JPH01174081A - Picture display device - Google Patents

Abstract

PURPOSE:To prevent fog at moving picture display and flickering at still picture display at the same time without using a large capacity memory and an element at a high speed operation and without sacrifycing the resolution by varying the after image time of an illuminant corresponding to each picture element. CONSTITUTION:With a video signal of the NTSC standard given to a picture signal input section 11, a switch 15 selects short after-image setting information 13 and an after-light time revision section 16 brings the after-image time of the illuminant of a display section 12 into a short after image, then the moving picture is displayed without fog. In the case of inputting a picture signal of a personal computer to the picture signal input section 11, the switch 15 selects long after image setting information (memory 14) and the after image time revision section 16 brings the after image time of the illuminant into a long after image, then the still picture is displayed with high resolution without flickering. As the illuminant of the display section 12, a ferroelectric liquid crystal with active matrix drive is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image display device for displaying images such as video signals or images generated by a computer.

The NTSC standard, which is a standard for conventional technical video signals, stipulates interlaced scanning in order to save the bandwidth required for signal transmission. According to the NTSC standard, l/60
The odd lines on the screen are scanned in seconds, and the even lines are scanned in the next 1760 seconds, and the process is repeated.

At this time, the screen consisting of only odd lines is called an odd field.
A screen consisting of only even lines is called an even field. From this point on, it takes 1/30 seconds to complete scanning all lines.

A screen made up of all these lines is called a frame. According to the above scanning method, one point on the screen is scanned every 1730 seconds.

When displaying a moving image transmitted by a video signal on a display unit, it is not possible to lengthen the afterglow time of the light emitting body of the display unit. This is because if the afterglow time period is long, the previously displayed image and the current image will overlap, and the quality of the displayed image will deteriorate. According to the NTSC standard, if the afterglow time is not set within the drawing time of one field, that is, 1160 seconds, blurring will occur due to the afterimage of the previous field. For this reason, display devices for general home televisions use display sections that are made of light emitters with an afterglow time of less than 1/60 second and that perform interlaced scanning. Such a display section is called an interlaced short afterglow display section.

By the way, when using the interlaced short afterglow display section as described above, one point on the screen is scanned every 1/30 seconds, so the light emitter emits light once and then is scanned again and emits light. It will disappear in time. The time from when a light stimulus is given to the human eye until the effect disappears, that is, the afterimage time, is this scanning period, l/30
shorter than seconds. For this reason, when a still image with no movement is displayed for a relatively long period of time, the light emitters corresponding to bright pixels repeatedly emit light, disappear, and emit light, resulting in a flicker phenomenon in which the screen flickers. In order to prevent this, it is necessary to shorten the scanning period of the screen and perform rescanning within the interval of afterimage of the eye, or to use a light emitter with a long afterglow time. For this reason, display devices for personal computers that rarely display fast-moving moving images use display sections that are made of light emitters with a short afterglow and perform non-interlaced scanning in 1/60 seconds or less, or display devices that display long afterglow. A display section made of a light emitting body is used. A display section that is made of a light emitter with a short afterglow and performs non-interlace scanning at l/60 seconds or less is called a non-interlace short afterglow display section, and a display section that is made of a light emitter that has a long afterglow is called a long afterglow display section. .

Now, it is not possible to use a long afterglow display section in televisions and the like that are designed to display moving images. Therefore, when considering sharing a display device with a television and a personal computer, a short afterglow display section is inevitably used. The following technologies have been developed for sharing a display device between a television and a personal computer.

First, a description will be given of Conventional Example 1, which is an approach technique for displaying a still image of a personal computer on an interlaced short afterglow display section for video signals.

Now, assume that one point on the image and one point adjacent above or below it both have the same color and brightness. At this time, even if the light emitted from the light emitting body for one point disappears because of the interlaced short afterglow display section, the light emitting body for the one point adjacent above or below continues to emit light with the same color and brightness. In such a case, there is a phenomenon in which the luminous body appears to the eyes to continue emitting light without disappearing. A display device that utilizes this phenomenon to draw the same image in odd and even fields and displays a still image on an interlaced short afterglow display section without flickering has been adopted in MSX standard personal computers. FIG. 6 shows a part of the screen displayed in such a display HK. In FIG. 6, the hiragana character "no" is stored in the memory. At this time, the data displayed on the screen is doubled in the vertical direction.

Next, conventional example 2, which is an approach technique for displaying a video signal on a non-interlaced short afterglow display section for a personal computer, will be described.

FIG. 7 shows the configuration of a display device that outputs an interlace scanning signal to a non-interlace short afterglow display section. In Fig. 7, 71 is a manual switch, 72 and 73
The memo 18 is capable of storing images for one field. 74 is an output changeover switch, and 75 is a non-interlaced short afterglow display section. In a display device having this configuration, when an odd field of a moving image signal is manually input to the display device, the manual changeover switch 71 is switched to the memory 72, and the odd field is stored in the memory 72.

