JP2007225945A - Display device - Google Patents

Abstract

The present invention provides a display device that can suppress an increase in cost by using an existing driver and is suitable for displaying a moving image, and a driving method thereof.
A display area comprising a plurality of scanning signal lines and a plurality of video signal lines, a scanning signal driver connected to the scanning signal lines in the display area, and a video signal connected to the video signal lines in the display area A timing controller that is connected to the video signal driver and that captures the same continuous image data two by two from the outside, and a frame memory that writes the image data captured by the timing controller. Is to write every other image data out of two consecutive image data to the frame memory, read out the frame frequency when writing the image data into the frame memory, and the image information converted from the frame memory. The frame frequency is different.
[Selection] Figure 2

Description

  The present invention relates to a liquid crystal display device, a hold-type display device such as an organic EL (Electro Luminescence) display and an LCOS (Liquid Crystal On Silicon) display, and a driving method thereof, and more particularly, a display device suitable for displaying moving images and its The present invention relates to a driving method.

  When the display devices are classified particularly from the viewpoint of moving image display, they are roughly classified into impulse-type display devices and hold-type display devices. An impulse type display device is a type in which a pixel shines only during a scanning period and the luminance of the pixel decreases immediately after scanning as in a cathode ray tube. A hold type display device is a display data as in a liquid crystal display device. Is a type that keeps the luminance based on the above until the next scan.

  As a feature of the hold-type display device, in the case of a still image, it is possible to obtain a good display quality without flickering, but in the case of a moving image, so-called moving image blur occurs where the surroundings of a moving object appear blurred. Display quality is degraded. This moving image blurring factor is caused by a so-called retinal afterimage in which the observer interpolates the display image before and after the movement with respect to the display image whose brightness is held when moving the line of sight as the object moves. Even if the response speed of the device is improved, the moving image blur is not completely eliminated.

  As a technique for solving the motion blur of the hold-type display device, for example, as disclosed in Patent Document 1, a technique for inserting blanking data (black display data) between continuous display data (hereinafter, black display data) There is a technique for displaying display data and blanking data in one frame period.

  As a technique for inserting black display data, for example, as described in Patent Document 2, in a hold-type display device, when writing a desired pixel value to a pixel, effective writing is performed during a frame period. In this case, the writing value in the partial period is set higher than the desired pixel value so that the desired pixel value is visually realized by writing in the partial period. Since the writing value of the pixel value is relatively low except during a part of the period, there is known a method for obtaining the visibility of a moving image similar to the impulse display device as a result. In this technique, when a frame period is divided into m and each period is expressed as a first period to an m-th period (m is an integer of 2 or more), a desired pixel value to be written in a pixel is multiplied by m and the first Means is provided for writing in the period and writing 0 in the second period and thereafter. Furthermore, in the same display device, when the pixel value multiplied by m exceeds the displayable range of the display device, the upper limit value of the range is written to the pixel in the first period, and the excess that has not been written is reached in the second period. After that, writing to the pixel is performed, and after that, the excess portion that could not be written in the i-th period (where i is 2 or more and m-1 or less) is sequentially written after the arrival of the i + 1-th period. Can improve sex. Hereinafter, in this specification, this driving method is defined as frame division driving.

  In the liquid crystal display device, moving image blur caused by a slow response speed of the liquid crystal element also occurs. In order to solve the problem of the response speed of the liquid crystal, the gradation of the input image signal of the current frame is input one frame before in accordance with the difference between the input image signal of the previous frame and the input image signal of the current frame. When the gradation is higher (brighter) than the gradation of the image signal, a driving voltage higher than the gradation voltage for the input image signal of the current frame is supplied to the liquid crystal display panel, and the gradation of the input image signal of the current frame is 1 frame. There is known a driving method for supplying a liquid crystal display panel with a driving voltage lower than the gradation voltage for the input image signal of the current frame when the gradation becomes lower (darker) than the previous input image signal (Patent Document). 3).

JP 2003-280599 A JP 2004-240317 A Japanese Patent Laid-Open No. 4-365094

  In general, a frame frequency of about 60 Hz is used as a frame frequency of a display screen in which image flickering is not noticeable. Above this frequency, flickering can be suppressed due to the effect of the afterimage phenomenon in the human eye, but there are cases where flickering occurs if there is an individual difference and is not above 70 Hz. When the frame frequency is 60 Hz, an image of 60 frames is drawn per second. For this reason, it is necessary to create 60 pieces of image data when the moving image content is adjusted to this speed. On the other hand, a specific image with slow movement may be able to cope with an image of 30 frames per second.

