JP4356781B2 - Drive device - Google Patents

Description

  The present invention relates to a drive device, and more particularly to a drive device that can prevent a low-level power source from shaking when a pixel is driven, thereby preventing image quality deterioration.

  FIG. 1 shows an example of the configuration of a pixel drive circuit (V drive circuit) of a complementary metal oxide semiconductor (CMOS) image sensor. In FIG. 1, only the portion for driving the pixels in the n-th row is illustrated and described for convenience of explanation. In FIG. 1, for the sake of simplicity, an AND circuit, an OR circuit, and a NOT circuit will be described. However, on the actual circuit, this is realized using a NAND circuit, a NOR circuit, and a NOT circuit.

  The pixel drive circuit 10 of FIG. 1 includes an address decoder 11, a timing adjustment unit 12, a driver unit 13, and a control unit 14, and includes a transfer gate signal TR (n) and a reset signal for driving the pixels in the nth row. RST (n) and select signal SEL (n) are generated and output.

  The address decoder 11 supplies a row selection signal φV_LINE (n) for selecting a pixel in the n-th row as a driving target to the timing adjustment unit 12 at a predetermined timing.

  The timing adjustment unit 12 adjusts the generation timing of the transfer gate signal TR (n), the reset signal RST (n), and the select signal SEL (n). Specifically, the timing adjustment unit 12 is an AND circuit 21, an AND circuit 22, an OR circuit 23, and a NOT circuit 24, which are logic gates that adjust the generation timing of the transfer gate signal TR (n), and a reset signal RST ( The AND circuit 25 and NOT circuit 26 are logic gates that adjust the generation timing of n), and the AND circuit 27 and NOT circuit 28 that are logic gates that adjust the generation timing of the select signal SEL (n). The

  The AND circuit 21 obtains a logical product of the row selection signal φV_LINE (n) input from the address decoder 11 and the timing signal φRTR input from the control unit 14, and supplies the resulting signal to the OR circuit 23. The AND circuit 22 obtains a logical product of the row selection signal φV_LINE (n) input from the address decoder 11 and the timing signal φSTR input from the control unit 14, and supplies the resulting signal to the OR circuit 23.

  The OR circuit 23 calculates the logical sum of the signal supplied from the AND circuit 21 and the signal supplied from the AND circuit 22 and supplies the resulting signal to the NOT circuit 24. The NOT circuit 24 obtains negation of the signal supplied from the OR circuit 23 and supplies the signal obtained as a result to the driver unit 13. Thereby, the generation timing of the transfer gate signal TR (n) generated by the driver unit 13 described later is controlled.

  The AND circuit 25 obtains the logical product of the row selection signal φV_LINE (n) input from the address decoder 11 and the timing signal φRST input from the control unit 14, and the resulting signal is sent to the NOT circuit 26. Supply. The NOT circuit 26 obtains negation of the signal supplied from the AND circuit 25 and supplies the resulting signal to the driver unit 13. As a result, the generation timing of the reset signal RST (n) generated by the driver unit 13 is controlled.

  Further, the AND circuit 27 obtains a logical product of the row selection signal φV_LINE (n) input from the address decoder 11 and the timing signal φSEL input from the control unit 14, and sends the resulting signal to the NOT circuit 28. Supply. The NOT circuit 28 obtains negation of the signal supplied from the AND circuit 27 and supplies a signal obtained as a result to the driver unit 13. Thereby, the generation timing of the select signal SEL (n) generated by the driver unit 13 is controlled.

  The driver unit 13 generates and outputs the transfer gate signal TR (n), the reset signal RST (n), and the select signal SEL (n) according to the signal supplied from the timing adjustment unit 12.

  Specifically, in the driver unit 13, a pMOS transistor (hereinafter referred to as pMOS) 31 and an nMOS transistor (hereinafter referred to as nMOS) 32 are connected in series, and the potential of the pMOS 31 is set as a high level potential. VDD is connected, and the potential VSS is connected to the source of the nMOS 32 as a low level potential. A signal supplied from the NOT circuit 24 of the timing adjustment unit 12 is supplied to the gates of the pMOS 31 and the nMOS 32. When the signal is low level, the pMOS 31 is turned on. When the signal is high level, the nMOS 32 is turned on. Become.

  As a result, the potential at the point where the drains of the pMOS 31 and the nMOS 32 are connected to each other (hereinafter referred to as the transfer gate connection point) is the potential VDD when the signal input to the gate is at the low level, and is at the high level. The potential becomes VSS. Then, the signal of this potential is applied as a transfer gate signal TR (n) to the transfer gate of the pixel in the nth row of the pixel portion composed of a plurality of pixels. As described above, the driver unit 13 generates and outputs the transfer gate signal TR (n) in accordance with the signal supplied from the timing adjustment unit 12.

  In the driver unit 13, similarly to the pMOS 31 and the nMOS 32, the pMOS 33 and the nMOS 34 are connected in series, the potential VDD is connected to the source of the pMOS 33, and the potential VSS is connected to the source of the nMOS 34. A signal supplied from the NOT circuit 26 of the timing adjustment unit 12 is supplied to the gates of the pMOS 33 and the nMOS 34. Then, a potential signal at a point where the drains of the pMOS 33 and the nMOS 34 are connected to each other (hereinafter referred to as a reset connection point) is input as a reset signal RST (n) to the pixels in the nth row of the pixel portion. As a result, the reset signal RST (n) of the potential VDD or the potential VSS is input to the pixel in the nth row of the pixel portion in accordance with the signal supplied from the timing adjustment unit 12.

  Further, in the driver unit 13, similarly to the pMOS 31 and the nMOS 32, the pMOS 35 and the nMOS 36 are connected in series, the potential VDD is connected to the source of the pMOS 35, and the potential VSS is connected to the source of the nMOS 36. A signal supplied from the NOT circuit 28 of the timing adjustment unit 12 is supplied to the gates of the pMOS 35 and the nMOS 36. Then, a signal having a potential at a point where the drains of the pMOS 35 and the nMOS 36 are connected to each other (hereinafter referred to as a select connection point) is input as a select signal SEL (n) to the pixels in the nth row of the pixel portion. As a result, the select signal SEL (n) at the potential VDD or the potential VSS is input to the pixel in the nth row of the pixel portion in accordance with the signal supplied from the timing adjustment unit 12.

  The control unit 14 generates high-level or low-level timing signals φSEL, φRST, φSTR, and φRTR at a predetermined timing, and supplies the timing signals to the timing adjustment unit 12.

  Next, timing of signals related to the output of the transfer gate signal TR (n) in the pixel drive circuit 10 of FIG. 1 will be described with reference to FIG.

As shown in FIG. 2, when the row selection signal φV_LINE (n) changes from the low level to the high level at time t ₁ , and then the timing signal φSTR or φRTR changes from the low level to the high level at time t ₂ , The signals generated by 21 and 22, the OR circuit 23, and the NOT circuit 24 are at a low level. Accordingly, the pMOS 31 is turned on and the nMOS 32 is turned off, and the transfer gate signal TR (n) having the potential VDD is output to the pixel portion as shown in FIG.

Next, as shown in FIG. 2, when the timing signal φSTR or φRTR changes from the high level to the low level at time t ₃ , the signals generated by the AND circuits 21 and 22, the OR circuit 23, and the NOT circuit 24 are Become high level. Accordingly, the pMOS 31 is turned off and the nMOS 32 is turned on, and the transfer gate signal TR (n) at the potential VSS is output to the pixel portion as shown in FIG.

Thereafter, as shown in FIG. 2, the row selection signal φV_LINE (n) changes from the high level to the low level at time t ₄ , but the signals generated by the AND circuits 21 and 22, the OR circuit 23, and the NOT circuit 24 are Remain high. Therefore, as shown in FIG. 2, the transfer gate signal TR (n) at the potential VSS continues to be output to the pixel portion.

