KR20020057506A - Screen-brightness control circuits of display device - Google Patents

Abstract

PURPOSE: A circuit for controlling screen brightness of a video display apparatus is provided to mount a simpler brightness control circuit and a mute circuit on a video apparatus, thereby reducing a defective proportion of the video apparatus and occupying a smaller PCB space. CONSTITUTION: An electron emission source(59) emits an electron reaching a screen to display R, G, B on a CDT front. A G1 voltage input unit(52) controls the amount of the electron with the size of a positive voltage. A vertical blanking generation circuit(53) adds a strong negative voltage to the G1 input unit by a vertical frequency, not to present a scanning line on the screen during a vertical blanking period. An input terminal(55) is applied with a negative 120 voltage inputted from an FBT(Fly Back Transformer). A microcomputer(56) outputs a mute signal and a brightness control signal for a brightness control and to control an abnormal state. Switches(Q1, Q2) are controlled by the mute signal and the brightness control signal.

Description

Screen brightness control circuit of video display device {SCREEN-BRIGHTNESS CONTROL CIRCUITS OF DISPLAY DEVICE}

The present invention relates to a voltage adjusting circuit of a video display device. More particularly, the present invention relates to a voltage control circuit of a video display device. The present invention relates to a circuit for suppressing a raster scan line returning at a frequency.

When an image display device receives heat from a heater and emits electrons displaying an R / G / B signal, the electrons reach the front of the CDT and the screen is visible. In this case, in order to adjust the brightness, the brightness of the screen, a negative voltage is applied to G1 of the CDT to control the amount of electrons of the R / G / B signal reaching the front of the CDT, where G1 is the negative voltage. Therefore, the electrons protruding from the electron emission source act to offset the force toward the screen by the repulsive force. G1 also plays a role of preventing electron arrival in order to prevent abnormal phenomena such as screen collapse and screen size reduction during transient periods such as 'power on / power off' and mode change.

1 is a circuit diagram illustrating a conventional circuit for controlling the voltage of the CDT.

The schematic diagram of the conventional circuit shown in FIG. 1 shows a CDT 11, an electron emission source 19 that emits electrons reaching the screen for displaying R, G, and B on the front of the CDT, and an amount of the electrons. The G1 voltage input unit 12 controlling the magnitude of the negative voltage and a strong blanking voltage at the vertical period Fv are added to the G1 input unit so that the scanning line does not appear on the screen during the vertical return. vertical blanking) generating circuit 13, Vcc voltage input terminal 14, input terminal 15 for receiving brightness control signal Vb output for brightness control from a microcomputer, and input from FBT (Flyback Transformer)- An input terminal 16 receiving a 120V voltage, an input terminal 17 receiving a mute signal Vc output from the microcomputer to control a screen abnormal phenomenon during a transition, and a voltage controlling a transient phenomenon during a transient period of the CDT. Input terminal 18 to which a voltage of 15 V is inputted, and It comprises a switch (Q1, Q6) controlled by the mute signal to the brightness control signal.

The operation of the brightness control in the circuit is as follows. First, the microcomputer outputs a brightness control signal as shown in FIG. 3. This Vb signal is input through the input terminal 15, integrated through R1 and C1, converted to direct current, and then applied to the base potential of Q6, depending on how much + V this DC base potential is. on) 'degree is determined. On the other hand, a -120V potential is applied from the FBT through the input terminal 16, which acts as the base potential of Q4 via R5 and R6 to control the degree of 'on' of Q4 and simultaneously acts on G1 through R7. Done. At this time, Vcc is also input from the input terminal 14, which controls the degree of 'on' of Q4 together with -120V through Q5 via R4. The influence of this Vcc is determined by the amount of collector current passing through Q5, and the amount of collector current is influenced by how much Q6 is 'on', so that the base potential of Q4 is controlled by controlling the Q6 base potential. Furthermore, the brightness of the screen can be adjusted by controlling the influence on G1 of (-) 120V, that is, the voltage applied to G1.

