JPH01314086A - Picture signal processor - Google Patents

Abstract

PURPOSE:To attain efficient luminescence of a fluorescent substance and to increase the peak brightness and contrast by approaching the intensity distribution of an electron beam on a picture screen to a rectangular form. CONSTITUTION:Data displayed at present and stored in a memory 104 and the data sent from a selector 103 and to be displayed next are compared by a comparator 105. If the level of picture data to light up the adjacent fluorescent substances differs from each other, the data in non-displayed parts 408 is decreased to a black level or below, and when the level of picture data lighting adjacent fluorescent substances is not so much different, the level of the non- displayed parts 408 is not brought into a black level at a data of a D/A conversion circuit 106. Thus, the distribution of the intensity of the electron beam on the picture screen is approached to a rectangular form. Thus, the fluorescent substance 407 is lighted efficiently, the peak of the brightness is increased and the contrast is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image signal processing device for an image display device used in a television or the like.

BACKGROUND ART FIG. 5 is a block diagram of a conventional image signal processing device, in which 100 is an image signal of each primary color, and 101 is an A/D converter for A/D converting the input image signal of each primary color. vessel, 10
2 is a timing generation circuit that generates the timing for displaying an image; 103 is a selector that extracts one data from each primary color according to a timing signal from the timing generation circuit 102; and 106 is a D/' 107 is a drive circuit that drives an image electron gun; 406 is an image electron gun that emits an image electron beam; 110 is a horizontal synchronization signal;
111 is a vertical synchronization signal, and 112 is an index signal.

FIG. 4(a) is a perspective view showing the main parts of the image display device, where 401 is an image screen coated with three primary color phosphors in stripes, and 402 is an image screen where electron beams are emitted onto the image screen. Index detection means for detecting the position; 403, vertical deflection means for deflecting the image electron beam in the vertical direction; 404, horizontal deflection means for deflecting the electron beam in the horizontal direction; 405, electrons for use in index detection indexing electron gun that emits a beam;
406 is an imaging electron gun that emits an imaging electron beam. FIG. 4B is an enlarged view showing the coating state of the phosphor on the image screen 401, where 407 is the red, green, and blue phosphor coated on the stripe, and 408 is the phosphor of each color. This is the non-light emitting part that exists in between.

For example, an image display device in which electron beams for images and for indexing exist separately is disclosed in Japanese Patent Application Laid-open No. 61
-121682 and JP-A-60-189848.

In the conventional image signal processing device configured as described above,
In this case, the image data 100 of each of the three primary colors of red, green, and blue is A.
A/D converter 101 performs A/D conversion and outputs to selector 103 . Further, the index detection means 402 provided at a predetermined position on the image screen is always emitted with a constant intensity from the index electron gun 405.
Similar to the image electron beam, the horizontal position of the index generation electron beam, which is deflected in the horizontal direction by the horizontal deflection means 404, on the image screen is detected, and index signals 11 and 2 are sent to the timing generation circuit 102. .

The timing generation circuit 102 uses this index signal 1
12 and data set in advance according to the vertical position of the image electron beam, the horizontal position of the image electron beam is calculated, and a timing signal for image display is generated. The selector 103 selects a signal to be displayed from among the primary colors according to a timing signal from the timing generation circuit 102. D/A conversion circuit 1
06 performs D/A conversion on the image data from the selector 103 and sends it to the drive circuit 107. The drive circuit 107 drives the imaging electron gun 406 to emit an imaging electron beam and display an image. Also, at the timing of the non-emitting part of the image screen 401, the electron beam is deflected,
In order to prevent a decrease in color purity due to the spread of the electron beam on the image screen 401, which occurs when the focus of the electron beam cannot be narrowed down, the black level or
In order to completely cut off the electron beam, the image display electron gun is driven with a smaller level signal so that the image display electron beam is not emitted.

Problems to be Solved by the Invention However, in the above configuration, the D/A conversion circuit,
Due to the characteristics of the drive circuit, electron gun, etc., the intensity distribution of the electron beam on the image screen does not become rectangular, so there has been a problem in that the phosphor cannot emit light efficiently.

