JP2001318765A - Coordinate position detector and coordinate position detection method for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect a coordinate position without lowering image quality by providing a coordinate position detection period only when a photosensor for coordinate position detection is operated. SOLUTION: The coordinate position detection period is provided in one field only at the time of detecting the coordinate position, drive signals for display position detection are outputted to a scanning driver 6 and a data driver 9 within the period and a coordinate position detection signal generation circuit 13 for generating optical signals for the coordinate position detection on a plasma display panel 5 is provided. A coordinate position detection circuit 15 is made to compare the timings of the respective output signals of the photosensor 14 for detecting the optical signals and the coordinate position detection signal generation circuit 13 to detect a display position on the plasma display panel 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting a coordinate position of a plasma display panel for detecting a coordinate position on the plasma display panel using an optical sensor.

[0002]

2. Description of the Related Art Recently, personal computers (hereinafter referred to as P
With the spread of C, electronic presentations that directly display PC data instead of blackboards, whiteboards, and overhead projectors in education, meetings, and the like have become common. However, the data display of the conventional PC has drawbacks such as a small screen and darkness. In contrast, plasma display panels have bright, large screens,
Due to its features such as a wide viewing angle, it has been widely used today as a display for electronic presentation. Recently, electronic blackboards, such as blackboards and whiteboards, capable of directly inputting lines, characters, and pictures from a display screen have been put to practical use. In such an electronic blackboard, it is necessary to arrange a coordinate position detecting element such as a touch switch or an input control element on a display screen. However, plasma display panels use discharge light emission and generate a lot of electromagnetic noise from the display screen.
It is difficult to use a touch switch using a transparent electrode. Conventionally, a switch using mainly a surface acoustic wave is arranged on a transparent plate and the switch is arranged on the front surface of a plasma display panel.

However, an input device using surface acoustic waves disposed on the front of such a plasma display panel is very expensive, and a transparent plate disposed on the display surface requires unnecessary light reflection and light. And the quality of a displayed image is deteriorated as a result.

On the other hand, a plasma display panel capable of directly inputting handwriting using a light pen has been proposed in, for example, Japanese Patent Application Laid-Open No. 50-108838.
This is because a one-field period for displaying one screen is divided into a plurality of sub-fields, the emission time in each sub-field is set to a different value to enable gradation display, and a plurality of abscissa detection sub-fields are set. The abscissa detection pattern is displayed during the subfield period, the light emission of the abscissa detection subfield is detected by the light pen, and the abscissa position indicated by the light pen is determined from the emission timing pattern. It is to ask. The ordinate position counts the horizontal synchronization signal,
The detection is performed by taking in the count value at the timing of detecting the light emission at that point.

[0005]

However, in such a conventional method for detecting the coordinate position of a plasma display panel, when the detection period of the abscissa is composed of many subfields, a large number of subfields are required for the abscissa detection. In this case, it is difficult to secure a sufficient period of the gradation display subfield, and it is not possible to display a bright (high luminance) and high-quality (image quality) image. was there. Further, there is at least one light emission in each abscissa detection subfield, for example, 64
The pixel emits light at least six times, and this light emission raises the brightness level of the black display portion, and there is a problem that the contrast of an image is significantly reduced. In addition, various proposals have been made for a coordinate position detecting device of a plasma display panel for lighting a display cell by utilizing a memory effect, but none of them proposes the subfield configuration, and therefore, many proposals are made. The gradation display cannot be performed, and the detection accuracy of the coordinate position is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. In a normal display, a subfield structure capable of displaying the highest quality without providing a coordinate position detection period can be employed. A coordinate position detection period and a coordinate position detection method for a plasma display panel capable of detecting a coordinate position with high accuracy by providing a coordinate position detection period and reducing the number of subfields only when an optical sensor is operated. Aim.

[0007]

To achieve the above object,
The present invention provides a coordinate position detection period in the one field only at the time of coordinate position detection, outputs a drive signal for detecting a coordinate position to a scanning driver and a data driver, and outputs an optical signal for detecting a coordinate position on a plasma display panel. A coordinate position detection signal generating circuit for generating the signal, and causing the coordinate position detection circuit to compare the timing of each output signal of the optical sensor for detecting the optical signal and the output signal of the coordinate position detection signal generation circuit, and Is detected.

Further, the present invention causes the image processing means to write a character, a line, a picture, or the like on an image displayed on the plasma display panel based on the detection output from the coordinate position detection circuit. Things.

In the present invention, the coordinate position detection period is divided and provided in two or more fields.

In the present invention, the coordinate position detection period may be set as follows:
While simultaneously applying video data to all the data electrode groups of the plasma display panel, a vertical position detection period for sequentially supplying a scanning signal to the scanning electrode groups, and simultaneously applying a scanning signal to all the scanning electrode groups. The period is divided into a horizontal position detection period in which video data is sequentially supplied to the data electrode group.