Another method of processing the micom mute signal for controlling the screen abnormal phenomenon during the transient is as follows. First, in normal operation, no voltage is input from the microcomputer to the input terminal 17. Then, since Q1 is 'off', + 15V input through the input terminal 18 is offset by -120V through R8 with the collector current of Q2. Eventually, the sum of the two voltages is input to G1, so only some of the effects of -120V are affected on the screen, and the screen looks normal. However, during the transition period, a + 5V signal as shown in FIG. 4 is output from the microcomputer and input to the input terminal 17. Then, Q1 is turned 'on', and the current due to + 15V input to the input terminal 18 flows mostly through R9 to ground rather than to R8. After all, most of the influence of -120V will be on G1 without any interruption, so the electrons will not reach the screen. In other words, the screen does not appear during the transition period.

Using such circuits, although their purpose can be achieved, there is a problem that the circuit configuration is very complicated. If the circuit configuration is complicated, not only the defects increase once and the area occupied by the components is wide, but also the manufacturing cost increases because of the large number of components.

The present invention has been made to solve the above problems, and an object thereof is to provide a luminance control circuit and a mute control circuit of a video device which is simpler than a conventional circuit configuration.

Another object of the present invention is to reduce the defect rate of the imaging device through the circuits as described above, and to provide an imaging device having a small PCB area and low production cost.

1 is a screen control circuit of a conventional video device.

2 is a schematic diagram showing an embodiment of the voltage Va applied to G1.

3 is a schematic diagram showing an embodiment of a luminance control signal Vb.

4 is a schematic diagram showing an embodiment of a mute control signal Vc.

5 is a screen control circuit of the imaging apparatus of the present invention.

Description of the main parts of the drawing

51: CDT 52: G1 voltage input

53: vertical blanking generating circuit 54: Vcc voltage input stage

55: -120V voltage input 56: Micom

The luminance control circuit of the present invention for achieving the above object includes a microcomputer for outputting a luminance control signal of a video device, a first transistor for receiving the output luminance control signal at a base potential, and the first transistor. A positive voltage input terminal coupled to generate a first collector current controlled by the base potential, a negative voltage input terminal generating a negative current summed with the controlled first collector current; And means for controlling the amount of electrons directed to the screen of the imaging apparatus by receiving the final voltage by the sum of the first collector current and the negative current. The means for controlling the amount of electrons here means the same means of action as the above-described G1. In addition, the mute control circuit of the present invention includes a microcomputer for outputting a mute control signal of a video device, a transistor for receiving the output mute control signal at a base potential, and a negative voltage input terminal for generating a negative current. And a positive current comprising a first positive current summed with the negative current and a second positive current flowing through the transistor to ground while being controlled by the base potential. And a means for controlling the amount of electrons to be input to the screen of the imaging apparatus by receiving a positive voltage input terminal and a final voltage generated by the combined first positive current and the negative current. It features. And further comprising a vertical blanking generating circuit which generates a negative voltage at a vertical period of the scan line and adds the voltage to the sum of the collector current and the negative current to prevent the scan line from appearing on the screen during the retrace period of the scan line. It can also be configured. The negative voltage may be input from FBT, and the positive voltage may be input in Vcc.

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

5 is a circuit diagram showing the configuration of the present invention. The circuit diagram of the present invention shown in FIG. 5 includes a CDT 51, an electron emission source 59 that emits electrons reaching the screen for displaying R, G, and B on the front of the CDT, and the amount of these electrons. A vertical blanking which adds a strong voltage to the G1 input section at a vertical period (Fv) to prevent the scan line from appearing on the screen during the vertical return. The generator circuit 53, the Vcc voltage input terminal 54, the input terminal 55 to which the -120V voltage input from the flyback transformer (FBT) is applied, the mute signal Vc and The microcomputer 56 outputs the brightness control signal Vb, and switches Q1 and Q2 controlled by the mute signal and the brightness control signal.