  In the above description, the timing signal φSTR or φRTR is described as being at a high level (or low level). However, this description applies to the case where both the timing signals φSTR and φRTR are at a high level (or low level). This means that one of the timing signals φSTR and φRTR is at a high level (or low level) and the other is always at a low level.

  Although not shown, in the pixel drive circuit 10 of FIG. 1, the level of the row selection signal φV_LINE (n) and the timing signal φSEL or φRST is similarly applied to the reset signal RST (n) and the select signal SEL (n). Accordingly, the potential of the reset signal RST (n) and the select signal SEL (n) becomes the potential VDD or the potential VSS.

  By the way, in the pixel drive circuit 10 of FIG. 1, the same signal input to the gates of the pMOS 31 (33, 35) and the nMOS 32 (34, 36) connected in series is ideally transmitted at completely the same timing. Although it is desirable to operate the pMOS 31 (33, 35) and the nMOS 32 (34, 36), the operation timing is shifted and both the pMOS 31 (33, 35) and the nMOS 32 (34, 36) are turned on. There may be moments when

  In particular, in a driving circuit (for example, Patent Document 1) that outputs three values such as a high level, a high level, a middle level, and a low level as the transfer gate signal TR (n) depending on the characteristics of the pixel, the pMOS of the driver unit In many cases, the number of logic gates in the previous stage is different from the number of logic gates in the previous stage of nMOS, and the possibility of skew deviation increases.

  Further, the pMOS 31 (33, 35) and the nMOS 32 (34, 36) of the driver unit 13 of the pixel driving circuit 10 usually use high-capacity transistors to simultaneously open and close the gates of the pixels for one row. Designed. For this reason, the operation timing of the pMOS 31 (33, 35) and the nMOS 32 (34, 36) of the driver unit 13 is shifted, and a moment when both the pMOS 31 (33, 35) and the nMOS 32 (34, 36) are turned on occurs. In this case, there is a concern that the through current flowing from the potential VDD to the potential VSS becomes large.

  When a large through current flows to the low-level power supply of the potential VSS and the low level fluctuates, for example, the low level that holds down the gates of the pixels in the rows during other accumulation periods also fluctuates. In particular, when the negative potential generated by the charge pump mounted inside the chip provided with the pixel driving circuit 10 is set to the low level potential VSS, depending on the capability of the charge pump, the fluctuation of the negative potential due to the through current is settled. It may take time. As a result, the image quality is adversely affected and the image quality is deteriorated.

JP 2002-77730 A

  As described above, in the pixel drive circuit 10 described above, when a through current flows from the potential VDD to the potential VSS, the low-level power supply of the potential VSS may fluctuate, which may adversely affect image quality.

  The present invention has been made in view of such a situation, and in the case of driving a pixel, it prevents a low-level power source from shaking, thereby preventing image quality deterioration. It is.

A driving device according to one aspect of the present invention is a driving device for driving a pixel, wherein the first first conductivity type transistor connected to a first potential is connected in series with the first first conductivity type transistor. The on-timing of any one of the first second conductivity type transistor connected to the second potential, the first first conductivity type transistor, and the first second conductivity type transistor is controlled. Control means for individually controlling the first first conductivity type transistor and the first second conductivity type transistor using a first ON signal, and connected in parallel to the first first conductivity type transistor The second first conductivity type transistor connected to the third potential, or the second second conductivity type connected to the first potential and connected in parallel to the first second conductivity type transistor. Conduction type transistor Or a is one transistor, said control means, said a first ON signal, using a second on-signal for controlling the timing of on of said transistor, said first transistor of the first conductivity type By individually controlling the first second conductivity type transistor and the transistor, the potential at the connection point is the first potential period, and the potential at the connection point is the first potential. The connection point is always at the time of transition from one of the second potential period having a potential of 2 and the third potential period in which the potential at the connection point is the third potential to the other one. The length and start timing of the first potential period, the second potential period, the third potential period, and the high impedance period so that a high impedance period in which the high impedance period is high impedance is provided. Controlling the first transistor of the first conductivity type, said first transistor of the second conductivity type, and the signal of the potential at the connection point of the transistor is input to the pixel as the drive signal.

In one aspect of the present invention, a first transistor of the first conductivity type connected to the first potential, which is connected in series with the first transistor of the first conductivity type, a first connecting the second potential A first on signal for controlling the on timing of any one of the second conductivity type transistors and a second potential connected in parallel to the first first conductivity type transistor and connected to a third potential The on-timing of a transistor that is one of the first conductivity type transistor or the second second conductivity type transistor connected in parallel to the first potential and connected in parallel to the first second conductivity type transistor The first on-conductivity type transistor, the first on-conductivity type transistor, and the transistor are individually controlled using the second on signal for controlling the first potential, so that the potential at the connection point becomes the first potential. Is potential From one potential period, a second potential period in which the potential at the connection point is the second potential, and a third potential period in which the potential at the connection point is the third potential to one another The length and start timing of the first potential period, the second potential period, the third potential period, and the high impedance period so that a high impedance period in which the connection point is high impedance is always provided at the transition of Is controlled.

  As described above, according to one aspect of the present invention, when driving a pixel, it is possible to prevent a low-level power source from shaking, thereby preventing deterioration in image quality.

  Embodiments of the present invention will be described below. Correspondences between the constituent elements of the present invention and the embodiments described in the specification or the drawings are exemplified as follows. This description is intended to confirm that the embodiments supporting the present invention are described in the specification or the drawings. Therefore, even if there is an embodiment which is described in the specification or the drawings but is not described here as an embodiment corresponding to the constituent elements of the present invention, that is not the case. It does not mean that the form does not correspond to the constituent requirements. Conversely, even if an embodiment is described here as corresponding to a configuration requirement, that means that the embodiment does not correspond to a configuration requirement other than the configuration requirement. Not something to do.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 3 shows a configuration example of the first embodiment of the pixel drive circuit of the CMOS image sensor to which the present invention is applied.

  In FIG. 3, for convenience of explanation, only the portion for driving the pixels in the n-th row is shown and described. In FIG. 3, for the sake of simplicity, an AND circuit, an OR circuit, and a NOT circuit will be described. However, on an actual circuit, it can be realized using a NAND circuit, a NOR circuit, and a NOT circuit. . The same applies to FIG. 8 described later.

  3 includes an address decoder 11, a driver unit 13, a timing adjustment unit 51, and a control unit 52, and includes a transfer gate signal TR (n), a reset signal RST (n), and a select signal SEL ( Generate and output n). In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted to avoid repetition.

  The timing adjustment unit 51 is a logic gate that adjusts the generation timing of the transfer gate signal TR (n), the NOT circuit 60, the OR circuit 61, the NOT circuit 66, and the generation of the reset signal RST (n). AND circuit 25, NOT circuit 26, OR circuit 62, and NOT circuit 65, which are logic gates for adjusting timing, and AND circuit 27, NOT circuit, which are logic gates for adjusting the generation timing of select signal SEL (n) 28, an OR circuit 63, and a NOT circuit 64.

  That is, in the timing adjustment unit 51, OR circuits 61 to 63 and NOT circuits 64 to 66 are arranged in the previous stage of the driver unit 13. Then, the timing adjustment unit 51 does not input the same signal to the pMOS 31 (33, 35) and the nMOS 32 (34, 36) of the driver unit 13, but uses a signal input to the nMOS 32 (34, 36). A signal obtained as a result of the sum is input to the pMOS 31 (33, 35).

  Further, in the timing adjustment unit 51, the AND circuit 22 and the OR circuit 23 provided in the pixel driving circuit 10 of FIG. 1 are not provided, and a signal output from the AND circuit 21 is directly input to the NOT circuit 60. Therefore, the control unit 52 does not need to generate the timing signal φSTR.