In view of this, an object of the present invention is to make the intensity distribution of an electron beam on an image screen closer to a rectangular shape, thereby improving peak brightness and contrast.

Means for Solving the Problems The present invention provides a memory having a capacity for at least one pixel for storing image data, and pixel data currently displayed and pixel data to be displayed next stored in the memory. and a D/A converter circuit that receives image data and changes the period data of the non-light-emitting portion under control from the comparator. The figure is a block diagram showing a driving method of an image signal processing device in one embodiment of the present invention, in which 100 is an input image signal of each primary color, 101 is an A/D converter for converting an image signal into an A/D converter.
An A/D converter for conversion; 102 is a timing generation circuit that provides timing for displaying an image; 103 is an A/D converter;
104 is a memory that stores pixel data; 105 is a comparator that compares data in the memory with data from the selector; 106 is a selector that selects a signal to be displayed from the three primary color image signals from the D converter; , a D/A conversion circuit that manipulates the image data from the selector with a control signal from the comparator, converts it into D/A based on the timing from the timing generation circuit, and outputs it to the drive circuit; 107 is an image electronics; 406 is an imaging electron gun that emits an imaging electron beam; 110 is a horizontal synchronization signal;
11 is a vertical synchronization signal, 112 is an index signal,
113 is a control signal.

FIG. 2 is various graphs showing the operation of the image signal processing device of this embodiment, in which (a) is the image signal of each primary color input to the A/D converter, (b) and (d) are , D/ of each pixel
The image data after A conversion, (C) and (e) are the brightness distribution of the electron beam on the image screen.

The operation of the image signal processing apparatus of this embodiment configured as described above will be described below.

The input image signals 100 of each primary color are sent to an A/D converter 1.
01, first A/D conversion is performed. Furthermore, the timing generation circuit 102 generates a timing signal for image display based on the input horizontal synchronization signal 110, vertical synchronization signal 111, index signal 112, and preset data. Based on this timing signal, the selector 103 selects data, and the D/A conversion circuit 106 outputs image data. These operations are similar to those described in the conventional example.

At this time, the image data selected by the selector is
At the same time as being output to the A conversion circuit 106, the memory 10
4 is stored. Hidden portion 4 of image screen 401
08 as shown in Figure 2(b), the black level or
When the electron gun is driven with data at a smaller level to cut off the electron beam, the characteristics of the D/A conversion circuit 106, drive circuit 107, and electron gun 406 cause the electrons on the image screen 401 to be cut off. The beam intensity distribution becomes as shown in the same figure ('c), and the waveform becomes dull. As a result, since the phosphor cannot emit light efficiently, the brightness at the peak time decreases, resulting in poor contrast. Therefore, the currently displayed data stored in the memory 104 and
The comparator 105 compares the data to be displayed next sent from the selector 103, and the image signals shown in FIG. 2(a), that is, the image data that causes adjacent phosphors to emit light, have different sizes. Sometimes, the data in the non-display area 408 is reduced to black or a lower level,
If the sizes of the image data that cause adjacent phosphors to emit light do not differ much, the data of the D/A conversion circuit 106 is not set to black level even in the non-display area 408, as shown in FIG. do it like this. Then, the intensity distribution of the electron beam on the image screen 401 becomes as shown in FIG. .

As described above, according to the present embodiment, the memory 104 and the comparator 105 are configured to compare data of adjacent pixels, and the image data in the non-display part of the image screen is adjusted according to the correlation between the data of adjacent pixels. By changing the brightness peak, the brightness peak is raised and the contrast is raised directly.

