JP2006330751A - Electro-optical device drive circuit, electro-optical device, and electronic apparatus - Google Patents

Abstract

In a liquid crystal device or the like that incorporates a drive circuit and simultaneously drives a plurality of data lines, the size of the device is reduced by efficiently using a region on a substrate.
On a substrate (10) of a liquid crystal device, a sampling circuit (301) for sampling an image signal and a sampling switch (302) connected to a plurality of adjacent data lines (6a) are simultaneously provided. And a data line driving circuit (101) for supplying a sampling control signal. When a transfer signal is input from the shift register circuit (400), the data line driver circuit shapes the waveform and outputs inverters (501 to 503) each having a thin film transistor as a sampling control signal corresponding to each latch circuit. Including a buffer circuit (500). The thin film transistor includes a channel portion having a channel width equal to a plurality of data line widths and a channel width direction being a horizontal direction.
[Selection] Figure 5

Description

  The present invention relates to a driving circuit including a data line driving circuit for driving an electro-optical device such as an active matrix driving type liquid crystal device driven by a transistor such as a thin film transistor (hereinafter referred to as TFT), and such a driving circuit. In particular, a drive circuit for an electro-optical device that employs a driving method for simultaneously driving a plurality of data lines to cope with high dot frequencies and color image signals, and such driving It belongs to the technical field of a type of electro-optical device with a built-in circuit.

  A driving circuit for this type of electro-optical device includes a data line driving circuit and a scanning line driving circuit for supplying an image signal and a scanning signal to a data line and a scanning line wired in an image display area of the electro-optical device at a predetermined timing. , Including a sampling circuit and the like.

  When such a drive circuit adopts a line sequential drive system, sampling is performed by sequentially supplying image signals supplied from the outside onto one image signal line corresponding to each data line from the data line drive circuit. According to the control signal, each sampling line is sampled by a plurality of sampling switches provided corresponding to each data line, and is supplied to each data line in a line sequential manner. In general, the data line driving circuit includes a shift register circuit including a plurality of arranged latch circuits that sequentially output transfer signals in accordance with a reference clock. Further, by interposing a buffer circuit between the latch circuit and the sampling circuit, the waveform of the transfer signal is shaped to obtain the above-described sampling control signal, and the driving capability of the latch circuit drives the sampling switch. Even if it is not sufficient, the buffer circuit is configured so that it can sufficiently cope with the load of the sampling switch.

  Here, under the recent demand for high-quality display images, the dot frequency in electro-optical devices such as liquid crystal devices has been increasingly increased, for example, as in the XGA method, SXGA method, and EWS method. When the dot frequency increases in this way, the sampling capability of the sampling switch described above becomes insufficient, or the delay time in each TFT constituting the drive circuit adversely affects the quality of the display image. For example, the image data for the previous data line is written to the next data line, resulting in a ghost or crosstalk. However, if the performance of the sampling switch and each TFT itself is increased in order to cope with this, the cost is significantly increased.

  Therefore, recently, for example, after an image signal is serial-parallel converted and divided into a plurality of parallel image signals, or in the case of a color image signal, the image signal is divided into parallel image signals for each color, A plurality of image signals (for example, 6, 12, 24, etc.) are simultaneously sampled by sampling a plurality of serial-parallel image signals in a sampling circuit. ) Technology to supply data lines simultaneously has been developed. According to this technique, the sampling time of each sampling switch can be increased approximately n times according to the number n of data lines to be driven simultaneously, so that the drive frequency in the drive circuit is substantially reduced to about 1 / n. I can do it. That is, as described above, it is possible to cope with a high dot frequency without having to improve the performance of the sampling switch or each TFT.

  When a plurality of data lines are simultaneously driven as described above, the data line driving circuit can withstand the total load of the plurality of sampling switches in order to supply the same sampling control signal to the plurality of sampling switches simultaneously. Only drive capability is required. That is, the drive capability of the buffer circuit interposed between the latch circuit and the sampling switch must be increased according to the total load of the plurality of sampling switches. For this purpose, the size of the TFT constituting the inverter included in the buffer circuit may be increased. However, if the size of the TFT is simply increased, it will be necessary to increase the driving capability of the latch circuit that drives the TFT with a transfer signal. The power consumption in the shift register circuit, which is regarded as a problem in the field of devices, is further increased. Therefore, a configuration is generally adopted in which the buffer circuit is configured by a plurality of stages of inverters connected in series, and the drive capability of the buffer circuit is increased step by step for each inverter. That is, the size of the TFT constituting the inverter on the latch circuit side of the buffer circuit is small, and the size of the TFT constituting the inverter on the sampling switch side of the buffer circuit is large.

  On the other hand, a drive circuit built-in type electro-optical device has been developed in which the drive circuit as described above is provided on a substrate constituting a main body of an electro-optical device such as a liquid crystal device. This electro-optical device with a built-in drive circuit is advantageous in reducing the size and cost of the entire device, compared to an electro-optical device in which a drive circuit is formed on a separate substrate and externally attached.

  However, if the above-described buffer circuit composed of a plurality of stages of inverters is provided in the above-described liquid crystal device with a built-in driving circuit, the area occupied by the enlarged buffer circuit in the region on the substrate of the liquid crystal device or the like is ineffective. The increase in the use area becomes a problem. In particular, as in the above-described conventional line-sequential drive type liquid crystal device, each inverter is composed of TFTs extending in the longitudinal direction along the data line, and this is formed in a plurality of stages in the longitudinal direction along the data line. When connected in series, the proportion of the area of ineffective use by the buffer circuit that occupies the region on the horizontally long substrate along the scanning line that exists between the normal image signal line and the shift register circuit is significantly increased. There is a problem. Eventually, the non-image display area for forming the data line driving circuit above or below the image display area widens, and the entire apparatus is reduced in size and weight, and the image display area in the same apparatus size is increased. There is a problem in that it causes a situation contrary to the general demand in the technical field of the electro-optical device.

  The present invention has been made in view of the above-described problems, and in an electro-optical device such as a liquid crystal device that employs a driving method in which a plurality of data lines are simultaneously driven and has a built-in driving circuit, the region on the substrate is efficiently formed. It is an object of the present invention to provide a drive circuit for an electro-optical device and an electro-optical device incorporating the drive circuit that can reduce the size of the device or increase the size of an image display area in the same device size.

