre-charge voltage is a voltage, upon application of which the TFT 62b is turned ON, and which is higher than or equal to a threshold voltage Vth. The TFT 64 causes leakage in response to light irradiation thereon, depending on the intensity of the light. As a result, an electric charge stored in the storage capacitor 63 is discharged through channels of the TFT 64.
In the photosensor pixel 27, the gate of the TFT 62b is pre-charged with a pre-charge voltage by the TFT 62a. That is, the TFT 62b in an initial state has a gate voltage equal to the pre-charge voltage. The gate voltage of the TFT 62a changes as voltages across the storage capacitor 63 change upon light irradiation on the TFT 64. The TFT 62b serves as a source follower circuit. The TFT 62c is turned ON upon application of an ON voltage from the gate driver circuit 12b to the gate signal line 22b connected to the TFT 62b. Here, if the TFT 62b is in an ON state, an electric charge of the photosensor output signal line 25 corresponding thereto is discharged to the common signal line 31 via the TFT 62c and the TFT 62b (or, the photosensor output signal line 25 corresponding thereto would be charged if a level of an electric charge of the common signal line 31 was sufficiently high). A change in an output voltage of the TFT 62b changes an electric charge of the photosensor output signal line 25 connected thereto, thereby changing a potential of the photosensor output signal line 25. In contrast, the electric charge of the photosensor output signal line 25 remains constant while the TFT 62b is in an OFF state, even if the TFT 62c is turned ON.
The photosensor pixel 27 supplies an output voltage to the corresponding one of the photosensor output signal lines 25, via which the output voltage is supplied to the photosensor processing circuit 18. The photosensor processing circuit 18 is provided directly on an array substrate.
Patent Literature 1
Japanese Patent Application Publication, Tokukai, No. 2006-267967 A (Publication Date: Oct. 5, 2006)
Patent Literature 2
Japanese Patent Application Publication, Tokukai, No. 2005-327106 A (Publication Date: Nov. 24, 2005)
Patent Literature 3
Japanese Patent Application Publication, Tokukai, No. 2002-62856 A (Publication Date: Feb. 28, 2002)
Patent Literature 4
Japanese Patent Application Publication, Tokukaihei, No. 10-91343 A (Publication Date: Apr. 10, 1998)
Patent Literature 5
Japanese Patent Application Publication, Tokukai, No. 2000-89912 A (Publication Date: Mar. 31, 2000)
Patent Literature 6
Japanese Patent Application Publication, Tokukai, No. 2005-148285 A (Publication Date: Jun. 9, 2005)
Patent Literature 7
Japanese Patent Application Publication, Tokukai, No. 2006-133786 A (Publication Date: May 25, 2006)
A liquid crystal display device including a conventional photosensor needs to include an AD converter so as to provide an output of the photosensor as digital data to outside. Such a liquid crystal display device includes a host controller 102 and a driver LSI 103 which are provided externally of the display panel 101. Further, the liquid crystal display is configured such that the output of the photosensor is supplied to an AD converter 104, and then the AD converter 104 returns an AD-converted output to the host controller 102 (for example, see
In the display panel 101, photosensor circuits 112 are driven by a scanning circuit 111. A photosensor output of each of the photosensor circuits 112 is transmitted from a point A, through a path B, to the AD converter 104 provided externally of the display panel 101. The paths B corresponding to the respective photosensor circuits 112 are merged together and connected to the AD converter 104. The photosensor outputs of the respective photosensor circuits 112 are sequentially inputted, as data 1, data 2, data 3, data 4, data 5, data 6, and so on, into the AD converter 104 through the respective paths B in a switched-over manner. The driver LSI 103 supplies display data to pixels.
The point A, of each of the photosensor circuits 112, from which the photosensor output is outputted, is connected also to corresponding one of the pixels.
However, the above configuration involves the following problem. A COG (Chip On Glass) technique is popularly employed to liquid crystal display devices in order to mount a chip of driver LSI on a display panel. However, such a COG technique has not been applicable to allow a display panel including a photosensor to have an additional function of AD conversion of a photosensor output.
The present invention has been made in view of the problems, and an object of the present invention is to provide (i) a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of a photosensor output, and (ii) a method of driving the display device.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being AC-driven is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into the digital output, the analog-to-digital conversion circuit converting the analog output during a first period overlapping neither (i) a period during which data signals are sent out to respective data signal lines nor (ii) a time point at which the voltage of the common electrode changes.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, the display device in accordance with the present invention is configured such that the first period falls within a period from (i) a time point at which all output of the data signals to the respective data signal lines is completed for one scanning signal line selection period to (ii) a time point at which the voltage of the common electrode COM changes for a first time since the time point (i).
