JPH054666U - CRT drive circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] The screen voltage of the CRT is kept constant and the brightness (black level) of the screen is stabilized. A high voltage obtained by rectifying a pulse voltage generated by horizontal deflection output is controlled by a DC voltage proportional to a peak voltage of the pulse voltage to supply a stable screen voltage to a second grid electrode of a CRT. It is characterized by having done.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention is a CRT drive circuit for reproducing an image on a CRT display, especially It is used in large-scale machines that consume large amounts of power and in receivers that use high deflection frequencies. A CRT drive circuit having a circuit configuration in which horizontal deflection and high voltage output are separated. Of.

[0002]

[Prior art]

  4, 5, and 6 are vertical deflection circuits and horizontal deflection circuits of conventional CRT drive circuits. It is a figure which shows an example of a high voltage generation circuit.   This CRT drive circuit 100 includes a vertical deflection circuit 2, a horizontal deflection circuit 3 and a high voltage generator. It has a circuit 4. Here, 5 is a picture tube (hereinafter referred to as CRT).

[0003]   The vertical deflection circuit 2 includes a vertical oscillation circuit 6, a vertical deflection drive circuit 7, and a vertical output circuit. With the passage 8. The vertical output circuit 8 is connected to one end of the vertical deflection coil 9 and Side pinkish which constitutes the vertical line distortion correction circuit 11 via the shaping circuit 10. It is connected to the primary side 12a of the correction transformer 12. . The other end of the vertical deflection coil 9 is It is connected to the vertical deflection drive circuit 7 via the line distortion correction circuit 13.

[0004]   Generated by the vertical oscillator circuit 6 in synchronization with the vertical sync signal pulse from the previous stage (not shown) The pulse voltage to be shaped is shaped and amplified by the vertical deflection drive circuit 7 and is then output by the vertical output circuit 8. And a sawtooth current for vertical deflection is supplied to the vertical deflection coil 9 of the CRT 4. It At this time, the vertical deflection drive circuit 7 causes the horizontal distortion correction circuit 13 to display on the screen. Correct the lower distortion and horizontal line horizontally.

[0005]   The horizontal deflection circuit 3 includes a horizontal oscillation circuit 14 and a horizontal deflection drive circuit that amplifies the oscillation voltage. A path 15 is provided with a horizontal output circuit 16 for supplying the deflection power to the horizontal deflection coil. Horizontal The output circuit 16 includes an npn transistor 17 for switching and a damper diode. A transistor 18 and a resonance capacitor 19 are provided. It is connected to one end of the primary side 30a of the transformer 30. Also, the transistor 17 The rector is a side that constitutes the vertical line distortion correction circuit 11 via the horizontal deflection coil 20. It is connected to the secondary side 12b of the pincushion correction transformer 12. In addition, in FIG. 53 and 54 are monostable multivibrators (MM).

[0006]   It is generated by the horizontal oscillator circuit 14 in synchronization with a horizontal sync signal pulse from the preceding stage (not shown). The oscillated pulse voltage is applied to a monostable multivibrator 53 and a horizontal deflection drive circuit. It is shaped and amplified by 15 and added to the base of transistor 17 of horizontal output circuit 16 Horizontal deflection coil by the switching action of the transistor 17 and diode 18 of A sawtooth wave current having a horizontal deflection period is passed through 20. At the same time, this transistor 17 The collector current is also passed through the pulse transformer 30.   At this time, the side pincushion correction transformer 12 By the vertical output signal applied to the primary side 12a, the vertical output signal is applied to the secondary side 12b. Create a parabolic voltage for the period and superimpose the correction current on the sawtooth current of horizontal deflection. Correct the distortion of the vertical line on the CRT.   In the vertical line distortion correction circuit 11, 21 is a linearity correction circuit and 22 is an S-shaped supplement. It is a positive capacitor.

[0007]   Further, the output (flyback pulse) of the horizontal oscillation circuit 14 is also supplied to the high voltage generation circuit 4. Be guided.   The high voltage generation circuit 4 includes a high voltage output drive circuit 23, a high voltage output circuit 24, and a booster circuit. A flyback transformer (FBT) 25 and a high voltage module 26 are provided. High pressure output The output circuit 24 is an npn transistor 27 for switching and a damper diode. 28 and a resonance capacitor 29.

