JP2006227312A - Liquid crystal display panel, liquid crystal display device, and video display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve animation characteristics without degrading luminance. <P>SOLUTION: The liquid crystal panel is attained by comprising; two or more scan lines located in the direction of rows; two or more signl lines located in the direction of columns; two or more liquid crystal pixels L<SB>mn</SB>matrix-located at each intersectional part of the two or more scan lines and the two or more signal lines; two or more storage means C1<SB>mn</SB>which are prepared correspondingly to the respective two or more liquid crystal pixels L<SB>mn</SB>, and temporarily hold one frame of video signals to be written in the liquid crystal pixels L<SB>mn</SB>, respectively; and a control means 67 which controls to write the video signals by a signal line driving means 62 in the storage means C1<SB>mn</SB>prepared correspondingly to the liquid crystal pixels L<SB>mn</SB>in the direction of rows selected by a scan line driving circuit 63, and which controls, after having finished writing all the video signals, to write one frame of the video signals written in the two or more storage means C1<SB>mn</SB>in all of the two or more corresponding liquid crystal pixels L<SB>mn</SB>, simultaneously. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device including a liquid crystal display panel that displays an image by being illuminated by a backlight device, and more specifically, a liquid crystal display panel that displays an image with excellent moving image characteristics, a liquid crystal display device, and an image table. Regarding the method.

  Instead of CRT (Cathode Ray Tube), which has been used for many years since the start of television broadcasting, it has been made very thin, such as a liquid crystal display (LCD) and a plasma display (PDP). Television receivers have been devised and put into practical use. In particular, liquid crystal display devices using a liquid crystal display panel can be driven with low power consumption, and it is considered that the liquid crystal display device will spread at an accelerated pace with the price reduction of large color liquid crystal display panels. This is a display device that can be expected to develop further in the future.

  In the liquid crystal display device, a backlight system in which an image is displayed by illuminating a transmissive liquid crystal display panel from the back side with a backlight device is mainly used. As a light source of the backlight device, a CCFL (Cold Cathode Fluorescent Lamp) that emits white light using a fluorescent tube, a light emitting diode (LED), or the like is used.

  As a liquid crystal display panel, for example, an active matrix type panel in which each display pixel is individually controlled by a switching element such as a thin film transistor (TFT) and crosstalk or the like hardly occurs and is suitable for high definition and large capacity. It has become mainstream.

  An active matrix type liquid crystal display device using such an active matrix type liquid crystal display panel supplies a video signal to liquid crystal cells arranged in a two-dimensional matrix via data lines arranged in a vertical direction. It is driven by a data line driving circuit and a gate line driving circuit that activates a switching element such as a TFT through a gate line arranged in the horizontal direction to display an image.

  Specifically, the video signal is serially transferred to the line memory of the data line driving circuit and held. Then, the gate line is activated by the gate line driving circuit, and a video signal is supplied to one line of liquid crystal cells arranged in the horizontal direction on the gate line. The gate line driving circuit sequentially selects the gate lines in the vertical direction, so that the video signals are written in the line sequential order in the liquid crystal cells arranged in a two-dimensional matrix. The liquid crystal display device repeats this every frame period to display a moving image corresponding to the video signal.

JP 2000-321551 A

  In general, a liquid crystal display device including such an active matrix liquid crystal display device can display an image having color and brightness only by combining a liquid crystal display panel and a backlight device.

  In other words, the image displayed on the liquid crystal display device depends not only on the change in transmittance of the liquid crystal sealed in the liquid crystal display panel according to the video signal, but also on the illumination light emitted from the backlight device. Will do. Usually, the illumination light emitted from the backlight device always illuminates the liquid crystal display panel with a constant luminance. On the other hand, the liquid crystal display panel adjusts the illumination light emitted from the backlight device by changing the liquid crystal transmittance of each liquid crystal cell according to the video signal, and adjusts the color and brightness. Is displayed.

  The video signal written in each liquid crystal cell of the liquid crystal display panel in a certain frame period is always held in the liquid crystal cell until the video signal is written in the next frame period. As described above, since the illumination light of the backlight device always illuminates the liquid crystal display panel, a transient state at the moment when a certain frame is switched to the next frame (between frames) is displayed. Become. A display method in which the display state of each pixel is held until the next frame period as in this active matrix type liquid crystal display device is called a hold-type display method.

  As is well known, the response characteristic of the liquid crystal is very slow. Thus, when the liquid crystal display panel is always illuminated, not only the image of the current frame but also the image of the immediately preceding frame are visually recognized. Therefore, the visually recognized image becomes an image having very poor moving image characteristics in which a so-called image blur occurs.

  There is a CRT (Cathode-Ray Tube) which has been used as a mainstream display as a display having a better moving image characteristic than a liquid crystal display device. The CRT displays an image by scanning the CRT tube surface with an electron beam in order from the upper side and causing the phosphor applied on the CRT tube surface to emit light. At this time, the phosphor at the irradiation point emits light for a few ms from the time when the electron beam is irradiated.

  For example, when the frame rate is 60 Hz, one frame period is approximately 16.7 ms. As described above, in the CRT, since the phosphor irradiated with the electron beam emits light for only several ms, each pixel has a light emitting state during one frame period as in the case of a hold type liquid crystal display device. Is not retained, so that the afterimage is not left in the next frame.