According to the above invention, it is possible to configure the active matrix display device such that a period during which analog-to-digital conversion is properly carried out can be easily set.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being driven so as to keep constant is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, the analog-to-digital conversion circuit converting the analog output during a first period not overlapping a period during which data signals are sent out to respective data signal lines.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, the display device in accordance with the present invention is configured such that the first period falls within a period from (i) a time point at which all output of the data signals to the respective data signal lines is completed for one scanning signal line selection period to (ii) a time point at which output of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to configure the active matrix display device such that a period during which analog-to-digital conversion is properly carried out can be easily set.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being AC-driven is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines receiving data signals in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of data signal lines in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (i) a time point within a period during which last output of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which the voltage of the common electrode changes for a first time since the time point (i).
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being driven so as to keep constant is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines receiving data signals in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of data signal lines in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (i) a time point within a period during which last output of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which output of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines receiving data signals in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of data signal lines in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (i) a time point within a period during which one output is in progress to (ii) a time point at the end of the one output.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines receiving data signals in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of data signal lines in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (i) a time point within a period during which one output, other than last output, of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which subsequent output of the data signals to corresponding ones of the data signal lines is initiated for the one scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being AC-driven is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines line-sequentially receiving data signals in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (a) a time point within a period during which output of the data signals to the data signal lines is in progress for one scanning signal line selection period to (b) a time point at which the voltage of the common electrode changes for a first time since the time point (a).
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines line-sequentially receiving data signals in one scanning signal line selection period, and the analog-to-digital conversion circuit converts the analog output during a first period, which falls within a period from (i) a time point within a period during which output of the data signals to the data signal lines in progress to (ii) a time point at which the output of the data signals to the data signal lines is completed.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being driven so as to keep constant is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, data signal lines line-sequentially receiving data signals in one scanning signal line selection period, and the analog-to-digital conversion circuit converting the analog output during a first period, which falls within a period from (a) a time point within a period during which the data signals are sent out to the data signal lines for one scanning signal line selection period to (ii) a time point at which transmission of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: AC-driving a voltage to be applied to a common electrode; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which overlaps neither (i) a period during which data signals are sent out to data signal lines nor (ii) a time point at which the voltage of the common electrode changes.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, the method of driving the display device in accordance with the present invention is configured such that the first period falls within a period from (i) a time point at which all output of the data, signals to the data signal lines is completed for one scanning signal line selection period to (ii) a time point at which the voltage of the common electrode COM changes for a first time since the time point (i).
According to the above invention, it is possible to configure the active matrix display device such that a period during which analog-to-digital conversion is properly carried out can be easily set.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: driving a voltage to be applied to a common electrode so that the voltage keeps constant; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which does not overlap a period during which data signals are sent out to data signal lines.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, the method of driving the display device in accordance with the present invention is configured such that the first period falls within a period from (i) a time point at which all output of the data signals to the data signal lines is completed for one scanning signal line selection period to (ii) a time point at which output of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to configure the active matrix display device such that a period during which analog-to-digital conversion is properly carried out can be easily set.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: AC-driving a voltage to be applied to a common electrode; sending out data signals to data signal lines in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of the data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which last output of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which the voltage of the common electrode changes for a first time since the time point (i).
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device of the present invention is a method of driving an active matrix display including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: driving a voltage to be applied to a common electrode so that the voltage keeps constant; and sending out data signals to data signal lines in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of the data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which last output of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which output of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: sending out data signals to data signal lines in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of the data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which one output is in progress to (ii) a time point at the end of the one output.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: sending out data signals to data signal lines in a dot-sequential manner such that the data signals are dot-sequentially supplied per a predetermined number of the data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which one output, other than last output, of the data signals to corresponding ones of the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which subsequent output of the data signals to corresponding ones of the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: AC-driving a voltage to be applied to a common electrode; line-sequentially sending out data signals to data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which output of the data signals to the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which the voltage of the common electrode changes for a first time since the time point (i).
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: line-sequentially sending out data signals to data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which output of the data signals to the data signal lines is in progress to (ii) a time point at which the output of the data signals to the data signal lines is completed.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
In order to attain the above object, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: driving a voltage to be applied to a common electrode so that the voltage keeps constant; line-sequentially sending out data signals to data signal lines in one scanning signal line selection period; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which falls within a period from (i) a time point within a period during which output of the data signals to the data signal lines is in progress for one scanning signal line selection period to (ii) a time point at which output of the data signals to the data signal lines is initiated for a subsequent scanning signal line selection period.