  In order to solve the above problems, the drive circuit of the electro-optical device according to the present invention includes an electro-optical material sandwiched between a pair of substrates, and a plurality of data lines intersecting on one of the pair of substrates. A drive circuit for an electro-optical device including a plurality of scanning lines, the sampling circuit supplying a plurality of sampling switches to each of the plurality of data lines by sampling an image signal in accordance with a sampling control signal on the one substrate; A data line driving circuit for supplying the sampling control signal simultaneously to each sampling switch connected to n (where n is an integer of 2 or more) data lines adjacent to the plurality of sampling switches. And the data line driving circuit outputs a transfer signal sequentially as a shift register circuit, and outputs the transfer signal as the sampling control signal. And a Ffa circuit, at least one transistor constituting the buffer circuit is characterized in that the the direction of the channel width on the substrate of one made is extended in a direction intersecting the data lines.

  According to the driving circuit of the electro-optical device of the present invention, the sampling control signal is simultaneously supplied to the n sampling switches for each sampling switch connected to the n adjacent data lines by the data line driving circuit. . At this time, in the data line driving circuit, the transfer signal is sequentially output by the shift register circuit, and this transfer signal is output as the above-described sampling control signal via the buffer circuit. Then, the image signal is sampled according to the sampling control signal by each sampling switch and supplied to the plurality of data lines. In this way, by simultaneously driving a plurality of sampling switches, it is possible to drive the data line even in response to an image signal having a high dot frequency such as XGA, SXGA, EWS, and the like.

  Here, in particular, at least one of the transistors included in the buffer circuit is a direction in which the channel width direction intersects the data line on one substrate (for example, a direction parallel to or substantially parallel to the scanning line). Therefore, as in a buffer circuit including an inverter corresponding to each latch circuit in the conventional line sequential drive system, the transistor constituting the inverter has a channel width of one data line (that is, the pitch of the data line). In the present invention, it is possible to provide a transistor having a wide channel width (that is, a large size transistor having a high driving capability capable of driving a sampling circuit having a larger load). .

  Alternatively, like a buffer circuit including an inverter corresponding to the output of a shift register in the conventional line sequential drive system, the channel width direction of the TFT constituting the inverter is matched with the vertical direction parallel to the data line, Compared with the case where the data lines are arranged so as to fit within the pitch of the data lines, it is possible to provide a large TFT with a wide channel width and a large size in a vertical region parallel to the data lines on the substrate.

  In one embodiment of the present invention, the channel of the transistor has a width within a data line pitch of 2 to n adjacent to each other.

  According to this aspect, in the conventional line-sequential driving method, the vertically long transistors corresponding to the pitch of the data lines are laid out on the substrate. However, in the present invention, the total width of n data lines that are driven simultaneously. The area on the substrate that extends longitudinally along the scanning line between the shift register circuit and the sampling circuit is efficiently used so that the channel width direction intersects the data line while being within a range. Thus, a horizontally long and large transistor corresponding to the total width of the plurality of data lines can be laid out on the substrate.

  As a result of the above, according to the present invention, a large-sized transistor capable of driving the load even if the load on the sampling circuit increases as the number of data lines to be simultaneously driven increases while effectively utilizing the area on the substrate. A buffer circuit including an inverter made of the above can be provided, and the drive circuit that saves space enables a good drive operation even at a high dot frequency.

  In one aspect of the drive circuit of the electro-optical device of the present invention, the buffer circuit includes m (where m is an integer of 2 or more) stages of inverters connected in series corresponding to the latch circuits.

  According to this aspect, the load in the sampling circuit that can be driven by the entire inverter can be increased by increasing the size of the transistors constituting the inverter of each stage with m stages of inverters, that is, simultaneous driving is possible. It becomes possible to increase the number of sampling switches.

  Therefore, since the size of the transistor constituting the first-stage inverter can be relatively small particularly when viewed from the latch circuit side, the size of the transistor constituting the latch circuit for inputting the transfer signal to this transistor can be small. Therefore, it is possible to reduce power consumption in a shift register circuit including a plurality of latch circuits.

  However, when the number of inverter stages (m) is increased, the total delay time by the transistors constituting these inverters also increases. Therefore, in practice, the number of stages of this inverter (m) in consideration of the dot frequency, required specifications, image quality, etc. so that the total delay time does not adversely affect the displayed image. To be determined.

  In this aspect, the channel width of the transistor included in the i + 1-th inverter counted from each latch circuit side may be larger than the channel width of the transistor included in the i-th inverter.

  With this configuration, the size of the transistors constituting the inverter of each stage increases stepwise, so the load on the sampling circuit that can be driven by the entire inverter can be increased, and the number of sampling switches that can be driven simultaneously is increased. Is possible.

  In an aspect in which the buffer circuit includes m-stage inverters, the m-stage inverters meander, and a first portion extending in a first direction intersecting the data line from a side close to the shift register circuit, A portion extending from the first portion in a direction opposite to the first direction may be sequentially arranged in a direction intersecting the scanning line.

  With this configuration, the channel width of the transistors constituting the inverter can be increased by the amount of meandering. For example, if meandering in an S-shape, a channel width that is approximately three times as large as that obtained when the channel width is simply taken straight in the first direction can be secured. Therefore, as the channel width increases, Thus, the driving capability of the transistor can be increased.

  In this case, the power supply wiring extending in the first direction may be shared between the first and second parts.

  With this configuration, since the power supply wiring extending in the first direction is shared between the first and second parts, the direction perpendicular to the first direction in the entire buffer circuit (for example, data The length in the vertical direction along the line can be shortened by the width of the shared power supply wiring.

  In another aspect of the drive circuit of the electro-optical device according to the aspect of the invention, the buffer circuit includes a single-stage inverter corresponding to each of the latch circuits.

  According to this aspect, since the inverter constituting the buffer circuit has one stage, the delay time of the entire buffer circuit is completely or substantially equal to the delay time in the transistors constituting the one-stage inverter. For this reason, the delay time can be shortened compared to the case where there are a plurality of inverters and the delay time is added in series.