[0008]   In addition, the collector of the transistor 27 is a flyback transformer (FBT) 25. It is connected to one end of the primary side 25a. 1 of this flyback transformer (FBT) 25 The other end of the secondary side 25a is the other end of the primary side 30a of the pulse transformer 30 and the B1 power source. Connect to. From the secondary side 25b of the flyback transformer (FBT) 25, The anode voltage and the fourth grid are controlled by the CRT 4 via the joule 26 to control the voltage. The second grid electrode that controls the focus voltage for adjusting the dust and the brightness of the CRT 4 Output pressure (screen voltage).   Reference numeral 31 is a voltage control circuit of the flyback transformer (FBT) 25.

[0009]   The pulse voltage oscillated by the horizontal oscillator circuit 14 is applied to the monostable multivibrator 54 and And high-voltage output drive circuit 23 shapes and amplifies the high-voltage output circuit 24 transistor. A switch of horizontal deflection period is added to the base of 27 and cooperates with the diode 28. Perform a motion operation. The pulse voltage generated at the collector of the transistor 27 is horizontally polarized. It is tuned to the opposite frequency and boosted by a flyback transformer (FBT) 25. The high voltage module 26 rectifies and divides the voltage to generate an anode voltage, a focus voltage, and a voltage. It becomes a lean voltage.

[0010]   Controlling the brightness of the CRT 4 does not directly change the cathode. That is, the CR in the previous stage Since the cathode electrode (K) can be controlled by the video signal from the T drive circuit 32 , Bias depth by changing cathode voltage according to change of video signal (luminance signal) , And the brightness is controlled by determining the amount of electron beam flow. Where electronic bee Cathode annotator for moving (scanning) the spot of the frame sequentially through each point on the screen. Deflection of the beam between the beams is performed using the vertical deflection circuit and the horizontal deflection circuit.   In the drawing, H is a heater, G1 is a first grid, G2 is a second grid, and Reference numeral 4 is a fourth grid, and A is an anode.

[0011]

[Problems to be solved by the device]

  However, this conventional CRT drive circuit has the following problems. (1) The amount of electron beam flow, that is, the beam current is Change causes high voltage fluctuation (specifically, the beam current increases and the screen becomes brighter). Then, the high pressure will decrease.) The lean voltage also fluctuates and the brightness of the CRT (particularly, the black level) changes. (2) When the horizontal deflection circuit is stopped, the beam current is concentrated in a vertical line and the phosphor is It can damage and destroy expensive CRTs. (3) When the vertical deflection circuit is stopped, the phosphor due to the beam current concentration on the horizontal line is removed. It can damage and destroy expensive CRTs.   The CRT driving circuit according to the present invention has been made to solve such a problem. Then, the purpose of the second grid voltage (screen voltage) that controls the brightness of the CRT is Stabilizes, and even when the horizontal and vertical deflection circuits stop, C This is to prevent the RT phosphor from being damaged.

[0012]

[Means for Solving the Problems]

  In order to solve the above problems, a CRT driving circuit according to the present invention is provided with a horizontal deflection output pulse. High voltage generation that rectifies the current and supplies the screen voltage to the second grid electrode of the CRT. Circuit and a detector for outputting a DC voltage proportional to the peak voltage of the horizontal deflection output pulse. An output circuit is provided, and the DC voltage of the detection circuit is applied to the second grid electrode of the CRT. The high voltage generation circuit that supplies the screen voltage is controlled.

[0013]   Further, in order to solve the above-mentioned problems, a CRT drive circuit according to the present invention has a horizontal deflection output. High voltage that rectifies the pulse and supplies the screen voltage to the second grid electrode of the CRT High voltage generating circuit, and a direct current proportional to the peak voltage of the horizontal deflection output pulse A detection circuit that outputs a voltage is provided, and the CRT first While controlling the high voltage generation circuit that supplies the screen voltage to the 2 grid electrodes, Provide a vertical amplitude detection circuit to detect the vertical deflection output pulse, and When detected, the output of this vertical amplitude detection circuit is used to output the second grid voltage of the CRT. The high voltage generation circuit that supplies the screen voltage to the poles is controlled.

[0014]

[Action]

  The CRT driving circuit according to the present invention rectifies the pulse voltage generated by the horizontal deflection output. Then, the high voltage is used as a power source to control the second grid voltage of the CRT. Also horizontal Using the secondary winding of the pulse transformer provided for the deflection output, the second grid voltage is Control. Further, by the output of the vertical amplitude detection circuit provided for the vertical deflection output, 2 Control the grid voltage.