According to the above invention, it is possible to carry out analog-to-digital conversion avoiding a timing at which a large electric current is supplied to a common impedance between power supplies of the data signal line drive circuit and to a common impedance between GNDs of the data signal line drive circuit. As such, it is possible to properly carry out the analog-to-digital conversion of the analog output supplied from the photosensor.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique whereby to add, to a display panel including a photosensor, a function of analog-to-digital conversion of the analog output supplied from the photosensor.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.
An embodiment of the present invention is described below with reference to
The liquid crystal display device 1 is an active matrix display device, and includes a display panel 2 and a host controller 3.
The display panel 2 includes a display/sensor region 2a, a source driver 4 (data signal line drive circuit), a gate scanning circuit 5 (scanning signal line drive circuit), and a sensor scanning circuit 6. The display/sensor region 2a is built into a display panel 2 by using, for example, amorphous silicon, polysilicon, CG silicon, or microcrystal silicon. As illustrated in
The host controller 3 is a control board 3 provided externally of the display panel 2. The host controller 3 supplies, to the source driver 4, (i) display data for the source driver 4, (ii) a clock signal and a start pulse etc. which are to be supplied to the gate scanning circuit 5, and (iii) a clock signal, a start pulse, and a supply voltage etc. which are to be supplied to the sensor scanning circuit 6. The above signals and voltages directed to the gate scanning circuit 5 or to the sensor scanning circuit 6 are supplied to the gate scanning circuit 5 or to the sensor scanning circuit 6 via the source driver 4.
The source driver 4 includes an I/O interface circuit 41, a sampling latch circuit 42, a holding latch circuit 43, an AD conversion circuit 45 (analog-to-digital conversion circuit), a DA conversion circuit 46, a source input-output circuit 47, a timing generation circuit 48, a data processing circuit 49, and a panel logic circuit 50.
The I/O interface circuit 41 is a block which receives the various signals and voltages supplied from the host controller 3. According to a timing signal supplied from the timing generation circuit 48, the sampling latch circuit 42 sequentially performs latching of digital display data supplied from the I/O interface circuit 41. The timing generation circuit 48 is a block which extracts various timings from a data transmission signal which has been supplied from the host controller 3 to the I/O interface circuit 41, and generates the timing signal. The holding latch circuit 43 is a block which holds digital display data of one line according to the timing signal supplied from the timing generation circuit 48, the digital display data having been latched by the sampling latch circuit 42. The DA conversion circuit 46 is a block which converts (digital-to-analog conversion) the digital data supplied from the holding latch circuit 43 so as to obtain an analog data signal. The source input-output circuit 47 is a block which buffers the analog data signal supplied from the DA conversion circuit 46 and supplies it to corresponding one of the data signal lines.
Meanwhile, the AD conversion circuit 45 receives, via the data signal lines and the source input-output circuit 47, analog sensor outputs supplied from the sensor circuits in the display/sensor region 2a. Next, the AD conversion circuit 45 samples and holds the analog sensor outputs. Then, the AD conversion circuit 45 converts (analog-to-digital conversion) the held analog sensor outputs into digital data. The data processing circuit 49 is a block which converts the digital data supplied from the AD conversion circuit 45 into a format suited for transmission, and supplies it to the host controller 3. The panel logic circuit 50 is a block which further logically generates, based on the timing signal generated by the timing generation circuit 48, a timing signal to be supplied to the gate scanning circuit 5 and the sensor scanning circuit 6.
In the display/sensor region 2a, each of the pixels includes a group of a R (red) picture element PIXR, a G (green) picture element PIXG, and a B (blue) picture element PIXB, and is provided with a sensor circuit SC. In each of the pixels, each of the picture element PIXR, the picture element PIXG, and the picture element PIXB is time-divisionally driven every one (1) horizontal scanning period. The picture element PIXR is provided at each intersection of a scanning signal line GL and a data signal line SLR. The picture element PIXG is provided at each intersection of the scanning signal line GL and a data signal line SLG. The picture element PIXB is provided at each intersection of the scanning signal line GL and a data signal line SLB. Each of the above picture elements includes (i) a TFT 51, which serves as a switching element and (ii) a liquid crystal capacitor CL, and is configured such that the liquid crystal capacitor CL receives a data signal via the TFT 51. The data signal lines SLR, SLG, and SWG in the same group are connected to an identical one of terminals P of the source driver 4 via switches SWR, SLG, and SWB, respectively. The picture elements do not have to be red, green and blue as above, and therefore can be any color.
