Patent Grant
8144103
The present invention relates to a circuit that drives a display device such as a liquid crystal display device.
The columns of the pixels of the horizontally oriented screen are divided into a predetermined section and extended sections. The predetermined section is assigned to a normal display. The extended sections each become a part of a wide display. The predetermined section contains pixels of the L+1th column to the Mth column. The extended sections contain pixels of the 1st column to the Lth column, and pixels of the M+1th to the Nth column. The horizontal shift register (SR) is divided into a predetermined-stage section (SRB) and extended-stage sections (SRA, SRC). The predetermined-stage section corresponds to the columns of the pixels in the predetermined section. The extended-stage sections (SRA, SRC) correspond to the columns of the pixels in the extended sections. In wide display, the predetermined-stage section (SRB) and the extended-stage sections (SRA, SRC) of the horizontal shift register are coupled serially to combine, and open and close all of the sampling switches sequentially. In normal display, the extended-stage sections (SRA, SRC) of the horizontal shift register are decoupled from the predetermined-stage section (SRB) so that only the sampling switches belonging to the predetermined section are opened and closed sequentially.
With this conventional arrangement, the horizontal shift register is divided into three sections: the extended front-stage section SRA; the predetermined in-between-stage section SRB; and the extended rear-stage section SRC. A first gate circuit G0 is connected to an input terminal of the extended front-stage section SRA. A second gate circuit G1 is provided across an output terminal of the extended front-stage section SRA and an input terminal of the predetermined in-between-stage section SRB. A third gate circuit G2 is provided across an output terminal of the predetermined in-between-stage section SRB and an input terminal of the extended rear-stage section SRC. The gate circuits G0, G1, G2 are controlled to switch in accordance with control signals CTL0, CTL1, CTL2 to selectively combine and decouple the horizontal shift register. The first gate circuit G0, which is provided at a front end, is fed with a start signal ST for the shift register.
In the foregoing arrangement, the control signals CTL0, CTL1, CTL2 are all set to Low-level in wide display by an external control circuit. In some cases, the signals CTL0, CTL1, CTL2 may be fed via a shared control line. If CTL0 is set to Low-level in wide display, the start signal ST having been fed into the first gate circuit G0 is fed into the extended front-stage section SRA of the horizontal shift register. SRA transfers the start signal ST sequentially in synchronization with a predetermined clock signal to sequentially open, via the horizontal driver 205, the sampling switches SW that correspond to the pixels of the 1st column to the Lth column. Consequently, the video signal Vsig fed from the signal line 204 is sampled by the data lines 203 that correspond to the pixels of the 1st column to the Lth column. Next, an output signal from the extended front-stage section SRA is fed into an input terminal of the predetermined in-between-stage section SRB. SRB, in the same manner; transfers the signal to sequentially control the driving of the corresponding pixels of the L+1th column to the Mth column. The output signal of SRB is fed into the extended rear-stage section SRC. SRC, in the same manner, transfers the signal to sequentially control the driving of the corresponding pixels of the M+1th column to the Nth column. As a result of the foregoing operation, the pixels of the 1st column to the Nth column are all driven sequentially to show a wide display.
On the other hand, the start signal ST having been fed into the first gate circuit G0 is fed into the second gate circuit G1 in normal display. Thus, the extended front-stage section SRA of the horizontal shift register is decoupled. Therefore, the start signal ST is fed into the input terminal of the predetermined in-between-stage section SRB. SRB transfers the start signal ST sequentially to drive the pixels of the L+1th column to the Mth column via the horizontal driver 205 and the switching devices SW. The output signal of the SRB cannot pass through the third gate circuit G2. Thus, the extended rear-stage section SRC is decoupled. Accordingly, the SRB transfers the signals only in normal display.
With this conventional arrangement, the horizontal shift register constituted by flip-flops connected to form multi-stages is divided into the predetermined-stage section and the extended-stage sections. The predetermined-stage section corresponds to the normal display. The extended-stage sections correspond to the extended section in wide display. The predetermined-stage section and the extended-stage sections are connected via the gate circuits. In wide display, the predetermined-stage section and the extended-stage sections are connected serially via the gate circuits to combine. In normal display, the extended-stage sections are decoupled from the predetermined-stage section. Accordingly, it is possible to switch the wide display and the normal display with a simple arrangement in which the gate circuits are added to the horizontal shift register that is divided.
However, with the conventional arrangement, the shift register is divided into three sections, namely the extended front-stage section SRA, the predetermined in-between-stage section SRB, and the extended rear-stage section SRC. In normal display, SRA and SRC are decoupled so that only SRB operates. This makes it necessary to stop the shifting at end sections of SRB. Therefore, a special stage that is different from the other stages is provided at the ends of SRB (at in-between sections of the entire shift register). Inclusion of the stage of different configuration in a section (in-between section) other than the end sections of the shift register causes the loads to vary, which causes signal defects such as phase shift due to pulse delays or the like. This causes deterioration in display quality. Moreover, displaying at high speed becomes difficult. Further, the conventional arrangement requires the gate circuits G0, G1, G2, which produces a problem of increase in circuit area (frame area of the display device) by the gate circuits.
The present invention is in view of the foregoing problems, and has as an object to provide a driving circuit of a display device by which high-quality display is possible while restraining the circuit area.
To solve the above problems, a driving circuit of a display device of the present invention is adapted so that the driving circuit of the display device, by which a non-display area is created on a display section of the display device so that a partial-screen display becomes available, includes a shift register, and a signal processing circuit that processes a signal (pulse signal) tapped off from the shift register, and the signal processing circuit interrupts (e.g. an active signal is made non-active), in partial-screen display, a signal tapped off from a predetermined stage of the shift register (e.g. stage corresponding to the non-display area).
