JP2007147790A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To emphasize a contour without using a frame memory in a display device. <P>SOLUTION: The display device provided with a display panel having a plurality of pixels and a driving circuit for driving the display panel on the basis of display data input from the outside has a memory for storing display data of a previous frame in j pixels smaller than all the pixels of the display panel out of the display data input from the outside and a decision circuit for deciding whether an image to be displayed on the display panel is a moving picture or not by comparing the display data of the previous frame in j pixels stored in the memory with the display data to be displayed on a current frame. When the image is decided to be a moving picture by the decision circuit, the driving circuit emphasizes and displays the contour of the display data input from the external in an area having pixels more than j pixels. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly, to a technique effective when applied to a drive circuit of a display device used for a mobile phone or the like.

A TFT (Thin Film Transistor) type liquid crystal display module having a small liquid crystal panel with a sub-pixel number of about 240 × 320 × 3 in color display is widely used as a display unit of a portable device such as a mobile phone.
On the other hand, for example, in a large-sized liquid crystal display device used for a large monitor or the like, there is a device in which outline enhancement is performed in order to make a display image sharp. (See Patent Document 1 below)

As prior art documents related to the invention of the present application, there are the following.
JP 7-199856 A

In a small liquid crystal display module used for a mobile phone or the like, since the screen of the liquid crystal display panel is small, there is a problem that it is difficult to see fine portions of the display screen, for example, a small ball such as a golf relay or a baseball relay. is there. This is particularly true for moving images.
In order to solve the above-described problems, it is effective to emphasize the edge of a small ball such as a golf relay or a baseball relay by a contour enhancement technique. On the other hand, a large liquid crystal display module includes a frame memory.
As a conventional well-known contour emphasis technique, there is a technique that increases the emphasis degree according to the spatial momentum of a moving image, but a frame memory is necessary for comparison with the previous frame. Is difficult to mount on a driver of a small liquid crystal display module.
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a technique capable of performing edge enhancement without using a frame memory in a display device. There is to do.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) A display device comprising a display panel having a plurality of pixels and a drive circuit for driving the display panel based on display data input from outside, wherein the display data is input from the outside A memory for storing display data of the previous frame in j pixels smaller than the total number of pixels of the display panel; display data of the previous frame in the j pixels stored in the memory; and A determination circuit that determines whether the image to be displayed on the display panel is a moving image by comparing with display data to be displayed, and the driving circuit is determined to be a moving image by the determination circuit In such a case, display is performed by emphasizing the outline of the display data input from the outside with respect to an area having more than j pixels.

(2) In (1), the j number is 1/10 or less of the total number of pixels of the display panel.
(3) In (1) or (2), the determination circuit compares the display data of the previous frame stored in the memory with the display data to be displayed in the current frame. When the predetermined number or more does not match, it is determined that the image to be displayed on the display panel is a moving image.
(4) In any one of (1) to (3), the drive circuit includes the memory and the determination circuit, and a memory capacity to be mounted is smaller than that of all pixels of the display panel.
(5) In any one of (1) to (4), the display panel is a display panel having a definition of 150 ppi or more.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the display device of the present invention, it is possible to perform contour enhancement without using a frame memory.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display module according to an embodiment of the present invention.
The liquid crystal panel (PNL) is provided with a plurality of scanning lines (or gate lines) (G1 to G320) and video lines (or drain lines) (S1 to S720) in parallel.
A pixel portion is provided corresponding to a portion where the scanning line (G) and the video line (S) intersect. The plurality of pixel portions are arranged in a matrix, and each pixel portion is provided with a pixel electrode (ITO1) and a thin film transistor (TFT). One pixel is three subpixels. In FIG. 1, the number of subpixels of the liquid crystal panel (PNL) is 240 × 320 × 3.
A common electrode (also referred to as a counter electrode or a common electrode) (ITO2) is provided so as to face each pixel electrode (ITO1) with the liquid crystal interposed therebetween. Therefore, a liquid crystal capacitor (LC) is formed between each pixel electrode (ITO1) and the common electrode (ITO2).
The liquid crystal panel (PNL) includes a glass substrate (substrate) (GLASS) provided with a pixel electrode (ITO1), a thin film transistor (TFT), and a counter substrate (not shown) on which a color filter or the like is formed. The two substrates are bonded together by a seal material provided in a frame shape near the peripheral edge between the two substrates, and the seal between the two substrates is sealed from the liquid crystal sealing opening provided in a part of the seal material. A liquid crystal is sealed and sealed inside the material, and a polarizing plate is attached to the outside of both substrates.
Both substrates are not limited to glass substrates. Further, since the present invention is not related to the internal structure of the liquid crystal panel, a detailed description of the internal structure of the liquid crystal panel is omitted. Furthermore, the present invention can be applied to a liquid crystal panel having any structure.

