KR0153662B1 - Circuit for protecting from malfunction in a display system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a malfunction prevention circuit in a display device. The present invention relates to a display device including a D-sub connector, a microcomputer, a vertical deflection unit, a horizontal deflection unit, a high voltage unit, a preamplifier, an image output unit, and a power supply unit. It consists of an inverter for inverting the mute signal output from the microcomputer and an inverted mute signal output from the inverter and an AND gate for outputting a normal selection signal after the mode change period by performing logical OR on the selection signal output from the microcomputer when the mode is changed. do. Therefore, when the mode is changed, a malfunction can be prevented by inverting the mute signal output from the microcomputer and performing a logical sum with the selection signal output from the microcomputer to output a normal selection signal.

Description

Malfunction prevention circuit in display device

1 is a block diagram schematically showing a color monitor to which the present invention is applied.

2 is a block diagram showing a malfunction preventing circuit according to the present invention in a display device.

3 is a waveform diagram for explaining the operation of the present invention shown in FIG.

* Explanation of symbols for main parts of the drawings

11: D-sub Connector 12: Key Input

13: micom 14: vertical deflection

15: horizontal deflection portion 16: high pressure portion

17: preamplifier 18: video output

19: CRT 20: power supply

21: malfunction prevention unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a circuit for preventing a malfunction when a signal output from a microcomputer is unstable due to a mode change.

Among the display devices, a monitor is an output device of an information processing device, and converts a binary data signal of an information processing device into an image signal using a cathode ray tube (CRT) and outputs it to a screen. Depending on the type of VGA (Video Graphic Adapter; VGA) monitor, Enhanced Graphic Adapter (EGA) monitor, Color Graphic Adapter (CGA) monitor, Mono Display Adapter; MDA) monitor.

Currently, there are many types of video cards of computer systems that are commonly used, such as CGA, MDA, EGA, EGA / CGA, PGA, VGA (3-mode), VGA 8514 (1-mode), and SVGA, as shown in Table 1 below. Different video cards have different vertical and horizontal sync signals. Synchronization signal is dualized into positive sync and negative sync to distinguish polarity, and each card has modes of horizontal frequency of 15.7㎑, 18.5㎑, 30.5㎑, 31.5㎑, 35.5㎑, 38.5㎑, 48.5㎑. , Vertical frequency has 50kHz, 60kHz, 70kHz, 87kHz mode.

Therefore, there is a demand for a multi-mode monitor that can switch modes according to such various vertical and horizontal frequencies. That is, the polarity of the vertical and horizontal sync signals outputted according to the graphics modes is different. Therefore, the multi-mode monitors that allow one monitor to be operated in various graphics modes of the computer system have different polarities of the vertical and horizontal sync signals. It is converted to be suitable for detecting and operating.

Most of these multi-mode monitors use a microcomputer (13 in FIG. 1). In the microcomputer 13, each parameter, for example, a horizontal position (H.Position), a horizontal size (H.Size), and a vertical position (V.Position) is used. ), The selected parameter is selected through the key input unit 12 from among V.Size, Pincushion, Tilt, and the like, and the digital / analog conversion value associated with the parameter is output. However, when the monitor is unstable due to a mode change or the like, the microcomputer 13 outputs an error signal due to noise or the like at each output pin, and this error signal may affect the rear end, causing the set to malfunction.

For example, when the rated B + voltage is applied from the microcomputer 13 to the high voltage section 16, but the period of the flyback pulse output from the horizontal deflection section 15 is increased due to a malfunction, the high voltage generated becomes higher than the rated voltage. The period of the flyback pulse output from the horizontal deflection section 15 is a rated period, and the high pressure generated when the B + voltage supplied from the microcomputer 13 to the high voltage section 16 due to a malfunction increases by higher than the rated voltage. There was a risk of damage.

Accordingly, an object of the present invention is to prevent the malfunction of outputting a normal selection signal by performing a logical sum with the selection signal output from the microcomputer after inverting the mute signal output from the microcomputer when the mode is changed in the display device to solve the above problems To provide a circuit.

In order to achieve the above object, a malfunction prevention circuit according to the present invention includes a D-sub connector for supplying R, G, B, horizontal / vertical synchronization signals supplied from a video card to each unit, and vertical / horizontal synchronization supplied from the video card. Microcom which performs readjustment such as horizontal / vertical synchronization, deflection optimization and deflection correction within a corresponding resolution using a signal, a vertical deflection portion generating a vertical sawtooth current using the vertical synchronization signal, and using the horizontal synchronization signal A horizontal deflection unit generating a horizontal sawtooth current and a flyback pulse, a high voltage unit generating a high pressure using the flyback pulse and applying the CRT to the CRT and amplifying the R, G, and B signals to a predetermined voltage level A display device comprising: a preamplifier and a video output unit; and a power supply unit for supplying power voltages of the respective units.