[0015]

【Example】

  An embodiment of the present invention will be described below with reference to the accompanying drawings.   1, 2 and 3 are a vertical deflection circuit and a horizontal deflection circuit of a CRT driving circuit according to the present invention. It is a figure which shows one Example of a deflection circuit and a high voltage | pressure generation circuit, Comprising: It is assumed that the parts given the same numbers as those in FIG. Is omitted.

[0016]   The CRT drive circuit 1 according to the present invention includes a high voltage generation circuit 33 in addition to a conventional circuit. And a detection circuit 34 for outputting a DC voltage proportional to the peak voltage of the horizontal deflection output pulse To provide.   If the diode 35 connected to the collector of the transistor 17 is a capacitor 36 And grounded via a resistor 37 and a capacitor 38, and at the same time an npn transistor It is connected to 39 collectors. The emitter of this transistor 39 is a diode 40 to the collector and a diode 41 to connect the base and And the capacitor 38.

[0017]   Also, this emitter is grounded through resistors 42 and 43, and this resistor 4 2 to the second grid. The diode 41 is connected to npn via the resistor 45. Connect to the collector of transistor 46. Here, 44 is a slider of the resistor 42, 4 Reference numeral 7 is a Zener diode for reference voltage, and 48 is a smoothing capacitor.

[0018]   The pulse voltage generated at the collector of transistor 17 is applied to diode 35 and The capacitor 36 rectifies it to a DC voltage. This voltage is divided by resistor 37 and This transistor 39 is made conductive by applying it to the base of the transistor 39. At this time, this The emitter voltage of the transistor 39 is led to the collector via the diode 40.

[0019]   On the other hand, the detection circuit 34 includes a pulse transformer 30 and a diode 49. The secondary side 30b of the transformer 30 is connected to the high voltage generating circuit 3 via the diode 49. 3 is connected to the base of the transistor 46. Also, this pulse transformer The number of windings on the secondary side 30b of 30 is 1 / n of the number of windings on the primary side 30a (where n is 2 The above integer).

[0020]   In this detection circuit 34, the transistor 17 is provided on the primary side 30a of the pulse transformer 30. Pulse generated at the collector of the transistor 17 is added to the secondary side 30b. Generates a DC voltage that is proportional to the peak voltage of the pulse generated in the Rector. This straight The base of the transistor 46 via the diode 49 with the flowing voltage as the detection voltage. In addition, the transistor 46 is turned on.

[0021]   When the transistor 46 becomes conductive, the emitter of the transistor 46 The base current and emitter current of the transistor 39 flow through the The zener voltage of the diode 47 rises. Accordingly, the transistor 39 The base current decreases as the source potential decreases. Therefore, the transistor 39 Rector current decreases and emitter voltage decreases. And this emitter voltage is To the second grid via 44.

[0022]   That is, the pulse voltage generated in the collector of the transistor 17 as described above is The emitter voltage of the transistor 39 is controlled by a proportional DC voltage to be a constant voltage. To do so. As a result, a constant screen voltage is always applied to the second grid of CRT4. Will be supplied. At this time, the second grid is formed by the slider 42 of the resistor 44. The voltage supplied to can be finely adjusted.

[0023]   In addition, if a failure occurs that stops the horizontal deflection circuit, the transistor 17 Since the pulse voltage is not generated in the reflector, the screen voltage drops and the brightness is reduced. The controlled anode current (beam current) is stopped.

[0024]   Further, in this invention, the vertical output circuit 8 and the high voltage generating circuit 33 are configured. A vertical amplitude detection circuit 50 and a diode 51 between the bases of the transistors 46 Set up. In addition, a DC voltage is applied to the vertical amplitude detection circuit 50 via the service switch 52. Connect the source (B2 power supply). In the service switch 52, N is normal and S is S. Means a service, and when S, the CRT screen has one horizontal line.

[0025]   In the state (N) shown in the figure, the switch 52 detects the vertical amplitude when the vertical deflection circuit stops. The diode 51 supplies a voltage of a level according to the voltage level supplied to the output circuit 50. Is supplied to the base of the transistor 46 via. That is, the vertical amplitude detection circuit 5 When the voltage level supplied to 0 is high level, the transistor 46 goes high. Level voltage is supplied to turn on transistor 46 and Lower the screen voltage to stop the beam current and increase the brightness of the CRT. Lower.