With this configuration, it is possible even in partial-screen display (e.g. the display area is created at a central area, and the non-display area is created at each side of the display section) to cause the shift register to shift from a shift starting stage up to a final stage (end stage of the shift register) to tap off a signal (generate a pulse), and to interrupt, at a lower stage of the shift register, a signal (pulse signal) of the stages corresponding to the non-display area. Thus, it is not necessary even in partial-screen display to stop the shift register between a first stage and a last stage of the shift register. Therefore, no special stage (stage of different configuration) needs to be provided in an in-between section of the shift register to stop the shifting. Accordingly, signal defects such as phase shifts resulting from inclusion of the stage of different configuration are restrained, so that high-quality display becomes possible. Further, the gate circuits that are necessary in the conventional configurations are unnecessary. This allows the circuit area to be restrained. Furthermore, it is possible to interrupt the signal (pulse signal) of the stages corresponding to the non-display area to stop the subsequent circuits. This allows reduction in power consumption.
In this configuration, it is possible to associate the partial-screen display (e.g. a display mode in which the display area is created at the central part, and the non-display area is created at each side of the display section) with a normal display mode, and to associate a full display with a wide display mode.
Further, it is preferable that each stage of the shift register include a set-reset flip-flop. A shift register employing a set-reset flip-flop must include a stage to stop the shifting. Therefore, when the shift register is applied to the conventional configurations, the shift register always includes the stage of different configuration in an in-between section of the shift register. On the contrary, in the present configuration, it is not necessary even in partial-screen display to stop the shift register between a first stage and a last stage of the shift register. Therefore, employment of a set-reset flip-flop does not result in inclusion of the stage of different configuration in an in-between section of the shift register. Thus, the present configuration is suitable for the case in which the shift register employs the set-reset flip-flop.
Further, it is preferable in the driving circuit of the display device that every stage of the shift register be same in configuration. This makes it possible to further restrain the signal defects such as phase shifts.
It is preferable that the shift register be enabled to shift in two directions. The shift register allowed to shift in two directions needs to have a stage, at each end section, to stop the shifting. Therefore, in the arrangement in which the shift register is to be stopped in between the first stage and the last stage of the shift register in partial-screen display, double stages of different configurations need to be provided in in-between sections of the shift register. On the other hand, in the present configuration, it is not necessary even in partial-screen display to stop the shift register between the first stage and the last stage of the shift register. Thus, although allowed to shift in two directions, the shift register does not include the stage of different configuration in an in-between section of the shift register. Therefore, the present configuration is suitable for the case in which the shift register that is enabled to shift in two directions is employed.
Further, the driving circuit of the display device may include an interrupting circuit that corresponds to the predetermined stage (stage that corresponds to the non-display area) of the shift register and is enabled to interrupt a signal tapped off from the stage. The signal to be tapped off from the stage may be a data sampling pulse or a precharge pulse.
Further, the interrupting circuit in the driving circuit of the display device may be arranged so as to use a partial-display mode signal, fed in partial-screen display, to interrupt a signal tapped off from a corresponding stage.
It is preferable in this arrangement that the interrupting circuit function as a delay circuit if the partial-display mode signal is not fed. Configuring the interrupting circuit in such a way as to, for example, function as a normal delay circuit if no partial-screen display signal is fed makes it possible to obtain the advantages above without increasing the size of the signal processing circuit. In this case, the interrupting circuit may be configured as follows. Specifically, the interrupting circuit includes a first NOR circuit and a logic circuit that includes a delay section. The logic circuit is fed with the partial-display mode signal and the signal tapped off from the corresponding stage. Two outputs of the logic circuit are both fed into the first NOR circuit. Note that at least one of the outputs of the logic circuit may be fixed in partial-screen display. Further, the logic circuit may be configured as follows. Specifically, the logic circuit includes a second NOR circuit and a delay section. The second NOR circuit is fed with the partial-display mode signal and an inversion signal of the signal tapped off from the corresponding stage. The delay section delays and inverts an output signal of the second NOR circuit. The logic circuit taps off the output signal of the delay section and the inversion signal of the signal tapped off from the corresponding stage. Note that an output signal of the delay section may be a fixed signal in partial-screen display.
Further, the driving circuit of the display device may be arranged such that a signal of a double pulse is tapped off from the shift register.
Further, the shift register in the driving circuit of the present display device may start shifting from an in-between stage of the shift register in partial-screen display. The in-between stage corresponds to the display section. For example, the shifting may be started at a stage corresponding to an end section of the non-display area of the display section in partial-screen display.
A method of driving a display device in accordance with the present invention is adapted so that, in the method of driving the display device, a pulse generated at each stage of a shift register is tapped off via a signal processing circuit to drive the display device, and to cause the display device to show a partial-screen display, the shift register is caused to operate from a shift starting stage up to a final stage and caused to tap off a pulse, and the signal processing circuit interrupts a pulse tapped off from a stage corresponding to a non-display area but does not interrupt a pulse tapped off from a stage corresponding to a display area.
It is possible in the method of driving the display device in accordance with the present invention that the pulse generated at the stage corresponding to the non-display area is interrupted by use of a partial-screen display signal.
It is possible in the method of driving the display device in accordance with the present invention that the shift register is caused to operate (shifting is started) from an in-between stage (this stage is determined on the basis of the position of the display area) to cause the display device to show a partial-screen display.
Further, it is possible in the method of driving the display device in accordance with the present invention that the pulse generated at the stage corresponding to the non-display area is interrupted by a NOR operation of the pulse and the partial-display signal that is a fixed signal.
Further, a method of driving a signal line in accordance with the present invention is adapted so that, in the method of driving a signal line, a pulse generated at each stage of a shift register is tapped off via a signal processing circuit to drive a plurality of signal lines, and to make a predetermined signal line non-active, the signal processing circuit interrupts a pulse generated at a predetermined stage of the shift register but does not interrupt a pulse generated at a stage other than the predetermined stage.
Further, the display device of the present invention is adapted so that the display device includes the driving circuit of the display device.