Further, the present invention makes it possible to perform gradation display by decomposing a video signal of one field for displaying one screen into a plurality of subfields having different display periods. The subfield configuration is changed to provide a coordinate position detection period, and light that is turned on by the write voltage applied to the intersection of the data electrode group and the scan electrode group of the plasma display panel during the coordinate position detection period using an optical sensor. By detecting, the display position of the light on the plasma display panel is detected.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a coordinate position detecting device for a plasma display panel according to the present invention.
In FIG. 1, reference numeral 1 denotes an external video processing device such as a personal computer as video processing means for outputting a digital RGB video signal. 2 receives an RGB video signal and decomposes it into video data for each subfield; A signal processing circuit serving as an input / output interface signal processing circuit that returns a video signal and various control signals to the external video processing device 1.

Reference numeral 3 denotes a frame video memory for storing video data for each subfield decomposed by the signal processing circuit 2, and 4 denotes a control circuit, which scans a scan driver 6 of a plasma display panel (PDP panel) 5. It has a scanning control unit 8 that sends out a scanning signal via the switching circuit 7. Reference numeral 4a denotes a video memory control unit that controls writing and reading of video data to and from the frame video memory.
Reference numeral 9 denotes video data stored in the frame video memory 3;
A data driver that writes data to the plasma display panel 5 via the data switching circuit 10 in synchronization with the scanning signal. The writing period of the subfield in the normal video display mode is as shown in FIG. Reference numeral 11 denotes a high-voltage pulse circuit that supplies a high-voltage pulse to the scan driver 6 under the control of a high-voltage pulse control unit 12 in the control circuit 4.

Further, FIG. 2 shows a diagram 13 set according to the present invention.
(B) Coordinates for outputting a drive signal for detecting a coordinate position to the data driver 9 and the scan driver 6 through the data switching circuit 10 and the scanning switching circuit 7 during the coordinate position detection period in the position detection display mode as shown in FIG. This is a position detection signal generation circuit. In addition, an optical signal for detecting a coordinate position is generated on the plasma display panel 5 by these drive signals. 14 is the plasma display panel 5
The optical sensor 15 for detecting the optical signal above is the optical sensor 1
4 is compared with each timing of the signal generated by the position detection signal generation circuit 13 to determine the display position on the coordinates on the plasma display panel 5, and via the signal processing circuit 2 to the external video processing device 1 is a coordinate position detection circuit to be input to 1.

Next, the operation will be described. The emission brightness of the plasma display panel is proportional to the number of driving pulses applied. In a plasma display panel, the entire screen is driven simultaneously using the memory effect of the panel in order to light many pixels brightly. In this case, in order to perform gradation display, a plurality of sub-fields having different luminances are provided in one frame, and a combination of the presence or absence of lighting for each sub-field indicates that a set of pixels that are lit at different luminances has a multi-gradation. The image is displayed. Subfield is 1
Period for writing and scanning for each line (writing period)
And the period during which all screens are driven and displayed simultaneously (display period)
It is composed of When such a digital gradation display is performed, when an image in which the gradation changes smoothly crosses the display screen, contour stripes or color changes occur, resulting in the "moving image false contour" phenomenon. I do. As a countermeasure, gray scale display is generally performed using a large number of subfields equal to or more than the number of input image binary digital signal bits. In order to display bright and good quality,
Usually, most of one field is used for a writing period and a display period.

First, a digital RGB video signal input from the external video processing device 1 is decomposed into video data for each subfield by a signal processing circuit 2 and stored in a frame video memory 3. In the sub-field writing period in the normal video display mode as shown in FIG.
The video data stored in the frame video memory 3 is transmitted to the data driver 9 in synchronization with the scanning signal transmitted from the scanning control unit 8 to the scanning driver 6, and written into the plasma display panel 5 as display data. On the other hand, in the display period as shown in FIG. 2A following the writing period, the scanning and data writing operations are stopped by the control of the control circuit 4, and the high-voltage pulse controller 12
Works. Therefore, during the display period, the high-voltage pulse circuit 1
1 drives the entire display surface of the plasma display panel 5 to light up and display the selected pixel during the writing period.

One field (NTSC) for displaying one screen
In the case of a signal, about 16.7 msec) is divided into a number of subfields having different display periods as shown in FIG. 2A (in the case of 8-bit video display, at least 8 subfields are required). However, since the brightness is proportional to the length of the display period of each sub-field, the brightness is proportional to the length of the display period of each sub-field. Can display an image with a tone (8-bit RGB
256 gradations for each color).