Next, when the even field is entered manually, the input changeover switch 71 is switched to the memory 73, and the even field is stored in the memory 73. At the same time, the output changeover switch 74 switches to the memory 72 and outputs the previously stored odd field to the non-interlaced short afterglow display section 75. At this time, one scanning line of the odd field is read out twice in the non-interlaced short afterglow display section 75 and displayed on two scanning lines. Next, when an odd field is manually input to this display device, the input changeover switch 71 is switched to the memory 72, the odd field is stored in the memory 72, and the output changeover switch 74 is switched to the memory 73, and the previously stored even field is stored in the memory 72. The field is output to the non-interlaced short afterglow display section 75.

Repeat this operation thereafter. With the above operation, this display device draws the planned surface in 1760 seconds when the L field is drawn, so that still images do not flicker even when manually drawn, and moving images move smoothly.

Problems to be Solved by the Invention However, in the method of conventional example 1, which outputs the same image for both odd and even fields, the vertical resolution of the screen drops to half of the normal resolution, as shown in Figure 6. It ends up.

In addition, in order to convert an interlaced scanning signal to a non-interlaced scanning signal as in Conventional Example 2, a large capacity memory is required and the scanning time is shortened, so an element capable of high-speed operation is required. The problem is that the overall cost is high.

Furthermore, in Conventional Example 2, when a still image is transmitted as a video signal, there is a problem in that the resolution is also halved.

Means for Solving the Problems The present invention includes an afterglow time setting section that sets the afterglow time of each pixel of an image, and a device that corresponds to each pixel according to the afterglow time set in the afterglow time setting section. The image display device includes an afterglow time changing unit that changes the afterglow time of a light emitting body, and a display unit that causes the light emitter to emit light and displays the image.

Effect: With the above-described configuration, the afterglow time value of each pixel is adjusted so that the afterglow time is long for a still image and short for a moving image, depending on the nature of the human image. The time setting section sets the afterglow time of the light emitting body based on the set value, the afterglow time changing section changes the afterglow time of the light emitting body, and the display section causes the light emitting body to emit light and displays an image. Still images can be displayed in high resolution with a long afterglow without flickering, and videos can be displayed with a short afterglow without blurring.

Example FIG. 1 is a block diagram of a first embodiment of the present invention.

In FIG. 1, reference numeral 11 denotes an image signal input unit, 12 a display unit that displays the image manually input by the image signal input unit 11 in 60Hz interlaced scanning, and 13° and 14 indicate short afterglow setting information and long afterglow setting information, respectively. memory where information is stored,
15 is a switch for selecting short afterglow setting information (memory 13) or long afterglow setting information (memory 14), and 16 is a switch for changing the afterglow time of each light emitting element on the display section 12 according to the afterglow time information. This is an afterglow time changing section.

In this first embodiment, the image signal input section 11 has an NTS
When manually inputting a C standard video signal, select the short afterglow setting information 13 with the switch 15, and change the afterglow time of the light emitting body of the display unit 12 to a short afterglow with the afterglow time changing unit 16 to create the video. It can be displayed without blurring. In addition, when inputting an image signal from a personal computer to the image signal input section 11, select long afterglow setting information (memory 14) with the switch 15, and select the long afterglow setting information (memory 14) with the afterglow time change section 16.
By making the afterglow time of the light emitter long, it is possible to display still images at high resolution without flickering.

As the light emitter of the display section 12, for example, an active matrix driven ferroelectric liquid crystal is used. The properties of the liquid crystal used at this time are shown in FIGS. 4 and 5.

FIG. 4 shows the relationship between the time change of the voltage and the time change of the light transmittance of the ferroelectric liquid crystal. Time T in FIG. . When the voltage applied to the liquid crystal rises to V,
The light transmittance increases to L and emits light through the background light. Even after the voltage returns to the original level, the light transmittance remains at L due to the properties of ferroelectric liquid crystal. Time T. When rr is reached and a voltage in the opposite direction to the previous one is applied, the light transmittance decreases and light emission stops.

The above is T. rrT. The time T obtained by n is the afterglow time. The afterglow time changing section shown in FIG. 1 has a function of changing this T. FIG. 5 shows the relationship between the voltage V applied to the liquid crystal and the light transmittance.

If a range from vg to V is used as the applied voltage V, gradations can be obtained, so color images or grayscale images can be displayed using a filter or the like.

FIG. 2 shows a second embodiment of the invention. In Figure 2, 2
1 is a video device that outputs an NTSC standard video signal;
22 is a personal computer. Reference numeral 23 denotes a synthesizing unit which synthesizes each image obtained from the video equipment 21 and the personal computer 22 to create one image;
4 is a display unit that displays the combined image obtained from the combining unit 23. 25 and 26 are short afterglow setting information, respectively.
Memo 18 27 in which long afterglow setting information is stored selects short afterglow setting information (memory 25) or long afterglow setting information (memory 26) based on the control information output from the combining section 23. The switch 28 is an afterglow time changing unit that changes the afterglow time of each light emitting body of the display section 24 according to the afterglow time information.