As the foregoing discusses, in the driving circuit of the display device in accordance with the present invention, it is possible even in partial-screen display to cause the shift register to shift up to a final stage to tap off a signal (generate a pulse), and to interrupt, at a lower stage of the shift register, a signal of the stages corresponding to the non-display area. Thus, it is not necessary even in partial-screen display to stop the shift register between a first stage and a last stage of the shift register. Therefore, no special stage (stage of different configuration) needs to be provided in an in-between section of the shift register to stop the shifting. Accordingly, signal defects such as phase shifts resulting from inclusion of a stage of different configuration are restrained, so that high-quality display becomes possible.
This is a circuit diagram showing a part of a configuration of a display device in accordance with Embodiment 1.
This is a circuit diagram showing a part of a configuration of a display device in accordance with Embodiment 1.
This is a timing diagram showing a relationship between an output of a shift register circuit and an output of a delay circuit, in accordance with Embodiment 1 (in wide display).
This is a timing diagram showing a relationship between an output of a shift register circuit and an output of a delay circuit, in accordance with Embodiment 1 (in partial-screen display).
This is a circuit diagram showing a configuration of a display device in accordance with Embodiment 1.
a)
This is a circuit diagram showing a configuration of a delay circuit in accordance with Embodiments 1 and 2.
b)
This is a circuit diagram showing a configuration of a delay circuit in accordance with Embodiments 1 and 2.
a)
This is a timing diagram showing operation of a delay circuit in accordance with Embodiments 1 and 2.
b)
This is a timing diagram showing operation of a delay circuit in accordance with Embodiments 1 and 2.
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a timing diagram showing operation of the shift register circuit shown in
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a timing diagram showing operation of a shift register (in wide display).
This is a timing diagram showing operation of a shift register (in partial-screen display).
This is a circuit diagram showing a part of a configuration of a display device in accordance with Embodiment 2.
This is a circuit diagram showing a part of a configuration of a display device in accordance with Embodiment 2.
This is a circuit diagram showing a configuration of a display device in accordance with Embodiment 2.
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a circuit diagram showing a configuration of a shift register circuit.
a)
This is a timing diagram showing operation of the shift register circuit shown in
b)
This is a timing diagram showing operation of the shift register circuit shown in
This is a timing diagram showing operation of a shift register (in wide display).
This is a timing diagram showing operation of a shift register (in partial-screen display).
a)
This is a diagram showing a logic circuit to set a display mode and a shifting direction.
b)
This is a truth table of the logic circuit shown in
This is a circuit diagram showing a configuration of an SR-FF (set-reset flip-flop).
This is a circuit diagram showing a configuration of a level shifter.
a)
This is a circuit diagram showing a configuration of a switch circuit that can replace the level shifter.
b)
This is a timing diagram showing operation of the switch circuit shown in
This is a circuit diagram showing a configuration of a switch provided to the shift register circuit.
a)
This is a circuit diagram showing a configuration of a precharge buffer circuit.
b)
This is a circuit diagram showing a configuration of a data buffer circuit.
a)
This is a circuit diagram showing a configuration of a sampling circuit.
b)
This is a circuit diagram showing a part of the sampling circuit shown in
This is a circuit diagram showing a configuration of a mask switch circuit.
This is a circuit diagram showing a configuration of a conventional display device.
The following describes an embodiment of the present invention.
The shift register 2 includes a plurality of shift-register stages (dummy stages SRd1 to SRd3, stages SR1 to SR307, and dummy stages SRd4 to SRd6 (in the order as provided, starting at an end)). The delay circuit section 4 includes a plurality of delay circuits (DLd3, DL1 to DL307, and DLd4 (in the order as provided, starting at an end)). The buffer circuit section 3 includes a plurality of buffer circuits (Bud3, Bu1 to Bu307, and Bud4 (in the order as provided, starting at an end)). The sampling circuit section 8 includes a plurality of sampling circuits (SMd3, SM1 to SM307, and SMd4 (in the order as provided, starting at an end)). The mask switch circuit section 9 includes a plurality of mask switch circuits (BLd3, BL1 to BL307, and BLd4 (in the order as provided, starting at an end)).
A shift-register stage Sri, a delay circuit Dli, a buffer circuit Bui, and a sampling circuit Smi are connected in this order, and a sampling circuit SMi is connected to an output line Si (i is an integer in the range of 1 to 307). In this manner, a shift-register stage SRd3, a delay circuit DLd3, a buffer circuit Bud3, a sampling circuit SMd3, and an output line Sd3 are connected. A shift-register stage SRd4, a delay circuit DLd4, a buffer circuit Bud4, a sampling circuit SMd4, and an output line Sd4 are connected in the same manner.
The display device 1 includes the following lines for input: L1 (ASPEB), L5 (ASPE), L2 (PVID), L3 (VID), and L4 (MVID); and SSPB, WR, WL, NR, NL, INI, LR, CK, and CKB. Each of SSPB, WR, WL, NR, NL, INI, and LR is fed as a signal with an electric potential of either High or Low of the operating voltage to drive the circuit. CK and CKB each have an amplitude smaller than the difference in electric potential between High and Low of the operating voltage to drive the circuit. Thus, CK and CKB need to be shifted in level, by a level shifter, to the operating voltage.
a) is a logic circuit showing a relationship between input (ASPE, LR) and output (WL, WR, NL, NR).
Two wide-display sections 5a and 5b are each provided at respective sides of the normal-display section 6, which is provided at a central part of the screen, so as to sandwich the normal-display section 6. Two dummy pixel sections 7a and 7b are provided so as to sandwich the wide-display sections 5a and 5b and the normal-display section 6.