  In this aspect, the one-stage inverter may include a plurality of inverters connected in parallel so as to extend in a direction intersecting the data line and to be arranged in order in a direction intersecting the scanning line.

  With this configuration, the one-stage inverter is composed of a plurality of inverters that are connected in parallel and arranged in order in a direction intersecting the scanning line (for example, a direction parallel or substantially parallel to the data line). The inverter can be laid out by efficiently using the area on the substrate having a width corresponding to the total width of the driven data lines.

  In this case, a power supply wiring extending in a direction crossing the data line may be shared between the plurality of inverters connected in parallel.

  With this configuration, since the power supply wiring extending in the direction intersecting the data line is shared between the plurality of inverters connected in parallel, the direction intersecting this direction in the entire buffer circuit (as compared to the case where the data line is not shared) ( For example, the length in the direction parallel or substantially parallel to the data line can be reduced by the width of the shared power supply wiring.

  In another aspect of the drive circuit of the electro-optical device according to the aspect of the invention, the transistor is a complementary transistor.

  According to this aspect, the input impedance of each inverter can be increased by the complementary transistor, and the high load sampling switch is driven through the complementary transistor based on the transfer signal from the latch circuit having a small driving capability. It becomes possible.

  In another aspect of the driving circuit of the electro-optical device according to the aspect of the invention, the data line driving circuit may include a phase adjustment circuit that limits a signal width of the transfer signal to a predetermined value between the latch circuit and the buffer circuit. Is further included.

  According to this aspect, the phase adjustment circuit interposed between the latch circuit and the buffer circuit limits the signal width of the transfer signal (the time during which the signal is at a high level) to a predetermined value (predetermined time width). Since the overlap between the transfer signals output before and after the latch circuit is reduced, the data lines driven in succession due to such an overlap (that is, every n lines) are generated. Crosstalk and ghost between data lines) can be prevented in advance.

  In another aspect of the drive circuit of the electro-optical device according to the aspect of the invention, a plurality of image signal lines are arranged along the scanning lines on the one substrate, and the buffer circuit includes the plurality of image signals. Formed in a region on the substrate between the line and the shift register circuit.

  According to this aspect, the sampling circuit samples the image signals supplied on the plurality of image signal lines according to the sampling control signal. Here, since the buffer circuit is formed in the region on the substrate between the plurality of image signal lines and the shift register circuit, the horizontally long inverter is disposed in the horizontally long region along the image signal lines and the scanning lines. Thus, efficient use of the area on the substrate is achieved.

  In another aspect of the drive circuit of the electro-optical device according to the aspect of the invention, the image signal is n-serial to parallel converted and is supplied to the sampling circuit via n image signal lines.

  According to this aspect, the image signal is n-serial-parallel converted and supplied to the sampling circuit via the n image signal lines. Therefore, even when the dot frequency is high, such as XGA, SXGA, EWS, etc., even if a sampling circuit having a relatively low sampling capability or a relatively low performance with respect to delay time is used, the serial-parallel conversion increases the frequency. A quality image can be displayed.

  In order to solve the above problems, an electro-optical device according to the present invention includes the above-described drive circuit for the electro-optical device according to the present invention.

  According to the electro-optical device of the present invention, since the drive circuit of the present invention described above is provided,

  An electro-optical device such as a liquid crystal device capable of reducing the overall size of the device or increasing the image display area of the same size device and simultaneously displaying a high-quality image can be realized.

  In one aspect of the electro-optical device of the present invention, a plurality of pixel electrodes arranged in a matrix and a plurality of transistors that respectively drive the plurality of pixel electrodes are further provided on one of the substrates. The plurality of data lines and the scanning line are connected to the plurality of transistors, respectively.

  According to this aspect, it is possible to realize an electro-optical device such as a so-called TFT active matrix driving type liquid crystal device capable of displaying a high-quality image.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention.

  According to this aspect, it is possible to provide an electronic apparatus including an electro-optical device capable of high-quality images.

  In another aspect of the drive circuit of the electro-optical device according to the aspect of the invention, a plurality of scanning lines, a plurality of data lines, and a plurality provided corresponding to each intersection of the plurality of scanning lines and the plurality of data lines. An electro-optical device driving circuit for driving an electro-optical device including a pixel, wherein the driving circuit is supplied with a transfer signal from the shift register circuit and the shift register circuit, and performs sampling control of the transfer signal. The buffer circuit includes a plurality of stages of transistor circuits connected in series, and the transistor circuits are arranged in the extending direction of the data line and are complementary to each other. The transistor is provided.

  The transistor circuit may constitute an inverter circuit, and the buffer circuit may include a plurality of inverter circuits arranged in parallel in the extending direction of the data line and connected in parallel.

  The complementary transistor may extend in a direction in which a channel width intersects the data line, and the channel width of the transistors included in the plurality of stages of transistor circuits connected in series is The channel width of the transistor included in the transistor circuit in the subsequent stage may be larger than the channel width of the transistor included in the transistor circuit.

  According to the electro-optical device of the present invention, a large-sized transistor capable of driving the load even if the load on the sampling circuit increases as the number of data lines to be simultaneously driven increases while effectively utilizing the area on the substrate. A buffer circuit including an inverter made of the above can be provided, and the drive circuit that saves space enables a good drive operation even at a high dot frequency. Therefore, finally, a high-quality image can be displayed while the size of the substrate can be reduced and the image display area on the same size substrate can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment of Liquid Crystal Device)
A configuration and operation of a first embodiment of a liquid crystal device which is an example of an electro-optical device according to the present invention will be described with reference to FIGS.

First, the circuit configuration of the liquid crystal device will be described with reference to the block diagram of FIG.
FIG. 1 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix that forms an image display area of a liquid crystal device.

  In FIG. 1, a plurality of pixels formed in a matrix forming the image display area of the liquid crystal device according to the present embodiment has a plurality of TFTs 30 for controlling the pixel electrodes 9 a formed in a matrix, and an image signal is The supplied data line 6 a is electrically connected to the source of the TFT 30.