  On the other hand, for the liquid crystal panel, the response speed of the liquid crystal becomes important in order to display a moving image. When this response speed is slow, it appears as moving image blur. As a method for improving the response speed, there are a method for increasing the speed of the liquid crystal material itself and a method for improving the display method. As one of the methods for improving the display method, the overdrive drive as described in Patent Document 3 is adopted. Even if the image is slow such as an image of 30 frames per second as described above, flickering occurs at the timing of image switching, so some countermeasure is necessary. However, such overdrive drive is used. Even if a countermeasure against flicker is taken, overdrive driving takes a correction amount from the difference between frames, and therefore there is a problem that the effect cannot be expected so much when the number of frames per second is small.

  In addition, there is so-called double speed driving in which the frame frequency is multiplied by m with respect to the frame frequency of the input display data. In order to perform double speed driving, a driver (for example, a liquid crystal driver) must correspond to that frequency. Therefore, it is necessary to newly develop a component that can handle double speed driving, which leads to an increase in cost.

  On the other hand, it has been found that existing general-purpose drivers that do not need to be newly developed can be used if the frame frequency is about 100 Hz.

  The present invention pays attention to the fact that an existing liquid crystal driver can be driven up to about 100 Hz, and provides a display device suitable for displaying moving images and a driving method thereof that can suppress cost increase by using an existing driver. For the purpose.

  In the present invention, an image of 30 frames per second is assumed to be an image of 90 frames per second in a pseudo manner, and one frame is assumed to be the same three frames, and arithmetic processing is performed on these three frames to improve moving image blur.

  According to one embodiment of the present invention, a display area constituted by a plurality of scanning signal lines, a plurality of video signal lines arranged to intersect the plurality of scanning signal lines, and the scanning signal lines of the display area A display device having a scanning signal driver connected to a video signal driver and a video signal driver connected to a video signal line in a display area, the video signal driver being connected to the video signal driver and receiving the same continuous image data two by two It has a timing controller that captures and a frame memory that writes image data captured by the timing controller, and this timing controller writes every other image data of the same continuous image data to the frame memory. Yes, the frame frequency when writing image data to this frame memory and the image data from this frame memory are changed. The frame frequency at the time of reading out image information are different that, is that.

  According to the present invention, a cost increase can be suppressed by using an existing driver, and a display device suitable for displaying a moving image and a driving method thereof can be provided.

  Further, the timing controller reads the image information from the frame memory at a frame frequency higher than the frame frequency for writing the image data to the frame memory.

  Specifically, the frame frequency when reading image information from the frame memory is 100 Hz or less, and the frame frequency when writing image data to the frame memory is 66 Hz or less.

  According to the present invention, a cost increase can be suppressed by using an existing driver, and a display device suitable for displaying a moving image and a driving method thereof can be provided.

  According to another embodiment of the present invention, a display area composed of a plurality of scanning signal lines, a plurality of video signal lines arranged to intersect the plurality of scanning signal lines, and a scanning signal line of the display area. A timing controller that includes a connected scanning signal driver and a video signal driver connected to a video signal line in a display area, and is a timing controller that is connected to the video signal driver and captures the same continuous image data two by two And a frame memory for writing the image data captured by the timing controller. The timing controller writes every other image data of the same continuous image data to the frame memory. In addition, this timing controller receives the same continuous image data two by two at a frame frequency of 66 Hz or less. Ri, the video signal driver, the frame frequency to output an image signal obtained by converting the image data at 100Hz below the display area, is that.

  Specifically, this timing controller writes image data to the frame memory at a frame frequency of 66 Hz or less, and reads image information obtained by converting the image data at a frame frequency of 100 Hz or less from the frame memory.

  According to still another embodiment of the present invention, a display area composed of a plurality of scanning signal lines, a plurality of video signal lines arranged to intersect the plurality of scanning signal lines, and a scanning signal line of the display area The scanning signal driver connected to the video signal driver, the video signal driver connected to the video signal line of the display area, the timing controller connected to the video signal driver, and the image data is written or converted by the timing controller. The timing controller has a frame memory for reading image information, and the timing controller writes every other image data out of the image data taken in by the timing controller to the frame memory at the first frame frequency. Reading image information at a second frame frequency higher than the frequency A.