In this embodiment, a drive circuit (DRV) is mounted on a glass substrate (GLASS).
The driving circuit (DRV) drives the controller circuit 100, a source driver (video line driving circuit) 130 for driving the video line (S) of the liquid crystal panel (PNL), and a scanning line (G) of the liquid crystal panel (PNL). A gate driver (scanning line driving circuit) 140 that performs power supply voltage necessary for displaying an image on the liquid crystal panel (PNL) (for example, a common voltage (Vcom) supplied to the common electrode (ITO2) of the liquid crystal panel (PNL)) ) And the like, and a memory circuit 150. In FIG. 1, FPC is a flexible circuit board.
Note that FIG. 1 illustrates the case where the drive circuit (DRV) is configured by one semiconductor chip. However, the drive circuit (DRV) includes, for example, a thin film transistor that uses low-temperature polysilicon for a semiconductor layer. And may be formed directly on a glass substrate (GLASS).
Similarly, a part of the circuit of the drive circuit (DRV) may be divided and the drive circuit (DRV) may be configured by a plurality of semiconductor chips. A thin film transistor using low-temperature polysilicon as a layer may be used to form directly on a glass substrate (GLASS).
Further, the drive circuit (DRV) or a part of the drive circuit (DRV) may be formed on the flexible circuit board instead of being mounted on the glass substrate (GLASS).

The controller circuit 100 receives each signal for controlling the entire liquid crystal display module based on display data and a display control signal input from a microcomputer on the main body side (hereinafter referred to as MCU) or from a graphic controller or the like. Output to.
The gate of the thin film transistor (TFT) in each pixel portion is connected to the scanning line (G), and the drain is connected to the video line (S1 to S720).
When the scanning signal from the gate driver 140 is output to the scanning line (G), the thin film transistor (TFT) is turned on. When the video voltage is applied from the source driver 130 to the video line (S) while the thin film transistor (TFT) is on, the video voltage is applied to the pixel electrode (ITO1) via the thin film transistor (TFT), and the liquid crystal capacitance (IT LC) is written video voltage. As a result, an image is displayed on the liquid crystal display panel (PNL). In FIG. 1, SC is the scanning direction.
FIG. 2 is a block diagram showing a schematic internal configuration of the source driver 130 shown in FIG.
In this embodiment, display data is stored at a predetermined address in the memory circuit 150. The display data stored in the memory circuit 150 is read from the memory circuit 150 in accordance with the driving timing of the liquid crystal, and temporarily stored as one row of display data in the data latch circuit 11 through the edge emphasis circuit 10.
On the other hand, the gradation voltage generation circuit 13 is a circuit that generates a plurality of gradation voltages necessary for gradation display, and generates, for example, 64 gradation voltages.
Next, the selector (also referred to as a decoder) 12 selects one gradation voltage from among the 64 gradation voltages according to the display data held in the data latch circuit 11, and the selector 12 selects the gradation voltage. The gradation voltage thus amplified is current-amplified by the output circuit 14 and output to the video lines (S1 to S720).