  In this embodiment, in particular, the image signals S1, S2,..., Sn written to the data line 6a are processed by a serial-parallel conversion circuit in the image signal processing circuit that supplies the image signals S1, S2,. N (n is an integer greater than or equal to 2) serial-parallel conversion is performed in advance, and serial-parallel converted image signals are simultaneously supplied to each group of n data lines 6a adjacent to each other. Yes. In general, the number of serial-parallel conversions is small, for example, 3 serial-parallel conversion, 6 serial-parallel conversion, etc. if the dot frequency is relatively low or the sampling capability in the sampling circuit described later is relatively high. It may be set. On the other hand, if the dot frequency is relatively high or the sampling capability is relatively low, it may be set large, for example, 12 serial-parallel conversion, 24 serial-parallel conversion, or the like. The serial-parallel conversion number is a multiple of 3 because the color image signal is made up of signals related to three colors (red, blue, yellow), such as NTSC display or PAL display. This is preferable for simplifying the control and circuit when displaying video. In the case of a high dot frequency such as the recent XGA method, SXGA method, EWS method, etc., in view of the existing TFT manufacturing technology, for example, serial-parallel conversion such as 12 serial-parallel conversion, 24 serial-parallel conversion, etc. It is preferable to set a large number of parallel conversions.

  Further, the scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are applied to the scanning line 3a in a pulse-sequential manner in this order at a predetermined timing. It is configured. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal S1, S2,..., Sn supplied from the data line 6a is obtained by closing the switch of the TFT 30 as a switching element for a certain period. Write at a predetermined timing. Image signals S1, S2,..., Sn written to the liquid crystal via the pixel electrode 9a are held for a certain period with a counter electrode (described later) formed on a counter substrate (described later). . The liquid crystal modulates light by changing the orientation and order of the molecular assembly according to the applied voltage level, thereby enabling gradation display. In the normally white mode, incident light cannot pass through the liquid crystal part according to the applied voltage. In the normally black mode, incident light passes through the liquid crystal part according to the applied voltage. Through the liquid crystal device as a whole, light having a contrast according to the image signal is emitted. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode. For example, the voltage of the pixel electrode 9a is held by the storage capacitor 70 for a time that is three orders of magnitude longer than the time when the source voltage is applied. Thereby, the holding characteristics are further improved, and a liquid crystal device with a high contrast ratio can be realized.

  Next, a driving circuit of the liquid crystal device of the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing an image display unit provided with scanning lines, data lines and the like as described above, and a drive circuit provided on the substrate of the liquid crystal device in the periphery of the image display unit.

  In FIG. 2, on the TFT array substrate 10 of the liquid crystal device, an image display unit 100a provided with the scanning lines 3a, the data lines 6a and the like described in FIG. A driving circuit 200 including a data line driving circuit 101, a scanning line driving circuit 104, and a sampling circuit 301 is provided. That is, the liquid crystal device of the present embodiment is configured as a TFT active matrix driving type liquid crystal device with a built-in driving circuit in which the driving circuit 200 is formed on the TFT array substrate 10.

  The scanning line driving circuit 104 pulse-lines scanning signals G1, G2,..., Gm with respect to the scanning line 3a at a predetermined timing according to the vertical synchronization signal of the image signal supplied from the external image signal processing circuit. Supply sequentially.

  The data line driving circuit 101 sends sampling control signals X1, X2,... Via the sampling control signal line 114 in accordance with the scanning line driving circuit 104 sending the scanning signals G1, G2,. Xn is supplied to the control terminal of each sampling switch 302 constituting the sampling circuit 301. The sampling circuit 301 samples the image signal supplied to the image signal line 115 according to the sampling control signals X1, X2,..., Xn and supplies the sampled image signal to the data line 6a. Particularly in the present embodiment, the sampling switches 302 connected to the 12 adjacent data lines corresponding to the 12 serial-parallel converted image signals VID1 to VID12 are simultaneously turned on in response to the same sampling control signal. The twelve data lines 6a are simultaneously supplied with one of the image signals VID1 to VID12.

  Next, with reference to FIGS. 3 and 4, more detailed configurations of the data line driving circuit 101 and the sampling circuit 301 will be described together with their operations. 3 is a block diagram showing the latch circuit 401 and the like constituting the data line driving circuit 101 together with the sampling circuit 301 and the like. FIG. 4 is a timing chart of various signals in the data line driving circuit 101. .

  In FIG. 3, the data line driving circuit 101 includes a shift register circuit 400 that sequentially outputs transfer signals and a buffer circuit 500 that shapes the waveform of the sequentially output transfer signals. The shift register circuit 400 includes a latch circuit 401 including a plurality of stages of delay flip-flop circuits connected in series. And a plurality of phase adjustment circuits 402 including, for example, NAND circuits 403 connected to the respective latch circuits 401. The buffer circuit 500 includes three stages of inverters 501, 502, and 503 connected in series for each group of sampling switches 302 that are driven simultaneously.

  As shown in FIGS. 3 and 4, the shift register circuit 400 is configured as follows.

  That is, when a start pulse SP synchronized with the horizontal synchronizing signals of the image signals VID1 to VID12 is input from an external image signal processing circuit, first, the leftmost latch circuit 401 first detects the X-side reference clock signal CLX (and its inverted clock signal). The transfer operation based on CLX ′ is started, the transfer signal ST1 is output to the corresponding NAND circuit 403 in the phase adjustment circuit 402, and the transfer signal ST1 is output to the latch circuit 401 at the next stage. Then, the latch circuit 401 at the next stage starts the transfer operation based on the X-side reference clock signal CLX (and its inverted clock signal CLX ′) and adjusts the phase of the transfer signal ST2 that rises at the fall timing of the transfer signal ST1. In addition to outputting to the corresponding NAND circuit 403 in the circuit 402, the transfer signal ST2 is output to the latch circuit 401 in the next stage. Subsequently, the same transfer operation is sequentially performed by the latch circuits 401 in each stage, and the transfer signals ST1, ST2,..., STn are output to the phase adjustment circuit 402 in one horizontal scanning period.

  In addition, the phase adjustment circuit 402 receives the transfer signal ST2i-1 (where i is a natural number) input from the corresponding latch circuit 401 and the phase adjustment signal ENB1 by the odd-numbered NAND circuits 403 from the left. NAND is taken and output to the buffer circuit 500. Further, the NAND circuits 403 of even-numbered stages counted from the left take the NAND of the transfer signal ST2i (where i is a natural number) input from the corresponding latch circuit 401 and the phase adjustment signal ENB2, and store them in the buffer circuit 500. It is configured to output.