  Therefore, the CRT can display an image with very good moving image characteristics without causing image blur and the like. A display method in which each pixel is caused to emit light for a very short period of one frame period, such as this CRT, is called an impulse display method.

  Further, when a video signal is written in each liquid crystal cell of the liquid crystal display panel within the frame period, as described above, the liquid crystal display panel is line-sequentially driven by the data line driving circuit and the gate line driving circuit, thereby 1 A frame image is displayed. Thus, when displaying an image by line-sequentially driving the liquid crystal display panel of the liquid crystal display device, if the light source of the backlight device is continuously lit (always lit), the above-described transient state between frames Similarly, the transient state of the liquid crystal, that is, the transient state in which line-sequential driving is performed is also visually recognized within the same frame. Therefore, an image blur occurs in an image that is visually recognized even in the same frame.

  As described above, since the active matrix liquid crystal display device is a hold type display method, the moving image characteristic is very poor as compared with the CRT of the impulse type display method. Therefore, in order to improve such moving image characteristics, a method has been devised in which the hold type display method is brought close to the impulse type display method.

  Specifically, the impulse-type display system is realized in a pseudo manner by lighting the liquid crystal display panel of the backlight device blinking every frame period, which is always turned on until now.

  For example, as shown in FIG. 15, a backlight device 110 having a light source in which four cold cathode fluorescent lamps CL1 to CL4 are arranged in a horizontal direction is used, and a liquid crystal display panel 120 as shown in FIG. Consider a liquid crystal display device 100 to be illuminated. At this time, the cold cathode tubes CL1 to CL4 that are the light sources of the backlight device 110 are controlled to blink simultaneously every one frame period (16.7 ms), thereby avoiding the visual recognition of the transient state. To see if it improves.

At this time, as shown in FIG. 16, the pixel GA1 belonging to the horizontal pixel line HA _u1 in the upper portion U, the pixel GA2 belonging to the horizontal pixel line HA _u2 , the pixel GA3 belonging to the horizontal pixel line HA _m1 in the middle M, and the horizontal pixel line HA _The pixel GA4 belonging to _m2 , the pixel GA5 belonging to the lower B horizontal pixel line HA _b1 , and the pixel GA6 belonging to the horizontal pixel line HA _b2 are used as sample pixels for verifying the transient state.

  FIG. 17 shows a light source emission period in the case where the cold cathode fluorescent lamps CL1 to CL4 are simultaneously blinked for every four frames, and a liquid crystal transmittance response of the liquid crystal sealed in the liquid crystal cell corresponding to each sample pixel. The waveform is shown. In general, a cold-cathode tube has a predetermined gradient between the rise until reaching the light emission peak and the fall from the light emission peak to extinction, but for the sake of clarity, the cold cathode tube has a steep rise. It is shown as an image that falls.

  The liquid crystal transmittance response waveform of each of the pixels GA1 to GA6 shown in FIG. 17 indicates that the state in which the waveform is flat indicates that the writing into the liquid crystal cell is completed and the transient state has passed. Conversely, the rise and fall of the liquid crystal transmittance response waveform indicate a transient state. In the liquid crystal display device 100, the liquid crystal display panel 120 is scanned line-sequentially, and therefore, as shown in FIG. It has changed.

  Therefore, even if the cold cathode tubes CL1 to CL4 that are the light sources of the backlight device 110 are controlled to blink simultaneously every frame period in order to approach the hold type display method to the impulse type display method, At the x mark shown in FIG. 17, the transient state of the liquid crystal is visually recognized.

  That is, by blinking the light source of the backlight device 110 for each frame period, the moving image characteristics between frames can be improved, but the image blur in one frame cannot be improved.

  Therefore, in order to improve the image blur in one frame, as shown in FIG. 18, the light emission timings of the cold cathode tubes CL1 to CL4 which are the light sources of the backlight device 110 are not simultaneously set as described above. There is a method in which the timing of the pixels of the liquid crystal display panel is synchronized with the line sequential scanning, that is, the light emission timing is sequentially shifted.

  When the liquid crystal display panel is divided into a predetermined number of blocks, for example, an upper block, an intermediate block, a lower block, etc., and the corresponding block is scanned, any of the corresponding cold cathode tubes CL1 to CL4 is scanned. Turn on the light and turn off the others.

  As described above, when the emission timings of the cold cathode tubes CL1 to CL4 are sequentially shifted, the light source emission period of the cold cathode tubes CL1 to CL4 and the liquid crystal transmission of the liquid crystal sealed in the liquid crystal cell corresponding to each sample pixel. The relationship with the rate response waveform is as shown in FIG. As shown in FIG. 19, by shifting the light emission timing within one frame period, it is possible to avoid illuminating the transient state of the liquid crystal, thereby eliminating image blur.

  However, although the image blur is eliminated, each cold cathode tube CL1 to CL4 constituting the light source of the backlight device 110 is caused to emit light for each block, and only the corresponding area of the liquid crystal display panel is illuminated. There is a problem that a new structure is required to appropriately guide light emission and prevent light from leaking outside the target region, resulting in an increase in manufacturing cost. In addition, since the light emission time of the light source is shortened within one frame period, it is difficult to secure a desired luminance, which causes an increase in power consumption.