While the terminals P are disposed on one side of the switches SWR, SWG, and SWB, the sensor circuit SC is provided on the other side of the switches SWR, SWG, and SWB, and is connected to the picture elements. Further, the sensor circuit SC includes a TFT 52, a capacitor 53, and a photodiode (photosensor) 54. The TFT 52 has a source terminal and a drain terminal, one of which is connected to the data signal line SLG and the other of which is connected to the data signal line SLB. The capacitor 53 and the photodiode 54 are connected in series with each other to form a series circuit. A connection point between the capacitor 53 and the photodiode 54 is connected to a gate of the TFT 52. The series circuit is connected to the sensor scanning circuit 6 at its both ends. The data signal line SLG connects the corresponding one of the terminals P with a power supply VO via a switch SWS.
In the source driver 4, outputs of the source input/output circuit 47 are connected to the respective terminals P. The source input-output circuit 47 includes a plurality of sets of a buffer 47a and a switching section 47b. The buffer 47a includes a voltage follower of an operation amplifier. The plurality of sets of the buffer 47a and the switching section 47b are connected to the respective terminals P. The buffer 47a has an input which is connected to an output of the DA conversion circuit 46, and an output which is connected to corresponding one of the terminals P. The switching section 47b switches between (i) connecting an input of the AD conversion circuit 45 to corresponding one of the terminals P and (ii) disconnecting the input of the AD conversion circuit 45 from the terminal P. The DA conversion circuit 46 is connected with a power supply exclusively for the DA conversion circuit 46 and is independently grounded. The AD conversion circuit 45 is connected with a power supply exclusively for the AD conversion circuit 45 and is independently grounded.
In a period for performing a display in the display/sensor region 2a, the buffer 47a is supplied with power, whereas the switching section 47b disconnects the input of the AD conversion circuit 45 from the terminal P. In this way, the display/sensor region 2a receives, in order of time, source outputs (data signals) Vd corresponding to R, G, and B. In the display/sensor region 2a, the switches SWR, SWG, and SWB are switched ON by turns so that the source outputs Vd are sequentially sent to the data signal lines SLR, SLG, and SLB. As such, a display is carried out on each of the picture elements PIXR, PIXG, and PIXB. Meanwhile, the switch SWS is switched OFF.
On the other hand, in a period for detecting light intensity in the display/sensor region 2a, the switches SWR, SWG, and SWB are switched OFF. Meanwhile, the switch SWS is switched ON so that the data signal line SLG is connected with the power supply VO. Here, the capacitor 53 has been charged in advance to a predetermined voltage via a forward direction of the photo diode 54 from the sensor scanning circuit 6. In this way, a gate of the TFT 52 has a voltage corresponding to intensity of light that the photodiode 54 received, in the period for detecting the light intensity. As such, the data signal line SLB has a voltage corresponding to the detected light intensity. Then, the switch SWB is switched ON so as to connect the data signal line SLB with corresponding one of the terminals P of the source driver 4.
Meanwhile, in the source driver 4, the buffer 47a is cut off from the power supply so that an output of the buffer 47a becomes high impedance. On the other hand, the switching section 47b connects the input of the AD conversion circuit 45 with the terminal P. In this way, a sensor voltage Vs, which is analog outputs of the sensor circuits SC, is inputted into the AD conversion circuit 45. Then, the AD conversion circuit 45 converts the sensor voltage Vs into digital data.
The AD conversion circuit 45 includes a comparator 45a, a DA converter 45b, a reference voltage generator 45c, a register 45d, and a sequence control circuit 45e. The comparator 45a receives the sensor voltage Vs which serves as an input voltage Vin. The comparator 45a further receives a voltage, which serves as a comparative voltage VP and is supplied from the DA converter 45b. The voltage is generated in such a manner that the DA converter 45b converts (digital-to-analog conversion) a register value of the register 45d with use of a reference voltage VREF generated by the reference voltage generator 45c. The register 45d makes a change to the register value according to an output from the comparator 45a. The sequence control circuit 45e converts the register value of the register 45d into serial data according to timing indicated by a clock input signal CK, and then outputs the serial data.