  The buffer circuit 500 includes three stages of inverters 501, 502, and 503 connected in series for each output terminal of each phase adjustment circuit 402. Then, as will be described later, by increasing the size of the TFTs constituting the inverters 501, 502 and 503 stepwise, the load on the sampling circuit 301 that can be driven by the whole inverter is increased, and the sampling switch 302 that can be driven simultaneously is increased. It is configured to increase the number (see FIG. 4).

  In this way, the transfer signals ST1, ST2,..., STn are limited in pulse width by the phase adjustment circuit 402, further shaped by the buffer circuit 500, and sampled as the sampling control signals X1, X2,. Is output.

  Especially in this embodiment, due to the limitation of the pulse width by the phase adjustment circuit 402, the sampling control signals X1, X2,..., Xn that follow each other have a slight time interval between the signal pulses (see FIG. 4). Thus, it is possible to suppress or prevent ghosts and crosstalk between the data lines 6a driven before and after due to the overlap of these signal pulses. Further, since the driving capability at the output of the buffer circuit 500 is set to be much larger than the driving capability at the output of the latch circuit 401 or the phase adjustment circuit 402, the sampling control signals X1, X2,. A plurality of sampling switches 302 whose load is much larger than that of one sampling switch 302 can be driven simultaneously well.

  Next, with reference to FIGS. 5 and 6, a specific configuration of the TFTs that constitute the inverters 501, 502, and 503 included in the buffer circuit 500 will be described. FIG. 5 is an enlarged plan view showing the buffer circuit 500, the image signal line 115, and the elements and wiring layout formed on the TFT array substrate 10 in the vicinity thereof. In the example, 12 serial-parallel converted image signals are supplied by 12 image signal lines 115, and 12 sampling switches 302 are simultaneously driven by the same sampling control signals X1, X2,. FIG. 6 is a circuit diagram showing the buffer circuit 500 shown in FIG. 5 corresponding to the layout.

  In FIG. 5, a high voltage wiring 601 and a low voltage wiring 602 for driving inverters 501, 502, and 503 are wired in the buffer circuit 500.

  First, the size of the complementary TFT constituting the first-stage inverter 501 when viewed from the latch circuit 401 side is relatively small. That is, it has a channel width in which only five contact holes 501a are arranged in the horizontal direction in the figure, which corresponds to about 2.5 times the pitch of the data lines 6a. Therefore, the size of the TFT constituting the latch circuit 401 for inputting the transfer signals ST1, ST2,... To this complementary TFT having a relatively high input impedance can be reduced. For this reason, it is possible to reduce power consumption in the shift register circuit 400 that includes a plurality of latch circuits 401 and in which large power consumption is a problem. Further, in the small complementary TFT constituting the first-stage inverter 501 in this way, the transfer signal wiring 404 supplied from the latch circuit 401 via the phase adjustment circuit 402 is extended to the gate electrode. In addition, a part of the high-voltage wiring 601 and a lead-out wiring 602a of the low-voltage (ground) wiring 602 serve as an input-side source or drain electrode.

  As shown in FIGS. 5 and 6, the source or drain electrode on the output side of the complementary TFT constituting the first stage inverter 501 is extended so that the gate of the complementary TFT of the second stage inverter 502 is provided. It is an electrode.

  The size of the complementary TFT constituting the second-stage inverter 502 is larger than that of the inverter 501. In other words, the channel width is such that ten contact holes 502a are arranged in the horizontal direction in the figure, which corresponds to about five times the pitch of the data lines 6a.

  In the present embodiment, in particular, the buffer circuit 500 composed of a total of three stages of inverters is provided meandering on the TFT array substrate 10, and the first and second stage inverters 501 and 502 are shown in the right side of the figure. In contrast, the third-stage inverter 503 extends toward the left in the figure. Further, as shown in FIG. 5, the third-stage inverter 503 includes two inverters connected in parallel. The source or drain electrodes on the output side of these two inverters are connected to the sampling control signal line 114. That is, the output voltage of the third-stage inverter 503 is used as the sampling control signal (X1, X2,...) From the buffer circuit 500.

  The size of the complementary TFT constituting the third stage inverter 503 is larger than that of the inverter 502. That is, it has a channel width that only 20 contact holes 503a are arranged in the horizontal direction in the figure, which corresponds to about 10 times the pitch of the data lines 6a. In FIG. 6, the voltage Vcc indicates a high voltage (for example, 5 V, 15 V, etc.) supplied from the high voltage wiring 601, and the voltage GND indicates a low voltage (for example, ground voltage) supplied from the low voltage wiring 602. Show.

  Here, the arrangement method of the three-stage inverters 501, 502, and 503 and the arrangement method of the plurality of buffer circuits 500 described above are shown in FIG.

  7A and 6, in this embodiment, in each buffer circuit 500, the three-stage inverters 501, 502, and 503 meander, and the third-stage inverter 503 has It consists of two inverters connected in parallel. The width of each buffer circuit 500 in the X direction is planarly laid out so as to coincide with the total width (ΔW) of the twelve data lines 6a that are driven simultaneously (see FIG. 7A).

  As described above, the channel width of the TFTs constituting the inverters 501, 502, and 503 can be increased by the amount of meandering of the buffer circuit 500, and the TFT driving capability in the buffer circuit 500 is increased according to the increase in the channel width. It becomes possible to raise.

  As described above with reference to FIGS. 5 to 7A, in the present embodiment, in particular, the TFTs constituting the inverters 501, 502, and 503 have the channel width direction on the TFT array substrate 10 in the X direction. And having a channel width equal to several times to about 10 times the pitch of the data line 6a, a TFT constituting an inverter like a buffer circuit including an inverter corresponding to each latch circuit in the conventional line sequential drive system. Compared with the case where the channel width is arranged to be within the pitch of the data line, it is possible to provide a TFT having a wide channel width and a large size for the inverter. Alternatively, in a layout in which the channel width direction of the TFT constituting the inverter corresponds to the Y direction, such as a buffer circuit including an inverter corresponding to each latch circuit in the conventional line sequential drive system, the data line pitch fits. Compared with the case where they are arranged in this way, a TFT having a large channel width and a large size can be provided for the inverter in a region on the substrate limited in the Y direction.