  Therefore, the present invention has been devised to solve the above-described problems, and a liquid crystal display panel, a liquid crystal display device, and a video display that display an image with excellent moving image characteristics without reducing luminance. It aims to provide a method.

  In order to achieve the above object, a liquid crystal display panel according to the present invention includes a plurality of scanning lines arranged in a row direction, a plurality of signal lines arranged in a column direction, the plurality of scanning lines, A plurality of liquid crystal pixels arranged in a matrix at each intersection with a plurality of signal lines and a video signal for one frame that is provided corresponding to each of the plurality of liquid crystal pixels and written to the liquid crystal pixels are temporarily A plurality of storage means for holding, a scanning line driving circuit that is connected to the scanning line, drives the scanning line sequentially to select the liquid crystal pixels in the row direction, and the row direction selected by the scanning line driving circuit After the video signal is written to the plurality of storage means by the signal line drive circuit for writing the video signal to the storage means provided corresponding to the liquid crystal pixels, and the signal line drive circuit, The plurality of storage means The written video signal of the one frame, for each corresponding plurality of liquid crystal pixels, and a controlling means for controlling to write all at the same time.

  In order to achieve the above object, a liquid crystal display device according to the present invention is a liquid crystal display device including a liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel. A plurality of scanning lines arranged in the direction, a plurality of signal lines arranged in the column direction, the plurality of scanning lines, and a plurality of liquid crystal pixels arranged in a matrix at each intersection of the plurality of signal lines A plurality of storage means provided corresponding to each of the plurality of liquid crystal pixels and temporarily holding a video signal for one frame to be written to the liquid crystal pixels, and connected to the scanning lines, The video signal is supplied to a scanning line driving circuit that selects the liquid crystal pixels in the row direction by line-sequential driving and the storage means provided corresponding to the liquid crystal pixels in the row direction selected by the scanning line driving circuit. Signal line to write The video signal written to the plurality of storage means is converted into the corresponding plurality of liquid crystal pixels after all of the writing of the video signal to the plurality of storage means is completed by the moving circuit and the signal line driving circuit. Each has write control means for controlling to write all at the same time.

  The backlight device includes a light source that emits illumination light that illuminates the liquid crystal display panel, and the video signal is written from the plurality of storage units to the plurality of liquid crystal pixels within one frame period. And a light source control means for controlling the light source to be turned on after the transient state has elapsed.

  Furthermore, in order to achieve the above object, an image display method according to the present invention includes a liquid crystal display panel and a liquid crystal display device including a backlight device that illuminates the liquid crystal display panel. The display panel is arranged in a matrix at each intersection of the plurality of scanning lines arranged in the row direction, the plurality of signal lines arranged in the column direction, the plurality of scanning lines, and the plurality of signal lines. A scanning line driving circuit connected to the scanning lines from a plurality of liquid crystal pixels drives the scanning lines line-sequentially to select the liquid crystal pixels in the row direction, and is provided corresponding to each of the plurality of liquid crystal pixels. In addition, among the plurality of storage units that temporarily hold one frame of video signals to be written to the liquid crystal pixels, the above description corresponding to the liquid crystal pixels in the row direction selected by the scanning line driving circuit is provided. After the video signal is written to the plurality of storage means by the signal line drive circuit, the video signal is written to the plurality of storage means. The video signal is controlled to be written simultaneously to each of the corresponding liquid crystal pixels, and the backlight device transmits the plurality of liquid crystal pixels to the plurality of liquid crystal pixels from the plurality of storage means within one frame period. The light source that emits the illumination light that illuminates the liquid crystal display panel is turned off in a transition state when the video signal is written, and the light source is controlled to be turned on after the transition state has elapsed. And

  According to the present invention, since all the liquid crystal pixels of the liquid crystal display panel are rewritten at the same timing, the light source of the backlight device is turned off in the transient state in accordance with the rewrite timing of the liquid crystal pixels and is turned on after the transient state has elapsed. Control can be performed easily and reliably.

  Therefore, since the video signal written in the liquid crystal pixel can be displayed in an impulse manner, the image blur of the moving image display due to the afterimage phenomenon can be suppressed, and the moving image characteristics can be improved.

  Since all video signals are written to all the liquid crystal pixels of the liquid crystal display panel at the same time, the timing for turning on the light source of the backlight device can be easily optimized so that the lighting period is maximized. Therefore, it is possible to improve luminance without increasing power consumption.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following examples, It cannot be overemphasized that it can change arbitrarily in the range which does not deviate from the summary of this invention.

  The present invention is applied to, for example, a color liquid crystal display device 50 configured as shown in FIG. The color liquid crystal display device 50 includes a transmissive color liquid crystal display panel 10 and a backlight device 40 provided on the back side of the color liquid crystal display panel 10. Although not shown, the color liquid crystal display device 50 includes a receiving unit such as an analog tuner and a digital tuner that receives terrestrial and satellite waves, and a video signal processing unit that processes a video signal and an audio signal received by the receiving unit, respectively. The audio signal processing unit may include an audio signal output unit such as a speaker that outputs the audio signal processed by the audio signal processing unit.