  Specifically, the NOT circuit 60 of the timing adjustment unit 51 obtains negation of the signal supplied from the AND circuit 21 and outputs a signal obtained as a result. A signal output from the NOT circuit 60 is input to the nMOS 32 of the driver unit 13 and also input to the OR circuit 61. The ON signal φTR_PMOS output from the control unit 52 for controlling the ON timing of the pMOS 31 is input to the NOT circuit 66. The NOT circuit 66 obtains the negation of the ON signal φTR_PMOS, and is obtained as a result. A signal is input to the OR circuit 61.

  The OR circuit 61 obtains a logical sum of the signal output from the NOT circuit 60 and the signal output from the NOT circuit 66 and inputs the resulting signal to the pMOS 31. That is, the OR circuit 61 uses the signal output from the NOT circuit 66 to generate a signal input to the pMOS 31 separately from the signal input to the nMOS 32 output from the NOT circuit 60. As a result, the timing adjustment unit 51 can individually control the pMOS 31 and the nMOS 32.

  A signal output from the NOT circuit 26 of the timing adjustment unit 51 is input to the nMOS 34 of the driver unit 13 and also input to the OR circuit 62. The ON signal φRST_PMOS output from the control unit 52 for controlling the ON timing of the pMOS 33 is input to the NOT circuit 65, and the NOT circuit 65 obtains the negation of the ON signal φRST_PMOS and obtains the result. The signal is input to the OR circuit 62.

  The OR circuit 62 calculates the logical sum of the signal output from the NOT circuit 26 and the signal output from the NOT circuit 65 and inputs the resulting signal to the pMOS 33. As a result, the timing adjustment unit 51 can control the pMOS 33 and the nMOS 34 individually.

  Further, the signal output from the NOT circuit 28 of the timing adjustment unit 51 is input to the nMOS 36 of the driver unit 13 and also to the OR circuit 63. The ON signal φSEL_PMOS for turning on the pMOS 35 output from the control unit 52 is input to the NOT circuit 64, and the NOT circuit 64 obtains the negation of the ON signal φSEL_PMOS and outputs the resulting signal as an OR circuit. 63.

  The OR circuit 63 calculates the logical sum of the signal output from the NOT circuit 28 and the signal output from the NOT circuit 64 and inputs the resulting signal to the pMOS 35. As a result, the timing adjustment unit 51 can control the pMOS 35 and the nMOS 36 individually.

  The control unit 52 generates high-level or low-level timing signals φSEL, φRST, and φRTR, and on signals φTR_PMOS, φRST_PMOS, and φSEL_PMOS at a predetermined timing, and supplies them to the timing adjustment unit 51.

  Next, with reference to FIG. 4, an example of signal timing related to the output of the transfer gate signal TR (n) in the pixel drive circuit 50 of FIG. 3 will be described.

As shown in FIG. 4, when the row selection signal φV_LINE (n) changes from the low level to the high level at time t ₁₁ , and then the timing signal φRTR changes from the low level to the high level at time t ₁₂ , the AND circuit 21. The signal generated by the NOT circuit 60 and input to the nMOS 32 is at a low level. At this time, as shown in FIG. 4, when the ON signal φTR_PMOS is at a low level, the signal generated by the AND circuit 21 NOT circuit 60, the OR circuit 61, and the NOT circuit 66 and input to the pMOS 31 is at a high level. It becomes. Accordingly, both the pMOS 31 and the nMOS 32 are turned off, and the transfer gate connection point becomes high impedance (Hi-Z) as shown in FIG.

Next, as shown in FIG. 4, when the ON signal φTR_PMOS changes from the low level to the high level at time t ₁₃ , the signal input to the nMOS 32 remains at the low level, but the signal input to the pMOS 31 is Become low level. Accordingly, the nMOS 32 remains off, but the pMOS 31 is turned on, and a high-level transfer gate signal TR (n) of the potential VDD is output to the pixel portion as shown in FIG.

As described above, when the timing signal φRTR becomes high level at time t ₁₂ , the nMOS 32 is turned off, and the output of the transfer gate signal TR (n) at the low level of the potential VSS is finished, but the on signal φTR_PMOS is high level. Until the time t ₁₃ when the pMOS 31 is reached, the pMOS 31 is not turned on, and the transfer gate connection point becomes high impedance.

Then, as shown in FIG. 4, an ON signal φTR_PMOS goes from high to low at time t _14, the signal inputted to nMOS32 the signal but remains at a low level, which is input to pMOS31 is high Return to level. Therefore, the nMOS 32 remains off, but the pMOS 31 returns to the off state, and the transfer gate connection point becomes high impedance again as shown in FIG.

Next, as shown in FIG. 4, when the timing signal φRTR becomes low level at time t ₁₅ , the signal input to the nMOS 32 becomes high level. At this time, as shown in FIG. 4, when the ON signal φTR_PMOS remains at a low level, the signal input to the pMOS 31 becomes a high level. Accordingly, the pMOS 31 remains off, but the nMOS 32 is turned on, and the low-level transfer gate signal TR (n) of the potential VSS is output to the pixel portion as shown in FIG.

Then, as shown in FIG. 4, the row selection signal φV_LINE at time t ₁₆ (n) is changed from the high level to the low level, the timing signal FaiRTR, and on signal φTR_PMOS is left at a low level, pMOS 31 and nMOS32 The signal input to is kept at a high level. Therefore, as shown in FIG. 4, the transfer gate signal TR (n) at the potential VSS continues to be output to the pixel portion.

  As described above, when the level of the transfer gate signal TR (n) is changed from the high level to the low level and from the low level to the high level, the transfer gate connection point becomes high impedance during the transition. The control unit 52 changes the level of the on signal φTR_PMOS, so that both the pMOS 31 and the nMOS 32 are instantaneously turned on at the time of transition, thereby preventing a through current from flowing from the potential VDD to the potential VSS.

  As a result, shaking of the low level power supply is prevented. In particular, when the negative potential generated by the charge pump mounted inside the chip provided with the pixel driving circuit 50 is the low level potential VSS, the load on the charge pump is eliminated. Accordingly, it is possible to prevent deterioration in image quality in the pixel portion.

  Further, the control unit 52 changes the timing and pulse length of the timing signal φRTR or the ON signal φTR_PMOS to change the transfer gate signal during the period when the potential of the transfer gate signal TR (n) is the potential VDD. The start timing and period (length) of the period in which the potential of TR (n) is the potential VSS and the period in which the transfer gate connection point is in the high impedance (hereinafter referred to as high impedance period) can be changed. The timing of switching the level of the timing signal φRTR or the ON signal φTR_PMOS and the change of the pulse length can be arbitrarily performed using a register (not shown) provided in the control unit 52, for example.

  For example, as shown in FIG. 5, the control unit 52 sets the transfer gate connection point to high impedance during the transition only when the level of the transfer gate signal TR (n) transitions from low level to high level. Only when the flow of the through current is suppressed or when the level of the transfer gate signal TR (n) is changed from the high level to the low level as shown in FIG. 6, the transfer gate connection point is set high during the transition. It is also possible to prevent the through current from flowing through the impedance.

As shown in FIG. 5, only when the level of the transfer gate signal TR (n) transitions from a low level to a high level, when the transfer gate connection point is set to high impedance in the middle of the transition, the control unit 52 rather than the time t ₁₄ before time t _15, at time t ₂₁ after time t _15, the oN signal φTR_PMOS from the high level to the low level. As a result, the pMOS 31 is turned off at the same time as the nMOS 32 is turned on. Therefore, when the level of the transfer gate signal TR (n) transitions from the high level to the low level, the transfer gate connection point does not become high impedance.