  As a result of the above, according to the present embodiment, it is possible to drive the sampling circuit 302 even if the load on the sampling circuit 302 increases as the number of data lines 6a to be simultaneously driven increases, while effectively using the area on the substrate. The buffer circuit 500 including the inverters 501, 502 and 503 made of large TFTs can be provided, and the data line driving circuit 101 which saves space can perform a good driving operation even at a high dot frequency. Become.

  Further, in the present embodiment, in particular, the channel width of the TFTs constituting the inverters 501, 502 and 503 increases from the first stage to the third stage, that is, the TFT size increases stepwise. Therefore, the load in the sampling circuit 301 that can be driven by the entire inverter can be increased efficiently, and the number of sampling switches 302 that can be driven simultaneously can be increased efficiently. In particular, since the channel width of each TFT constituting the inverters 501, 502 and 503 is increased by about 2 to 4 times for each stage, the total of the three stages is 23 to 43 compared with the case where there is no buffer circuit. = A sampling circuit 301 having a load of about 8 to 64 times can be driven. In the present embodiment, the TFTs constituting the inverters 501, 502, and 503 are complementary TFTs. Therefore, if the channel width is increased e times (about 2.73 times) for each stage, so-called “ According to the “e-times theorem”, the driving capability can be increased very efficiently.

  In the present embodiment, particularly, as shown in FIG. 5, each of the TFTs constituting the inverters 501 and 502 and the upper TFT constituting the inverter 503 share the lead-out wiring 602 a of the low-voltage wiring 602. Yes. Further, the upper TFT and the lower TFT constituting the inverter 503 share the lead-out wiring 601a of the high-voltage wiring 601. Therefore, compared with the case where these are not shared, the length in the Y direction in the entire buffer circuit 500 can be shortened by one lead wire 601a and one lead wire 602a. For example, if the width of the power supply wiring is 10 μm, the total of the two wires can be shortened by 20 μm in the Y direction.

  In the first embodiment described above, the arrangement of the three-stage inverters 501 and the arrangement of the buffer circuits 500 in each buffer circuit 500 are as shown in FIG. 7A. 7 (b) or 7 (c). That is, as shown in FIG. 7B, in each buffer circuit 500 ′, the third-stage inverter 503 ′ may be composed of a single inverter. Alternatively, as shown in FIG. 7C, each buffer circuit 500 ″ may include an inverter 503 ″ in which three or more third-stage inverters 503 ′ are connected in parallel. Since the driving capability of the inverter 503 at the third stage becomes the capability of driving the sampling circuit 301 as the buffer circuit 500, the size of the TFTs constituting the inverter 503 at the third stage (final stage) can be adjusted in this way. This is very advantageous in terms of device design.

  A specific configuration example of the sampling switch 302 constituting the sampling circuit 301 in this embodiment is the one shown in the circuit diagram of FIG.

  That is, as shown in FIG. 8A, the TFT of the sampling circuit 301 may be composed of an N-channel TFT 302a, or may be composed of a P-channel TFT 302b as shown in FIG. As shown in FIG. 8 (3), the TFT may be composed of a complementary TFT 302c. 8A to 8C, the image signal VID input via the image signal line 115 illustrated in FIG. 2 is input to each of the TFTs 302a to 302c as a source voltage. Similarly, sampling control signals 114a and 114b inputted from the data line driving circuit 101 shown in FIG. 2 via the sampling control signal line 114 are inputted to the respective TFTs 302a to 302c as gate voltages. The sampling control signal 114a applied as a gate voltage to the N-channel TFT 302a and the sampling control signal 114b applied as a gate voltage to the P-channel TFT 302b are mutually inverted signals. Therefore, when the sampling circuit 301 is configured by the complementary TFT 302c, at least two sampling control signal lines 114 for the sampling control signals 114a and 114b are required. In addition, each sampling switch 302 constituting the sampling circuit 301 is preferably configured from an N-channel type, a P-channel type, a complementary type, or the like that can be manufactured by the same manufacturing process as the TFT 30 in the pixel portion from the viewpoint of manufacturing efficiency. Is done.

  As described above in detail, according to the first embodiment, since the buffer circuit 500 is laid out so as to efficiently use the region on the TFT array substrate 10, the entire liquid crystal device can be reduced in size and the same size. The image display area in the device can be enlarged, and at the same time, a liquid crystal device that can cope with a high dot frequency and display a high-quality image can be realized.

(Second Embodiment of Liquid Crystal Device)
A second embodiment of a liquid crystal device which is an example of an electro-optical device according to the present invention will be described with reference to FIGS. FIG. 9 is an enlarged plan view showing a buffer circuit, image signal lines, elements formed on the TFT array substrate 10 in the vicinity thereof, and a wiring layout. FIG. 10 shows an arrangement system of a plurality of inverters and a plurality of buffer circuits. It is a block diagram which shows the arrangement | sequence system of 500. 9 and 10, the same components as those in the first embodiment shown in FIGS. 5 and 7 are denoted by the same reference numerals, and the description thereof is omitted.

  In the liquid crystal device of the second embodiment, the configuration of the buffer circuit is different from that of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, the buffer circuit will be described below.

  9 and 10, in the second embodiment, the buffer circuit 1500 includes one-stage inverter 1501 corresponding to each latch circuit 401. This one-stage inverter 1501 is composed of a plurality of inverters connected in parallel so as to extend in the X direction and to be arranged in order in the Y direction. More specifically, a transfer signal wiring 1404 input from the latch circuit 401 via the phase adjustment circuit 402 is extended, and the direction of the channel width coincides with the X direction and is connected in parallel. The gate electrodes of complementary TFTs constituting the inverters are used, and the source or drain on the output side of these complementary TFTs is connected to the sampling control signal line 114.

  According to the second embodiment, the single-stage inverter 1501 is composed of a plurality of inverters connected in parallel and sequentially arranged in the Y direction, so that it corresponds to the total width ΔW of the twelve data lines 6a that are driven simultaneously. The inverter 1501 can be laid out by efficiently utilizing the area on the substrate having a large area (see FIG. 10). Further, since the inverter 1501 constituting the buffer circuit 1500 has one stage, the delay time of the entire buffer circuit 1500 is completely or substantially equal to the delay time in the TFT constituting the one-stage inverter 1501. For this reason, as compared with the case where there are a plurality of stages of inverters 501, 502 and 503 and the delay times are added in series as in the first embodiment, the delay time can be shortened.