The sampling circuit SMd3 is connected to the dummy pixel section 7a via the output line Sd3. The sampling circuits SM1 to SM38 are connected to the wide-display section 5a via the output lines S1 to S38, respectively. The sampling circuits SM39 to SM269 are connected to the normal-display section 6 via the output lines S39 to S269, respectively. The sampling circuits SM270 to SM307 are connected to the wide-display section 5b via the output lines S270 to S307, respectively. The sampling circuit SMd4 is connected to the dummy pixel section 7b via the output line Sd4. The mask switch circuit BLd3 is connected to the dummy pixel section 7a. The mask switch circuits BL1 to BL38 are connected to the wide-display section 5a. The mask switch circuits BL39 to BL269 are connected to the normal-display section 6. The mask switch circuits BL270 to BL307 are connected to the wide-display section 5b. The mask switch circuit BLd4 is connected to the dummy pixel section 7b.
The shift register 2 is configured for double pulses. With the shift register 2, shifting in two directions is possible. Further, the shift register 2 performs shifting operation to divide the shift register by two to show a partial-screen display (only the normal-display section 6 shows a display). Specifically, in partial-screen display, if the shifting is rightward (see the arrows in the figure), the shift register circuits SR37 to SRd6 operate. If the shifting is leftward (see the arrows in the figure), the shift register circuits SR271 to SRd1 operate. Further, in wide display (the wide-display section 5 as well as the normal-display section 6 show a display), the shift register circuits SRd2 to SRd6 operate if the shifting is rightward, and the shift register circuits SRd5 to SRd1 operate if the shifting is leftward.
The following describes a configuration and operation of the respective shift register circuits.
The set-reset flip-flop (SR-FF) provided to the shift register circuit SR is configured by the circuit shown in
The level shifter provided to the shift register circuit SR is configured by the circuit shown in
The switch SW (30, 31, 32) provided to the shift register circuit SR is configured as shown in
Back to
Operation of the switch 30 is as shown in
Operation of the switch 31 is as shown in
Operation of the NOR 36 and the level shifter 35 are as shown in
The components of the shift register circuit Y are connected and operate in the same manner as in the shift register circuit X, except for the switch 32. Specifically, the input-b of the switch 32 of the shift register circuit Y is connected to the input end SSPB of the shift register circuit Y. The input end NL (in the case of SR37)/NR (in the case of SR271) of the shift register circuit Y is connected to the input-cb of the switch 32. The input end NL (in the case of SR37)/NR (in the case of SR271) is also connected to the input-c (of the switch 32) via an inverter. In the shift register circuit Y in partial-screen display (when ASPE is “L”), a start pulse (SSPB) fed into an in-between stage (SR37, SR271) of the shift register 1 is transmitted to the NOR 36, the level shifter 35, and the SR-FF 37 by the switch 32 so that shifting operation starts between a first stage and a last stage of the shift register.
Operation of the switch 32 in the shift register circuit Y is as shown in
The components of the shift register circuit Z are connected and operate in the same manner as in the shift register circuit X, except for the switch 32. Specifically, the input-b of the switch 32 of the shift register circuit Z is connected to the input end SSPB of the shift register circuit Z. The input end WL (in the case of SRd2)/WR (in the case of SRd5) of the shift register circuit Z is connected to the input-cb of the switch 32. input end WL (in the case of SRd2)/WR (in the case of SRd5) of the shift register circuit Z is also connected to the input-c (of the switch 32) via an inverter. In the shift register circuit Z in wide display (when ASPE is “H”), a start pulse (SSPB) having been fed into a dummy stage (SRd2, SRd5) of the shift register 1 is transmitted to the NOR 36, the level shifter 35, and the SR-FF 37 by the switch 32 to start the shifting from an end of the shift register.
Operation of the switch 32 in the shift register circuit Z is as shown in
The following describes how the shift register circuits are connected in the shift register 2 (see
For example, the shift register circuits SR37 and SR38 are respectively connected as follows. Regarding SR37, QB1 is connected to QB of SR36, QBr is connected to QB of SR38, Rrr is connected to Ls of SR39, R11 is connected to Ls of SR35, QB is connected to both QBr of SR36 and QB1 of SR38, P is connected to the precharge delay circuit DLP37, Ls is connected to both Rrr of SR35 and R11 of SR39, and Q is connected to the data delay circuit DLS37. Regarding SR38, QB1 is connected to QB of SR37, QBr is connected to QB of SR39, Rrr is connected to Ls of SR40, R11 is connected to Ls of SR36, QB is connected to both QBr of SR37 and QB1 of SR39, P is connected to the precharge delay circuit DLP38, Ls is connected to both Rrr of SR36 and R11 of SR40, and Q is connected to the data delay circuit DLS38.
Accordingly, the respective shift register circuits SRn (n is in the range of 1 to 307) shown in
Regarding SRd1, QB1 is connected to VDD, QBr is connected to QB of SRd2, Rrr is connected to Ls of SRd3, R11 is connected to an output of the inverter IN1, QB is connected to QB1 of SRd2, and Ls is connected to an input of the inverter 2 connected serially to the inverter IN1, R11 of SRd2, and R11 of SRd3. Regarding SRd2, QB1 is connected to QB of SRd1, QBr is connected to QB of SRd3, Rrr is connected to Ls of SR1, R11 is connected to an input of the inverter IN2, QB is connected to QBr of SRd1 and QB1 of SRd3, and Ls is connected to R11 of SR1.
Regarding SRd5, QB1 is connected to QB of SRd4, QBr is connected to QB of SRd6, Rrr is connected to Rrr of SRd4 and Ls of SRd6, R11 is connected to Ls of SR307, QB is connected to QBr of SRd4 and QB1 SRd6, and Ls is connected to Rrr of SR307. Regarding SRd6, QB1 is connected to QB of SRd5, QBr is connected to VDD, Rrr is connected to an output of the inverter IN4 connected serially to the inverter IN3, R11 is connected to Ls of SRd4, QB is connected to QBr of SRd5, and Ls is connected to Rrr of SRd4, Rrr of SRd5, and an input of the inverter IN3.