FIG. 3 is a block diagram of an image signal processing device showing a second embodiment of the present invention. 100 is an input image signal of each primary color; 101 is an A/D converter that A/D converts the image signal; 102 is a timing generation circuit that provides timing for displaying the image; 103 is an A/D conversion circuit. 3 from the vessel
A selector 106 selects a signal to be displayed from the primary color image signals, a D/A conversion circuit 106 modifies the input image signal with a control signal and outputs it as a timing signal from the timing generation circuit 102, and 107 a D/A conversion circuit for the image. 110 is a horizontal synchronization signal; 111 is a vertical synchronization signal; and 112 is an index signal. The configuration is similar to that of . The difference from FIG. 1 is that the L memory 30 has a storage capacity of at least several trios.
4, a color detection circuit 305 is provided to detect colors from the data in the L memory 304, and the D/A conversion circuit is given an image signal output from the L memory, and is controlled by the color detection circuit 305. It is.

The operation of the image signal processing apparatus of the second embodiment configured as described above will be explained below.

If the image signal to be displayed has a pattern in which white and other colors appear alternately in each trio, outputting and displaying data as shown in Figures 2(d) and (e) will result in white being displayed. Only the green phosphor in the middle of the displayed trio emits more light than the red and blue phosphors, which may result in a greenish white color. Therefore, several trios of image data are stored, and only when the same color (excluding single colors) continues for at least several trios, the color detection circuit 305 sends the D/A conversion circuit 106 to change the data of the non-light emitting part to black level. Make sure not to drop it.

By doing this, the color reproduction of white is disturbed only in an extremely small range of one trio at each end where a color change occurs when displaying a pattern of continuous white.

According to this embodiment, by providing the L memory 304 and the color detection circuit 305 to detect that the same color continues for several trios, it is possible to realize an image signal processing device with good white reproducibility.

Effects of the Invention As described above, according to the present invention, cost and power consumption can be reduced while preventing deterioration of color purity due to spread of the electron beam on the image screen caused by deflection and focusing characteristics of the electron beam. It is possible to increase the brightness peak and improve the contrast without having to improve the characteristics of the drive circuit, electron gun, etc., which would lead to an increase in the brightness.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image signal processing device according to an embodiment of the present invention, FIG. 2 is a various graph showing the operation of the same device, and FIG. 3 is a block diagram of an image signal processing device according to another embodiment of the present invention. 4 is a perspective view showing the configuration of the main parts of the display device in the same device, and FIG. 5 is a block diagram of a conventional image signal processing device. 100... Image signal, 101... A/D converter, 1
02...Timing generation circuit, 103...Selector, 10'4...Memory, 105...Comparator,
106...D/A conversion circuit, 107...drive circuit,
110... Horizontal synchronization signal, 111... Vertical synchronization signal, 112... Index signal, 113... Control signal, 304... L memory, 305... Color detection circuit,
401... Image screen 402... Index detection means 403... Vertical deflection means, 404...
Horizontal deflection means, 405... indexing electron gun, 4
06... Imaging electron gun, 407... Fluorescent material, 408
...Non-light emitting part. Name of agent Patent attorney Toshio Nakao 1 person (a> (b) (c)

Claims (2)

[Claims] (1) An image screen in which phosphors of the three primary colors of red, green, and blue are coated in stripes, with non-emissive areas between the phosphors of each color, and an electron beam that emits electron beams that cause the phosphors to emit light. An imaging electron gun common to red, green, and blue phosphors,
means for deflecting an electron beam in vertical and horizontal directions; an index electron gun that emits an index generation electron beam different from that for images; and an index generation electron gun located at at least one predetermined position on the image screen; This is an image signal processing device for an image display device, which is equipped with an index detection means for detecting the position of an electron beam on an image screen operated by the beam. A timing generation circuit that calculates the beam position and generates the timing for outputting display data, a memory having a capacity of at least one pixel for storing image data, and the currently displayed image stored in the memory. A comparison circuit that compares the data with the image data to be displayed next, and a comparison circuit that receives the image data and changes the data of the period of the non-light emitting part under control from the comparator, An image signal processing device comprising: a D/A conversion circuit that outputs a signal; and a drive circuit that drives the imaging electron gun with an image signal from the D/A conversion circuit. (2) The image signal processing device according to claim 1, further comprising a color detection circuit that detects that the same color continues for several trios.