  The transmissive color liquid crystal display panel 10 has two transparent substrates (TFT substrate 11 and counter electrode substrate 12) made of glass or the like arranged opposite to each other, and, for example, a twisted nematic (TN) liquid crystal in the gap. The liquid crystal layer 13 encapsulating the liquid crystal layer 13 is provided. On the TFT substrate 11, signal lines 14 arranged in a matrix, scanning lines 15, thin film transistors 16 serving as switching elements arranged at intersections of the signal lines 14 and the scanning lines 15, and pixel electrodes 17 are formed. Has been. The thin film transistor 16 is sequentially selected by the scanning line 15 and writes the video signal supplied from the signal line 14 to the corresponding pixel electrode 17. On the other hand, a counter electrode 18 and a color filter 19 are formed on the inner surface of the counter electrode substrate 12.

FIG. 2 shows an equivalent circuit of the color liquid crystal display panel 10, and the configuration of the color liquid crystal display panel 10 will be described in more detail. For the sake of explanation, the signal line 14, the scanning line 15, and the thin film transistor 16 are referred to as a signal line Y _n (n is a natural number), a scanning line X _m (m is a natural number), and a thin film transistor T1 _mn , respectively. To. Further, a pixel formed by the liquid crystal layer 13 sandwiched between the pixel electrode 17 and the counter electrode 18 is referred to as a liquid crystal pixel L _mn .

As shown in FIG. 2, the thin film transistor T1 _mn is connected the source electrode to the signal line Y _n, a gate electrode connected to the scan line X _m, and a drain electrode connected to the storage capacitor C1 _mn. The color liquid crystal display panel 10 has not been shown in FIG. 1, a thin film transistor _{T 2mn,} and _{T 3 mn,} and an auxiliary capacitor _{C 2mn.}

The thin film transistor T2 _mn has a source electrode connected to the drain electrode of the thin film transistor T _mn and the auxiliary capacitor C1 _mn , a gate electrode connected to the common electrode Gcom1, a drain electrode connected to the liquid crystal pixel L _mn (pixel electrode 17 side), It is connected to the auxiliary capacitor _C2mn .

The thin film transistor T3 _mn has a source electrode connected to the drain electrode of the thin film transistor T _2mn , a liquid crystal pixel L _mn (on the pixel electrode 17 side), and an auxiliary capacitor C2 _mn , a gate electrode connected to the common electrode Gcom2, and a drain electrode connected to the liquid crystal The counter electrode 18 has the same potential as the counter electrode voltage Vcom of the counter electrode 18 of the pixel _Lmn .

FIG. 3 shows an equivalent circuit of the liquid crystal display panel 120 included in the conventional active matrix liquid crystal display device 100 shown in FIG. As shown in FIG. 3, the liquid crystal display panel 120 includes a thin film transistor T _mn , a pixel electrode L _mn, and an auxiliary capacitor C _mn for each pixel. The thin film transistor T _mn has a source electrode connected to the signal line Y _n , a gate electrode connected to the scanning line X _n , and a drain electrode connected to the liquid crystal pixel L _mn (on the pixel electrode 17 side) and the auxiliary capacitor C _mn . .

Thus, the liquid crystal display panel 10 shown in FIG. 2, the conventional liquid crystal display panel 120, which is a thin film transistor _{T 2mn,} and _{T 3 mn,} a configuration obtained by adding the auxiliary capacitance _{C 2mn.} The liquid crystal display panel 10 configured as described above can simultaneously write the pixel data written in the liquid crystal pixels L _mn in line sequential manner in all the liquid crystal pixels L _mn in the conventional liquid crystal display panel 120. The pixel data writing operation to the liquid crystal display panel 10 will be described in detail later.

  The color filter 19 is divided into a plurality of segments corresponding to each pixel. For example, as shown in FIG. 4, it is divided into three segments of a red filter CFR, a green filter CFG, and a blue filter CFB which are three primary colors. The arrangement pattern of the color filter 19 includes, in addition to the stripe arrangement as shown in FIG. 4, a delta arrangement and a square arrangement, although not shown.

  The configuration of the transmissive color liquid crystal display device 50 will be described again with reference to FIG. In the transmissive color liquid crystal display device 50, the transmissive color liquid crystal display panel 10 having such a configuration is sandwiched between two polarizing plates 31 and 32, and white light is irradiated from the back side by the backlight device 40. By driving with an active matrix system, a desired full-color image can be displayed.

  The backlight device 40 illuminates the color liquid crystal display panel 10 from the back side. As shown in FIG. 1, the backlight device 40 includes a backlight housing 40 that uniformly illuminates a light source (not shown) or white light emitted from the light source over the entire color liquid crystal display panel 10. The body 20 includes a diffusion plate 41, an optical function sheet group 45 such as a diffusion sheet 42, a prism sheet 43, and a polarization conversion sheet 44 that are arranged on the diffusion plate 41.

  The diffusion plate 41 uniformizes the luminance in surface emission by internally diffusing the light emitted from the light source in the backlight housing unit 20.

  In general, the optical function sheet group has, for example, a function of decomposing incident light into orthogonal polarization components, a function of compensating for a phase difference of light waves to achieve a wide-angle viewing angle and preventing coloring, a function of diffusing incident light, and a brightness improvement And is provided to convert light emitted from the backlight device 40 into illumination light having optical characteristics optimal for illumination of the color liquid crystal display panel 10. . Therefore, the configuration of the optical function sheet group 45 is not limited to the above-described diffusion sheet 42, prism sheet 43, and polarization conversion sheet 44, and various optical function sheets can be used.