The following describes the delay circuit section 4, the buffer circuit section 3, and the sampling circuit section 8 (see
Here, the precharge delay circuits (DLPd3, DLP1 to DLP38, DLP270 to DLP307, DLPd4) corresponding to the wide-display sections 5a and 5b and the data delay circuits (DLSd3, DLS1 to DLS38, DLS270 to DLS307, DLPd4) corresponding to the wide-display section 5a and 5b are connected to the display-mode line L1. The precharge delay circuits (DLP39 to DLP269) corresponding to the normal-display section 6 and the data delay circuits (DLS39 to DLS269) corresponding to the normal-display section 6 are not connected to the display-mode line L1. An inversion signal of a display mode signal ASPE is transmitted to the line L1.
The precharge delay circuit DLP is connected to the sampling circuit SM via the precharge buffer circuit BuP. The data delay circuit DLS is connected to the sampling circuit SM via the data buffer circuit BuS. Specifically, a precharge delay circuit DLPi (i is an integer in the range of 1 to 307) is connected to a sampling circuit Smi via a precharge buffer circuit BuPi. A data delay circuit DLSi (i is an integer in the range of 1 to 307) is connected to a sampling circuit Smi via a data buffer circuit BuSi. A precharge delay circuit DLPd3 is connected to a sampling circuit SMd3 via a precharge buffer circuit BuPd3. A data delay circuit DLSd3 is connected to a sampling circuit SMd3 via a data buffer circuit BuSd3. The same applies to a precharge delay circuit DLPd4 and a data delay circuit DLSd4.
The sampling circuits SM (SMd3, SM1 to SM307, and SMd4 (in the order as provided, starting at an end)) are connected to the output lines (Sd3, S1 to S307, Sd4), respectively. Specifically, a sampling circuit Smi (i is an integer in the range of 0 to 307) is connected to an output line Si. The same applies to the sampling circuits SMd3 and SMd4. The sampling circuits SMd3 and SMd4 are connected to output lines Sd3 and Sd4, respectively. The respective sampling circuits SM are connected to the precharge line L2 and the video line L3. The precharge line L2 and the video line L3 are each fed with a precharge signal (electric potential) PVID and a video signal (electric potential) VID. The respective sampling circuits SM connect the output line S and the precharge line L2 in response to a signal from the precharge buffer circuit BuP, and connect the output line S and the video line L3 in response to a signal from the data buffer circuit BuS. With the foregoing arrangement, precharging and writing on video data are performed on the respective output lines (Sd3, S1 to S307, Sd4).
An exemplary configuration of the sampling circuit SM is shown in
a) is a circuit diagram showing a configuration of the data delay circuit DLS (interrupting circuit) of the present embodiment. As shown in this figure, the data delay circuit DLS includes inverters 41 to 44, a NOR 46 having two inputs, and a NOR 47 having two inputs. The data delay circuit DLS has input ends in1 and in2 and an output end O. The inverters (41 to 44) each amplify a signal of positive logic to produce a signal of negative logic as an output. An input of the inverter 41 is connected to the input end in1. An output of the inverter 41 is connected to a first input of the NOR 46 and to a first input of the NOR 47. A second input of the NOR 46 is connected to the input end in2. An output of the NOR 46 is connected to an input of the inverter 42. An output of the inverter 42 is connected to an input of the inverter 43. An output of the inverter 43 is connected to an input of the inverter 44. An output of the inverter 44 is connected to a second input of the NOR 47. An output of the NOR 47 is connected to the output end O.
The input ends in1 of the data delay circuits (DLSd3, DLS1 to DLS307, DLSd4) are connected to Q of their corresponding shift register circuits (SRd3, SR1 to SR307, SRd4). Further, the input ends in2 of the data delay circuits (DLSd3, DLS1 to DLS38, DLS270 to DLS307, DLSd4) corresponding to the wide-display section are connected to the display-mode line L1. The input ends in2 of the data delay circuits (DLS39 to DLS269) corresponding to the normal-display section 6 are connected to VSS. The output ends O of the data delay circuits (DLSd3, DLS1 to DLS307, DLSd4) are connected to their corresponding data buffer circuits (BuSd3, BuS1 to BuS307, BuSd4).
In the data delay circuit DLS shown in
b) is a circuit diagram showing a configuration of the precharge delay circuit DLP (interrupting circuit) of the present embodiment. As shown in this figure, the precharge delay circuit DLP includes inverters 51 to 54, a NOR 56 having two inputs, and a NOR 57 having two inputs. The precharge delay circuit DLP has input ends in1 and in2 and an output end O. The inverters (51 to 54) each amplify a signal of positive logic to produce a signal of negative logic as an output. An input of the inverter 51 is connected to the input end in1. An output of the inverter 51 is connected to a first input of the NOR 56 and to a first input of the NOR 57. A second input of the NOR 56 is connected to the input end in2. An output of the NOR 56 is connected to an input of the inverter 52. An output of the inverter 52 is connected to an input of the inverter 53. An output of the inverter 53 is connected to an input of the inverter 54. An output of the inverter 54 is connected to a second input of the NOR 57. An output of the NOR 57 is connected to the output end O.
The input ends in1 of the precharge delay circuits (DLPd3, DLP1 to DLP307, DLPd4) are connected to P of their corresponding shift register circuits (SRd3, SR1 to SR307, SRd4), respectively. Further, the input ends in2 of the precharge delay circuits (DLPd3, DLP1 to DLP38, DLP270 to DLP307, DLPd4) corresponding to the wide-display section are connected to the display-mode line L1. The input ends in2 of the precharge delay circuits (DLP39 to DLP269) corresponding to the normal-display section 6 are connected to VSS. The output ends O of the precharge delay circuits (DLPd3, DLP1 to DLP307, DLPd4) are connected to their corresponding precharge buffer circuits (BuPd3, BuP1 to BuP307, BuPd4).