Further, as shown in FIG. 6, only when the level of the transfer gate signal TR (n) is changed from the high level to the low level, when the transfer gate connection point is set to high impedance during the transition, the control unit 52 , rather than time t ₁₃ after time t _12, at time t ₃₁ before time t _12, the oN signal φTR_PMOS from the low level to the high level. As a result, the pMOS 31 is turned on at the same time as the nMOS 32 is turned off. Therefore, when the level of the transfer gate signal TR (n) changes from the low level to the high level, the transfer gate connection point does not become high impedance.

  Further, when it is desired to prioritize the reduction of the time (clock period) by reducing the high-impedance period rather than preventing the through current, the control unit 52 performs the transfer gate signal TR (n) as shown in FIG. Whether the level is changed from the high level to the low level or when the level is changed from the low level to the high level, the transfer gate connection point may not be set to high impedance during the transition.

In this case, as shown in FIG. 7, the control unit 52 at time t ₃₁ before time t _12, and an ON signal φTR_PMOS from the low level to the high level at time t ₂₁ after time t _15, the ON signal Change φTR_PMOS from high level to low level. That is, the control unit 52 makes the pulse length of the ON signal φTR_PMOS equal to or longer than the pulse length of the timing signal φRTR.

  In addition, while the level of the timing signal φRTR is high, the control unit 52 changes the level of the on signal φTR_PMOS to turn on or off the pMOS 31 so that a high impedance period is provided or not provided. Can be. Therefore, for example, the high impedance period may be provided a plurality of times while the level of the timing signal φRTR is high, or no high impedance period may be provided at all.

  In the above description, the transfer gate signal TR (n) has been described, but the control unit 52 similarly sets the levels of the on signals φRST_PMOS and φSEL_PMOS for the reset signal RST (n) and the select signal SEL (n). By changing the level of the reset signal RST (n) and select signal SEL (n), the reset connection point and the select connection point are set to high impedance and the through current flows from the potential VDD to the potential VSS. Can be prevented.

  FIG. 8 shows a configuration example of a second embodiment of a pixel drive circuit of a CMOS image sensor to which the present invention is applied.

  The pixel drive circuit 100 in FIG. 8 includes an address decoder 11, a timing adjustment unit 101, a driver unit 102, and a control unit 103. The high-level and low-level transfer gate signal TR (n) and the reset signal RST (n) In addition to the select signal SEL (n), the middle level transfer gate signal TR (n), the reset signal RST (n), and the select signal SEL (n) are generated and output.

  In FIG. 8, for convenience of explanation, only the portion that generates the transfer gate signal TR (n) is illustrated and described. However, the reset signal RST (n) and the select signal SEL (n) are also transferred to the transfer gate signal TR ( Generated and output as in n). In FIG. 8, the same components as those in FIGS. 1 and 3 are denoted by the same reference numerals, and the description thereof will be omitted because it will be repeated.

  In the timing adjustment unit 101, two OR circuits 111 and 112 and two NOT circuits 113 and 114 are provided in the preceding stage of the driver unit 102 in order to adjust the generation timing of the transfer gate signal TR (n). Be placed. Then, the timing adjustment unit 101 individually inputs signals to the two pMOSs 121 and 122 and the one nMOS 123 for generating the transfer gate signal TR (n) of the driver unit 102.

  Specifically, a signal output from the NOT circuit 60 of the timing adjustment unit 101 is input to the nMOS 123 of the driver unit 102 and also input to the OR circuits 111 and 112. The ON signal φTR_PMOS1 for controlling the ON timing of the pMOS 121 output from the control unit 103 is input to the NOT circuit 113, and the NOT circuit 113 obtains the negation of the ON signal φTR_PMOS1 and is obtained as a result. A signal is input to the OR circuit 111. The OR circuit 111 calculates a logical sum of the signal output from the NOT circuit 60 and the signal output from the NOT circuit 113 and inputs the resulting signal to the pMOS 121.

  Further, the ON signal φTR_PMOS2 for controlling the ON timing of the pMOS 122 output from the control unit 103 is input to the NOT circuit 114, and the NOT circuit 114 obtains the negation of the ON signal φTR_PMOS2 and is obtained as a result. The signal is input to the OR circuit 112. The OR circuit 112 calculates the logical sum of the signal output from the NOT circuit 60 and the signal output from the NOT circuit 114 and inputs the resulting signal to the pMOS 122.

  As described above, the OR circuit 111 generates a signal input to the pMOS 121 separately from the signal input to the nMOS 123 output from the NOT circuit 60 using the signal output from the NOT circuit 113. The OR circuit 112 uses the signal output from the NOT circuit 114 to generate a signal input to the pMOS 122 separately from the signal input to the nMOS 123. Thereby, the timing adjustment unit 101 can individually control the pMOSs 121 and 122 and the nMOS 123.

  The driver unit 102 generates a transfer gate signal TR (n) and the like according to the signal supplied from the timing adjustment unit 101. Specifically, in the driver unit 102, the pMOS 121 and the pMOS 122 are connected in parallel, and the nMOS 123 is connected in series. A potential VDD1 is connected to the source of the pMOS 121 as a high level potential, a potential VDD2 is connected to the source of the pMOS 122 as a middle level potential, and a potential VSS is connected to the source of the nMOS 123 as a low level potential.

  Further, a signal supplied from the OR circuit 111 of the timing adjustment unit 101 is supplied to the gate of the pMOS 121, a signal supplied from the OR circuit 112 is supplied to the gate of the pMOS 122, and a signal supplied from the NOT circuit 60 is supplied to the gate of the nMOS 123. Each signal is input.

  The pMOS 121, the pMOS 122, and the nMOS 123 are turned on or off according to the level of the signal supplied to the respective gates. As a result, the drains of the pMOS 121, the pMOS 122, and the nMOS 123 are connected to each other (hereinafter referred to as 3 connections). The potential of the point) is the potential VDD1, the potential VDD2, or the potential VSS. Then, this potential signal is applied as a transfer gate signal TR (n) to the transfer gate of the pixel in the nth row of the pixel portion. As described above, the driver unit 102 generates and outputs the transfer gate signal TR (n) in accordance with the signal supplied from the timing adjustment unit 101.

  The control unit 103 generates a high-level or low-level timing signal φRTR, an on signal φTR_PMOS1, an on signal φTR_PMOS2, and the like at a predetermined timing, and supplies them to the timing adjustment unit 101.

  In FIG. 8, the potential VDD2 is connected to the pMOS 122, but may be connected to the nMOS. In this case, the nMOS to which the potential VDD2 is connected is connected in parallel to the nMOS 123, and a signal obtained by inverting the signal output from the OR circuit 112 is input to the gate of the nMOS.

  Next, with reference to FIG. 9, an example of signal timing related to the output of the transfer gate signal TR (n) in the pixel driving circuit 100 of FIG. 8 will be described.

As shown in FIG. 9, when the row selection signal φV_LINE (n) changes from the low level to the high level at time t ₅₁ , and then the timing signal φRTR changes from the low level to the high level at time t ₅₂ , it is input to the nMOS 123. The signal to be output becomes a low level. At this time, as shown in FIG. 9, when the ON signals φTR_PMOS1 and φTR_PMOS2 are at low level, both the signal input to the pMOS 121 and the signal input to the pMOS 122 are at high level. Accordingly, all of the pMOSs 121 and 122 and the nMOS 123 are turned off, and the three connection points become high impedance (Hi-Z (1)) as shown in FIG.

Next, as shown in FIG. 9, an ON signal φTR_PMOS1 changes from low level to high level at time t _53, the signal input to the pMOS122 remains at a high level, the signal input to the nMOS123 a low level However, the signal input to the pMOS 121 is at a low level. Accordingly, the pMOS 122 and the nMOS 123 remain off, but the pMOS 121 is turned on, and a high-level transfer gate signal TR (n) at the potential VDD1 is output to the pixel portion as shown in FIG.