  Specifically, the second frame frequency is preferably 100 Hz or less, and the first frame frequency is 66 Hz or less.

  According to the present invention, the video signal driver can process the image signal obtained by converting the image data at a frame frequency of 100 Hz or less (for example, about 90 Hz). A display device can be provided.

  The present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a system configuration of the present invention. The present invention relates to a display device. Here, a liquid crystal display device will be described as an example of the display device.

  Reference numeral 1 denotes an entire configuration of the liquid crystal display device of the present invention. In the liquid crystal display device 1, a display area 10 and a drive driver arranged around the display area 10 are arranged. In the display area 10, a plurality of scanning signal lines 11 and a plurality of video signal lines 12 arranged so as to intersect the plurality of scanning signal lines 11 via an insulating film are arranged. Pixels are configured corresponding to the areas surrounded by the video signal lines 12. Each pixel is provided with a switching element 13 arranged corresponding to the intersection of the scanning signal line 11 and the video signal line 12, and a pixel electrode 14 connected to the switching element 13 and a common electrode (not shown). Is configured to control the liquid crystal. The liquid crystal display device is configured by sandwiching liquid crystal between a pair of substrates, and the display region 10 is configured on one of the pair of substrates. The common electrode may be disposed on either side of the pair of substrates.

  The scanning signal line 11 is connected to the scanning signal driver 15, and the video signal line 12 is connected to the video signal driver 16.

  A timing controller 22 (hereinafter referred to as “TCON”) disposed on the TCON substrate 21 of the liquid crystal display device 1 receives content 101 having a slow motion with a frame frequency of 30 Hz from the graphic chip 20 outside the liquid crystal display device 1. Reference numerals 23 and 24 denote SDRAMs (frame memories) arranged on the TCON substrate 21.

  In this embodiment, the signal sent from the graphic controller 20 to the TCON 22 and the signal until the TCON 22 writes to the SDRAM 1, 2 (23, 24) are called image data, and the TCON 22 is called from the SDRAM 1, 2 (23, 24). A signal to be read is called image information, and a signal when this image information is output to the video signal line 12 of the display area 10 via the video signal driver 16 is called an image signal.

  Next, the driving method of the present invention will be described with reference to FIG.

  FIG. 2 is a diagram showing a timing chart of the present invention.

  DATA in FIG. 2 indicates image data input from the graphic controller 20 to the TCON board 21. In this embodiment, the image A is sent twice from the graphic controller 20 at a frame frequency of 60 Hz. If the view is changed, the image A as image data is sent once at 30 Hz.

  The TCON 22 indicates that the image A sent from the graphic controller 20 is written in the SDRAM 1 (23) at a frame frequency of 60 Hz, and the written image A is subsequently held. In other words, the TCON 22 writes every other piece of image data out of the same continuous image data in the SDRAM 1 (23) (frame memory).

  Next, an image B is sent twice from the graphic controller 20 to the TCON 22 at a frame frequency of 60 Hz. At this timing, the TCON 22 reads the image A as image information from the SDRAM 1 (23) at a frame frequency of 90 Hz, and then continues to the frame. Similarly, image A is read out at a frequency of 90 Hz. Furthermore, black data is read out at a frame frequency of 90 Hz.

  The TCON 22 sends the image A, the image A, and the black data as the read image information to the video signal driver 16 as DOUT102.

  The graphic controller 20 sends the image B twice to the TCON 22 at a frame frequency of 60 Hz. At this timing, the TCON 22 writes the image B to the SDRAM 2 (24) at the frame frequency of 60 Hz, and then holds the image B. ing.

  Next, an image C is sent twice from the graphic controller 20 to the TCON 22 at a frame frequency of 60 Hz. At this timing, the TCON 22 reads the image B from the SDRAM 2 (24) at a frame frequency of 90 Hz, and then continues at the frame frequency of 90 Hz. Read image B. Further, black data is read out at a frame frequency of 90 Hz.

  The TCON 22 sends the read image B, image B, and black data to the video signal driver 16 as DOUT102.

  The graphic controller 20 sends the image C twice to the TCON 22 at a frame frequency of 60 Hz. At this timing, the TCON 22 writes the image C to the SDRAM 1 (23) at the frame frequency of 60 Hz, and subsequently holds the image C. That's it.