In this embodiment, an edge emphasis circuit 10 is provided before the data latch circuit 11.
FIG. 3 is a block diagram showing a schematic configuration of an example of the contour emphasizing circuit 10 shown in FIG. In FIG. 3, Lat and Latb are storage circuits that operate according to the latch clock DCLK. For example, a latch circuit or a memory can be used, but in the following description, description will be made as a latch circuit.
In the edge emphasis circuit shown in FIG. 3, the display data f (X (n + 1)) of the subpixel immediately after the target subpixel and the display data f (x of the target subpixel delayed by the latch circuit (Latb)). Xn) and the display data f (X (n-1)) of the subpixel immediately before the target subpixel delayed by the two latch circuits (Latb) are input to the arithmetic circuit 21, and the arithmetic circuit 21 The display data of the three consecutive subpixels is weighted to generate display data F (Xn) with enhanced contours.
The moving image detection circuit 20 determines whether or not the displayed image is a moving image, and when the displayed image is a moving image, controls the multiplexer (MP) to select the display data F (Xn) with the contour enhanced. When the displayed image is a still image, normal display data is selected.
Now, the display data value of the target sub-pixel (Xn) is f (Xn), and the display data value of the sub-pixel (X (n-1)) immediately before the target sub-pixel is f (X (n-1)). , F (X (n + 1)) is the display data value of the subpixel (X (n + 1)) immediately after the target subpixel, and F (Xn) is the display data value of the target subpixel with the outline enhanced , The arithmetic circuit 21 executes the following equation (1).
[Equation 1]
F (Xn) = A * f (X (n-1)) + B * f (Xn) + C * f (X (n + 1))
.... (1)
However, A, B, and C are filter coefficients.

For example, when the original data has the values shown in Table 1 and A = −0.3, B = 1.6, and C = −0.3, the display data values of the emphasized subpixels (X3) and (X8) are enhanced. Is obtained by the following equation (2).
[Equation 2]
F (X3) = A * f (X2) + B * f (X3) + C * f (X4)
= −0.3 × 20 + 1.6 × 50−0.3 × 100
= 44
F (X8) = − 0.3 × 100 + 1.6 × 50−0.3 × 20
= 44
(2)
When the original data has the values shown in Table 1 and the filter coefficients are A = −0.3, B = 1.6, and C = −0.3, the display data value with the edge emphasis is converted into the converted data (D1 in Table 1). ).
Furthermore, the display data value with the edge emphasis when the original data is the value shown in Table 1 and the filter coefficients are A = −0.6, B = 2.2, and C = −0.6 is converted into the post-conversion data in Table 1. Shown in (D2).
A graph of Table 1 is shown in FIG.
In the graph shown in FIG. 4, (D0) is the original data (D0) and (D1) shown in Table 1, the converted data (D1) and (D2) in Table 1, and the converted data (D2) in Table 1. ).
[Table 1]

FIG. 5 is a block diagram showing a schematic configuration of another example of the edge enhancement circuit 10 shown in FIG. In the contour emphasis circuit shown in FIG. 5, the arithmetic circuit 21 weights the display data f (Xn) of the target subpixel and the display data f (X (n-1)) of the subpixel immediately before the target subpixel. To generate display data with enhanced outline.
Now, the display data value of the target sub-pixel (Xn) is f (Xn), and the display data value of the sub-pixel (X (n-1)) immediately before the target sub-pixel is f (X (n-1)). When the display data value in which the contour of the subpixel of interest is emphasized is F (Xn), the arithmetic circuit 21 performs the calculation of the following equation (3).
[Equation 3]
F (Xn) = A ′ × f (X (n−1)) + B ′ × f (Xn)
.... (3)
However, A ′ and B ′ are filter coefficients.
For example, when the original data has the values shown in Table 2 and A ′ = − 0.3 and B ′ = 1.3, the display data values of the emphasized sub-pixels (X3) and (X8) with the edge emphasis are as follows: It is obtained by the equation (4).
[Equation 4]
F (X3) = A ′ × f (X2) + B ′ × f (X3)
= -0.3 x 20 + 1.3 x 50
= 59
F (X8) = − 0.3 × 100 + 1.3 × 50
= 35
.... (4)
When the original data is the value shown in Table 2 and the filter coefficients are A ′ = − 0.3 and B ′ = 1.3, the display data value with the enhanced edge is converted into converted data (D1) in Table 2. Show.
Further, when the original data has the values shown in Table 2 and the filter coefficients are A ′ = − 0.6 and B ′ = 1.6, the display data value with the edge enhanced is converted to the post-conversion data (D2) in Table 2. Shown in
A graph of Table 2 is shown in FIG.
In the graph shown in FIG. 6, (D0) is the original data (D0) and (D1) shown in Table 2, the converted data (D1) and (D2) in Table 2 are the converted data (D2) in Table 2. ).
[Table 2]