On the other hand, only during input / output control on the screen of the plasma display panel 5 (position detection display mode), a coordinate position detection period is provided by changing the subfield configuration as shown in FIG. During this coordinate position detection period, a driving signal for detecting a display position is output from the coordinate position detection signal generation circuit 13 to the data driver 9 and the scanning driver 6 through the data switching circuit 10 and the scanning switching circuit 7, and the display signal is displayed on the plasma display panel 5. Generates an optical signal for detecting the coordinate position. Therefore, light generated by the drive signal is detected by the optical sensor 14. The coordinate position detection circuit 15 determines the display position on the plasma display panel 5 by comparing the signal output from the optical sensor 14 with the timing of the signal generated by the coordinate position detection signal generation circuit 13, and passes the signal through the signal processing circuit 2. The processing is output to the external video processing device 1 and the processing is performed. The processing determined by the detection position can be executed, and characters, lines, pictures, and the like can be written on the image.

FIG. 3 shows the plasma display panel 5.
It is explanatory drawing which shows notionally. According to this, the display surface of the plasma display panel has one or more data electrode groups X1, X2. . . . Xn and scanning electrode groups Y1, Y2. . . . Ym, display block groups D11, D12. . . . Dmn. Then, during the coordinate position detection period, a writing voltage is applied to the display block at the intersection of one or more data electrode groups and the scanning electrode group to emit light. Therefore, the light emission scanning of the display blocks D11 to Dmn is performed on an arbitrary position on the screen of the plasma display panel 5 or on the entire screen of the plasma display panel 5, and the coordinate position is detected using the optical sensor as described above. FIG. 4 is an example showing the drive timing of the data electrode group and the scan electrode group when performing the light emission scan of the display blocks D11 to Dmn. Here, when a high-level drive signal is applied to both the data electrode group and the scan electrode group, the display blocks D11 to Dmn at the intersections are turned on.

That is, in FIG. 4, while a voltage is first applied to the Y1 electrode group, X1, X2, X3. . . .
If a voltage is sequentially applied to the Xn electrode group, the display block D1
1, D12, D13. . . . D1n can be sequentially turned on. Similarly, Y2. . . . The Ym rows are sequentially driven and lit, and the display blocks on the entire display surface are scanned and lit. Here, when the size of the display block is set to one pixel, it is possible to write a pattern by detecting a high-definition coordinate position corresponding to the number of pixels of the entire screen, and when a large display block is associated with an icon, Thus, input control by a pen using an optical sensor can be performed. In order to shorten the coordinate position detection period and reduce the influence on the video display period, the method is suitable for specifying a specific coordinate position with a relatively large pattern such as an icon. Further, even if the coordinate position detection period is divided into two or more fields, the coordinate position can be detected.

Next, another method of detecting the coordinate position of the plasma display panel 5 will be described. In this method, a vertical coordinate position and a horizontal coordinate position are independently detected. In the vertical coordinate position detection period, as shown in FIG. 5, a linear display block DY crossing the display surface including one or a plurality of scan electrode groups in the horizontal direction.
1, DY2,. . . DYm, each display block D
Y1 to DYm are sequentially scanned and lit over the entire display surface. Then, the position in the vertical direction is obtained from the drive timing of the display block from which light emission is detected by the optical sensor 14. Next, during the detection period in the horizontal direction, as shown in FIG. 6, linear display blocks DX1, DX3, DX3,... Traversing the display surface including one or a plurality of data electrode groups in the vertical direction. . . DXn
And the display blocks DX1 to DXn are sequentially scanned and lit over the entire display surface. Then, the position in the horizontal direction is obtained from the drive timing of the display block where the light sensor 4 has detected the light emission.

FIG. 7 is an example showing the drive timing of the data electrode group and the scan electrode group when the light emission scan of each display block as shown in FIGS. 5 and 6 is performed. Here, when a high-level drive signal is applied to both the data electrode group and the scan electrode group, the driven display block is turned on.

That is, in FIG. 7, all the data electrode groups X1, X2, X
3,. . . Xn are simultaneously applied to the scan electrode groups Y1, Y2,. . . Applying voltage to Ym sequentially
The display blocks DY1, DY2,. . . DYm is sequentially turned on, and the display blocks on all display surfaces are scanned and turned on. on the other hand,
During the horizontal coordinate position detection period, all the scan electrode groups Y1, Y
2,. . . While simultaneously applying a voltage to Ym, the data electrode groups X1, X2, X3,. . . Xn are sequentially applied to the display blocks DX1, DX2,. . . DXn is sequentially turned on, and the display blocks on all the display surfaces are scanned and turned on. Here, when the width of the display block is set to one pixel, it is possible to write a pattern by detecting a coordinate position with high definition corresponding to the number of pixels of the entire screen, and to convert a large display block into a pattern such as an icon. If this is done, input control with a pen or the like using an optical sensor becomes possible. In addition, according to this coordinate position detection method, it is possible to detect the position on the entire display surface by performing only one scan in each of the vertical direction and the horizontal direction, so that complicated information input such as line and picture drawing input can be performed. Are suitable. There is no particular limitation on the order of the position detection directions, and detection is possible even if the coordinate position detection period is divided into two or more fields.