For example, the register 45d is set such that (i) an initial value of a most significant bit is 1 and (ii) initial values of the other bits are 0. The comparator 45a carries out a comparison between each of the input voltages Vin and the comparative voltage VF at every timing indicated by the clock input signal CK. The comparator 45a then outputs Low when the input voltage Vin is greater than the comparative voltage VF, and outputs High when the input voltage Vin is less than the comparative voltage VF. The register 45d holds the register value constant when Low is supplied from the comparator 45a, and changes the most significant bit of the register value to 0 when High is supplied from the comparator 45a. Here, the register 45d changes also a second significant bit of the register value to 1. The register value thus held or thus changed is converted (digital-to-analog conversion) by the DA converter 45b so as to obtain a new comparative voltage VF. The new comparative voltage VF is inputted into the comparator 45a while the register 45d determines a next bit in a same way as above. The process as above is repeated so that bits are sequentially determined from the most significant bit to the least significant bit.
As described above, it is possible for the register 45d to digitally output all bits in a form of parallel data, and for the sequence control circuit 45e to digitally output the bits in a form of serial data. The sequence control circuit 45e feedbacks its output to an input terminal of the register 45d so that the sequence control circuit 45e stably outputs data.
Meanwhile, as illustrated in
In a case of the display device, the power supplies and the GNDs, each of which is independently provided for corresponding one of the circuits in the source driver, are connected with one another via an identical wire on a substrate when, for example, the source driver is mounted on an FPC (flexible print circuit) or on a PWB (print wiring board). When an electrical current passes through one circuit in the above source driver, the electrical current flows from the power supply and the GND in the one circuit. Accordingly, an electrical current equivalent to the above electrical current is transmitted to the power supplies and the GNDs on the FPC or on the PWB. As a result, a voltage drop due to wire resistances occurs in these power supplies and the GNDs on the FPC or on the PWB to which the electrical current is transmitted. If this is the case, the other circuits in the source driver on the FPC or on the PWB are operated with the power supplies and the GNDs in which the voltage drop is caused. As a result, the other circuits come under influence of the one circuit.
The source driver 4, of the liquid crystal display 1, which is mounted by COG bonding, is connected with power supplies and GNDs which are provided outside the chip and on the display panel 2. Therefore, the wire resistances are extremely high, and thus the voltage drop due to the common impedance makes serious effect on the source driver 4. The details are as follows. When switches SSW1, SSW2, and SSW3 (corresponding to SWR, SWG, and SWB of
In a case of a display device employing a dot-sequential drive, which is performed per a predetermined number of data signal lines (e.g., three data signal lines R, G, and B (see
Accordingly, (i) a power supply voltage AD-VDD of the AD conversion circuit, (ii) a reference voltage VREF which is generated by using the power supply voltage, and (iii) voltages of the GNDs etc. change at timings at which the electric current Ivdd occurs. Under the circumstances, if the AD conversion is carried out at the timings at which the voltages change, that is, if the AD conversion is carried out by using voltages having noises superimposed thereon, then the AD conversion may be abnormally carried out.
In view of the above problem, the present embodiment is configured such that the AD conversion is carried out by the AD conversion circuit 45 during a first period, during which the large electric current Ivdd does not occur. In the present embodiment, the source driver 4 receives each of the source output and the sensor output time-divisionally via an identical terminal. This means that sampling for the AD conversion is carried out during a period during which the source driver 4 receives the sensor output. Note however that the sampling and the AD conversion do not necessarily have to be carried out sequentially without interruption between them, and therefore may be carried out sequentially with interruption between them. That is, it may be arranged such that, once the sampling has been carried out, the AD conversion is carried out during a period other than the period during which the source driver 4 receives the sensor output.
Specifically, in a case of a display device employing the dot-sequential drive, which is performed per a predetermined number of the data signal lines (e.g., the three data signal lines R, G, and B, see
As described above, according to
It is not necessary to take into consideration the voltage of the common electrode COM in a case where the common electrode COM does not receive the voltage being driven, i.e., in a case where a voltage being driven so as to keep constant is applied to the common electrode COM. In this case, the first period can be any period as long as it falls within a period t1′. The period t1′ is for example from (i) a time point at which all output of the source outputs to the data signal lines is completed for one scanning signal line selection period to (ii) a time point at which output of the source outputs to the data signal lines is initiated for a subsequent scanning signal line selection period. The time point (ii) at which transmission of the source outputs to the data signal lines is initiated for one scanning signal line selection period is generally after a time point at which the voltage of the common electrode COM changes for this scanning signal line selection period.