  FIG. 5A shows a schematic configuration in the backlight housing unit 20 from which the diffusion plate 41 and the optical function sheet group 45 are removed. As shown in FIG. 5 (a), the backlight housing 20 includes cold cathode fluorescent lamps (CCFLs) CL1 to CL4 that emit white light as light sources. The four cold-cathode tubes CL1 to CL4 are substantially equal to the vertical direction of the backlight casing 20 so that the longitudinal direction in the backlight casing 20 coincides with the horizontal direction of the color liquid crystal display panel 10. Arranged at intervals.

  FIG. 5B shows a cross-sectional view of the backlight casing 20 taken along the line XX shown in FIG. Here, the diffusion plate 41 that has been removed in FIG. 5A is provided. In order to increase the utilization efficiency of the light emitted from the cold cathode tubes CL1 to CL4, the inner surface 20a and the bottom surface 20b of the backlight casing 20 shown in FIGS. A plate is provided. As a result, the white light emitted from the cold cathode fluorescent lamps CL1 to CL4 is reflected without absorbing the light partially reflected by the diffuser plate 41, and is emitted as illumination light through the diffuser plate 41. Therefore, the light use efficiency can be greatly improved.

  The color liquid crystal display device 50 is driven by, for example, a drive circuit 60 as shown in FIG.

  The driving circuit 60 is supplied from the outside by a power source 61 that supplies driving power for the color liquid crystal display panel 10 and the backlight device 40, a signal line driving circuit 62 and a scanning line driving circuit 63 that drive the color liquid crystal display panel 10. An RGB process processing unit 65 to which a video signal received and a video signal received by a receiving unit (not shown) included in the color liquid crystal display device 50 and processed by the video signal processing unit are supplied via an input terminal 64, An image memory 66 and a control unit 67 connected to the RGB process processing unit 65, a backlight drive control unit 68 for driving and controlling the backlight device 40, and the like are provided.

  In the drive circuit 60, the video signal input through the input terminal 64 is subjected to signal processing such as chroma processing by the RGB process processing unit 65, and further suitable for driving the color liquid crystal display panel 10 from the composite signal. It is converted into an RGB separate signal and supplied to the controller 67 and also supplied to the signal line drive circuit 62 via the image memory 66.

  The control unit 67 controls the signal line driving circuit 62 and the scanning line driving circuit 63 at a predetermined timing according to the RGB separate signal, and is supplied to the signal line driving circuit 62 through the image memory 66. By driving the color liquid crystal display panel 10 with the RGB separate signal, an image corresponding to the RGB separate signal is displayed.

  The backlight drive control unit 68 generates a desired control signal from the voltage supplied from the power supply unit 61, and drives the cold cathode tubes CL <b> 1 to CL <b> 4 that are light sources of the backlight device 40. The backlight drive control unit 68 secures desired luminance and avoids complicating the structure of the backlight device 40, so that a transient state between frames as shown in FIG. The cold cathode tubes CL1 to CL4 are driven by a driving method in which the cold cathode tubes CL1 to CL4 are simultaneously turned on every frame period to avoid visual recognition.

  As described in the prior art, when the cold cathode fluorescent lamps CL1 to CL4 are simultaneously turned on every frame period, the liquid crystal transient state is visually recognized within one frame period as shown in FIG. Therefore, as will be described in detail later, the color liquid crystal display panel 10 is controlled so that pixel data is simultaneously written to all the pixels so that the transient state is not visually recognized.

  The user interface 69 selects a channel to be received by the above-described receiving unit (not shown), adjusts an audio output amount to be output by an audio output unit (not shown), or from the backlight device 40 that illuminates the color liquid crystal display panel 10. This is an interface for executing white light brightness adjustment, white balance adjustment, and the like.

  Subsequently, an operation of writing pixel data to the liquid crystal display panel 10 will be described. Before describing the pixel data writing operation to the liquid crystal display panel 10, the pixel data writing operation to the conventional liquid crystal display panel 120 shown in FIG. 3 will be described.

First, when writing pixel data to the liquid crystal display panel 120, the signal line driving circuit writes the video signal supplied to the signal lines Y _n. For example, the signal lines Y _1, as a video signal, an analog data signal V _d1 as shown in FIG. 7 are written.

In response to this, the scanning line driving circuit sequentially supplies the selection signal V _xn to the scanning line _Xn to turn on the thin film transistor _Tmn . 8A and 8B show the state of the selection signals V _x1 and V _x2 supplied to the scanning lines X ₁ and X ₂ .

Thereby, the thin film transistor T _1n and the thin film transistor T _{2n ... Are} sequentially turned on. By repeating this up to the scanning line _Xn , all the thin film transistors _Tmn can be turned on in line order.

The period during which the selection signal V _xn is supplied to one scanning line _Xn is a 1H period determined by 1H (sec) ≦ 1/60 [Hz] / n when the frame rate is 60 Hz. That is, the scanning line _Xn is sequentially selected every 1H period. When the frame rate is 60 Hz, the same scanning line _Xn is selected with a period of 16.67 ms.

