KR970004690B1 - Video tape recorder having cathod ray tube - Google Patents

Abstract

A video tape recorder does not check a recording state of a tape through TV(2), and checks a recording state of VTR by mounting CRT in VTR. The video tape recorder includes the CRT. The CRT is mounted to a predetermined position on a front panel of the video tape recorder, is controlled by an internal signal processor, and displays an operation state of the video tape recorder.

Description

Video tape recorder with CRT

1 is an external view of a conventional VTR recording and reproducing apparatus and a TV receiver.

2 is an external view of the VTR of the present invention with a CRT in the future.

3 is a block diagram showing an EVF circuit mounted on a VTR recording / playback apparatus according to the present invention.

4 is a diagram illustrating an operation of a vertical deflection circuit according to the present invention.

5 is a view showing the operation of the horizontal fan smell circuit according to the present invention.

6 is a diagram illustrating a process of reproducing a video signal of a VTR to the bottom surface according to the present invention.

* Explanation of symbols for main parts of the drawings

10: VTR 20: TV receiver

100: switch 200: signal separation IC

220: vertical synchronization separator 230: vertical oscillator

210: synchronization separator 240: vertical deflection coil drive

250: amplifier circuit 260: phase comparator

270: horizontal oscillator 300: vertical deflection circuit

400: vertical deflection circuit 500: deflection yoke

600: Video Amplifier 700: Flyback Trax

800: CRT

The present invention relates to a videotape recorder (hereinafter referred to as a VTR) recording and reproducing apparatus, and more particularly, to a CRT mounted to a VTR recording and reproducing apparatus.

FIG. 1 shows a conventional VTR recording / reproducing apparatus and TV receiver 20. As shown in FIG. The conventional VTR recording / reproducing apparatus can confirm the recording and playback of the videotape only through the TV receiver 20. Such a device is constructed in which a VTR 10 for recording and reproducing a video audio signal is connected to a TV receiver 20 in which a user can confirm recording and reproduction of a video audio signal.

Such a conventional VTR recording / reproducing apparatus may not know the state of being recorded at the time of tape recording, and in order to check the recording state after recording, it may be necessary to check the VTR receiver 20 connected to the VTR by replaying the tape. And, when watching the VTR broadcast, the user cannot find the desired playback operation position of the tape correctly, and when the user wants to watch one broadcast channel and record another broadcast channel on the TV, the user checks the broadcast status recorded on the tape. Not only can not. There is a problem that the contents of the already recorded tape can be erased.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide an apparatus for checking the state of recording and reproducing of a VTR by attaching a CRT to the VTR without confirming the recording and reproducing state of a tape via the TV receiver 2.

First, the apparatus of the present invention will be described in detail with reference to the drawings of FIGS. 2 to 7.

2 shows a VTR 10 equipped with an electronic view finder (EVF) according to the present invention. The CTR 800 is provided at the front of the VTR 10 so that a user can check the recording and reproducing state of the tape. To monitor the current operating status of the VTR. As described above, the CRT 800 mounted on the front portion of the VTR 10 can check the recording and reproducing state of the tape even while watching the VTR, and can record other broadcast channels.

Therefore, it is possible to reduce the hassle of checking through the TV receiver 20 shown in FIG.

3 is an EVF block diagram showing an EVF circuit mounted in a VTR recording / playback apparatus according to the present invention. The EVF refers to a monitor receiver that allows a user to check the operation state of the VTR using the CRT 800. The EVF receives a video signal from a free amplifier in the VTR and uses the small CRT 800 in the EVF. It is a device for displaying an image. The configuration of such a system consists of a power supply (+ 5V), a video signal from the VTR, and an EVF stage.

As shown in FIG. 3, the power stage supplies + 5V power from the main power in the VTR via the switch 100 to supply the EVF stage. Switch 100 provides a + 5V power supply into the EVF circuit. If the commercialist does not need to check the recording and playback state of the videotape, that is, does not use the CRT 800 of the VTR 100, it is not necessary to operate the switch 100. Therefore, the switch 100 is a control switch that a user can select and use an EVF circuit.

In the EVF block diagram shown in FIG. 3, the video signal is input from a free amplifier (not shown) in the VTR and applied to the dedicated IC 200 for signal separation of the EVF stage.

