JPH0482480A - Display device - Google Patents

Abstract

PURPOSE:To make a display area width of video image constant by providing a means detecting a change width of a sawtooth wave current from a deflection means to the display device and changing the amplitude of the sawtooth wave current outputted from the deflection means is an output signal of the detection means into a prescribed amplitude. CONSTITUTION:A deflection current change width detection circuits 15, 18 detect a change in a sawtooth wave current from a horizontal deflection circuit 7 and a vertical deflection circuit 8 for a period of a pulse width of a white level pattern signal sent from a white level pattern signal generating circuit 13. Change difference detection circuits 28, 30 detect a difference from a change between a change reference outputted from change reference voltage generating circuits 29, 14 and an output from A/D converter circuits 19, 27, jitter correction circuit 16, 20 convert a difference of change after jitter correction into an analog voltage and output the result to a horizontal amplitude control circuit 6 and a vertical amplitude control circuit 9. Thus, the display area width of the video image is made constant and the adjustment of the display area width is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device used in computer output devices, word processors, and the like.

2. Description of the Related Art Conventionally, display devices have been provided with an adjustment function for adjusting the width of an image display area so that it does not extend beyond the screen.

A conventional display device will be explained below.

FIG. 3 is a block diagram of a conventional display device.

In FIG. 3, 22 is a cathode ray tube display, 1 is a computer, and 23 is a video board that generates a signal for sending output information from the computer 1 to the cathode ray tube display 22.

In the video board 23, 2 is a luminance signal generation circuit that generates a luminance signal to be sent to the cathode ray tube display 22 from the output information of the computer 1, and 3 is a luminance signal generating circuit that generates a dot clock signal that is the basis of the horizontal synchronization signal and vertical synchronization signal. The dot clock generation circuit 24 is a timing signal generator circuit that generates a vertical synchronization signal and a horizontal synchronization signal using the dot clock signal.

In the cathode ray tube display 22, 4 is a cathode ray tube, and 5 is a deflection yoke. 7 is a horizontal deflection circuit which generates a sawtooth wave current from the horizontal synchronization signal and supplies it to the deflection yoke 5; It changes depending on the width of change in wave current. Reference numeral 6 denotes a horizontal amplitude control circuit that adjusts the width of the display area of the image in the horizontal direction by changing the amplitude of the sawtooth wave current generated by the horizontal deflection circuit 7 by changing the power supply voltage of the horizontal deflection circuit 7. When is applied to the horizontal amplitude control circuit 6, the horizontal amplitude control circuit 6 changes the power supply voltage of the horizontal deflection circuit 6 according to the applied voltage. 25 is a horizontal display area width adjustment volume, and by turning this horizontal display area width adjustment volume 25, the voltage applied to the horizontal amplitude control circuit 6 is changed. 8 is a vertical deflection circuit that generates a sawtooth wave current from a vertical synchronization signal and supplies it to the deflection yoke 5. The vertical image display area width is determined by the sawtooth wave current within the period from the start to the end of the brightness information of the brightness signal. Varies depending on the range of change. 9 is a vertical amplitude control circuit that adjusts the width of the vertical image display area by changing the amplitude of the sawtooth wave current generated by the vertical deflection circuit 8 by changing the power supply voltage of the vertical deflection circuit 8; is applied to this vertical amplitude control circuit 9, the vertical amplitude control circuit 9 changes the vertical deflection circuit 9 according to the applied voltage.
change the power supply voltage. 26 is a vertical display area width adjustment volume, and by turning this vertical display area width adjustment volume 26, the voltage applied to the vertical amplitude control circuit 9 is changed.

Regarding the display device configured as described above, a method of adjusting the width of the display area of the video so that it does not protrude from the screen will be described below.

The output information of the computer 1 is displayed on the cathode ray tube 4 of the cathode ray tube display 22 using the luminance signal, horizontal synchronization signal, and vertical synchronization signal generated by the video board 23, and the display area width of this image is determined by the pulse width of the luminance signal. It is determined by the deflection current value, which is the change width of the sawtooth wave current within the period of .

First, when the user of the computer 1 wants to adjust the display area width of the image in the horizontal direction so that it does not protrude from the screen, the user turns the horizontal display area width adjustment volume 25 to apply a voltage to the horizontal amplitude control circuit 6. The horizontal amplitude control circuit 6 changes the power supply voltage of the horizontal deflection circuit 7 according to this applied voltage, and by changing the amplitude of the sawtooth wave current generated by the horizontal deflection circuit 7, the width of the display area of the image in the horizontal direction is adjusted. Ru.

Next, when adjusting the display area width of the image in the vertical direction so that it does not protrude from the screen, the user turns the vertical display area width adjustment volume 26 to apply a voltage to the vertical amplitude control circuit 9. The vertical amplitude control circuit 9 changes the power supply voltage of the vertical deflection circuit 8 according to this applied voltage, and by changing the amplitude of the sawtooth wave current generated by the vertical deflection circuit 8, the display area width of the image in the vertical direction is changed. is adjusted.

