The present application is based on, and claims priority from JP Application Serial Number 2019-032211, filed Feb. 26, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a timing controller and a display device, for example.
Display devices such as liquid crystal displays are commonly configured such that a display panel thereof has scan lines driven by a Y driver, and data lines driven by an X driver. Such display devices are also commonly configured to temporarily input video data generated by a host device to a circuit called a timing controller, and the timing controller then generates a timing signal necessary for driving the display panel, and a data signal obtained by converting the video data is supplied to the display panel in synchronization with the timing signal.
A technique in which a waveform of a start pulse, which is one timing signal, is deformed to reflect an abnormality in the signal to be inspected, and a determination is made based on the deformed signal is given as an example of a method of inspecting such a display device (see JP-A-2018-109705).
P-A-2018-109705 is an example of the related art.
However, with the technique described above, it is presumed that there is no abnormality in the transmission path of the start pulse. Therefore, a problem with the technique described above is that even if there is an abnormality in the transmission path of the start pulse, for example, the abnormality cannot be detected.
A timing controller according to the present disclosure controls a drive circuit of a display panel, the timing controller including: a delay output unit configured to output a delay value based on a delay time of a second pulse with respect to a first pulse that is output by the drive circuit, the first pulse being generated in synchronization with a data signal supplied to the display panel; and an error output unit configured to compare the delay value and a threshold value to each other and output an error signal based on a result of the comparison, and the second pulse is a pulse that is output from the drive circuit based on the first pulse.
The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The following describes a timing controller according an embodiment with reference to the drawings. However, the size and scale of the components shown in the drawings are appropriately different to the size and scale of the actual components. Also, the embodiments in the following description are favorable specific examples of the present disclosure and therefore various technically favorable limitations are imposed. However, the scope of the present disclosure is not limited thereto, unless limitations to the present disclosure are specifically mentioned in the following description.
The host device 10 executes various types of arithmetic processing, control processing, and the like in accordance with a program, generates video data Vdata to be displayed on the display panel 3, and supplies the video data Vdata to the timing controller 20 in synchronization with a clock signal Clk. Note that the video data Vdata and the clock signal Clk may be supplied from the host device 10 to the timing controller 20 via LVDS, for example. LVDS is an acronym for Low Voltage Differential Signaling.
The timing controller 20 receives the video data Vdata and the clock signal Clk from the host device 10, generates a timing signal for driving the display panel 3, converts the received video data Vdata into an analog data signal Vsig, and supplies the data signal Vsig and the timing signal to the display panel 3 in synchronization with the generated timing signal.
Here, the timing signal is a signal used for vertically and horizontally scanning the display panel 3. Specifically, the timing signal may have a pulse Stv_in for designating the start of vertical scanning on the display panel 3, a clock signal Cly for transferring the pulse Stv_in, a pulse Sth_in for designating the start of horizontal scanning on the display panel 3, a clock signal Clx for transferring the pulse Sth_in, and the like.
Note that if the timing controller 20 detects an abnormality, which will be described later, error signals Err_V and Err_H are output at a H level to notify that an abnormality has occurred in the display panel 3 or the like.
The display panel 3 is provided with a plurality of scan lines 312 that run horizontally in the drawings, and a plurality of data lines 314 that run vertically in the drawings and are insulated from the scan lines 312. The display panel 3 is provided with liquid crystal display elements (not shown) in correspondence with where the scan lines 312 and the data lines 314 intersect with each other. The transmittance or reflectance of liquid crystal display elements changes according to a holding voltage as is well known, and therefore the liquid crystal display elements function as pixels. For this reason, the area in which the scan lines 312 and the data lines 314 intersect each other is the arrangement area of the pixels, that is, a display area 300.
The display panel 3 is provided with a drive circuit 30 outside of the display area 300. The drive circuit 30 is broadly divided into Y drivers 32a and 32b, and X drivers 34a, 34b, and 34c.
The Y drivers 32a and 32b include shift registers (not shown). If the display area 300 is hypothetically split in two in the up-down direction of
In the present embodiment, the pulse that is input in the initial stage of the shift register in the Y driver 32a is the pulse Stv_in from the timing controller 20, and the pulse that is output from the final stage of the shift register in the Y driver 32b is a pulse Stv_out.