  However, in this case, the driving capability sufficient to withstand the load of the one-stage inverter 1501 is required in the latch circuit 401 and the phase adjustment circuit 402 located in the preceding stage.

  Also in the second embodiment, as in the case of the first embodiment shown in FIG. 5, as shown in FIG. 9, the voltage wiring 601 extending in the X direction between a plurality of inverters connected in parallel and The lead wirings 601a and 602b of 602 are shared. For this reason, the length in the Y direction in the entire buffer circuit 1500 can be shortened by two voltage wirings (for example, 10 μm × 2 = 20 μm) as compared with the case where it is not shared.

(Overall configuration of liquid crystal device)
The overall configuration of each embodiment of the liquid crystal device configured as described above will be described with reference to FIGS. 11 is a plan view of the TFT array substrate 10 as viewed from the side of the counter substrate 20 together with the components formed thereon, and FIG. It is H 'sectional drawing.

  In FIG. 11, a sealing material 52 is provided on the TFT array substrate 10 along the edge thereof, and a light shielding film 53 serving as a peripheral parting is provided in parallel to the inside thereof. A data line driving circuit 101 and a mounting terminal 102 are provided along one side of the TFT array substrate 10 in a region outside the sealing material 52, and the scanning line driving circuit 104 extends along two sides adjacent to the one side. Is provided. Needless to say, if the delay of the scanning signal supplied to the scanning line 3a is not a problem, the scanning line driving circuit 104 may be provided on only one side. Further, the data line driving circuit 101 may be arranged on both sides along the side of the image display area. For example, the odd-numbered data lines supply image signals from the data line driving circuit disposed along one side of the image display area, and the even-numbered data lines extend along the opposite side of the image display area. You may make it supply an image signal from the arrange | positioned data line drive circuit. If the data lines 6a are driven in a comb-like shape in this way, the occupied area of the data line driving circuit 101 can be expanded, so that a complicated circuit can be configured. Further, on the remaining side of the TFT array substrate 10, a plurality of wirings 105 are provided for connecting between the scanning line driving circuits 104 provided on both sides of the image display area. Further, at least one corner portion of the counter substrate 20 is provided with a vertical conductive material 106 for electrical conduction between the TFT array substrate 10 and the counter substrate 20. As shown in FIG. 12, the counter substrate 20 having substantially the same contour as the sealing material 52 shown in FIG. 11 is fixed to the TFT array substrate 10 by the sealing material 52, and the TFT array substrate 10 and the counter substrate 20 are fixed. Thus, a liquid crystal device in which the liquid crystal layer 50 is sealed is configured. Further, on the side of the counter substrate 20 facing the liquid crystal layer 50, an opening region of each pixel is defined, and generally called a black mask or a black matrix for improving the contrast ratio and preventing color mixture between adjacent pixels. A light shielding film 23 is provided.

  The TFT array substrate 10 of the liquid crystal device according to each embodiment described above with reference to FIGS. 1 to 12 is further converted into an image signal for each data line 6a in order to reduce the load of writing the image signal to the data line 6a. A precharge circuit for writing a precharge signal of a predetermined potential at a preceding timing may be formed, or an inspection circuit for inspecting the quality, defects, etc. of the liquid crystal device during manufacture or at the time of shipment may be formed. Good. Further, instead of providing a part of peripheral circuits such as the data line driving circuit 101 and the scanning line driving circuit 104 on the TFT array substrate 10, for example, a driving LSI mounted on a TAB (tape automated bonding substrate). In addition, it may be electrically and mechanically connected through an anisotropic conductive film provided on the periphery of the TFT array substrate 10.

  In each of the above embodiments, a light-shielding film made of a refractory metal, for example, may be provided at a position facing the TFT 30 on the TFT array substrate 10 (that is, below the TFT 30). Thus, if a light shielding film is also provided on the lower side of the TFT 30, it is possible to prevent the return light from the TFT array substrate 1 side from entering the TFT 30 in advance.

  Furthermore, for example, the TN (twisted nematic) mode, the STN (super TN) mode, and the D-STN (double) are respectively provided on the side on which the projection light of the counter substrate 20 enters and the side on which the outgoing light of the TFT array substrate 10 exits. -A polarizing film, a retardation film, a polarizing plate, and the like are arranged in a predetermined direction according to an operation mode such as a -STN mode or a normally white mode / normally black mode.

  The liquid crystal device in the embodiment described above can be applied to a color liquid crystal projector. In this case, three liquid crystal devices are used as RGB light valves, and light of each color separated through RGB color separation dichroic mirrors is incident on each panel as projection light. Become. Therefore, in the embodiment, the counter substrate 20 is not provided with a color filter. However, an RGB color filter may be formed on the counter substrate 20 together with the protective film in a predetermined region facing the pixel electrode 9a where the light shielding film 23 is not formed. In this way, the liquid crystal device according to the embodiment can be applied to a color liquid crystal device such as a direct-view type or a reflective type color liquid crystal television other than the liquid crystal projector. Furthermore, a microlens may be formed on the counter substrate 20 so as to correspond to one pixel. In this way, a bright liquid crystal device can be realized by improving the collection efficiency of incident light. Furthermore, a dichroic filter that produces RGB colors by using interference of light may be formed by depositing several layers of interference layers having different refractive indexes on the counter substrate 20. According to this counter substrate with a dichroic filter, a brighter color liquid crystal device can be realized.

    Further, the switching element provided in each pixel may be a normal staggered type or coplanar type polysilicon TFT, but each embodiment also applies to other types of TFTs such as an inverted staggered type TFT and an amorphous silicon TFT. Is valid. Further, it is effective not only for TFTs but also for transistors formed on a silicon substrate.

  (Electronics)

  Next, an embodiment of an electronic device including the liquid crystal device 100 described in detail above will be described with reference to FIGS.

  First, FIG. 13 shows a schematic configuration of an electronic apparatus including the liquid crystal device 100 as described above.