Thus, when the video signal is written to the signal line Y _n and the thin film transistor T _mn is turned on, the liquid crystal pixel L _mn and the auxiliary capacitor C _mn are turned on at the timing when the thin film transistor T _mn is turned on. voltage of the signal line Y _n is applied. As a result, the transmittance of the liquid crystal of the liquid crystal pixel L _mn changes to a desired transmittance, so that the video signal is written as pixel data.

FIGS. 8C and 8D show the state of the voltage values V _d11 and V _d21 applied to the liquid crystal pixels L ₁₁ and L ₂₁ at the timing when the selection signals V _x1 and V _x2 are in the high state. Further, FIG. 9 (a), the (b), the in the case the liquid crystal of the liquid crystal pixel _{L 11, L 21} is a so-called normally black, indicating the respective liquid crystal pixels _{L 11, L 21} luminance.

As can be seen from FIGS. 9A and 9B, the writing timing of the pixel data to the liquid crystal pixels L ₁₁ and L ₂₁ adjacent in the vertical direction is delayed by the 1H period from the writing timing to the liquid crystal pixel L ₂₁ . . Thus, in the conventional liquid crystal display panel 120, it can be seen that writing to the liquid crystal pixels _Lmn is executed in line order.

  Next, an operation of writing pixel data to the liquid crystal display panel 10 shown in FIG. 2 which is provided in the color liquid crystal display device 50 shown as the best mode for carrying out the present invention will be described.

First, when writing pixel data to the liquid crystal display panel 10, the signal line driving circuit 62 shown in FIG. 6 writes the supplied video signal to the signal lines Y _n. For example, the signal lines Y _1, as a video signal, an analog data signal V _d1 as shown in FIG. 10 is written.

In response to this, the scanning line driving circuit 63 sequentially supplies the selection signal V _xn to the scanning line _Xn to turn on the thin film transistor T1 _mn . FIGS. 11A and 11B show the state of the selection signals V _x1 and V _x2 supplied to the scanning lines X ₁ and X ₂ .

Thereby, the thin film transistor T1 _1n and the thin film transistor T1 _{2n ... Are} sequentially turned on. By repeating this up to the scanning line _Xn , all the thin film transistors T1 _mn can be turned on in line sequential order.

The period during which the selection signal V _xn is supplied to one scanning line _Xn is a 1H period determined by 1H (sec) ≦ 1/60 [Hz] / n when the frame rate is 60 Hz. That is, the scanning line _Xn is sequentially selected every 1H period. When the frame rate is 60 Hz, the same scanning line _Xn is selected with a period of 16.67 ms.

As described above, when the video signal is written to the signal line Y _n and the thin film transistor T1 _mn is turned on, the auxiliary capacitor C1 _mn has a voltage value of the signal line Y _n at the timing when the thin film transistor T1 _mn is turned on. Is applied.

FIGS. 11C and 11D show the states of the voltage values V _d11 and V _d21 applied to the auxiliary capacitors C1 ₁₁ and C1 ₂₁ at the timing when the selection signals V _x1 and V _x2 are in the high state.

When voltages are applied to all C1 _mn in this way, at the next timing, as shown in FIG. 12A, the common electrode Gcom2 is in a high state and all thin film transistors T3 _mn are in an ON state. The As a result, the counter electrode voltage Vcom is applied to both ends of all the liquid crystal pixels L _mn and the auxiliary capacitance C2 _mn and reset.

When the liquid crystal pixel L _mn and the auxiliary capacitor C2 _mn are reset, the common electrode Gcom2 is set to the low state and all the thin film transistors T3 _mn are set to the OFF state. At the same timing, the common electrode Gcom1 as shown in FIG. 12 (b) becomes a High state, all of the thin-film transistor _{T2 mn} is the ON state. Thereby, as shown in FIG. 12C, the voltage value stored in the auxiliary capacitor C1 _mn is simultaneously set to all the liquid crystal pixels L _mn and the auxiliary capacitor C1 at the timing when the common electrode Gcom1 is set to the High state. applied to _mn .

As a result, the transmissivity of the liquid crystal of all the liquid crystal pixels L _{mn included in} the liquid crystal display panel 10 changes to the transmissivity corresponding to the applied voltage value, so that the video signal is written as pixel data.

Further, FIG. 12 (d), the in (e), when the liquid crystal of the liquid crystal pixel _{L 11, L 21} is a so-called normally black, indicating the respective liquid crystal pixels _{L 11, L 21} luminance.

As can be seen from FIGS. 12D and 12E, the writing timing of the pixel data to the liquid crystal pixels L ₁₁ and L ₂₁ adjacent in the vertical direction is the same timing. Thus, it can be seen that in the liquid crystal display panel 10 included in the liquid crystal display device 50 shown as the embodiment of the present invention, writing to the liquid crystal pixel L _mn is executed collectively for each frame.

In this manner, in the liquid crystal display panel 10, the timing of writing the pixel data for all pixels, since the voltage supply timing of the common electrode Gcom1, liquid crystal in the liquid crystal pixel L _mn can be specified easily period in a transient state Therefore, it is possible to control the timing at which the four cold-cathode tubes CL1 to CL4, which are the light sources of the backlight device 40, emit light at the same time so as to avoid a period in which the liquid crystal is in a transient state.