In the precharge delay circuit DLP shown in
a) and 7(b) show the operation of the delay circuits DL (the precharge delay circuit and the data delay circuit) shown in
In
In
The buffer circuit Bu is configured as shown in
The following describes the mask switch circuits shown in
On the basis of the foregoing, the following describes the operation of the shift register 2.
If SSPB becomes “L (active)”, the output of the switch 32 of the NOR 36 (input EN of the level shifter 35) of the shift register circuit SRd2 becomes “H (active)”. Thus, CKB shifted in level is tapped off from the (even-numbered) level shifter 35 of the shift register circuit SRd2. If CKB becomes “L”, the output of the level shifter 35 becomes “L”, and the output of the output end Ls of the shift register circuit SRd2 becomes “H (active)”.
The output “L” of the level shifter 35 of SRd2 is fed into the input SB of the SR-FF of this SRd2. Thus, lagging behind the event that the output end Ls of SRd2 becomes “H (active)”, the output (output end Q) of SRd2 becomes “H (active)” (output end QB is “L (active)”). If Q of SRd2 becomes “H”, the output of the NOR 36 of SRd2 becomes “L”, the output of the level shifter 35 becomes “H”, and Ls of SRd2 becomes “L”.
QB of SRd2 is connected to QB1 of SRd3. Therefore, if becomes “L”, the output of the switch 32 of SRd3 becomes “L”, and the output end P (output of the NOR 36) of the shift register circuit SRd3 becomes “H”.
If the output of the NOR 36 of SRd3 becomes “H”, CK shifted in level is tapped off from the (odd-numbered) level shifter 35 of SRd3. If CK becomes “L”, the output of the level shifter 35 becomes “L”, and the output end Ls of the shift register circuit SRd3 becomes “H (active)”.
The output “L” of the level shifter 35 of SRd3 is fed into the input SB of the SR-FF of this SRd3. Thus, lagging behind the event that the output end Ls of SRd3 becomes “H (active)”, the output Q of SRd3 becomes “H (active)”, and the output of the NOR 36 of SRd3 (P of SRd3) becomes “L”.
Around the time when this P of SRd3 becomes “L”, the precharge signal (electric potential) from PVID is sampled at SMd3 and written onto the output Sd3 corresponding to SRd3.
If Ls of the shift register circuit SR1 becomes “H”, “H” is fed into the reset R of the SR-FF of SRd2 via the switch 31 of SRd2, because Ls of SR1 is connected to Rrr of SRd2. Specifically, lagging behind the event of “H (active)” of Ls of SR1, the output Q of SRd2 becomes “L (inactive)”.
Thereafter, if Ls of the shift register circuit SR2 becomes “H”, “H” is fed into the reset R of the SR-FF of SRd3 via the switch 31 of SRd3, because Ls of SR2 is connected to Rrr of the shift register circuit SRd3. Specifically, lagging behind “H (active)” of Ls of SR2, the output Q of SRd3 becomes “L (inactive)”. Around the time when Q of SRd3 becomes “L”, the video data Dd3 from VID is sampled at SMd3 and written onto the output Sd3 corresponding to SRd3.
The foregoing shifting is repeated so that the shifting from the shift register circuit SRd2 to the shift register circuit SRd6 are carried out.
When SSPB is fed into the shift register circuit SR37, the shifting starts. Around the time when P of SR39 becomes “L”, the precharge signal (electric potential) from PVID is sampled at SM39 and written onto the output S39 corresponding to SR39. Thereafter, around the time when Q of SR39 becomes “L”, the video data D39 from VID is sampled at SM39 and written onto the output S39 corresponding to SR39. In SR37, SR38, SR270, and the stages subsequent to SR270, “H (active)” signals of P and Q are made “L (inactive)” at the delay circuits DL. By the foregoing way, the shifting from the shift register circuit SR37 to the shift register circuit SRd6 is carried out.
The following describes another embodiment of the present invention.
The shift register 102 includes a plurality of shift-register stages (dummy stages Srd1 to Srd2, stages Sri to Sr307, and dummy stages Srd3 to Srd4 (in the order as provided, starting at an end)). The delay circuit section 104 includes a plurality of delay circuits (dLd2, dL1 to dL307, and dLd3 (in the order as provided, starting at an end)). The buffer circuit section 103 includes a plurality of buffer circuits (bud2, bu1 to bu307, and bud3 (in the order as provided, starting at an end)). The sampling circuit section 108 includes a plurality of sampling circuits (Smd2, Sm1 to Sm307, and Smd3 (in the order as provided, starting at an end)). The mask switch circuit section 109 includes a plurality of mask switch circuits (bLd2, bL1 to bL307, bLd3 (in the order as provided, starting at an end)).
A shift-register stage Sri, a delay circuit dLi, a buffer circuit bui, and a sampling circuit Smi are connected in this order, and the sampling circuit Smi is connected to an output line si (note that i is an integer in the range of 1 to 307). In this manner, a shift-register stage Srd2, a delay circuit dLd2, a buffer circuit bud2, a sampling circuit Smd2, and an output line sd2 are connected. A shift-register stage Srd3, a delay circuit dLd3, a buffer circuit bud3, a sampling circuit Smd3, and an output line sd3 are connected in the same manner.
The sampling circuit Smd2 is connected to the dummy pixel section 107a via the output line sd2. The sampling circuits Sm1 to Sm38 are connected to the wide-display section 105a via the output lines s1 to s38, respectively. The sampling circuits Sm39 to Sm269 are connected to the normal-display section 106 via the output lines s39 to s269, respectively. The sampling circuits Sm270 to 307 are connected to the wide-display section 105b via the output lines s270 to 307. The sampling circuit Smd3 is connected to the dummy pixel section 107b via the output line sd3. The mask switch circuit bLd2 is connected to the dummy pixel section 107a. The mask switch circuits bL1 to 38 are connected to the wide-display section 105a. The mask switch circuits bL39 to 269 are connected to the normal-display section 106. The mask switch circuits bL270 to 307 are connected to the wide-display section 105b. The mask switch circuit bLd3 is connected to the dummy pixel section 107b.