The X drivers 34a, 34b, and 34c include shift registers and switches, and if the display area 300 in
In the present embodiment, the pulse input in the initial stage of the shift register in the X driver 34a is the pulse Sth_in from the timing controller 20, and the pulse output from the final stage of the shift register in the X driver 34c is the pulse Sth_out. Note that
The conversion circuit 210 converts the video data Vdata supplied from the host device 10 into the data signal Vsig, and generates the pulse Stv_in, the clock signal Cly, the pulse Sth_in, and the clock signal Clx, all of which are timing signals. Note that the conversion circuit 210 may also perform processing such as gamma correction, overdriving, or the like when converting the video data Vdata into the data signal Vsig.
In the inspection circuit 220, the counting circuit 222 counts up at the rising edge of the pulse Stv_in output from the conversion circuit 210, and outputs a count value Cn_V resulting from the counting up. The count value Cn_V from the counting circuit 222 is reset by the pulse Stv_out from the Y driver 32b. Also, the initial value of the count value Cn_V is zero.
Note that in the drawings, the counting circuit 222 directly inputs the pulse Stv_out, but a configuration is also possible in which the pulse Stv_out is fetched with an internal clock, and the count value Cn_V is reset by the fetched signal.
The comparison circuit 224 outputs the error signal Err_V at the H level if the count value Cn_V is larger than a value V_th that is read out from a register 240, and outputs the error signal Err_V at a L level if not.
In the inspection circuit 230, the counting circuit 232 counts up at the rising edge of the pulse Sth_in output from the conversion circuit 210, and outputs a count value Cn_H resulting from the counting up. The count value Cn_H from the counting circuit 232 is reset by the pulse Sth_out from the X driver 34c. Also, the initial value of the count value Cn_H is zero.
Note that in the drawings, the counting circuit 232 directly inputs the pulse Sth_out, but a configuration is also possible in which the pulse Stv_out fetched with an internal clock, and the count value Cn_H is reset by the fetched signal.
The comparison circuit 234 outputs the error signal Err_H at the H level if the count value Cn_H is larger than a value H_th that is read out from the register 240, and outputs the error signal Err_H at the L level if not.
Note that in the present embodiment, the counting circuits 222 and 232 count up at the rising edge of pulses, but configurations are also possible in which counting is performed at the falling edge of pulses, or in which counting down is performed rather than counting up.
The register 240 is a non-volatile memory such as an EEPROM, for example, and stores the values V_th and H_th. Here, EEPROM is an acronym for Electrically Erasable Programmable Read Only Memory.
Note that the values V_th and H_th from the register 240 may be, for example, read out by a control device (not shown), or latched by a circuit (not shown). Also, in the present embodiment, the values V_th and H_th that are stored in the register 240 can be rewritten by the control device described above. In the present embodiment, the value V_th may be “2”, for example, and the value H_th may also be “2”, for example. The meaning of the values V_th and H_th will be described later. Also, a configuration is possible in which the register 240 is external to the timing controller 20.
As shown in
The period from vertical scanning of the display panel 3 being started by the pulse Stv_in to the pulse Stv_out returning to the timing controller 20 substantially corresponds to one vertical scanning period 1V, but, in practice, delay exists due to the circuits, wires, and the like described above. For this reason, “a certain period of time” is, in practice, a period of time longer than or equal to one vertical scanning period 1V when the above-described delay is considered, and may be shorter than two vertical scanning periods 2V.
If the circuits, wires, and the like used for vertically scanning the display panel 3 are operating normally, as shown in
If an abnormality such as disconnection occurs in the circuits, wires, and the like used for vertically scanning the display panel 3, as shown in
Note that the horizontal scanning inspection operation is similar to the vertical scanning inspection operation except that the panels to be inspected are different.