In the contour enhancement circuit shown in FIG. 5, the arithmetic circuit 21 weights the display data f (Xn) of the target subpixel and the display data f (X (n + 1)) of the subpixel immediately after the target subpixel. It is also possible to generate display data with an enhanced outline.
Now, the display data value of the target subpixel (Xn) is f (Xn), and the display data value of the subpixel (X (n + 1)) immediately after the target subpixel is f (X (n + 1)). When the display data value in which the contour of the subpixel of interest is emphasized is F (Xn), the arithmetic circuit 21 executes the following equation (5).
[Equation 5]
F (Xn) = B ′ × f (Xn) + C ′ × f (X (n + 1))
(5)
However, B ′ and C ′ are filter coefficients.
For example, when the original data has the values shown in Table 3, and B ′ = 1.3 and C ′ = − 0.3, the display data values of the emphasized subpixels (X3) and (X8) with the contour emphasis are as follows: It is obtained by the equation (6).
[Equation 6]
F (X3) = B ′ × f (X3) + C ′ × f (X4)
= 1.3 × 50−0.3 × 100
= 35
F (X8) = 1.3 × 50−0.3 × 20
= 59
.... (6)
When the original data is the value shown in Table 3 and the filter coefficients are B ′ = 1.3 and C ′ = − 0.3, the display data value with the edge emphasis is converted into the converted data (D1) in Table 3. Show.
Further, when the original data has the values shown in Table 3 and the filter coefficients are B ′ = 1.6 and C ′ = − 0.6, the display data value with the enhanced edge is converted into the post-conversion data (D2) in Table 3. Shown in
A graph of Table 3 is shown in FIG.
In the graph shown in FIG. 7, (D0) is the original data (D0) and (D1) shown in Table 3, the converted data (D1) and (D2) in Table 3, and the converted data (D2) in Table 3 ).
[Table 3]

The moving image detection circuit 20 shown in FIGS. 3 and 5 determines whether or not the displayed image is a moving image. When the displayed image is a moving image, the moving image detecting circuit 20 controls the multiplexer (MP) to display the outline-enhanced display. When data is selected and the displayed image is a still image, normal display data is selected.
Therefore, the moving image detection circuit 20 needs to store the display data of the previous frame, but in this embodiment, not all the display data of the previous frame is stored, but the liquid crystal display panel (PNL). ) Save the display data of any multiple points.
FIG. 8 is a diagram showing a plurality of points for storing display data of the previous frame in the liquid crystal display panel (PNL) in the present embodiment. In FIG. 3, a circled portion (P) in FIG. 3 is a point for storing display data of the previous frame, and is shown as four in this embodiment.
In this embodiment, the unit for storing the display data of the previous frame is a pixel or a subpixel, and the number of points to be stored is 1 or more and less than the total number of subpixels (here, 240 × 320 × 3), Preferably, it is 1 or more and several tens of subpixels (about 1/2 to 1/10 at most). Further, the plurality of points for storing the display data of the previous frame are preferably near the center of the liquid crystal display panel (PNL).
The moving image detection circuit 20 compares the display data of the previous frame and the display data of the next frame at the point described above to determine whether or not the image is a moving image. For example, when there is a change in at least one of the above-mentioned points, or a predetermined number of points or more, it is determined as a moving image.
In this embodiment, only a part of the screen displayed on the liquid crystal display panel (PNL) is seen and it is judged whether or not it is a moving image, so there is a possibility of making an erroneous determination. It is effective for implementation.