As described above, when the timing signal φRTR becomes high level at time t _52, NMOS 123 is turned off, the output of the potential VSS of low level transfer gate signal TR (n) is completed, the ON signal φTR_PMOS1 or φTR_PMOS2 until time t ₅₃ becomes high level, since the pMOS121 or 122 does not turn on, 3 connecting point becomes a high impedance.

Then, as shown in FIG. 9, an ON signal φTR_PMOS1 at time t ₅₄ is returned from the high level to the low level, the signal input to pMOS122 and nMOS123 are remains intact, the signal input to the pMOS121 a high level Return to. Therefore, the pMOS 122 and the nMOS 123 remain off, but the pMOS 121 returns to the off state, and the three connection points become high impedance (Hi-Z (2)) as shown in FIG.

  As described above, the control unit 103 sets the on signal φTR_PMOS1 to the high level while the timing signal φRTR is at the high level, thereby turning on the pMOS 121 and setting the level of the transfer gate signal TR (n) to the high level. can do. Therefore, the control unit 103 controls the ON period of the pMOS 121 by controlling the period during which the ON signal φTR_PMOS1 is set to the high level while the timing signal φRTR is at the high level, and the level of the transfer gate signal TR (n) It is possible to control the presence / absence, length, start timing, and the like of a high level period in which is high.

Next, as shown in FIG. 9, an ON signal φTR_PMOS2 changes from low level to high level at time t _55, the signal inputted to the signal and nMOS123 inputted to pMOS121 is the intact, is input to pMOS122 Signal becomes low level. Accordingly, the pMOS 121 and the nMOS 123 remain off, but the pMOS 122 is turned on, and the middle level transfer gate signal TR (n) at the potential VDD2 is output to the pixel portion as shown in FIG.

Then, as shown in FIG. 9, an ON signal φTR_PMOS2 at time t ₅₆ is returned from the high level to the low level, the signal input to pMOS121 and nMOS123 are remains intact, the signal input to the pMOS122 a high level Return to. Therefore, the pMOS 121 and the nMOS 123 remain off, but the pMOS 122 returns to the off state, and the three connection points become high impedance (Hi-Z (3)) as shown in FIG.

  As described above, the control unit 103 sets the ON signal φTR_PMOS2 to the high level while the timing signal φRTR is at the high level, thereby turning on the pMOS 122 and setting the level of the transfer gate signal TR (n) to the middle level. can do. Therefore, the control unit 103 controls the ON period of the pMOS 122 by controlling the period during which the ON signal φTR_PMOS2 is set to the high level while the timing signal φRTR is at the high level, and the level of the transfer gate signal TR (n). It is possible to control the presence / absence, length, start timing, and the like of the middle level period in which is the middle level.

Next, as shown in FIG. 9, when the timing signal φRTR returns from the high level to the low level at time t ₅₇ , the signal input to the nMOS 123 becomes the high level. At this time, as shown in FIG. 9, if the on signals φTR_PMOS1 and φTR_PMOS2 remain at a low level, both the signal input to the pMOS 121 and the signal input to the pMOS 122 are at a high level. Accordingly, the pMOSs 121 and 122 remain off, but the nMOS 123 is turned on, and the low-level transfer gate signal TR (n) at the potential VSS is output to the pixel portion as shown in FIG.

As shown in FIG. 9, at time t ₅₈ , the row selection signal φV_LINE (n) changes from the high level to the low level, but the timing signal φRTR and the on signals φTR_PMOS1 and φTR_PMOS2 remain at the low level. All the signals input to the pMOSs 121 and 122 and the nMOS 123 remain at the high level. Therefore, as shown in FIG. 9, the low-level transfer gate signal TR (n) of the potential VSS is continuously output to the pixel portion.

  As described above, in FIG. 9, when the level of the transfer gate signal TR (n) is changed from the low level to the high level, from the high level to the middle level, and from the middle level to the low level, in the middle of the transition. The level of the transfer gate signal TR (n) is set to high impedance. Thus, by providing a period in which the three connection points are in a high impedance during the transition, it is possible to prevent a through current from flowing from the potential VDD to the potential VSS during the transition.

  As shown in FIG. 9, while the timing signal φRTR is at a high level, a period in which both the on signal φTR_PMOS1 and the on signal φTR_PMOS2 are at a low level is a period in which the three connection points are set to high impedance. Therefore, by changing the level switching timing and the pulse period of the on signals φTR_PMOS1 and φTR_PMOS2, it is possible to provide a period in which the three connection points having any length are set to high impedance at any timing.

  For example, Hi-Z (1) only, Hi-Z (2) only, Hi-Z (3) only, Hi-Z (1) and Hi-Z (2) only, Hi-Z (1) And only Hi-Z (3) or only Hi-Z (2) and Hi-Z (3) can be provided. In addition, the control unit 103 may not provide a high impedance period at all when it is desired to reduce the high impedance period and give priority to shortening the time rather than preventing the through current.

  In the pixel driving circuit 50 and the pixel driving circuit 100 described above, the AND circuit 22 and the OR circuit 23 in FIG. 1 are not provided. However, as in the pixel driving circuit 10 in FIG. May be provided. The pixel driving circuit in this case will be described below.

  FIG. 10 shows a configuration example of a third embodiment of a pixel drive circuit of a CMOS image sensor to which the present invention is applied.

  In FIG. 10, for convenience of explanation, only the portion for driving the pixels in the n-th row is shown and described. Further, in FIG. 10, for the sake of simplicity, description will be made using an AND circuit, an OR circuit, and a NOT circuit, but on an actual circuit, it can be realized using a NAND circuit, a NOR circuit, and a NOT circuit. . The same applies to FIG. 15 described later.

  The pixel drive circuit 150 in FIG. 10 includes an address decoder 11, a driver unit 13, a timing adjustment unit 151, and a control unit 152, and includes a transfer gate signal TR (n), a reset signal RST (n), and a select signal SEL ( Generate and output n). In FIG. 10, the same components as those in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The timing adjustment unit 151 is a logic gate that adjusts the generation timing of the transfer gate signal TR (n). The AND circuit 21, the AND circuit 22, the OR circuit 23, the NOT circuit 24, the OR circuit 61, and the NOT circuit 66 are reset. AND gate 25, NOT circuit 26, OR circuit 62 and NOT circuit 65, which are logic gates that adjust the generation timing of signal RST (n), and logic gates that adjust the generation timing of select signal SEL (n) And an AND circuit 27, a NOT circuit 28, an OR circuit 63, and a NOT circuit 64.

  In other words, in the timing adjustment unit 151, OR circuits 61 to 63 and NOT circuits 64 to 66 are arranged in front of the driver unit 13. The timing adjustment unit 151 does not input the same signal to the pMOS 31 (33, 35) and the nMOS 32 (34, 36) of the driver unit 13, but uses a signal input to the nMOS 32 (34, 36). A signal obtained as a result of the sum is input to the pMOS 31 (33, 35).

  Specifically, a signal output from the NOT circuit 24 of the timing adjustment unit 151 is input to the nMOS 32 of the driver unit 13 and to the OR circuit 61. The ON signal φTR_PMOS output from the control unit 152 for controlling the ON timing of the pMOS 31 is input to the NOT circuit 66, and the NOT circuit 66 obtains the negation of the ON signal φTR_PMOS and is obtained as a result. A signal is input to the OR circuit 61.

  The OR circuit 61 calculates a logical sum of the signal output from the NOT circuit 24 and the signal output from the NOT circuit 66 and inputs the resulting signal to the pMOS 31. That is, the OR circuit 61 uses the signal output from the NOT circuit 66 to generate a signal input to the pMOS 31 separately from the signal input to the nMOS 32 output from the NOT circuit 24. As a result, the timing adjustment unit 151 can individually control the pMOS 31 and the nMOS 32.