The shift register 102 is configured for one-fold pulses. With the shift register 2, shifting in two direction is possible. Further, the shift register 2 performs shifting operation to divide the shift register by two in partial-screen display (only the normal-display section 106 shows a display). Specifically, in partial-screen display, if the shifting is rightward (see the arrows in the figure), the shift register circuits Sr37 to Srd4 operate. If the shifting is leftward (see the arrows in the figure), the shift register circuits Sr271 to Srd1 operate. On the other hand, in wide display (the wide-display section 105 as well as the normal-display section 106 show a display), the shift register circuits Srd1 to Srd4 operate if the shifting is rightward, and the shift register circuits Srd4 to Srd1 operate if the shifting is leftward.
The following describes a configuration and operation of the respective shift register circuits.
The input-a of the switch 30 is connected to the input end Q1. The input-b of the switch 30 is connected to the input end Qr. The input-c of the switch 30 is connected to the input end LR. The input-cb of the switch 30 is connected to an output of the inverter 38. An input of the inverter 38 is connected to LR. The input-a of the switch 31 is connected to Qr. The input-b of the switch 31 is connected to Q1. The input-c of the switch 31 is connected to the input end LR. The input-cb of the switch 31 is connected to the output of the inverter 38. The input-a of the switch 32 is connected to the output-o of the switch 30. The input-b of the switch 32 is connected to VSS. The input-c of the switch 32 is connected to VDD. The input-cb of the switch 32 is connected to VSS. The output-o of the switch 32 is connected to the input end EN of the level shifter 35. The output-ob of the level shifter 35 is connected to an input of the NAND 33. The other one of the inputs of the NAND 33 is connected to VDD. An output of the NAND 33 is connected to the input SB of the SR-FF 37. The reset R of the SR-FF 37 is connected to the output-o of the switch 31. The output of the SR-FF is connected to the output end Q of the shift register circuit x. P of the shift register circuit x is connected to the output-o of the switch 32.
The switch 30 of the shift register circuit x operates as shown in
How the switch 32 is connected and how the NAND 33 is connected differ from those in the shift register circuit x, but the rest are same. Specifically, the input-b of the switch 32 is connected to SSP. In Sr37, NR is fed into an inverter. An output of the inverter is connected to one of the inputs of the NAND 33. The input-cb of the switch 32 is connected to the input end NL. The input end NL is connected to the input-c of the switch 32 via an inverter. Further, in Sr271, NL is fed into an inverter. An output of the inverter is connected to the one of the inputs of the NAND 33. The input-cb of the switch 32 is connected to NR. The input end NR is connected to the input-c of the switch 32 via an inverter.
The switch 32 of the shift register circuit y operates as follows. With regard to Sr37, if NL is “H” and NR is “L” (ASPE is “L” and LR is “H”), Sr37 operates as shown in
The NAND 33 operates as follows (two inputs of the NAND 33 are referred to as Nin1 and Nin2, and an output of the NAND 33 is referred to as Nout). Specifically, with regard to Sr37, if NL is “H” and NR is “L” (Nin1 is “H”), Sr37 operates as shown in
How the switch 32 is connected differs from that in the shift register circuit x, but the rest are same. The input-a of the switch 31 is connected to Rr, and the input-b of the switch 31 is connected to R1. The input-b of the switch 32 is connected to SSP. In Srd1, the input end WL is connected to the input-c of the switch 32, and the input end WL is also connected to the input-c of the switch 32 via an inverter. In Srd4, the input end WR is connected to the input-c of the switch 32, and the input end WR is also connected to the input-c of the switch 32 via an inverter.
The switch 32 of the shift register circuit z operates as follows. Specifically, with regard to Srd1, if WL is “H” and WR is “L” (ASPE is “H” and LR is “H”), Srd1 operates as shown in
The shift register circuits in the shift register 102 are connected as follows.
The following discusses the shift register circuits Srn (n is in the range of 1 to 307) shown in
With regard to Srd1, Q1 is connected to VSS, Qr is connected to Rr of Srd1 and to Q of Srd2, Rr is connected to Q of SRd2, R1 is connected to an output of an inverter IN1, Q is connected to both Q1 of Srd2 and an input of an inverter 2 connected serially to the inverter IN1.
With regard to Srd4, Qr is connected to Vss, Q1 is connected to both R1 of Srd4 and Q of Srd3, R1 is connected to Q of SRd3, Rr is connected to both an output of an inverter IN3 and Qr of Srd3, and Q is connected to an input of an inverter 4 connected serially to the inverter IN3.
The following describes the delay circuit section 104, the buffer circuit section 103, and the sampling circuit section 108. Each delay circuit dL (dLd2, dL1 to dL307, and dLd3 (in the order as provided, starting at an end)) includes a precharge delay circuit dLP and a data delay circuit dLS. Specifically, a delay circuit dLi (i is an integer in the range of 1 to 307) includes a precharge delay circuit dLPi and a data delay circuit dLSi. A delay circuit dLd2 includes a precharge delay circuit dLPd2 and a data delay circuit dLSd2.
Further, each buffer circuit bu includes a precharge buffer circuit buP and a data buffer circuit buS. Specifically, a buffer circuit bui (i is an integer in the range of 1 to 307) S includes a precharge buffer circuit buPi and a data buffer circuit buSi. A buffer circuit bud2 includes a precharge buffer circuit buPd2 and a data buffer circuit buSd2.
The precharge delay circuits (dLP1 to dLP38, dLP270 to dLP307) corresponding to the wide-display sections 105a and 105b and the data delay circuits (dLS1 to dLS38, dLS270 to dLS307) corresponding to the wide-display sections 105a and 105b are connected to the display-mode line L1. Note that the precharge delay circuits (dLP39 to dLP269) corresponding to the normal-display section 106 and the data delay circuits (dLS39 to dLS269) corresponding to the normal-display section 106 are not connected to the display-mode line L1. An inversion signal of the display mode signal ASPE is transmitted to the line L1.