[0026]

[Effect of device]

  With the above-mentioned configuration, the CRT drive circuit according to the present invention has the following effects. Play the fruit. (1) The screen voltage does not depend on the horizontal deflection frequency and changes in the signal level Because of the change in the anode current caused by it, the high voltage output is constant without changing. , CRT screen brightness (especially black level) is stabilized. (2) Even if the horizontal deflection circuit is stopped, the brightness of the CRT decreases It is possible to prevent the phosphor from being damaged by the concentration of the beam current above. (3) Even if the vertical deflection circuit is stopped, the brightness of the CRT decreases, so a horizontal line It is possible to prevent the phosphor from being damaged by the concentration of the beam current above.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a vertical deflection circuit of a CRT driving circuit according to the present invention.

FIG. 2 is a diagram showing an embodiment of a horizontal deflection circuit of a CRT driving circuit according to the present invention.

FIG. 3 is a diagram showing an embodiment of a high voltage generating circuit of a CRT driving circuit according to the present invention.

FIG. 4 is a diagram showing an example of a vertical deflection circuit of a conventional CRT drive circuit.

FIG. 5 is a diagram showing an example of a horizontal deflection circuit of a conventional CRT drive circuit.

FIG. 6 is a diagram showing an example of a high voltage generation circuit of a conventional CRT drive circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CRT drive circuit, 2 ... Vertical deflection circuit, 3 ... Horizontal deflection circuit, 4 ... High voltage generation circuit, 5 ... Picture tube (CRT), 6 ...
Vertical oscillation circuit, 7 ... Vertical deflection drive circuit, 8 ... Vertical output circuit, 9 ... Vertical deflection coil, 10 ... Waveform shaping circuit, 1
DESCRIPTION OF SYMBOLS 1 ... Vertical line distortion correction circuit, 12 ... Side pincushion correction transformer, 13 ... Horizontal line distortion correction circuit, 14 ... Horizontal oscillation circuit, 15 ... Horizontal deflection drive circuit, 16 ... Horizontal output circuit, 17, 27, 39, 46 ... npn transistor, 18, 28, 35, 40, 41, 49, 51 ... Diode, 19, 22, 29, 36, 38, 48 ... Capacitor, 20 ... Horizontal deflection coil, 21 ... Linearity correction circuit,
23 ... High-voltage output drive circuit, 24 ... High-voltage output circuit, 2
5 ... Flyback transformer (FBT), 26 ... High voltage module, 30 ... Pulse transformer, 31 ... High voltage control circuit,
32 ... CRT drive circuit, 33 ... High voltage generation circuit, 3
4 ... Peak voltage detection circuit, 37, 42, 43, 45 ... Resistor, 44 ... Slider, 47 ... Zener diode, 50 ... Vertical amplitude detection circuit, 52 ... Switch, 53, 54 ... Monostable multivibrator (MM) .

Claims (2)

[Scope of utility model registration request] 1. A high voltage generation circuit for rectifying a horizontal deflection output pulse to supply a screen voltage to a second grid electrode of a CRT in a CRT drive circuit for reproducing an image on a CRT display, and the horizontal deflection output pulse. Is provided with a detection circuit for outputting a DC voltage proportional to the peak voltage, and a high voltage generation circuit for supplying a screen voltage to the second grid electrode of the CRT is controlled by the DC voltage of the detection circuit. CRT drive circuit. 2. A CRT drive circuit for reproducing an image on a CRT display, a high voltage generation circuit for rectifying a horizontal deflection output pulse to obtain a high voltage for supplying a screen voltage to a second grid electrode of a CRT, A detection circuit for outputting a DC voltage proportional to the peak voltage of the horizontal deflection output pulse is provided, and the CR is detected by the DC voltage of the detection circuit.
A high voltage generation circuit that supplies a screen voltage to the second grid electrode of T is controlled, and a vertical amplitude detection circuit that detects a vertical deflection output pulse is provided. When a vertical deflection output pulse is detected, this vertical amplitude detection circuit A CRT driving circuit, wherein a high voltage generating circuit for supplying a screen voltage to the second grid electrode of the CRT is controlled by an output.