  A signal output from the NOT circuit 26 of the timing adjustment unit 151 is input to the nMOS 34 of the driver unit 13 and also input to the OR circuit 62. The ON signal φRST_PMOS output from the control unit 152 for controlling the ON timing of the pMOS 33 is input to the NOT circuit 65. The NOT circuit 65 obtains the negation of the ON signal φRST_PMOS, and is obtained as a result. The signal is input to the OR circuit 62.

  The OR circuit 62 calculates the logical sum of the signal output from the NOT circuit 26 and the signal output from the NOT circuit 65 and inputs the resulting signal to the pMOS 33. As a result, the timing adjustment unit 151 can individually control the pMOS 33 and the nMOS 34.

  Further, a signal output from the NOT circuit 28 of the timing adjustment unit 151 is input to the nMOS 36 of the driver unit 13 and also input to the OR circuit 63. The ON signal φSEL_PMOS for turning on the pMOS 35 output from the control unit 152 is input to the NOT circuit 64, and the NOT circuit 64 obtains the negation of the ON signal φSEL_PMOS and outputs the resulting signal as an OR circuit. 63.

  The OR circuit 63 calculates the logical sum of the signal output from the NOT circuit 28 and the signal output from the NOT circuit 64 and inputs the resulting signal to the pMOS 35. As a result, the timing adjustment unit 151 can control the pMOS 35 and the nMOS 36 individually.

  The control unit 152 generates high-level or low-level timing signals φSEL, φRST, φSTR, and φRTR, and on signals φTR_PMOS, φRST_PMOS, and φSEL_PMOS at a predetermined timing, and supplies them to the timing adjustment unit 151.

  Next, with reference to FIG. 11, an example of signal timing related to the output of the transfer gate signal TR (n) in the pixel drive circuit 150 of FIG. 10 will be described.

As shown in FIG. 11, at time t _11, the row selection signal φV_LINE (n) is from a low level to a high level, then, at time t _12, the timing signal φSTR or φRTR changes from a low level to a high level, the AND Signals generated by the circuits 21 and 22, the OR circuit 23, and the NOT circuit 24 and input to the nMOS 32 are at a low level. At this time, as shown in FIG. 11, when the ON signal φTR_PMOS is at a low level, the AND circuits 21 and 22, the OR circuit 23, the NOT circuit 24, the OR circuit 61, and the NOT circuit 66 generate the signal. The input signal is at a high level. Therefore, both the pMOS 31 and the nMOS 32 are turned off, and the transfer gate connection point becomes high impedance (Hi-Z) as shown in FIG.

Next, as shown in FIG. 11, when the ON signal φTR_PMOS changes from the low level to the high level at time t ₁₃ , the signal input to the nMOS 32 remains at the low level, but the signal input to the pMOS 31 is Become low level. Accordingly, the nMOS 32 remains off, but the pMOS 31 is turned on, and a high-level transfer gate signal TR (n) with the potential VDD is output to the pixel portion as shown in FIG.

As described above, when the timing signal φSTR or φRTR becomes high-level at time t _12, nMOS 32 is turned off, the output of the potential VSS of low level transfer gate signal TR (n) is completed, the ON signal φTR_PMOS until time t ₁₃ becomes high level, because the pMOS31 does not turn on the transfer gate connection point becomes a high impedance.

Then, as shown in FIG. 11, an ON signal φTR_PMOS goes from high to low at time t _14, the signal inputted to nMOS32 the signal but remains at a low level, which is input to pMOS31 is high Return to level. Therefore, the nMOS 32 remains off, but the pMOS 31 returns to the off state, and the transfer gate connection point becomes high impedance again as shown in FIG.

Next, as shown in FIG. 11, the timing signal φSTR or φRTR goes low at time t _15, the signal inputted to nMOS32 is at the high level. At this time, as shown in FIG. 11, if the ON signal φTR_PMOS remains at the low level, the signal input to the pMOS 31 becomes the high level. Accordingly, the pMOS 31 remains off, but the nMOS 32 is turned on, and the low-level transfer gate signal TR (n) of the potential VSS is output to the pixel portion as shown in FIG.

As shown in FIG. 11, the row selection signal φV_LINE (n) changes from the high level to the low level at time t ₁₆ , but if the timing signal φSTR or φRTR and the on signal φTR_PMOS remain at the low level, the pMOS 31 The signals input to the nMOS 32 remain at a high level. Accordingly, as shown in FIG. 11, the transfer gate signal TR (n) at the potential VSS continues to be output to the pixel portion.

  As described above, when the level of the transfer gate signal TR (n) is changed from the high level to the low level and from the low level to the high level, the transfer gate connection point becomes high impedance during the transition. The control unit 152 changes the level of the ON signal φTR_PMOS, so that both the pMOS 31 and the nMOS 32 are instantaneously turned on at the time of transition, thereby preventing a through current from flowing from the potential VDD to the potential VSS.

  As a result, shaking of the low level power supply is prevented. In particular, when the negative potential generated by the charge pump mounted inside the chip provided with the pixel driving circuit 150 is the low level potential VSS, the load on the charge pump is eliminated. Accordingly, it is possible to prevent deterioration in image quality in the pixel portion.

  Further, the control unit 152 changes the timing of switching the level of the timing signal φSTR or φRTR or the ON signal φTR_PMOS and the pulse length so that the transfer gate signal TR (n) is transferred during the period when the potential is the potential VDD. The start timing and period (length) of the period in which the potential of the gate signal TR (n) is the potential VSS and the period in which the transfer gate connection point is in the high impedance (hereinafter referred to as high impedance period) can be changed. . The timing of switching the level of the timing signal φSTR or φRTR or the ON signal φTR_PMOS and the change of the pulse length can be arbitrarily performed using a register (not shown) provided in the control unit 152, for example.

  For example, as shown in FIG. 12, the control unit 152 sets the transfer gate connection point to high impedance in the middle of the transition only when the level of the transfer gate signal TR (n) transitions from the low level to the high level. Only when the flow of the through current is suppressed or when the level of the transfer gate signal TR (n) is changed from the high level to the low level as shown in FIG. 13, the transfer gate connection point is set high during the transition. It is also possible to prevent the through current from flowing through the impedance.

As shown in FIG. 12, only when the level of the transfer gate signal TR (n) transitions from a low level to a high level, when the transfer gate connection point is set to high impedance during the transition, the control unit 152 rather than the time t ₁₄ before time t _15, at time t ₂₁ after time t _15, the oN signal φTR_PMOS from the high level to the low level. As a result, the pMOS 31 is turned off at the same time as the nMOS 32 is turned on. Therefore, when the level of the transfer gate signal TR (n) transitions from the high level to the low level, the transfer gate connection point does not become high impedance.

Further, as shown in FIG. 13, only when the level of the transfer gate signal TR (n) is changed from the high level to the low level, when the transfer gate connection point is set to high impedance during the transition, the control unit 152 , rather than time t ₁₃ after time t _12, at time t ₃₁ before time t _12, the oN signal φTR_PMOS from the low level to the high level. As a result, the pMOS 31 is turned on at the same time as the nMOS 32 is turned off. Therefore, when the level of the transfer gate signal TR (n) changes from the low level to the high level, the transfer gate connection point does not become high impedance.

  Further, when the control unit 152 wants to prioritize the reduction of the time (clock period) by reducing the high impedance period rather than preventing the through current, as shown in FIG. 14, the control unit 152 sets the transfer gate signal TR (n). Whether the level is changed from the high level to the low level or when the level is changed from the low level to the high level, the transfer gate connection point may not be set to high impedance during the transition.

In this case, as shown in FIG. 14, the control unit 152 at time t ₃₁ before time t _12, and an ON signal φTR_PMOS from the low level to the high level at time t ₂₁ after time t _15, the ON signal Change φTR_PMOS from high level to low level. That is, the control unit 152 makes the pulse length of the ON signal φTR_PMOS longer than the pulse length of the timing signal φSTR or φRTR.