  The video signal driver 16 sends the image information sent from the TCON 22 to the video signal line 12 in the display area 10 as an image signal.

  Note that the TCON 22 writes image data sent from the graphic controller 20 or reads image information using the SDRAM 1 (23) and SDRAM 2 (24), but when writing, the frame frequency is set to 60 Hz. In the case of reading, the frame frequency is 90 Hz. As described above, the TCON 22 captures the same continuous image data by two, and the TCON 22 writes every other image data of the same continuous two pieces of data to the SDRAM 1, 2 (23, 24). It is one of the features of the present invention that the TCON 22 reads at a frame frequency higher than the frame frequency at which the SDRAM 1 and 2 (23, 24) write.

  One feature is that the frame frequency for reading is set to 90 Hz, which is 100 Hz or less, which can be handled by a general-purpose driver, and the frame frequency for writing is set to 1.5 times the 60 Hz. As described above, in order to perform the reading frame frequency higher than the frame frequency at which the TCON 22 performs writing to the SDRAMs 1, 2 (23, 24), the TCON 22 and the SDRAMs 1, 2 (23, 24) This can be done by increasing the bus width.

  In the case of the present invention, by changing the frequency (60 Hz) at which the TCON 22 writes to the SDRAM 1, 2 (23, 24) and the frequency (90 Hz) at which reading is performed, It is possible to read three times, in other words, three times for two times of writing, and in this three times of reading, processing such as overdrive and black writing can be performed. Can be displayed. In this example, the reading is described as 90 Hz and the writing as 60 Hz. However, the reading may be 100 Hz or less, and the writing may be 66 Hz or less.

  In addition, as in the conventional display device, even when the frequency (for example, 60 Hz) at which the TCON 22 performs writing to the SDRAMs 1 and 2 (23, 24) and the frequency at which the reading is performed (for example, 60 Hz) is the same, On the other hand, since it is possible to perform reading twice, black data can be written using one of the two readings. In this case, overdrive or black writing is performed in the two readings. It is not possible to perform processing by performing various data conversions. In this case, the writing is performed twice. For convenience, the writing may be performed once and the remaining one may be retained.

  In the case of the present embodiment, 1.5 readings are performed for one writing, in other words, three readings are performed for two writings. Such driving is also possible.

  That is, as a first example, image information obtained by overdriving, for example, the image A is read out in the first one of the three readings, and is output to the video signal driver 16 as DOUT102, and in the next two times. A process of reading the normal image A twice is conceivable.

  Furthermore, as a second example, image information obtained by overdriving the image A at the first time is read, the normal image A is read at the next time, and black data is read at the next time. Conceivable.

  Furthermore, a method of adjusting the second and third image information described in the second example will be described as a third example. In the third example, since the signal overdriving the image A is read at the first time and the deterioration of the image brightness is reduced at the second time and the third time, the brightness is slightly increased from the normal image A at the second time. The image information is read out, the image information is read out by lowering the brightness so that the brightness increased in the third time is close to black data, and the average of the brightness in the second and third times is two normal images. It can be considered to be almost the same as the average of minutes.

  As described above, according to the present invention, it is possible to provide a display device capable of reducing flicker and reducing moving image blur by setting the image information read from the TCON to be read three times per second.

  Next, another driving method of the present invention will be described with reference to FIG.

  FIG. 3 shows a timing chart of the present invention.

  DATA in FIG. 3 indicates image data input from the graphic controller 20 to the TCON board 21. In the present embodiment, the graphic controller 20 sends image A, which is image data at a frame frequency of 60 Hz, twice. If the view is changed, the image A is sent once at 30 Hz.

  In the case of FIG. 3, the TCON 22 converts the images A, A, B, B, C,... Sent from the graphic controller 20 into the images A, A, like the timing chart of FIG. Captured at the timing of image B. In the timing chart shown in FIG. 3, the TCON 22 indicates that the image A is written in the SDRAM 1 (23) at a frame frequency of 60 Hz and is subsequently held. That is, the image B is captured, but the image B is not used for writing to the SRAM 1.

  Next, an image B and an image C sent from the graphic controller 20 to the TCON 22 at a frame frequency of 60 Hz are captured. At this timing, the TCON 22 receives an image A from the SDRAM 1 (23) as image information at a frame frequency of 90 Hz. Next, the image A is similarly read out at a frame frequency of 90 Hz. Furthermore, black data is read out at a frame frequency of 90 Hz.