[0024]

As described above, according to the present invention, gradation display can be performed by decomposing a video signal of one field for displaying one screen into a plurality of subfields having different display periods. A coordinate position detection period is provided by changing the subfield configuration within the one field only at the time of position detection, and the lighting is performed by the write voltage applied to the intersection of the data electrode group and the scan electrode group of the plasma display panel during the coordinate position detection period. Detected light using an optical sensor makes it possible to detect the display position of the light on the plasma display panel, and one feed is composed of a large number of subfields, so that the gradation is changed smoothly with good quality. In addition to being able to display images, the sub-display allows for the highest quality display in normal display without the need for a coordinate position detection period. Can take Rudo configuration, reduces the number of observed subfields when Hatarakashi light sensor for position detection, the effect is obtained that allows the coordinate position detection with high accuracy. Regarding such a decrease in the number of subfields, there is usually a sufficient number of subfields, so that the image is slightly deteriorated, and there is no practical problem. If there is no margin in the number of subfields, it can be improved to a level at which there is no practical problem by using video techniques such as error diffusion and dither. As a result, during normal use, the highest quality image can be displayed, and a product that emphasizes high quality can be made.On the other hand, as a high value-added function, various applications using the position detection function can be provided. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus for detecting a coordinate position of a plasma display panel according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing details of a screen display field in a normal display mode and a position detection display mode in the plasma display panel of the present invention.

FIG. 3 is an explanatory diagram showing display blocks of the plasma display panel in FIG.

FIG. 4 is a timing chart showing driving timings of data electrodes and scanning electrodes of the plasma display panel in FIG.

FIG. 5 is an explanatory view showing a display block of a plasma display panel for implementing another coordinate position detecting method of the present invention.

FIG. 6 is an explanatory diagram showing a display block of a plasma display panel for implementing another coordinate position detecting method of the present invention.

FIG. 7 is a timing chart showing driving timings of data electrodes and scanning electrodes of the plasma display panel in FIGS. 5 and 6.

[Explanation of symbols]

2 I / O interface signal processing circuit (signal processing circuit) 3 Frame image memory 4 Control circuit 5 Plasma display panel (PDP panel) 6 Scan driver 8 Scan control unit 9 Data driver 13 Coordinate position detection signal generation circuit 14 Optical sensor 15 Coordinate position Detection circuit

Claims (5)

[Claims] 1. A signal processing circuit for decomposing a video signal of a field for displaying one screen into a plurality of subfields having different display periods, and a frame for storing video data of each subfield decomposed by the signal processing circuit. An image memory, a scan control unit for controlling transmission of a scan signal to a scan driver of the plasma display panel, and synchronizing with a scan signal from the scan control unit, image data from the frame image memory to the plasma display panel. A high-voltage pulse control unit that drives the entire display surface of the plasma display panel during the display period following the video data write period to turn on and display the selected pixel during the write period; A coordinate position detection period is provided in the one field only at the time of position detection, A coordinate position detection signal generation circuit that outputs a drive signal for detecting a coordinate position to a driver and a data driver, and generates an optical signal for detecting a coordinate position on the plasma display panel; and an optical sensor that detects the optical signal; A coordinate position detection circuit for comparing the timing of each output signal of the optical sensor and the coordinate position detection signal generation circuit to detect a display position on the plasma display panel. Coordinate position detecting device. 2. The image processing apparatus according to claim 1, further comprising video processing means for writing characters, lines, pictures, and the like on an image displayed on said plasma display panel based on a detection output from said coordinate position detection circuit. Item 2. A coordinate position detecting device for a plasma display panel according to item 1. 3. The apparatus according to claim 1, wherein the coordinate position detection period is divided into two or more fields. 4. The coordinate position detection period includes a vertical position detection period for sequentially supplying a scan signal to the scan electrode groups while simultaneously applying video data to all data electrode groups of the plasma display panel. 2. The coordinate position of the plasma display panel according to claim 1, further comprising a horizontal position detection period for sequentially supplying video data to the data electrode group while simultaneously applying the scan signal to the scan electrode group. Detection device. 5. A gradation signal can be displayed by decomposing a video signal of one field for displaying one screen into a plurality of subfields having different display periods, and a subfield is included in the one field only when a coordinate position is detected. A coordinate position detection period is provided by changing the configuration, and light emitted by the write voltage applied to the intersection of the data electrode group and the scan electrode group of the plasma display panel during the coordinate position detection period is detected using an optical sensor. And detecting the display position of the light on the plasma display panel.