In general, image quality tends to deteriorate when edge enhancement is performed on a low definition panel such as a large TV, and the above-described contour enhancement is a high definition panel such as a liquid crystal display module used in a mobile phone or the like. It is more effective in the case of, and the video looks beautiful with edge enhancement. Therefore, in this embodiment, the definition of the liquid crystal display panel (PNL) is preferably 150 PPI (Pixels per Inch) or more.
There is no particular upper limit on the definition, but the upper limit on the definition is limited to about 1000 PPI due to manufacturing restrictions.
For example, when the scan direction of the original image is the direction shown in FIG. 9A, the scan direction of the image displayed on the mobile phone is assumed to be the direction shown in FIG. 10B.
In this case, in the above-described edge enhancement, the arrangement direction of the subpixels to be weighted is different from the scanning direction.
In such a case, instead of the latch circuit (Latb) in the contour emphasis circuit shown in FIGS. 3 and 5, a line memory for storing display data for two continuous display lines or three continuous display lines is provided. It is only necessary to generate the contour emphasis display data in the arithmetic circuit 21 based on two or three pieces of display data on the same column stored in the line memory.
Needless to say, when only a part of the screen of the liquid crystal display panel (PNL) is displayed, for example, in a window, the processing described above is performed on display data only in the window.
In FIG. 1, the memory circuit 150 can be omitted when a line memory is unnecessary.
In the above description, the embodiment in which the present invention is applied to the TFT type liquid crystal display module has been described. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can also be applied to an EL display device having an EL element or other display devices.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

It is a block diagram which shows schematic structure of the liquid crystal display module of the Example of this invention. FIG. 2 is a block diagram showing a schematic internal configuration of a source driver shown in FIG. 1. FIG. 3 is a block diagram illustrating a schematic configuration of an example of an edge emphasis circuit illustrated in FIG. 2. It is the graph which made Table 1 a graph. FIG. 3 is a block diagram illustrating a schematic configuration of another example of the contour enhancement circuit illustrated in FIG. 2. 3 is a graph obtained by graphing Table 2. It is the graph which formed Table 3 into a graph. In the liquid crystal display module of the Example of this invention, it is a figure which shows the several point which preserve | saves the display data of the last flame | frame in a liquid crystal display panel (PNL). It is a figure which shows the scanning direction of an original image. It is a figure which shows the scanning direction of the image displayed on a mobile telephone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Outline emphasis circuit 11 Data latch circuit 12 Selector 13 Gradation voltage generation circuit 14 Output circuit 20 Movie detection circuit 21 Arithmetic circuit 100 Controller circuit 120 Liquid crystal drive power supply generation circuit 130 Source driver 140 Gate driver 150 Memory circuit PNL Liquid crystal panel S Video line (Or drain wire)
G Scan line (or gate line)
TFT Thin film transistor ITO1 Pixel electrode ITO2 Common electrode (counter electrode or common electrode)
LC liquid crystal capacity GLASS glass substrate (substrate)
DRV drive circuit Lata, Latb latch circuit MP multiplexer FPC Flexible circuit board

Claims (5)

A display panel having a plurality of pixels;
A display device including a drive circuit for driving the display panel based on display data input from the outside,
A memory for storing display data of a previous frame in j pixels smaller than the total number of pixels of the display panel among display data input from the outside;
The display data of the previous frame in the j pixels stored in the memory and the display data to be displayed in the current frame are compared to determine whether the image to be displayed on the display panel is a moving image. A determination circuit,
When the determination circuit determines that the image is a moving image, the drive circuit performs display while emphasizing the outline of the display data input from the outside with respect to an area having more than j pixels. A display device characterized by that.   The display device according to claim 1, wherein the j number is 1/10 or less of the total number of pixels of the display panel.   The determination circuit compares the display data of the previous frame stored in the memory with the display data to be displayed in the current frame, and when the predetermined number or more of the j pieces do not match, the display circuit The display device according to claim 1, wherein the image to be displayed on the panel is determined to be a moving image.   4. The drive circuit according to claim 1, wherein the drive circuit includes the memory and the determination circuit, and a memory capacity to be mounted is smaller than that of all pixels of the display panel. Display device.   The display device according to claim 1, wherein the display panel is a display panel having a definition of 150 ppi or more.

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