As shown in
Note that the period from horizontal scanning of the display panel 3 being started by the pulse Sth_in to the pulse Sth_out returning to the timing controller 20 roughly corresponds to one horizontal scanning period 1H, but, in practice, delay exists due to the circuits, wires, and the like described above. For this reason, “the different period of time” is, in practice, a period of time that is longer than or equal to one horizontal scanning period 1H when the above-described delay is also considered, and may be less than two horizontal scanning periods 2H.
If the circuits, wires, and the like used for horizontally scanning the display panel 3 are operating normally, as shown in
If an abnormality such as disconnection occurs in the circuits, wires, and the like used for horizontally scanning the display panel 3, as shown in
Error processing will be executed if the error signal Err_V or the error signal Err_H becomes the H level. Specific examples of error processing include processing in which the conversion circuit 210 in the timing controller 20 stops generating a timing signal, processing in which the host device 10 stops outputting the video data Vdata, and processing that uses lighting of a warning lamp or audio to notify that an abnormality has occurred in the circuits, wires, or the like that are used for inspecting the display panel 3.
In the present embodiment, if the pulse Stv_in is taken as an example of a first pulse and the pulse Stv_out is taken as an example of a second pulse, the counting circuit 222 resets the count value Cn_V obtained by counting the pulse Stv_in with the pulse Stv_out, and therefore the count value Cn_V shows the delay time of the pulse Stv_out with respect to the pulse Stv_in. For this reason, the counting circuit 222 is an example of a delay output unit, and the comparison circuit 224 is an example of an error output unit because the comparison circuit 224 compares the count value Cn_V, which shows the delay time, to a threshold value V_th and outputs the error signal Err_V based on the result of the comparison. Also, in the present embodiment, if the pulse Sth_in is taken as an example of a first pulse and the pulse Sth_out is taken as an example of a second pulse, the counting circuit 232 resets the count value Cn_H of the counted pulse Sth_in with the pulse Sth_out, and therefore the count value Cn_H shows the delay time of the pulse Sth_out with respect to the pulse Sth_in. For this reason, the counting circuit 232 is an example of a delay output unit, and the comparison circuit 234 is an example of an error output unit because the comparison circuit 234 compares the count value Cn_H, which shows the delay time, to a threshold value H_th and outputs the error signal Err_H based on the result of the comparison.
With the present embodiment, if an abnormality occurs in the circuits, wires, or the like, used for horizontally or vertically scanning the display panel 3, the abnormality can be detected within two vertical scanning periods 2V or two horizontal scanning periods 2H from the start of the scanning. Thus, it is possible to promptly execute error processing.
In the first embodiment, abnormalities are detected in horizontal scanning and vertical scanning by the delay of the pulse Stv_out with respect to the pulse Stv_in, or the delay of the pulse Sth_out with respect to the pulse Sth_in, exceeding a threshold value. This detection can also be described as follows.
In other words, if (a), (b), and (c) of the pulse Stv_in are output in chronological order as shown in
Also, in the first embodiment, the count value Cn_V is reset by the pulse Stv_out, and therefore even if the vertical scanning is normal up to a given point in time, if an abnormality occurs in the vertical scanning during display, the abnormality can be detected within two vertical scanning periods 2V from the abnormality occurring. This detection can also be described as follows.
In other words, if (a), (b), (c) and so on of the pulse Stv_in are output in chronological order as shown in
Similarly, in the first embodiment, the count value Cn_H is reset by the pulse Sth_out, and therefore even if the horizontal scanning is normal up to a given point in time, if an abnormality occurs in the horizontal scanning during display, the abnormality can be detected within two horizontal scanning periods 2H from the abnormality occurring. This detection can also be described as follows.
In other words, if (a), (b), (c) and so on of the pulse Sth_in are output in chronological order as shown in
Note that in the present embodiment, the pulse Stv_in and the pulse Sth_in are described as an example of first pulses, but a synchronization signal that is synchronized with the data signal Vsig may also be given as an example of a first pulse. For example, a configuration is also possible in which the timing controller 20 outputs the synchronization signal that is synchronized with the data signal Vsig to the X driver 34a as an example of the first pulse, and inputs the pulse that is output from the X driver 34c as the pulse Stv_out, which is an example of the second pulse. With this configuration, the X driver 34 generates a start pulse that corresponds to the pulse Stv_in based on the synchronization signal, and the start pulse is supplied to the X drivers 34b and 34c.
