JPH0584704B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable not only to the reception of television broadcasts in the normal format, but also to the reception of television broadcasts in different broadcast formats, and the display of video signals from computers, etc. The present invention relates to a multi-scanning receiver capable of receiving video signals having different vertical frequencies and vertical deflection widths.

[Conventional technology]

For example, in an NTSC television signal, an image is formed with a vertical frequency of approximately 60 Hz and a horizontal frequency of approximately 15.75 KHz. In contrast, the so-called
In the CCIR method, the vertical frequency is 50Hz.

Furthermore, a conversion device has been proposed that doubles the number of scanning lines through arithmetic processing or the like to improve the quality of the received image. When this device is used, the signal output from this has a vertical frequency of, for example, 60 Hz and a horizontal frequency of approximately 31.5 kHz.

In addition, some output signals from so-called high-resolution display computers have a horizontal frequency of about 25 kHz. Furthermore, in so-called high-definition televisions, the horizontal frequency is expected to be approximately 33.75kHz.

A multi-scanning receiver has been proposed that allows a single device to receive various signals having different vertical and horizontal frequencies.

First, a multi-scanning type receiver proposed by the applicant of the present application will be explained below.

Figure 2 shows the overall block diagram. In this figure, when receiving a normal composite video signal from a normal television broadcast tuner, video tape recorder, video disk player, satellite broadcast tuner, some personal computers, etc., it is supplied to input terminal 1. A video signal is supplied to a switch circuit 2, and this switch circuit 2
is controlled by a video/RGB switching signal supplied to the input terminal 3. The video signal from this switch circuit 2 is supplied to a video processing circuit 4 to form three primary color signals. These three primary color signals
It is supplied to the RGB switch circuit 5. This switch circuit 5 is controlled by a switching signal from the above-mentioned input terminal 3, whereby the three primary color signals from the selected video signal are supplied to the cathode ray tube 6.

Further, the video signal from the switch circuit 2 is supplied to a synchronization separation circuit 7, where vertical and horizontal synchronization signals are separated. Furthermore, the switching signal from the input terminal 4 is supplied to the separation circuit 7, whereby the vertical synchronizing signal from the selected video signal is supplied to the vertical deflection circuit 8, and the vertical deflection signal thus formed is transmitted to the cathode ray tube 6.
vertical deflection yoke 9. Also, the horizontal synchronization signal from the video signal selected by the separation circuit 7 is
A signal from the AFC circuit 10 is supplied to the horizontal oscillation circuit 11, and a normal control signal from the mode detection circuit 12 is supplied to the oscillation circuit 11. The signal from this oscillation circuit 11 is then supplied to the horizontal deflection circuit 13, and the formed horizontal deflection signal is supplied to the horizontal deflection yoke 14 of the cathode ray tube 6. Furthermore, deflection circuit 1
3 is supplied to a high voltage generating circuit 15 such as a flyback transformer, the generated high voltage is supplied to a high voltage terminal 16 of the cathode ray tube 6, and part of the signal is supplied to the AFC circuit 10.

Further, commercial power from the power supply input 17 is supplied to the power supply circuit 18, and a normal voltage according to the signal from the detection circuit 12 is supplied to the horizontal deflection circuit 13. Also, commercial power from the power input 17 is supplied to another power supply circuit 19, and the voltage formed is supplied to other circuits.

This allows normal video signal reception. On the other hand, when receiving analog or digital RGB signals from some personal computers, so-called captain demodulators, teletext demodulators, or scan converters, the signals are supplied to input terminals 20R, 20G, and 20B. Analog RGB signal and input terminals 21R, 21G, 2
The digital RGB signal supplied to 1B is supplied to the changeover switch 22, and the RGB signal is selected by the analog/digital changeover signal from the input terminal 24.
The signal is supplied to a switch circuit 5, selected by a switching signal from an input terminal 3, and supplied to a cathode ray tube 6.