  For example, is it possible to control the cold cathode tubes CL1 to CL4, which are the light sources of the backlight device 40, to blink simultaneously every frame period (16.7 ms), avoiding the visual recognition of the transient state, and improving the moving image characteristics? Verify whether.

As shown in FIG. 13, when the display area of the liquid crystal display panel 10 is roughly divided into an upper part U, an intermediate part M, and a lower part B, the pixels G1 and the horizontal pixel line _Hu2 belonging to the horizontal pixel line _Hu1 in the upper part U pixel G2, the pixel G3 belonging to the horizontal pixel line _{H m1} of the intermediate portion M, a pixel G4 belonging to the horizontal pixel line _{H m @ 2,} the pixel G5 belonging to the horizontal pixel line _{H b1} of the lower B, pixel G6 belonging to the horizontal pixel line _{H b2} belonging Are used as sample pixels for verifying the transient state.

  FIG. 14 shows a light source emission period in the case where the cold cathode fluorescent lamps CL1 to CL4 are simultaneously blinked for every four frames, and a liquid crystal transmittance response of the liquid crystal sealed in the liquid crystal cell corresponding to each sample pixel. The waveform is shown. In general, a cold-cathode tube has a predetermined gradient between the rise until reaching the light emission peak and the fall from the light emission peak to extinction, but for the sake of clarity, the cold cathode tube has a steep rise. It is shown as an image that falls.

The liquid crystal transmittance response waveform of each of the pixels G1 to G6 shown in FIG. 14 indicates that when the waveform is flat, writing into the liquid crystal cell is completed and the transient state has passed. Conversely, the rise and fall of the liquid crystal transmittance response waveform indicate a transient state. As described above, in the liquid crystal display panel 10, the writing to the liquid crystal pixels L _mn is simultaneously performed at the same time. Therefore, as shown in FIG. The upper portion U, the middle portion M, and the lower portion B occur in the same period.

  Therefore, in order to bring the hold type display method closer to the impulse type display method, the cold cathode tubes CL1 to CL4 that are the light sources of the backlight device 40 are provided with liquid crystal transients every frame period as shown in FIG. It is easy to control to turn off the lights at the same time so as to avoid the state and turn them on at the same time when the writing is completed.

  In other words, by simultaneously flashing the light source of the backlight device 10 for each frame period, not only image blur between frames but also image blur within one frame period can be improved without lowering the luminance. Can do.

Since the timings at which video signals are written to all the liquid crystal pixels L _mn of the liquid crystal display panel 10 are all simultaneous, the lighting period is the maximum when the cold cathode tubes CL1 to CL4 that are the light sources of the backlight device 40 are turned on. Therefore, the luminance can be improved without increasing power consumption.

  Although the cold cathode tubes CL1 to CL4 are used as the light source of the backlight device 40, the present invention is not limited to this. For example, three primary color (R, G, B) light emitting diodes, An electroluminescence (EL) lamp, a plasma lamp, or the like may be used as the light source.

It is a figure for demonstrating the structure of the color liquid crystal display device shown as the best form for implementing this invention. It is the figure which showed the equivalent circuit of the color liquid crystal display panel with which the same color liquid crystal display device is provided. It is the figure which showed the equivalent circuit of the general active matrix type liquid crystal display panel with which the conventional liquid crystal display device is provided. It is a figure for demonstrating the color filter of the color liquid crystal display panel with which the same color liquid crystal display device is provided. (A) is a top view for demonstrating the structure of a backlight apparatus, (b) is sectional drawing when the backlight apparatus shown to (a) is cut | disconnected by XX. It is a block diagram for demonstrating the drive circuit which drives the color liquid crystal display device. It is the figure which showed an example of the video signal written in a signal line in the conventional liquid crystal display panel. In a conventional liquid crystal display panel, (a) and (b) are diagrams showing examples of selection signals supplied to scanning lines, and (c) and (d) are voltage values applied to liquid crystal pixels. It is the figure shown about. (A), (b) is the figure which showed the time change of the brightness | luminance of the liquid crystal pixel on a different horizontal line. 4 is a diagram showing an example of a video signal written to a signal line in the liquid crystal display panel of the present invention. FIG. In the liquid crystal display panel of the present invention, (a) and (b) are diagrams showing examples of selection signals supplied to scanning lines, and (c) and (d) are voltages applied to liquid crystal pixels. It is the figure shown about the value. (A) is a figure which showed the mode of the signal supplied at the timing which erases the image data already written in the liquid crystal pixel collectively, (b) is the signal supplied at the write timing to the liquid crystal pixel. It is the figure which showed the mode of. (C), (d) is the figure which showed the time change of the brightness | luminance of the liquid crystal pixel on a different horizontal line. It is the figure which showed the position of the liquid crystal pixel of the liquid crystal display panel which shows the relationship between the write-in timing to the liquid crystal pixel demonstrated in FIG. 14, and the lighting timing of the light source of a backlight apparatus, and a light extinction timing. It is the figure which showed the relationship between the write-in timing to a liquid crystal pixel, and the lighting on / off timing of the light source of a backlight apparatus. It is the top view which showed the structure of the backlight apparatus with which the liquid crystal display device shown as a prior art is provided. FIG. 19 is a diagram showing the position of the liquid crystal pixel of the liquid crystal display panel showing the relationship between the writing timing to the liquid crystal pixel described in FIGS. 17 and 18 and the timing of turning on / off the light source of the backlight device in the liquid crystal display device. . In the same liquid crystal display device, it is the figure which showed the relationship between the write-in timing to a liquid crystal pixel, and the lighting timing of the light source of a backlight apparatus, and a light extinction timing. It is the figure which showed a mode that the light source of a backlight apparatus was driven sequentially in the perpendicular direction and blinked. In the same liquid crystal display device, it is the figure which showed the relationship between the write-in timing to a liquid crystal pixel, and the lighting timing of the light source of a backlight apparatus, and a light extinction timing.