The following describes the timing controller 20 according to a second embodiment.
Similar to the counting circuit 222 shown in
In the inspection circuit 250, a latch circuit 252 latches the count value Cn_V output from the counting circuit 215 by the rising edge of the pulse Stv_out from the Y driver 32b, and a count value Lcn_V, which is the result of the latching, is output.
At the timing of the rising edge of the pulse Stv_in, a differential circuit 253 outputs a value Def_V obtained by subtracting the count value Lcn_V from the count value Cn_V.
A comparison circuit 254 outputs the error signal Err_V at the H level if the value Def_V is larger than the threshold value V_th, and outputs the error signal Err_V at the L level if not.
Note that the timing controller 20 is provided with a circuit corresponding to the inspection circuit 230 in
As shown in
If the circuits, wires, and the like used for vertically scanning the display panel 3 are operating normally, as shown in
If an abnormality such as disconnection occurs in the circuits, wires, and the like used for vertically scanning the display panel 3, as shown in
Note that a circuit (not shown) corresponding to the inspection circuit 230 is only different in terms of vertical scanning and horizontal scanning.
In the second embodiment, if the pulse Stv_in is taken as an example of a first pulse and the pulse Stv_out is taken as an example of a second pulse, the value Def_V obtained by subtracting the count value Lcn_V from the count value Cn_V indicates the delay time of the pulse Stv_out with respect to the pulse Stv_in. For this reason, the differential circuit 253 is an example of a delay output unit, and the comparison circuit 254 is an example of an error output unit because the comparison circuit 254 compares the value Def_V, which shows the delay time, to the threshold value V_th and outputs the error signal Err_V based on the result of the comparison.
Note that if the pulse Stv_in is swapped with the pulse Sth_in and the pulse Stv_out is swapped with the pulse Sth_out, similarly, it is possible to detect an abnormality such as disconnection in the circuits, wires, and the like used for horizontally scanning the display panel 3.
With the second embodiment, similar to the first embodiment, if an abnormality occurs the circuits, wires, or the like used for vertically or horizontally scanning the display panel 3, the abnormality can be detected within two vertical scanning periods 2V or two horizontal scanning periods 2H. Thus, it is possible to promptly execute error processing.
With the second embodiment also, in comparison to the first embodiment, there is no need to newly provide the inspection circuit 250 with the counting circuit 215 that counts the pulse Stv_in, and therefore it is possible to simplify the timing controller 20.
Note that the first and second embodiments employ a so-called dot sequential configuration in which the X drivers 34a, 34b, and 34c sample the data signal Vsig, in accordance with a signal obtained by sequentially shifting the pulse Sth_in based on the clock signal Clx, and supply the sampled signal as a data signal to the data lines 314. There is no limitation to this, and a so-called phase expansion configuration is also possible in which the data signal Vsig is split into a plurality of channels, and each channel is supplied with a data signal.
Also, in the present configuration, vertically scanning the display panel 3 is performed with two Y drivers 32a and 32b, and horizontally scanning the display panel 3 is performed with three X drivers 34a, 34b, and 34c, but a configuration is also possible in which one, or a plurality of drivers are provided for vertical scanning or horizontal scanning.
The display panel 3 is not limited to a liquid crystal panel that uses liquid crystal display elements for pixels, and an organic light-emitting panel that uses organic light emitting elements may also be used as the display panel 3.
Number | Date | Country | Kind |
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JP2019-032211 | Feb 2019 | JP | national |
Number | Name | Date | Kind |
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20160365066 | Lim | Dec 2016 | A1 |
20180047339 | Morita | Feb 2018 | A1 |
20180190171 | Tashiro | Jul 2018 | A1 |
Number | Date | Country |
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5762330 | Aug 2015 | JP |
2018-109705 | Jul 2018 | JP |
Number | Date | Country | |
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20200273391 A1 | Aug 2020 | US |