In this second embodiment, the afterglow time changing section 28 and the display section 24 are the same as the afterglow time changing section 16 and the display section 12 in the first embodiment, respectively.

In the second embodiment, a video signal obtained from a video device 21 and an image signal obtained from a personal computer 22 are manually combined into a single image by a combining section 23,
It is displayed on the display section 24.

At this time, the synthesizing section 23 outputs information as to whether each pixel of the synthesized image is from the video signal of the video device 21 or from the personal computer 22 to the switch 27. The switch 27 selects the short afterglow setting information (memory 25) for pixels in the composite image that is the video signal of the video equipment 21, and selects the short afterglow setting information (memory 25).
For the pixels in the composite image of No. 2, long afterglow setting information (memory 26) is selected. The afterglow time changing section 28 changes the afterglow time of the display section 24 based on the afterglow time setting selected by the switch 27. As a result, in the composite image displayed on the display unit 24, the video signal portion of the video device 21 has a short afterglow and the moving image can be displayed without blurring, and the image signal portion of the personal computer 22 has a long afterglow and remains static. The image can be displayed at the same time as the video without flickering and at high resolution.

FIG. 3 shows a third embodiment of the present invention. In Figure 3, 3
1 is a video device that outputs an NTSC standard video signal;
32 is a display unit that displays a video signal obtained from the video equipment 32. 33 is a motion detection unit that determines whether there is movement for each pixel of the video signal; 34 and 35 are memories in which short afterglow setting information and long afterglow setting information are stored; and 36 is a unit from the motion detection unit 33. A switch 37 selects short afterglow setting information (memory 34) or long afterglow setting information (memory 35) based on the output control information, and 37 controls each light emission of the display section 32 according to the afterglow time information. This is an afterglow time changing section that changes the afterglow time of the body.

In the third embodiment, afterglow time changing section 37/display section 32
is the afterglow time changing unit 16 and display unit 1 in the first embodiment.
2 are the same.

In the third embodiment, the video signal output from the video equipment 31 is displayed on the display section 32. At this time, the motion detection section 33 determines whether or not there is movement for each pixel in the video signal, and outputs the information to the switch 36. The switch 36 selects short afterglow setting information (memory 34) for pixels in the video signal determined to have movement, and selects long afterglow setting information (memory 34) for pixels in the video signal determined to have no movement. 35). The afterglow time changing section 37 changes the afterglow time of the display section 32 based on the afterglow time setting selected by the switch 36.

As a result, the image of the video signal displayed on the display unit 32 has a short afterglow in moving parts and can be displayed without blurring, and a long afterglow in non-moving parts without flickering and with high resolution. Can be displayed.

In the above example, the video signal is based on the NTSC standard, but it goes without saying that other standards such as the PAL standard and the SEACAM standard can be realized with a similar configuration.

As described in detail, the present invention makes the afterglow time of the light emitter corresponding to each pixel variable, thereby eliminating the need for sacrificing resolution or using large-capacity memory or high-speed operation elements. The practical effect is great because it can simultaneously prevent blurring when displaying moving images and flickering when displaying still images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image display device according to a first embodiment of the present invention, FIG. 2 is a block diagram of an image display device according to a second embodiment of the present invention, and FIG. 3 is a block diagram of an image display device according to a third embodiment of the present invention. FIG. 4 is a block diagram of the image display device; FIG. 4 is a diagram showing the relationship between the temporal change in the voltage of the liquid crystal used as the light emitter of the display section and the degree of light transmittance in the first, second, and third embodiments; Figure 5 is a diagram showing the relationship between applied voltage and light transmittance of the same liquid crystal, Figure 6 is a diagram showing the relationship between the image in memory and the displayed image in Conventional Example 1, and Figure 7 is a block diagram of the image display device in Conventional Example 2. be. 11... Image signal human power section, 12... Display section, 13.
...Memory in which short afterglow setting information is stored, 14...
・Memory in which long afterglow setting information is stored, 15...
Switch, 16... Afterglow time changing unit, 21... Video equipment, 22... Personal computer, 23...
- Synthesis unit, 24...Display unit, 25...Memory in which short afterglow setting information is stored, 26...Memory in which long afterglow setting information is stored, 27...Switch, 28・
...Afterglow time changing section, 31...Video equipment, 32...
・Display unit, 33...Motion detection unit, 34...Memory in which short afterglow setting information is stored, 35...Memory in which long afterglow setting information is stored 36...Switch ,
37... Afterglow time change section. Name of agent: Patent attorney Toshio Nakao 1 person Figure 1 Figure 2 Figure 3 Figure 3? Figure 4 Figure 5 sVe

Claims (1)

[Claims] an afterglow time setting section that sets the afterglow time of each pixel of the image;
The method further includes: an afterglow time changing section that changes the afterglow time of a light emitter corresponding to each pixel according to the afterglow time set in the afterglow time setting section; and a display section that causes the light emitter to emit light. Characteristic image display device.