  The TCON 22 sends the read image A, image A, and black data to the video signal driver 16 as DOUT102.

  In addition, at the timing of capturing the image B and image C sent from the graphic controller 20 to the TCON 22 at a frame frequency of 60 Hz, the TCON 22 writes the image B to the SDRAM 2 (24) at the frame frequency of 60 Hz and subsequently holds this image B. is doing.

  Next, at the timing of fetching the image C and the image D sent from the graphic controller 20 to the TCON 22 at a frame frequency of 60 Hz, the TCON 22 reads the image B from the SDRAM 2 (24) at a frame frequency of 90 Hz, and then continues at a frame frequency of 90 Hz. Similarly, the image B is read out. Further, black data is read out at a frame frequency of 90 Hz.

  The TCON 22 sends the read image B, image B, and black data to the video signal driver 16 as DOUT102.

  In addition, at the timing of capturing the image C and the image D sent from the graphic controller 20 to the TCON 22 at the frame frequency of 60 Hz, the TCON 22 writes the image C to the SDRAM 1 (23) at the frame frequency of 60 Hz and subsequently holds this image C. is doing.

  Thus, the timing chart as shown in FIG. 3 results in the same output data as the timing chart shown in FIG.

It is drawing which shows the whole structure of this invention. It is drawing which shows the timing chart of this invention. It is drawing which shows another timing chart of this invention.

Explanation of symbols

1 display device, 10 display area, 11 scanning signal line, 12 video signal line,
13 switching elements, 14 pixel electrodes, 15 scanning signal drivers,
16 video signal driver, 20 graphic controller, 21 TCON board,
22 Timing controller, 23 SDRAM1, 24 SDARM2

Claims (9)

A display area constituted by a plurality of scanning signal lines and a plurality of video signal lines arranged to intersect the plurality of scanning signal lines;
A scanning signal driver connected to the scanning signal line of the display area;
A video signal driver connected to the video signal line of the display area,
A timing controller connected to the video signal driver and capturing the same continuous image data two by two;
A frame memory for writing the image data captured by the timing controller;
The timing controller is
Of every two consecutive identical image data, every other image data is written into the frame memory,
A display device in which a frame frequency for writing the image data in the frame memory is different from a frame frequency for reading image information obtained by converting the image data from the frame memory. In claim 1,
The display device, wherein the timing controller reads the image information from the frame memory at a frame frequency higher than a frame frequency for writing the image data to the frame memory. In claim 2,
A display device having a frame frequency of 100 Hz or less when reading the image information from the frame memory. In claim 3,
A display device having a frame frequency of 66 Hz or less when the image data is written in the frame memory. A display area constituted by a plurality of scanning signal lines and a plurality of video signal lines arranged to intersect the plurality of scanning signal lines;
A scanning signal driver connected to the scanning signal line of the display area;
A video signal driver connected to the video signal line of the display area,
A timing controller connected to the video signal driver and capturing the same continuous image data two by two;
A frame memory for writing the image data captured by the timing controller;
The timing controller writes every other image data in the frame memory among the same continuous image data two by two,
The timing controller receives the same continuous image data two by two at a frame frequency of 66 Hz or less,
The video signal driver is a display device that outputs an image signal obtained by converting the image data with a frame frequency of 100 Hz or less to the display area. In claim 5,
The display device, wherein the timing controller writes the image data at a frame frequency of 66 Hz or less into the frame memory, and reads out image information obtained by converting the image data at a frame frequency of 100 Hz or less from the frame memory. A display area constituted by a plurality of scanning signal lines and a plurality of video signal lines arranged to intersect the plurality of scanning signal lines;
A scanning signal driver connected to the scanning signal line of the display area;
A video signal driver connected to the video signal line of the display area;
A timing controller connected to the video signal driver;
A frame memory for writing image data by the timing controller and reading image information obtained by converting the image data;
The timing controller writes every other image data of the image data captured by the timing controller to the frame memory at a first frame frequency, and outputs a second higher than the first frame frequency from the frame memory. A display device that reads out the image information at a frame frequency. In claim 7,
The display device, wherein the second frame frequency is 100 Hz or less. In claim 8,
The display device, wherein the first frame frequency is 66 Hz or less.

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