Problems to be Solved by the Invention However, in the conventional configuration described above, not only does the pulse width of the luminance signal vary depending on the video board, but also the pulse width of the luminance signal changes due to switching of the scanning frequency of the video board. The width of the video display area changes by switching the scanning frequency of the board or video board. Therefore, each time the video board is replaced or the scanning frequency is switched, the user must turn the horizontal display area width adjustment volume and vertical display area width adjustment volume while checking the video display area width so that the video display area width is smaller than the screen. There was a problem in that it had to be adjusted so that it did not protrude.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a sawtooth wave from a deflecting means within a pulse width period of a color pattern signal indicating the beginning and end of luminance information of a luminance signal generated in a signal source. A change width detection means for detecting a change width of the current, and an amplitude value variable means for changing the amplitude value of the sawtooth wave current outputted from the deflection means to a predetermined magnitude based on the output signal of the change width detection means. Ta.

Effect of the Invention With the above-described configuration, the present invention can make the width of the video display area constant.

Embodiment FIG. 1 is a block diagram of a display device in an embodiment of the present invention.

In FIG. 1, 1 is a computer, 2 is a luminance signal generation circuit, 3 is a dot clock generation circuit, 4 is a cathode ray tube, and 5 is a luminance signal generation circuit.
is a deflection yoke, 6 is a horizontal amplitude control circuit, 7 is a horizontal deflection circuit, 8 is a vertical deflection circuit, and 9 is a vertical amplitude control circuit. These are the same configuration as the conventional example shown in Fig. 3, so the details will be explained below. Further explanations will be omitted. 10 is a cathode ray tube display,
] 1 is a video board that generates a signal for sending output information from the computer 1 to the cathode ray tube display 10 .

In the video board 11, 12 is a timing signal generator circuit that generates a vertical synchronization signal, a horizontal synchronization signal, a front porch signal, and a back porch signal using a dot clock signal, and 13 is a timing signal generator circuit that generates a front porch signal and a luminance signal from a back porch signal. This is a white pattern signal generator circuit that generates a white pattern signal with all white information from the beginning to the end.

In the cathode ray tube display 10, 15 is a deflection current change width detection circuit, and a white pattern signal generator circuit 13
The width of change in the sawtooth wave current from the horizontal deflection circuit 7 during the pulse width period of the white pattern signal sent from the horizontal deflection circuit 7 is detected. 31 is a current/voltage conversion circuit that converts the current detected by the deflection current change width detection circuit 15 into a voltage proportional to the current, and 19 is an analog/digital converter that converts the analog voltage output from the current/voltage conversion circuit 31 into digital. A conversion circuit 29 is a variation width reference voltage value generation circuit that generates a variation width reference value of the sawtooth wave current from the horizontal deflection circuit 7 within the period of the pulse width of the white pattern signal, and 28 is a variation width reference voltage value generation circuit. A width difference detection circuit detects the difference in the change width output from the analog/digital conversion circuit 19 with respect to the change width reference value output from the circuit 29, and 16 is a jitter of the difference in the change width output from the width difference detection circuit 28. A jitter correction circuit 17 is a digital/analog conversion circuit that converts the difference in change width after jitter correction into an analog voltage and outputs it to the horizontal amplitude control circuit 6.

A deflection current change width detection circuit 18 detects the change width of the sawtooth wave current from the vertical deflection circuit 8 within the period of the pulse width of the white pattern signal sent from the white pattern signal generator circuit 13. 32 is a current/voltage conversion circuit that converts the current detected by the deflection current change width detection circuit 18 into a voltage proportional to it; 27 is a current/voltage conversion circuit 32;
An analog/digital conversion circuit 14 converts the analog voltage output from the vertical deflection circuit 8 into digital, and 14 is a change that generates a reference value of the change width of the sawtooth wave current from the vertical deflection circuit 8 within the period of the pulse width of the white pattern signal. A width reference voltage value generation circuit; 30 is a width difference detection circuit that detects the difference between the variation width output from the analog/digital conversion circuit 27 with respect to the variation width reference value output from the variation width reference voltage value generation circuit 14; A jitter correction circuit 21 corrects the jitter of the difference in change width output from the width difference detection circuit 30, and a digital/analog conversion circuit 21 converts the difference in change width after jitter correction into an analog voltage and outputs it to the vertical amplitude control circuit 9. It is a circuit.

Regarding the display device configured as described above, the operation of adjusting the width of the display area of the video so that it does not protrude from the screen will be described below.

In the video board 11, based on the dot clock signal outputted from the dot clock generation circuit 3, the timing signal generator circuit 12 generates signals as shown in FIGS.
As shown in (e), a horizontal synchronization signal, a vertical synchronization signal, a back porch signal, and a front porch signal are generated.

The white pattern signal generator circuit 13 uses the front porch signal and the back porch signal as shown in FIG. 2(f).
As shown in FIG. 3, a white pattern signal in which all the luminance information of the luminance signal from the beginning to the end is converted into white information is generated and output to the cathode ray tube display 10.