As described above, the AD conversion is carried out during the first period. In this way, it is possible to carry out the AD conversion during a period which does not overlap timings at which noise occurs (see
The AD conversion according to
The AD conversion can be carried out in a manner illustrated in
The AD conversion according to
Further, the AD conversion can be carried out in a manner illustrated in
The AD conversion of
According to
It is not necessary to take into consideration the voltage of the common electrode COM in the case where the common electrode COM does not receive the voltage being driven, i.e., in the case where the voltage being driven so as to keep constant is applied to the common electrode COM. In this case, the first period can be any period as long as it falls within a period t2′. The period t2′ is for example from (i) a time point at which all output of the source outputs of RGB to the respective data signal lines is completed for one scanning signal line selection period to (ii) a time point at which output of the source outputs of RGB to the respective data signal lines is initiated for a subsequent scanning signal line selection period.
The AD conversion of
The AD conversion of
The AD conversion of
According to the configurations of
Further, according to the configurations of
The AD conversion of
In a case where the AD conversion of
In a case where the AD conversion of
In a case of the display device employing the dot-sequential drive which is performed per a predetermined number of the data signal lines (such as those illustrated in
In a case of time-divisionally driving each of the data signal lines, the data signal lines do not necessarily have to be divided into three groups as illustrated in
The following description discusses, with reference to
A switch SW1 is equivalent to the switch section 47b of
When sampling of the sensor outputs is carried out, a buffer 47a is deactivated, whereas the switch SW1 is turned ON. Further, the switches SW2 and SW4 are turned ON, whereas the switch SW3 is turned OFF. In this way, the hold condenser C1 is charged so that it has an electrical charge corresponding to the sensor outputs. As such, the sampling of the sensor outputs is carried out.
Next, a hold period comes along as illustrated in
Next, an AD conversion period comes along as illustrated in
The above description dealt with an example in which the AD conversion circuit 45 includes the DA converter 45b. Note however that it is possible to provide an AD conversion circuit which carries out the AD conversion in a manner illustrated in
There has been described the present embodiment. It is clear that the present invention is applicable for use in any other display device such as an EL display device or a display device employing dielectric liquid. Further, the light sensor can output another signal such as an electric current indicative of detected light intensity.
The invention is not limited to the description of the embodiments above, but may be altered within the scope of the claims. An embodiment based on a proper combination of technical means disclosed in different embodiments is encompassed in the technical scope of the invention.
As so far described, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being AC-driven is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into the digital output, the analog-to-digital conversion circuit converting the analog output during a first period overlapping neither (i) a period during which data signals are sent out to respective data signal lines nor (ii) a time point at which the voltage of the common electrode changes.
As so far described, a display device in accordance with the present invention is an active matrix display device, including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity; and a common electrode, to which a voltage being driven so as to keep constant is applied, the data signal line drive circuit including an analog-to-digital conversion circuit which converts the analog output supplied from the photosensor into a digital output, the analog-to-digital conversion circuit converting the analog output during a first period not overlapping a period during which data signals are sent out to respective data signal lines.
Accordingly, it is possible to provide a display device employing a COG technique which is capable of carrying out, on a display panel including the photosensor, the analog-to-digital conversion of the analog output supplied from the photosensor.
As so far described, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: AC-driving a voltage to be applied to a common electrode; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which overlaps neither (i) a period during which data signals are sent out to data signal lines nor (ii) a time point at which the voltage of the common electrode changes.
As so far described, a method of driving a display device in accordance with the present invention is a method of driving an active matrix display device including: a data signal line drive circuit mounted by COG (Chip On Glass) bonding; and a photosensor, which is included in a display region, for (i) detecting light intensity and (ii) sending out an analog output serving as a signal indicative of the detected light intensity, said method, including: driving a voltage to be applied to a common electrode so that the voltage keeps constant; and causing the data signal line drive circuit to convert the analog output supplied from the photosensor into a digital output during a first period, which does not overlap a period during which data signals are sent out to data signal lines.
Accordingly, it is possible to provide a method of driving a display device employing a COG technique which is capable of carrying out, on a display panel including the photosensor, the analog-to-digital conversion of the analog output supplied from the photosensor.
The embodiments discussed in the foregoing description of embodiments and concrete examples serve solely to illustrate the technical details of the present invention, which should not be narrowly interpreted within the limits of such embodiments and concrete examples, but rather may be applied in many variations within the spirit of the present invention, provided such variations do not exceed the scope of the patent claims set forth below.
The present invention is suitably applicable for use in particularly a display device such as a liquid crystal display device or an EL display device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-104017 | Apr 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/050356 | 1/14/2009 | WO | 00 | 7/22/2010 |