  In FIG. 13, the electronic apparatus includes a display information output source 1000, a display information processing circuit 1002, a drive circuit 1004, a liquid crystal device 100, a clock generation circuit 1008, and a power supply circuit 1010. The display information output source 1000 includes a ROM (Read Only Memory), a RAM (Random Access Memory), a memory such as an optical disk device, a tuning circuit that tunes and outputs an image signal, and the like. Based on this, display information such as an image signal in a predetermined format is output to the display information processing circuit 1002. The display information processing circuit 1002 includes various known processing circuits such as an amplification / polarity inversion circuit, a serial-parallel conversion circuit, a rotation circuit, a gamma correction circuit, and a clamp circuit, and is input based on a clock signal. Digital signals are sequentially generated from the displayed information and output to the drive circuit 1004 together with the clock signal CLK. The drive circuit 1004 drives the liquid crystal device 100. The power supply circuit 1010 supplies predetermined power to the above-described circuits. Note that the drive circuit 1004 may be mounted on the TFT array substrate constituting the liquid crystal device 100, and in addition to this, the display information processing circuit 1002 may be mounted.

  Next, specific examples of the electronic apparatus configured in this way are shown in FIGS.

  In FIG. 14, a liquid crystal projector 1100 as an example of an electronic device prepares three liquid crystal display modules including the liquid crystal device 100 in which the drive circuit 1004 described above is mounted on a TFT array substrate. It is configured as a projector used as 100G and 100B. In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. The light is divided into B and led to the light valves 100R, 100G, and 100B corresponding to the respective colors. At this time, in particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 100R, 100G, and 100B are synthesized again by the dichroic prism 1112 and then projected as a color image on the screen 1120 via the projection lens 1114.

  In FIG. 15, a laptop personal computer (PC) 1200 compatible with multimedia, which is another example of an electronic device, includes the above-described liquid crystal device 100 in a top cover case, and further includes a CPU, a memory, a modem, and the like. And a main body 1204 in which a keyboard 1202 is incorporated.

  In addition to the electronic devices described above with reference to FIGS. 14 to 15, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, an electronic notebook, a calculator, a word processor, an engineering workstation ( EWS), a mobile phone, a video phone, a POS terminal, a device provided with a touch panel, and the like are examples of the electronic device shown in FIG.

  As described above, according to the present embodiment, it is possible to realize various electronic devices including a liquid crystal device capable of high-quality image display with high manufacturing efficiency.

FIG. 3 is a block diagram of an equivalent circuit such as various elements and wirings provided in a plurality of pixels in a matrix form constituting an image forming area in the first embodiment of the liquid crystal device. The block diagram which shows the pixel part and drive circuit which were provided on the TFT array substrate in 1st Embodiment. The block diagram which shows the detailed structure of the data line drive circuit and sampling circuit in 1st Embodiment. 6 is a timing chart of various signals in the data line driving circuit according to the first embodiment. FIG. 3 is an enlarged plan view illustrating a buffer circuit included in the data line driving circuit according to the first embodiment, together with peripheral wiring and the like. FIG. 6 is a circuit diagram of the buffer circuit shown in FIG. 5. The block diagram which shows the various structural examples of the inverter in the buffer circuit in 1st Embodiment. FIG. 3 is a circuit diagram illustrating various configuration examples of a sampling switch included in the sampling circuit according to the first embodiment. The enlarged plan view which expands and shows the buffer circuit contained in the data line drive circuit in 2nd Embodiment of this invention with its periphery wiring. The block diagram of the inverter in the buffer circuit in 2nd Embodiment. The top view which looked at the TFT array board | substrate in each embodiment of a liquid crystal device from the opposing board | substrate side with each component formed on it. HH 'sectional drawing of FIG. The block diagram which shows schematic structure of embodiment of the electronic device by this invention. Sectional drawing which shows a liquid crystal projector as an example of an electronic device. The front view which shows the personal computer as another example of an electronic device.

Explanation of symbols

3a ... scanning line, 3b ... capacitor line, 6a ... data line, 9a ... pixel electrode, 10 ... TFT array substrate, 20 ... counter substrate, 30 ... TFT, 50 ... liquid crystal layer, 52 ... sealing material, 70 ... storage capacitor, DESCRIPTION OF SYMBOLS 101 ... Data line drive circuit 104 ... Scan line drive circuit 114 ... Sampling control signal line 115 ... Image signal line 301 ... Sampling circuit 302 ... Sampling switch 400 ... Shift register circuit 401 ... Latch circuit 402 ... Phase adjustment circuit, 403 ... NAND circuit, 500 ... buffer circuit, 501 ... inverter (first stage), 502 ... inverter (second stage), 503 ... inverter (third stage), 601 ... high voltage wiring, 602 ... low Voltage wiring, 1500... Buffer circuit, 1501.

Claims (7)

A plurality of scan lines;
Multiple data lines,
An electro-optical device drive circuit for driving an electro-optical device including a plurality of pixels provided corresponding to each intersection of the plurality of scanning lines and the plurality of data lines,
The drive circuit is
A shift register circuit;
A transfer circuit supplied with a transfer signal from the shift register circuit and outputting the transfer signal as a sampling control signal;
The buffer circuit includes a plurality of stages of transistor circuits connected in series,
The drive circuit for an electro-optical device, wherein the transistor circuit includes a plurality of transistors arranged in the extending direction of the data line and complementary to each other.   The drive circuit for an electro-optical device according to claim 1, wherein the transistor circuit forms an inverter circuit.   The drive circuit for an electro-optical device according to claim 2, wherein the buffer circuit includes a plurality of the inverter circuits arranged in parallel in the extending direction of the data line and connected in parallel.   4. The drive circuit of the electro-optical device according to claim 1, wherein the complementary transistor has a channel width direction extending in a direction intersecting the data line. 5.   The channel width of the transistors included in the transistor circuits connected in series in the plurality of stages is larger than the channel width of the transistors included in the transistor circuit in the subsequent stage than the channel width of the transistors included in the transistor circuit in the previous stage. The drive circuit of the electro-optical device according to claim 1, wherein   An electro-optical device comprising the drive circuit for the electro-optical device according to claim 1. An electronic apparatus comprising the electro-optical device according to claim 6.

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