In the cathode ray tube display 10, when adjusting the width of the horizontal video display area so that it does not extend beyond the screen, the second
As shown in Figure (g), the current value A of the sawtooth wave current that the horizontal deflection circuit 7 supplies to the deflection yoke 5 is adjusted by the edge trigger at the rising edge of the white pattern signal sent from the video board 11. The current value B of this sawtooth wave current is detected by the falling edge trigger, and from these values A and B, the sawtooth wave current that the horizontal deflection circuit 7 supplies to the deflection yoke 5 within the period of the pulse width of the white pattern signal is determined. The deflection current change width detection circuit 15 outputs the change width E as E=A+B. This current change width E is converted from a current value to a voltage value by a current/voltage conversion circuit 31, from analog to digital by an analog/digital conversion circuit 19, and is converted from a change width reference voltage value generation circuit 29 by a width difference detection circuit 28. A difference in the change width with respect to the output change width reference value is detected. The jitter of this change width difference is corrected by the jitter correction circuit 16, and the voltage is converted into an analog voltage by the digital/analog conversion circuit 17 and applied to the horizontal amplitude control circuit 6. The horizontal amplitude control circuit 6 controls the horizontal deflection circuit 7 according to this applied voltage.
By varying the power supply voltage and changing the amplitude of the sawtooth current generated by the horizontal deflection circuit 7, the width of the display area of the image in the horizontal direction is adjusted.

When adjusting the width of the vertical video display area so that it does not protrude from the screen, the edge trigger at the rising edge of the white pattern signal at the top of one screen sent from the video board 11 is used as shown in Figure 2 (h). The current value C of the sawtooth wave current supplied by the vertical deflection circuit 8 to the deflection yoke 5 is detected by the edge trigger of the falling edge of the white pattern signal at the bottom of one screen.
, D, the change width of the sawtooth wave current supplied by the vertical deflection circuit 8 to the deflection yoke 5 within the period of the pulse width of the white pattern signal is outputted from the deflection current change width detection circuit 18 as I=C+D. . This current change amplitude is converted from a current value to a voltage value by a current/voltage conversion circuit 32, from analog to digital by an analog/digital conversion circuit 27, and from a change width reference voltage value generation circuit 14 by a width difference detection circuit 30. A difference in the change width with respect to the output change width reference value is detected. The jitter of this change width difference is corrected by the jitter correction circuit 20, and the voltage is converted into an analog voltage by the digital/analog conversion circuit 21 and applied to the vertical amplitude control circuit 9. The vertical amplitude control circuit 9 controls the vertical deflection circuit 8 according to this applied voltage.
By changing the power supply voltage of the vertical deflection circuit 8 and changing the amplitude of the sawtooth wave current generated by the vertical deflection circuit 8, the width of the display area of the image in the vertical direction is adjusted.

Effects of the Invention As described above, the present invention detects the width of change in the sawtooth wave current from the deflection means within the pulse width period of the color pattern signal indicating the start and end of the luminance information of the luminance signal generated by the signal source. Image display is possible by including a change width detection means and an amplitude value variable means for changing the amplitude value of the sawtooth wave current outputted from the deflection means to a predetermined magnitude based on the output signal of the change width detection means. The width of the area can be kept constant, and there is no need to adjust the width of the video display area so that it does not protrude from the screen when replacing the video board or switching the scanning frequency of the video board.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a display device according to an embodiment of the present invention, FIG. 2 is a timing chart of a display device according to an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional display device. 1...Computer 2...Brightness signal generation circuit 3...Dot clock generation circuit 4...Cathode ray tube 5...Deflection yoke 6...Horizontal amplitude control circuit 7...Horizontal deflection circuit 8. ... Vertical deflection circuit 9 ... Vertical amplitude control circuit 10 ... Cathode ray tube display 11 ... Video board 12 ... Timing signal generator circuit 3 ... White pattern signal generator circuit 4 ... Change width reference Voltage value generation circuit 5...Deflection current change width detection circuit 6...Jitter correction circuit 7...Digital/analog conversion circuit 8...Deflection current change width detection circuit 9...Analog/digital conversion circuit 0・-・Jitter correction circuit 1 ・Digital/analog conversion circuit 7 ・Analog/digital conversion circuit 8 ・Change width difference detection circuit 9 ・Change width reference voltage value generation circuit 0 ・Width difference Detection circuit 1 -- Current/voltage conversion circuit 2 -- Current/voltage conversion circuit

Claims (1)

[Claims] It has a cathode ray tube, a deflection yoke attached to the cathode ray tube, and deflection means for supplying a sawtooth wave current to the deflection yoke from a synchronization signal generated by a signal source, and the luminance information of a luminance signal generated by the signal source. change width detection means for detecting the change width of the sawtooth wave current outputted from the deflection means within the period of the pulse width of the color pattern signal indicating the start and end of the change width detection means; and the deflection means using the output signal of the change width detection means. A display device comprising amplitude value variable means for changing the amplitude of a sawtooth wave current output from the sawtooth wave current to a predetermined magnitude.