  In addition, while the level of the timing signal φSTR or φRTR is high, the control unit 152 changes the level of the on signal φTR_PMOS to turn on or off the pMOS 31 to provide a high impedance period or not. And so on. Therefore, for example, the high impedance period can be provided a plurality of times while the level of the timing signal φSTR or φRTR is high, or no high impedance period can be provided at all.

  In the above description, the transfer gate signal TR (n) has been described. However, the control unit 152 similarly sets the levels of the on signals φRST_PMOS and φSEL_PMOS for the reset signal RST (n) and the select signal SEL (n). By changing the level of the reset signal RST (n) and select signal SEL (n), the reset connection point and the select connection point are set to high impedance and the through current flows from the potential VDD to the potential VSS. Can be prevented.

  FIG. 15 shows a configuration example of a fourth embodiment of a pixel drive circuit of a CMOS image sensor to which the present invention is applied.

  A pixel driving circuit 200 in FIG. 15 includes an address decoder 11, a timing adjustment unit 201, a driver unit 102, and a control unit 202, and includes a high-level and low-level transfer gate signal TR (n) and a reset signal RST (n). In addition to the select signal SEL (n), the middle level transfer gate signal TR (n), the reset signal RST (n), and the select signal SEL (n) are generated and output.

  In FIG. 15, for convenience of explanation, only the part that generates the transfer gate signal TR (n) is illustrated and described. However, the reset signal RST (n) and the select signal SEL (n) are also transferred to the transfer gate signal TR ( Generated and output as in n). Further, in FIG. 15, the same components as those in FIGS. 1 and 8 are denoted by the same reference numerals, and the description thereof will be omitted because it will be repeated.

  In the timing adjustment unit 201, two OR circuits 111 and 112 and two NOT circuits 113 and 114 are provided in the preceding stage of the driver unit 102 in order to adjust the generation timing of the transfer gate signal TR (n). Be placed. Then, the timing adjustment unit 201 individually inputs signals to the two pMOSs 121 and 122 and the one nMOS 123 for generating the transfer gate signal TR (n) of the driver unit 102.

  Specifically, a signal output from the NOT circuit 24 of the timing adjustment unit 201 is input to the nMOS 123 of the driver unit 102 and also input to the OR circuits 111 and 112. The ON signal φTR_PMOS1 for controlling the ON timing of the pMOS 121 output from the control unit 202 is input to the NOT circuit 113, and the NOT circuit 113 obtains the negation of the ON signal φTR_PMOS1 and is obtained as a result. A signal is input to the OR circuit 111. The OR circuit 111 calculates the logical sum of the signal output from the NOT circuit 24 and the signal output from the NOT circuit 113 and inputs the resulting signal to the pMOS 121.

  Further, an ON signal φTR_PMOS2 output from the control unit 202 for controlling the ON timing of the pMOS 122 is input to the NOT circuit 114, and the NOT circuit 114 obtains the negation of the ON signal φTR_PMOS2 and is obtained as a result. The signal is input to the OR circuit 112. The OR circuit 112 calculates the logical sum of the signal output from the NOT circuit 24 and the signal output from the NOT circuit 114 and inputs the resulting signal to the pMOS 122.

  As described above, the OR circuit 111 generates a signal input to the pMOS 121 separately from the signal input to the nMOS 123 output from the NOT circuit 24 using the signal output from the NOT circuit 113. The OR circuit 112 uses the signal output from the NOT circuit 114 to generate a signal input to the pMOS 122 separately from the signal input to the nMOS 123. Thereby, the timing adjustment unit 201 can individually control the pMOSs 121 and 122 and the nMOS 123.

  The driver unit 102 generates a transfer gate signal TR (n) and the like according to the signal supplied from the timing adjustment unit 201. Specifically, in the driver unit 102, the pMOS 121 and the pMOS 122 are connected in parallel, and the nMOS 123 is connected in series. A potential VDD1 is connected to the source of the pMOS 121 as a high level potential, a potential VDD2 is connected to the source of the pMOS 122 as a middle level potential, and a potential VSS is connected to the source of the nMOS 123 as a low level potential.

  Further, a signal supplied from the OR circuit 111 of the timing adjustment unit 201 is supplied to the gate of the pMOS 121, a signal supplied from the OR circuit 112 is supplied to the gate of the pMOS 122, and a signal supplied from the NOT circuit 24 to the gate of the nMOS 123. Each signal is input.

  The pMOS 121, the pMOS 122, and the nMOS 123 are turned on or off according to the level of the signal supplied to the respective gates. As a result, the drains of the pMOS 121, the pMOS 122, and the nMOS 123 are connected to each other (hereinafter referred to as 3 connections). The potential of the point) is the potential VDD1, the potential VDD2, or the potential VSS. Then, this potential signal is applied as a transfer gate signal TR (n) to the transfer gate of the pixel in the nth row of the pixel portion. As described above, the driver unit 102 generates and outputs the transfer gate signal TR (n) in accordance with the signal supplied from the timing adjustment unit 201.

  The control unit 202 generates a high-level or low-level timing signal φSTR, a timing signal φRTR, an on signal φTR_PMOS1, an on signal φTR_PMOS2, and the like at a predetermined timing and supplies them to the timing adjustment unit 201.

  In FIG. 15, the potential VDD2 is connected to the pMOS 122, but may be connected to the nMOS. In this case, the nMOS to which the potential VDD2 is connected is connected in parallel to the nMOS 123, and a signal obtained by inverting the signal output from the OR circuit 112 is input to the gate of the nMOS.

  Next, with reference to FIG. 16, an example of signal timing related to the output of the transfer gate signal TR (n) in the pixel drive circuit 200 of FIG. 15 will be described.

As shown in FIG. 16, when the row selection signal φV_LINE (n) changes from the low level to the high level at time t ₅₁ , and then the timing signal φSTR or φRTR changes from the low level to the high level at time t ₅₂ , the nMOS 123. The signal input to is at a low level. At this time, as shown in FIG. 16, when the ON signals φTR_PMOS1 and φTR_PMOS2 are at a low level, both the signal input to the pMOS 121 and the signal input to the pMOS 122 are at a high level. Accordingly, all of the pMOSs 121 and 122 and the nMOS 123 are turned off, and the three connection points become high impedance (Hi-Z (1)) as shown in FIG.

Next, as shown in FIG. 16, an ON signal φTR_PMOS1 changes from low level to high level at time t _53, the signal input to the pMOS122 remains at a high level, the signal input to the nMOS123 a low level However, the signal input to the pMOS 121 is at a low level. Accordingly, the pMOS 122 and the nMOS 123 remain off, but the pMOS 121 is turned on, and a high-level transfer gate signal TR (n) at the potential VDD1 is output to the pixel portion as shown in FIG.

As described above, when the timing signal φSTR or φRTR becomes high level at time t _52, NMOS 123 is turned off, the output of the transfer gate signal TR of a low-level potential VSS (n) is completed, the on signal φTR_PMOS1 or φTR_PMOS2 until time t ₅₃ which becomes the high level, since the pMOS121 or 122 does not turn on, 3 connecting point becomes a high impedance.

Then, as shown in FIG. 16, an ON signal φTR_PMOS1 at time t ₅₄ is returned from the high level to the low level, the signal input to pMOS122 and nMOS123 are remains intact, the signal input to the pMOS121 a high level Return to. Therefore, the pMOS 122 and the nMOS 123 remain off, but the pMOS 121 returns to the off state, and the three connection points become high impedance (Hi-Z (2)) as shown in FIG.