Explanation of symbols

10 liquid crystal display panel, 40 backlight device, 50 liquid crystal display device, CL1, CL2, CL3, CL4 cold cathode tube, _Lmn liquid crystal pixel, _T1mn , _T2mn , _T3mn thin film transistor, _C1mn , _C2mn auxiliary capacitance

Claims (6)

A plurality of scanning pixels arranged in a row direction, a plurality of signal lines arranged in a column direction, a plurality of liquid crystal pixels arranged in a matrix at each intersection of the plurality of scanning lines and the plurality of signal lines When,
A plurality of storage means provided corresponding to each of the plurality of liquid crystal pixels, each temporarily storing a video signal for one frame to be written to the liquid crystal pixels;
A scanning line driving circuit connected to the scanning line and driving the scanning line sequentially to select the liquid crystal pixels in the row direction;
A signal line driving circuit for writing the video signal to the storage means provided corresponding to the liquid crystal pixels in the row direction selected by the scanning line driving circuit;
After all writing of the video signal to the plurality of storage means is completed by the signal line driving circuit, the video signal for one frame written to the plurality of storage means is converted into the corresponding plurality of liquid crystal pixels. A liquid crystal display panel comprising control means for controlling writing to each of them simultaneously. The control means, after the writing of the video signals to the plurality of storage means is completed by the signal line driving circuit, simultaneously outputs all the video signals for one frame already written to the plurality of liquid crystal pixels. The liquid crystal display panel according to claim 1, wherein the liquid crystal display panel is erased. In a liquid crystal display device comprising a liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel,
The liquid crystal display panel is arranged in a matrix at each intersection of a plurality of scanning lines arranged in a row direction, a plurality of signal lines arranged in a column direction, the plurality of scanning lines, and the plurality of signal lines. A plurality of liquid crystal pixels,
A plurality of storage means provided corresponding to each of the plurality of liquid crystal pixels, each temporarily storing a video signal for one frame to be written to the liquid crystal pixels;
A scanning line driving circuit connected to the scanning line and driving the scanning line sequentially to select the liquid crystal pixels in the row direction;
A signal line driving circuit for writing the video signal to the storage means provided corresponding to the liquid crystal pixels in the row direction selected by the scanning line driving circuit;
After the writing of the video signal to the plurality of storage means is completed by the signal line driving circuit, the video signal written to the plurality of storage means is sent to each of the corresponding plurality of liquid crystal pixels. Write control means for controlling all writing simultaneously,
The backlight device includes a light source that emits illumination light that illuminates the liquid crystal display panel;
Within one frame period, the light source is turned off in a transient state when the video signal is written from the plurality of storage means to the plurality of liquid crystal pixels, and the light source is turned on after the transient state has elapsed. And a light source control means for controlling the liquid crystal display device. The writing control means of the liquid crystal display panel is provided for one frame already written in the plurality of liquid crystal pixels after all the writing of the video signal to the plurality of storage means is completed by the signal line driving circuit. The liquid crystal display device according to claim 3, wherein all video signals are erased simultaneously. In a video display method of a liquid crystal display device comprising a liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel,
The liquid crystal display panel is arranged in a matrix at each intersection of a plurality of scanning lines arranged in a row direction, a plurality of signal lines arranged in a column direction, the plurality of scanning lines, and the plurality of signal lines. From the plurality of liquid crystal pixels, a scanning line driving circuit connected to the scanning lines selects the liquid crystal pixels in the row direction by driving the scanning lines line-sequentially,
The plurality of storage means provided corresponding to each of the plurality of liquid crystal pixels and temporarily storing one frame worth of video signals to be written to the liquid crystal pixels are selected by the scanning line driving circuit. The video signal is written by the signal line driving circuit to the storage means corresponding to the liquid crystal pixels in the row direction,
After the writing of the video signal to the plurality of storage means is completed by the signal line driving circuit, the video signal written to the plurality of storage means is sent to each of the corresponding plurality of liquid crystal pixels. , Control to write all at the same time,
The backlight device emits illumination light for illuminating the liquid crystal display panel in a transient state when the video signal is written from the plurality of storage units to the plurality of liquid crystal pixels within one frame period. Is turned off,
An image display method comprising: controlling the light source to be turned on after the transient state has elapsed. In the liquid crystal display panel, after all the writing of the video signals to the plurality of storage units is completed by the signal line driving circuit, all the video signals for one frame already written in the plurality of liquid crystal pixels are displayed. 6. The video display method according to claim 5, wherein the video display method is erased simultaneously.

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