The block 200 is a signal separation IC (for example, AN 25126S), and the synchronization separation unit 210 which derives the synchronization signal by using the amplitude difference between the synchronization signal and the image signal, and the frequency and phase of the vertical deflection. Vertical synchronization separator 220 for separating the vertical synchronization to accurately match the transmission side to prevent the screen from flowing up and down, vertical oscillator 230 for vertically oscillating the vertical synchronization signal, and vertical deflection generating a sawtooth current of 60 Hz The coil drive 240, the vertical blocking signal of the vertical oscillator 230, the horizontal blocking signal of the horizontal oscillator 270, the synchronous separator 240, the vertical blocking signal of the vertical oscillator 230, and the horizontal oscillator 270. An amplifier 250 for amplifying the horizontal blocking signal of the signal and the synchronization signal of the synchronization separator 210, a phase comparator 260 for comparing the phase of the synchronization signal output from the synchronization separator 210, and a horizontal of 15.75 KHz. Horizontal oscillator (270) for generating oscillation frequency It is composed of

First, when the video signal is applied to the signal separation IC 200, the vertical synchronization separation signal obtained by separating the video image signal from the synchronization separation unit 210 and separating the vertical synchronization from the vertical synchronization separation unit 220. Is added to the vertical oscillator 230 is a vertical oscillation. Then, the vertical deflection coil 500 is driven using the sawtooth wave (1/60 sec) current generated by the vertical deflection coil drive 240, and the horizontal deflection coil of 15.75 KHz generated by the horizontal oscillator 270 is horizontal deflection coil. When applied to the drive 400, a period generates an impulse voltage of 63.5 μsec during a low period to drive the horizontal deflection coil 500. Meanwhile, the input video signal is amplified by the amplifier 250 in the signal separation IC 200 and applied to the video amplifier 600. In the video amplifier 600, the amplified video signal is loaded on a DC biased with a negative voltage, amplified, and then input to the control grid of the CRT 800 and modulated to bend.

3 and 4, the vertical deflection circuit 300 flows a sawtooth current of 60 Hz through the deflection yoke 500 and the vertical deflection coil to vertically scan the residual beam from the electron gun of the CRT 800. The circuit is directly connected to the vertical deflection yoke 500 through the variable resistor RV1, which adjusts the vertical size, because the output-side optimum impedance is as low as a few ohms. In addition, since the vertical width is adjusted by adjusting the magnitude of the sawtooth wave current flowing through the vertical deflection coil of the deflection yoke 500, the variable resistor RV1 can be used to adjust the magnitude of the sawtooth wave input voltage and correct the linearity of the sawtooth wave. The sawtooth wave having a good linearity can be obtained by feeding back the output to the IC 200 for signal separation.

In addition, the variable resistor RTH1 is used for temperature compensation, and is compensated by using a dummyster in which the resistance value due to the temperature rise of the resistor increases.

The vertical oscillator 230 is a 60 Hz vertical synchronous signal separated from the video image TV signal by the synchronous circuit and drives the oscillating circuit to synchronize. In this way, the vertical oscillator 230 operates by inputting a vertical synchronous signal obtained by integrating the output of the synchronous separation circuit. Since the sawtooth wave voltage generated in the vertical oscillator 230 cannot drive the output circuit of the final stage, the amplification circuit 250 is used. In addition, since the sawtooth wave voltage generated by the charging and discharging of the CR circuit is slightly curved in the straight portion and linear distortion occurs in the output circuit of the rear stage, the amplification stage 250 is used to comprehensively correct the distortion in the first half of the vertical deflection circuit 300. It has a waveform shaping circuit and a waveform correction adjustment function.

Referring to FIGS. 3 and 5, the horizontal deflection circuit 400 flows a sawtooth current of 15.75 KHz to the horizontal deflection coil of the horizontal deflection coil 500, thereby directing the electron beam from the electron gun of the receiving tube from the left to the right of the screen. For scanning, a horizontal blocking (square wave) signal obtained from the signal separation IC 200 is applied to the base terminal of the transistor Q1 after the direct current component is removed to obtain a switching pulse of 15.75 KHz. In the on section of the transistor Q1, a counter voltage generated during the syringe flows from the collector to the emitter, but in the off section, LC resonance between the coil of the flyback transformer 700 and the capacitor C1 is performed. You get a square wave of voltage Vp-p. The square wave is input to the horizontal deflection yoke 500 via a direct current coupling, and the horizontal deflection yoke 500 uses a magnetic field made by flowing a current to the coil in deflecting the electron beam. On the other hand, the horizontal deflection coil 500 is much like the circuit on the left side because the left component is much larger than the right component, but the sawtooth wave current is supplied to supply the square wave to the circuit on the left side and the horizontal deflection pulse can be obtained.

Deflection yoke 500 is a combination of horizontal and vertical deflection coils called deflection coils. A coil is installed around the electrons and passes a uniform magnetic field to change the path of electrons by the action of electrons. It is mounted on the CRT 800 as a device for moving.