The operation of the brightness control in the circuit is as follows. When the microcomputer 56 outputs Vb, it is shown in FIG. 3, and the Vb signal changed into direct current through R6 and C1 is applied to the base potential of Q2. This base potential is applied to Q2 by Vcc to control the current output as the collector current. That is, when the base potential of Q2 is high + V, the collector current Ic of Q2 hardly flows. On the contrary, when the base potential of Q2 is low, the collector current Ic flows relatively much. On the other hand, since the current input by the potential of -120V exists at the input terminal 55, the collector current (Ic) of Q2 and the current of -120V experience a relative cancellation with each other, and the sum current is applied to G1 to the surface of the CDT. Determine the amount of electrons hit by. The amount of these electrons determines the screen brightness. Therefore, the brightness of the screen can be controlled by controlling the amount of current input to G1 by the base potential of Q2.

Another object of the present invention, the mute adjustment method for removing the screen abnormal phenomenon during the transition works as follows. First, if it is not a transient, the microcomputer applies a 0V signal to the base of Q1, so Q1 is in the 'off' state. At this time, the Vcc voltage input through the input terminal 24 passes through R1 and R2 to the collector current Ic of Q2. As in the case of the luminance adjustment described above, Vcc acts as a offset to -120V so that electrons reach the screen, which is the case of normal operation. However, during the transition period, the microcomputer outputs the mute signal Vc as shown in FIG. 4. That is, if the microcomputer outputs a + 5V voltage, this signal is applied to the base of Q1 through R10, so that Q1 is 'on' during this period. When Q1 is 'on', the current due to the Vcc voltage, i.e. the offset current to -120V, all flows to ground, so the rest of Ic is near zero. As a result, there is little offsetting effect by Vcc, so -120V is completely caught by G1, so that electrons hardly reach the screen. That is, the abnormal phenomenon in the transition period is not seen, thereby achieving the desired mute.

Further, in addition to the G1 voltage configuration for the above two purposes, the vertical blanking generation circuit 54 further generates a waveform of about -40V during the vertical period and adds it to the original G1 to provide a raster during the vertical retrace period. You can also make the scan lines appear invisible. The signal of FIG. 2 adds the pulse waveform of the negative voltage output from the vertical blanking generation circuit 54 in addition to the voltage applied to G1 due to the circuits. The interval between -40V and G1 is the return period of the scanning line, in which case nothing appears on the screen.

For reference, the figures described and illustrated in the present invention are only examples for explanation, and the present invention is not limited to these figures.

According to the present invention, a luminance control circuit and a mute circuit, which are simpler than the conventional circuit configuration, can be attached to a video device. Therefore, this has the advantage of reducing the defect rate of the video device, and can produce a video device with a low production cost while occupying a small PCB area.

Claims (6)

In the luminance control circuit of the video device, A microcomputer for outputting a luminance control signal of a video device; A first transistor receiving the output luminance control signal at a base potential; A positive voltage input terminal coupled to the first transistor to generate a first collector current controlled by the base potential; A negative voltage input terminal for generating a negative current summed with the controlled first collector current; Means for controlling the amount of electrons received by the summed first collector current and the negative voltage by the negative current toward the screen of the imaging apparatus; A luminance control circuit of a video device comprising a. In the mute control circuit of the video device, A microcomputer that outputs mute control signals of video equipment, A transistor for receiving the output mute control signal at a base potential; A negative voltage input terminal for generating a negative current, Generating a positive current comprising a first positive current summed with the negative current and a second positive current flowing through the transistor to ground while being controlled by the base potential Positive voltage input, Means for controlling the amount of electrons received by the summed first positive current and the negative voltage by the negative current toward the screen of the imaging apparatus; Mute control circuit of a video device comprising a. The method according to claim 1 or 2, wherein a negative voltage is generated at a vertical period of the scan line and added to the sum of the combined collector current and the negative current to prevent the scan line from appearing on the screen during the retrace period of the scan line. The control circuit of the video device further comprises a vertical blanking generating circuit. The brightness control circuit of claim 1, wherein the negative voltage is input from an FBT. The brightness control circuit of claim 1, wherein the positive voltage is input in Vcc. The method of claim 1, The microcomputer further outputs a mute control signal, And a second transistor configured to receive the output mute control signal at a base potential. The positive voltage input terminal receives a second collector current flowing through the second transistor to ground while being controlled by a base potential of the second transistor in addition to the first collector current. And further outputting the luminance control circuit of the video apparatus.