JPS6325556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video display device that displays a multi-gradation moving image such as a television signal by arranging a large number of display elements such as incandescent bulbs.

Structure of conventional example and its problems This type of large display device generally uses an incandescent light bulb as a display element. In Figure 1, incandescent light bulbs L ₁ , L ₂ ...L _o-1 , _Lo each form one picture element on the screen, and a large number of incandescent light bulbs are arranged side by side and turned on according to the screen. control,
Performs multi-gradation video display. Individual incandescent light bulb L ₁ ~
Switches S ₁ to _{S o each} control the lighting,
Switch control circuits C ₁ to _{C o} are provided, which select a signal (gradation level) corresponding to each picture element from the video signal sent from the video signal sending device 101 to the line 102, and control the switches S ₁ to _{S o.} The incandescent light bulbs L ₁ to _{L o} are controlled by opening and closing.

P _s is a power source for lighting the light bulbs L ₁ to L _o , and supplies power to the light bulbs through lines 103 and 104.
When displaying television images, S ₁ to S _o are driven by a PWM signal that turns on and off at a frequency sufficiently higher than the field frequency or frame frequency (60 Hz/sec or 30 Hz/sec in the Japanese standard system).
The light emission gradation of the light bulb is controlled by changing the ON/OFF duty according to the gradation using the field frequency or frame frequency. When controlling a light bulb and displaying a video using this method,
The disadvantage is that the response speed of the light bulb is not sufficient and the movement on the screen cannot be adequately displayed.

FIG. 2 is an extracted diagram of the circuit of the light bulb portion of FIG. 1. Also, switch S at time t ₂ to _{t 6}
Figure 3 shows the response characteristics of the light bulb when the opening/closing duty of the light bulb is changed. In addition, S in Figure 3 is
It is expressed as an average value when changing the ON/OFF duty. When the duty of switch S is changed to 100% brightness at time t ₀ , the brightness of the light bulb changes from 0 → A → B → C, and at time t ₄
The brightness reaches 100% and becomes stable. again time t ₆
When the duty of switch S is controlled to 0% brightness at point D, the brightness of the light bulb starts to decrease from point D and reaches a stable state at time _t7 . However, when the brightness reaches 30% at time _t2 , if the duty of switch S is further changed to control the brightness to 60%, the brightness of the bulb does not change from A to B, but from A to E.
changes, reaching 60% at time t ₅ and becoming stable. time
When the switch S is controlled so that the brightness becomes 30% at _{time t6} , the brightness decreases from F and reaches 30% at time _t8 , resulting in an equilibrium state. The response delay time until reaching t ₅ , t _{8 ,} etc. is long, resulting in an afterimage phenomenon when displaying a moving image.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the conventional devices mentioned above and
The purpose is to provide a sufficiently responsive display in moving image display.

Structure of the Invention The present invention detects changes in the brightness of each part of the displayed screen by temporarily storing the screen in a memory and comparing multiple screens, and changes the brightness based on the detected output. The above object is achieved by controlling the display elements in a portion so as to speed up the response of the display elements.

Description of examples Examples of the present invention will be described below.

For example, at time t ₂ , a light bulb with a brightness of 30% has a brightness of 60%.
%, the duty of switch S is controlled so that the steady state brightness is 100% between t ₂ and _{t 3} , and the duty of S is set to 60% brightness at time t ₃ . If controlled, the brightness change will be A
→B→E, and the response time is improved from _t5 - _t2 to _t3 - _t2 . Figure 4 shows a signal processing circuit for controlling the switch based on this idea, and Figure 5 shows the relationship between the screen and the processed waveform when signal processing is performed according to Figure 4. be.

In FIG. 5, 105 is a line to which a video signal is added, 106 is an analog-to-digital converter, and 1
07 is the line where the digital signal is output, 10
8 is a screen memory in which one screen or multiple screens are stored; 109 is a line to which the signal read from the memory 108 is added; 110 is a subtracter for calculating input/output signals of the memory 108; and 111 is the subtracter 1.
10 is a line to which the output signal is applied, 112 is an adder, 113 is a line to which the output signal is applied, and a signal for controlling the switch S in FIG. 2 is applied.

Next, the operation of this embodiment will be explained.

The video signal applied to line 105 is converted into a digital signal by analog-to-digital converter 106. The signal applied to the line 107 is a digital signal, but to simplify the representation, the screen and waveform are shown as analog signals in Figure 5 A, i.e., 107-1 to 107-1.
Shown in 07-6. The screen is a uniform halftone screen with white circles moving from left to right at 107-2, 107-3,
107-4. The analog-to-digital converted digital video signal is temporarily stored in the memory 108, and then read out onto the line 109 with a delay of exactly one screen time (or multiple screen times). Screens related to the signals on line 109 are shown in FIG. The screen 107 and the screen 109 are subtractor 11
0, and a signal indicating the difference between the previous screen 109 and the current screen 107, that is, the movement, can be obtained on the line 111.

In the signal diagram C of the line 111 in FIG. 5, for example, a white circle 111-3 indicates a change toward white, and a black circle indicates a change toward black. The motion signal of this line 111 and the video signal 107 are added by an adder 112 to obtain a signal for controlling the switch S. This signal controls the switch to emphasize white for one screen time when the screen changes to white (as mentioned above).
When changing from % brightness to 60% brightness, between t ₂ and _{t 3}
(equivalent to controlling in the direction of 100% brightness), and in the case of a change toward black, the opposite control is performed to speed up the response.

Effects of the Invention As described above, according to the present invention, it is possible to increase the response speed of a video display device using a relatively slow-response element such as an incandescent light bulb, and display a moving image more accurately. This idea can also be applied to displaying a moving image using an element with a similarly slow response speed, such as a liquid crystal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a general video display device, FIG. 2 is a circuit diagram of its main parts, FIG. 3 is a diagram showing the response characteristics of a light bulb, and FIG. 4 is a video display device according to an embodiment of the present invention. FIG. 5 is a block diagram showing the processing status of the screen. 106...Analog-digital converter, 10
8...Memory, 110...Subtractor, 112...Adder.

Claims (1)

[Claims] 1. A converter that converts the video signal into digital, a digital memory that stores the digital signal of the video signal for one screen or multiple screens, and a signal of the front image read from this digital memory that is compared with the signal of the current screen. and detecting means for detecting changes in brightness in each part of the screen by combining the output of the detecting means with the signal of the current screen to detect the response of the display element in the part where the brightness has changed. A video display device characterized in that the display element is driven in the direction of speeding up the display.