An inverter for inverting a mute signal output from the micom when a mode is changed; And

And an AND gate for outputting a normal selection signal after a mode change period by performing a logical OR on the inverted mute signal output from the inverter and the selection signal output from the micom when the mode is changed.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

FIG. 1 is a block diagram showing a color monitor to which the present invention is applied. The D-sub connector 11, the key input unit 12, the microcomputer 13, the vertical deflection unit 14, the horizontal deflection unit 15, The high voltage section 16, the preamplifier 17, the video output section 18, the CRT 19 and the power supply section 20.

2 is a block diagram showing a malfunction prevention circuit according to the present invention in a color monitor, in which the malfunction prevention section 21 selects an inverter INV1 for inverting the mute signal a and an output signal and selection of the inverter INV1. And AND gate AND1 performing an AND operation on the signal b.

3 is a waveform diagram for explaining the operation of the present invention shown in FIG. 2, wherein a is a mute signal output from the microcomputer 13, b is output from the microcomputer 13, and a retrace capacitor ( A selection signal is connected to a relay (not shown) for switching modes and linearity coils (not shown) for each mode, and b 'is a selection signal output from the AND gate AND1. Here, t1 is a mode change period.

Then, the operation of the present invention with reference to Figures 1 to 3 as follows.

In FIG. 1, the vertical synchronizing signal V-sync and the horizontal synchronizing signal H-sync supplied from a predetermined video card through the D-sub connector 11 are applied to the microcomputer 13, and R, The G and B signals are applied to the preamp 17.

The microcomputer 13 uses the vertical / horizontal synchronization signal supplied from the video card to readjust the parameters such as horizontal / vertical synchronization, deflection optimization, and deflection correction within the corresponding resolution. Then, the preamplifier 17 is controlled according to a command applied through the key input unit 22, and the vertical deflection unit 14 and the vertical and horizontal synchronizing signals having a corresponding frequency within a resolution allowable in the multi-mode monitor are respectively. To the horizontal deflection section 15.

The vertical deflection unit 14 generates a vertical deflection sawtooth current using the vertical synchronizing signal parameter output from the microcomputer 13, and the horizontal deflection unit 15 uses the horizontal synchronizing signal parameter output from the microcomputer 13. A horizontal deflection sawtooth current is generated, and a flyback pulse, which is used to generate high voltages, is generated.

The high voltage unit 16 generates a high voltage with a fly-back transformer (FBT) using a flyback pulse and applies it to each grid and anode terminal of the CRT 19.

The preamplifier 17 and the video output unit 18 are for amplifying a low voltage level video signal supplied from the D-sub connector 11 to maintain a constant voltage level. In this case, the switching amplifier may be sufficient, but in general, a monitor requires a specific range of luminance values (from black to white) to display a screen. That is, the cathode of the grid or CRT 29 should be adjustable up to a predetermined maximum voltage in a cut-off state. Cathode grid drives are rarely used because of their low capacitance and simple interfacing, and most monitors use cathode drives.

The power supply unit 20 supplies the power voltages of each unit, that is, the microcomputer 13, the vertical deflection unit 14, the horizontal deflection unit 15, the high voltage unit 16, the preamplifier 17 and the video output unit 18. It is for.

In FIG. 2, in the malfunction prevention unit 21, a mute signal (a in FIG. 3) is output from the a output pin of the microcomputer 13 during the mode change period t1, and during this period, If an error signal occurs as shown in b of FIG. 3 at the b output pin of the microcomputer 13 due to a malfunction, the mute signal (a in FIG. 3) is inverted at the inverter INV1, and the inverter is operated at the AND gate AND1. A logical product is performed on the output signal of INV1 and the signal (b in FIG. 3) of the b output pin of the microcomputer 13 to output a signal such as b 'in FIG. Therefore, the normal b signal is output after the mode change period t1.

As described above, in the display device, the malfunction prevention circuit according to the present invention may invert the mute signal output from the microcomputer and change the mode and perform a logical sum with the selection signal output from the microcomputer to output a normal selection signal to prevent the malfunction. There is an advantage to this.

Claims (1)

D-sub connector for supplying R, G, B, horizontal / vertical sync signal from video card to each part, and horizontal / vertical sync and deflection within the corresponding resolution by using vertical / horizontal sync signal from video card A microcomputer for performing readjustment such as optimization and deflection correction, a vertical deflection unit for generating a vertical sawtooth current using the vertical synchronization signal, a horizontal deflection unit for generating a horizontal sawtooth current and a flyback pulse using the horizontal synchronization signal, The high voltage unit generates a high voltage by using the flyback pulse and applies the CRT to a predetermined voltage level, and supplies a preamplifier and a video output unit that amplifies the R, G, and B signals to a predetermined voltage level and applies the power voltages to the CRT. A display device having a power supply, comprising: an inverter for inverting a mute signal output from the micom when a mode is changed; And an AND gate for outputting a normal selection signal after a mode change period by performing a logical OR on an inverted mute signal output from the inverter and a selection signal output from the micom when a mode is changed. Malfunction prevention circuit.