Since the video signal amplified by the dedicated IC 200 for signal separation is weak, a signal of several tens of voltages (Vpp) is required to sufficiently luminance modulate the CRT 800 so that it is amplified again by the video amplifier 600 to be CRT 800. It is applied to the control grid (G1) of the control to control the amount of electrons emitted from the cathode, and the brightness is low, and the greater the voltage applied to the bare grid (-) to the cathode, the greater the suppression force of electron emission, so the impact on the fluorescent surface The amount of electrons decreases and becomes dark. Therefore, the brightness of the light spot is changed (luminance modulation) by converting the negative voltage of the control grid.

The flyback transformer 700 is an output transformer of a single power supply that catches impedance matching so that the horizontal deflection coil becomes an optimum load of the horizontal output tube. The flyback transformer 700 has a large deflection power, so that the core cross section is large and the high voltage winding is thick. In addition, since the high voltage of 20kV or more is applied, a large area of the window is used to keep a certain distance from other components.

As shown in FIGS. 3 and 6, the flyback transformer 700 receives a power supply (+ 5V) as a transformer for boosting the voltage generated during the return period, and generates a horizontal pulse voltage, and the flyback voltage is flybacked. Amplified by the back transformer 700, a high voltage is applied to the VH terminal of the CRT 800, and a negative voltage is output to use as a bias voltage of the video amplifier circuit. In addition, the focus can be adjusted by outputting a medium voltage (about 500V) and supplying it to the focus grid G3 of the VRT.

Referring again to FIGS. 3 and 6, the CRT 800 includes a glass tube for maintaining a high vacuum state, an electron gun for making an electron beam, a fluorescent film for colliding electrons, and a deflection coil for deflecting up, down, left, and right. It is a black-and-white (approximately 3-inch) water tube consisting of a fluorescent tube that emits light when an electron strikes it and an electron gun that makes electrons into a thin beam, and reproduces the video signal of a VTR on the screen. If the electron beam emitted from the electron gun of the receiving tube hits the fluorescent film to make a light spot, deflect it into a magnetic field, cause the scanning line to appear, and at the same time, luminance modulation (change the brightness of the light spot) as the image signal (video signal) of the VTR, The screen can be reproduced.

As described above, the CRT 800, which is a device that can be monitored during VTR recording and playback according to the present invention, is mounted instead of the display unit mounted on the front of the VTR. Thus, the user of the present invention can check the tape recording state while recording on the VTR tape. In addition, since the user can record the tape and simultaneously view the recording status with the CRT, the user does not need to check the TV receiver and replay the tape to check the recording status after recording. ) You can find the location on the CRT, and you can check the recording status of the broadcast being recorded on the tape when you want to watch one broadcast channel on TV and record another broadcast channel.

Claims (4)

A video tape recorder which executes reproduction, recording, and reservation recording of a program in response to a key operation signal from an operation switch having a plurality of operation keys, wherein the video tape recorder is mounted at a predetermined position on the front panel of the video tape recorder. A video tape recorder, further comprising a CRT controlled by signal processing means to display the active state of the video tape recorder at all times. 2. The power supply unit of claim 1, wherein the signal processing unit comprises a power supply unit for supplying a predetermined voltage from a main power in the VTR to an electronic view finder (EVF) terminal through a switch, and is generated from a free amplifier in the VTR to dedicate signal for the EVF stage. And a video signal provided to the IC (200) and the EVF stage. 3. The EVF stage of claim 2, wherein the EVF stage receives a video video signal and separates the video video signal each time, and a sawtooth current flows through the vertical deflection coil to vertically direct the electron beam of the CRT 800. A vertical deflection linearity correction circuit 300 for scanning and a horizontal deflection circuit 400 for scanning an electron beam generated from the electron gun of the water pipe by flowing a sawtooth current of 15.75 KHz through a horizontal deflection coil of the deflection yoke 500; A deflection yoke 500 for generating a uniform magnetic field to move a light spot by the action of electrons, a video amplifier 600 for amplifying a video image signal applied from the signal separation means 200, and the deflection yoke 500 The horizontal deflection coil is connected to the flyback transformer 700 which is a single winding output transformer for impedance matching so as to be the optimum load of the horizontal feed pipe, and the output terminal of the video amplifier 600 to display the video signal on the screen. A video tape recorder, further comprising a CRT (800) for reproducing. 4. The signal separating means (200) according to claim 3, wherein the signal separating means (200) receives a video image signal and extracts the synchronization signal using the amplitude difference between the synchronization signal and the image signal. Vertical oscillator 230 for vertical oscillation, vertical deflection coil drive 240 for generating saw tooth wave current of 60 Hz, vertical blocking signal of the vertical oscillator 230 and horizontal blocking signal of the horizontal oscillator 270 and the synchronous separation An amplifier 250 for amplifying the synchronizing signal of the unit 210, a phase comparator 260 for comparing the phase of the synchronizing signal outputted from the synchronizing separator 210, and a horizontal generating frequency of 15.75 KHz Video tape recorder, characterized in that consisting of an oscillator (270).