  As described above, the control unit 202 sets the ON signal φTR_PMOS1 to the high level while the timing signal φSTR or φRTR is at the high level, thereby turning on the pMOS 121 and increasing the level of the transfer gate signal TR (n). Can be level. Therefore, the control unit 202 controls the ON period of the pMOS 121 by controlling the period during which the ON signal φTR_PMOS1 is set to the high level while the timing signal φSTR or φRTR is at the high level, and the transfer gate signal TR (n) It is possible to control the presence / absence, length, start timing, and the like of the high level period in which the level is high.

Next, as shown in FIG. 16, an ON signal φTR_PMOS2 changes from low level to high level at time t _55, the signal inputted to the signal and nMOS123 inputted to pMOS121 is the intact, is input to pMOS122 Signal becomes low level. Therefore, the pMOS 121 and the nMOS 123 remain off, but the pMOS 122 is turned on, and as shown in FIG. 16, the middle level transfer gate signal TR (n) at the potential VDD2 is output to the pixel portion.

Then, as shown in FIG. 16, an ON signal φTR_PMOS2 at time t ₅₆ is returned from the high level to the low level, the signal input to pMOS121 and nMOS123 are remains intact, the signal input to the pMOS122 a high level Return to. Therefore, the pMOS 121 and the nMOS 123 remain off, but the pMOS 122 returns to the off state, and the three connection points become high impedance (Hi-Z (3)) as shown in FIG.

  As described above, the control unit 202 sets the ON signal φTR_PMOS2 to the high level while the timing signal φSTR or φRTR is at the high level, thereby turning on the pMOS 122 and setting the level of the transfer gate signal TR (n) to the middle level. Can be level. Therefore, the control unit 202 controls the ON period of the pMOS 122 by controlling the period during which the ON signal φTR_PMOS2 is set to the high level while the timing signal φSTR or φRTR is at the high level, and the transfer gate signal TR (n) It is possible to control the presence / absence, length, start timing, and the like of the middle level period in which the level is the middle level.

Next, as shown in FIG. 16, the timing signal φSTR or φRTR returns from the high level to the low level at time t _57, the signal inputted to the nMOS123 is at the high level. At this time, as shown in FIG. 16, if the ON signals φTR_PMOS1 and φTR_PMOS2 remain at low level, both the signal input to the pMOS 121 and the signal input to the pMOS 122 are at high level. Accordingly, the pMOSs 121 and 122 remain off, but the nMOS 123 is turned on, and the low level transfer gate signal TR (n) at the potential VSS is output to the pixel portion as shown in FIG.

Then, as shown in FIG. 16, at time t _58, the row selection signal φV_LINE (n) is changed from the high level to the low level, the timing signal φSTR or FaiRTR, and on signal φTR_PMOS1 and φTR_PMOS2 is remains low level All the signals input to the pMOSs 121 and 122 and the nMOS 123 remain at the high level. Accordingly, as shown in FIG. 16, the transfer gate signal TR (n) having a low level of the potential VSS is continuously output to the pixel portion.

  As described above, in FIG. 16, when the level of the transfer gate signal TR (n) is changed from the low level to the high level, from the high level to the middle level, and from the middle level to the low level, in the middle of the transition. The level of the transfer gate signal TR (n) is set to high impedance. Thus, by providing a period in which the three connection points are in a high impedance during the transition, it is possible to prevent a through current from flowing from the potential VDD to the potential VSS during the transition.

  Further, as shown in FIG. 16, the period in which both the ON signal φTR_PMOS1 and the ON signal φTR_PMOS2 are at the low level while the timing signal φSTR or φRTR is at the high level is the period in which the three connection points are set to the high impedance. . Therefore, by changing the level switching timing and the pulse period of the on signals φTR_PMOS1 and φTR_PMOS2, it is possible to provide a period in which the three connection points having any length are set to high impedance at any timing.

  For example, Hi-Z (1) only, Hi-Z (2) only, Hi-Z (3) only, Hi-Z (1) and Hi-Z (2) only, Hi-Z (1) And only Hi-Z (3) or only Hi-Z (2) and Hi-Z (3) can be provided. In addition, the control unit 202 may be configured not to provide a high impedance period at all when it is desired to reduce the high impedance period and give priority to shortening the time rather than preventing the through current.

  The level of each signal is an arbitrary value suitable for the pixel drive circuit 50 (100, 150, 200) using a register (not shown) provided in the control unit 52 (103, 152, 202). Can be set.

  In the description of FIGS. 11 to 14 and FIG. 16 described above, the timing signal φSTR or φRTR is described as being at a high level (or low level). However, this description indicates that both the timing signals φSTR and φRTR are at a high level. (Or low level) means that one of the timing signals φSTR or φRTR is at a high level (or low level) and the other is always at a low level. At this time, high impedance control can be performed using the ON signal regardless of whether the timing signal that goes to the high level is φSTR or φRTR.

  Further, in this specification, the step of describing the program stored in the program recording medium is not limited to the processing performed in time series in the described order, but is not necessarily performed in time series. Or the process performed separately is also included.

  Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

It is a figure which shows an example of a structure of the conventional pixel drive circuit. It is a figure explaining the timing of the signal in the drive circuit of FIG. It is a figure which shows the structural example of 1st Embodiment of the pixel drive circuit to which this invention is applied. It is a figure explaining the timing of the signal in the pixel drive circuit of FIG. FIG. 4 is a diagram illustrating another timing of signals in the pixel drive circuit of FIG. 3. FIG. 4 is a diagram for explaining still another timing of signals in the pixel drive circuit of FIG. 3. FIG. 4 is a diagram for explaining still another timing of signals in the pixel drive circuit of FIG. 3. It is a figure which shows the structural example of 2nd Embodiment of the pixel drive circuit to which this invention is applied. FIG. 9 is a diagram for describing signal timings in the pixel drive circuit of FIG. 8. It is a figure which shows the structural example of 3rd Embodiment of the pixel drive circuit to which this invention is applied. It is a figure explaining the timing of the signal in the pixel drive circuit of FIG. It is a figure explaining the other timing of the signal in the pixel drive circuit of FIG. FIG. 11 is a diagram illustrating still another timing of signals in the pixel drive circuit of FIG. 10. FIG. 11 is a diagram illustrating still another timing of signals in the pixel drive circuit of FIG. 10. It is a figure which shows the structural example of 4th Embodiment of the pixel drive circuit to which this invention is applied. It is a figure explaining the timing of the signal in the pixel drive circuit of FIG.

Explanation of symbols

  31 pMOS, 32 nMOS, 50 pixel drive circuit, 51 timing adjustment unit, 100 pixel drive circuit, 121 pMOS, 150 pixel drive circuit, 151 timing adjustment unit, 200 pixel drive circuit

Claims (1)

In a driving device for driving a pixel,
A first first conductivity type transistor connected to a first potential;
The first being connected to the first conductive type transistor in series with a first transistor of the second conductivity type connected to the second potential,
The first ON signal using, said first transistor of the first conductivity type for controlling the timing of any one of the on of said first of said first conductivity type transistor first transistor of the second conductivity type And control means for individually controlling the first second conductivity type transistors ;
A second first conductivity type transistor connected to a third potential connected in parallel to the first first conductivity type transistor; or a parallel connection to the first second conductivity type transistor; A transistor that is one of the second second conductivity type transistors connected to the third potential ,
The control means uses the first on-signal and the second on-signal for controlling the on-timing of the transistor to use the first first conductivity type transistor and the first second conductivity type transistor. And a first potential period in which the potential at the connection point is the first potential, and a second potential period in which the potential at the connection point is the second potential by individually controlling the transistors. And at the time of transition from one of the third potential periods in which the potential at the connection point is the third potential to another one, a high impedance period in which the connection point is at high impedance is always provided. And controlling the length and start timing of the first potential period, the second potential period, the third potential period, and the high impedance period,
The first first conductivity type transistor, the first second conductivity type transistor, and a potential signal at a connection point of the transistor are input to the pixel as the drive signal .

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