The precharge delay circuit dLP is connected to the sampling circuit Sm via the precharge buffer circuit buP. The data delay circuit dLS is connected to the sampling circuit Sm via the data buffer circuit buS. Specifically, a precharge delay circuit dLPi (i is an integer in the range of 1 to 307) is connected to a sampling circuit Smi via a precharge buffer circuit buPi. A data delay circuit dLSi (i is an integer in the range of 1 to 307) is connected to a sampling circuit Smi via a data buffer circuit buSi. A precharge delay circuit dLPd2 is connected to a sampling circuit Smd2 via a precharge buffer circuit buPd2. A data delay circuit dLSd2 is connected to a sampling circuit Smd2 via a data buffer circuit buSd2. The same applies to a precharge delay circuit dLPd3 and a data delay circuit dLSd3.
The sampling circuits Sm (Smd2, Sm1 to Sm307, and Smd3 (in the order as provided, starting at an end)) are connected to the output lines (sd2, s1 to s307, and sd3). Specifically, a sampling circuit Smi (i is an integer in the range of 1 to 307) is connected to an output line si. The same applies to the sampling circuits Smd2 and Smd3. The sampling circuits Smd2 and Smd3 are connected to the output lines sd2 and sd3, respectively. The respective sampling circuits Sm are connected to the precharge line L2 and the video line L3. The precharge signal (electric potential) PVID is transmitted to the precharge line L2, and the video signal (electric potential) VID is transmitted to the video line L3. The respective sampling circuits Sm connect the output line s and the precharge line L2 in response to a signal from the precharge buffer circuit buP, and connect the output line and the video line L3 in response to a signal from the data buffer circuit buS. With the foregoing arrangement, precharging and writing on video data are performed on the respective output lines (sd2, s1 to s307, sd3).
The data delay circuit dLS and the precharge delay circuit dLP are configured and operate in the same manner as the data delay circuit DLS and the precharge delay circuit DLP of Embodiment 1.
The following describes the mask switch circuits shown in
The following describes operation of the shift register 102.
As the foregoing describes, in the present embodiment, to show a partial-screen display, the shift register 2 is caused to operate up to an end section to tap off a signal (generate a pulse), and signals from the stages corresponding to the wide-display section are interrupted at the delay circuit DL, which is at the lower stage of the shift register 2, by use of the partial-screen display signal (ASPE). Accordingly, it is not necessary even in partial-screen display to stop the shift register 2 between a first stage and a last stage of the shift register 2. Thus, it is not necessary to provide a special stage (stage of different configuration) in an in-between section of the shift register 2 to stop the shifting. This prevents signal defects such as phase shifts resulting from pulse delays that occur as a result of inclusion of a stage of different configuration, so that high-quality display becomes possible. Further, a gate circuit that is necessary in the conventional configurations becomes unnecessary, which makes it possible to reduce an area of the circuits.
Further, in the present embodiment, the shift register 2 is not stopped at an in-between section of the shift register 2 even if a partial-screen display. Thus, even if the set-reset flip-flop is employed, no stage of different configuration is provided in an in-between section of the shift register 2. Therefore, high-quality display becomes possible, compared with a case of source drivers in which a set-reset flip-flop is employed as the shift register.
Further, in the present embodiment, the shift register circuits SR are identical in configuration. This makes it possible to further prevent signal defects such as phase shifts. Further, in the present embodiment, the shift register is not stopped between the first stage and the last stage of the shift register in partial-screen display. This makes the shifting in two directions possible, and makes it possible to avoid inclusion of a stage of different configuration at an in-between section of the shift register. Thus, shifting in two directions and high-quality display are both realized.
Note that the level shifter 35 of the respective shift register circuits SR may be configured with the circuit shown in
Accordingly, with the present configurations, it becomes possible to interrupt sampling pulses and precharge pulses of stages corresponding to the mask section (wide-display section), without increasing pulse delay. Conventionally, it has been necessary to feed video data corresponding to the mask section, both at the beginning and at the end of scanning. This becomes unnecessary by interrupting the pulses. Specifically, no special process needs to be carried out on the video signals at an external circuit that drives the panel. Further, a timing relationship of clocks needs to be changed neither in full (wide) display nor in partial-screen display.
Further, the foregoing Embodiments discuss a method in which the precharging is carried out sequentially prior to the sampling, but the present invention is not limited thereto. For example, the present concept is applicable to a method in which data lines are all precharged at once before the sampling in the display section starts (prior to a horizontal blanking period). Further, in the present embodiment, interruption of pulses is carried out at each delay circuit DL. Thus, the foregoing effects are produced without increasing the circuit size of the source driver.
The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person 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 present invention.
The following are descriptions of some of the reference numerals: 1 and 101 are display devices; 2 and 102 are shift registers; 3 and 103 are buffer circuit sections; 4 and 104 are delay circuit sections; 5 and 105 are wide-display sections (mask section); 6 and 106 are normal-display sections; 7 and 107 are dummy pixel sections; 8 and 108 are sampling circuit sections; 9 and 109 are mask switch circuit sections; 30 to 32 are switches; 33 is NAND; 35 is a level shifter; 36 is NOR; SR and Sr are shift register circuits; DL and dL are delay circuits; Bu and bu are buffer circuits; SM and Sm are sampling circuits; S and s are output lines; L1 is a display-mode line; L2 is a precharge line; and L3 is a video line.
A driving circuit (source driver) of a display device in accordance with the present invention is widely applicable to display devices such as display panels of mobile devices, TV, and monitors.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-174387 | Jun 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/311758 | 6/12/2006 | WO | 00 | 12/3/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/134873 | 12/21/2006 | WO | A |
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