Further, an analog synchronizing signal from the input terminal 20S and a digital synchronizing signal from the input terminal 21S are supplied to the changeover switch 23, selected by the changeover signal from the input terminal 24, and supplied to the switch circuit 2, and then the input terminal 3. It is selected by a switching signal from and supplied to the synchronization separation circuit 7. Further, the signal from the separation circuit 7 is supplied to the mode detection circuit 12, where a control signal corresponding to the frequency of the horizontal synchronization signal is formed and supplied to the horizontal oscillation circuit 11, the horizontal deflection circuit 13, and the power supply circuit 18. Note that the input terminal 25 is supplied with an AV signal indicating that an analog RGB signal is supplied.

This allows analog or digital RGB
Signal reception is performed. Furthermore, when performing so-called superimposed image reception in which an RGB signal is displayed superimposed on the above-mentioned normal video signal, the video signal from the input terminal 1 is supplied to an external computer (not shown) through the output terminal 26. The RGB signal for superimposition formed in synchronization with this video signal is input to input terminals 20R, 20G,
20B. Furthermore, the above-mentioned video signal is supplied to the input terminal 20S through the computer. Then, the switching signal supplied to input terminal 3 is
The RGB mode is set, and the Y _S signal indicating the position of the superimposed signal supplied to the input terminal 27 and the Y _N signal indicating the superimposed range are supplied to the RGB switch circuit 3. A video signal is inserted between the Y _S and Y _n signals.
Switching between the RGB signal and the like is performed.

Various signals are received in the manner described above. Further, in the above-described apparatus, the horizontal deflection system is specifically configured as follows. In FIG. 3, a horizontal synchronizing signal from a separation circuit 7 is supplied to a frequency-voltage conversion circuit (FVC) 31 constituting a mode detection circuit 12 to form a voltage according to a horizontal frequency. A voltage controlled oscillator (VCO) that configures the horizontal oscillation circuit 11 through a limiter circuit 32 and a buffer B amplifier 33 in which this voltage determines the lower limit.
34. The oscillation output of this VCO 34 is supplied through a drive circuit 35 to a switching transistor 36 forming the horizontal deflection circuit 13.

Further, the voltage from the FVC 31 is supplied to, for example, a YZ type parametric power supply circuit 39 constituting the power supply circuit 18 through a limiter circuit 37 that determines upper and lower limits and a gain control GC amplifier 38. The output voltage of this power supply circuit 39 is fed back to the amplifier 38 through the voltage dividing circuit 40, and the output voltage is stabilized. This output voltage is supplied to the flyback transformer 41.

A transistor 36 is connected in series to this flyback transformer 41. Further, a damper diode 42 , a resonant capacitor 43 , and a series circuit of a horizontal deflection yoke 14 and an S-shaped correction capacitor 44 are connected in parallel to this transistor 36 .

Further, the horizontal synchronizing signal is supplied to the detection circuit 45 constituting the AFC circuit 10, and a signal from the voltage dividing circuit 46 provided in series with the transistor 36 is supplied to the detection circuit 45 to form an AFC signal. This signal is passed through low pass filter (LPF) 4
7 to the control terminal of the VCO 34.

Furthermore, capacitors 49 and 50 are connected in parallel to the resonant capacitor 43 through a switch circuit 48. Further, capacitors 52 and 53 are connected in parallel to the S-shaped correction capacitor 44 through a switch circuit 51. In addition, the voltage from the FVC 31 is supplied to a comparator circuit 54 that compares the voltage with values corresponding to voltages of 20 kHz and 30 kHz of the input horizontal frequency, and outputs a three-value comparison corresponding to each range of 20 kHz or less, 20 to 30 kHz, and 30 kHz or more. is formed, and control is performed so that the two switches built in each of the switch circuits 48 and 51 are both turned off or one of them is turned on in accordance with this comparison output.

As a result, in this horizontal deflection system,
15 to 15 in synchronization with the input horizontal synchronization signal at VCO34
An oscillation signal that changes to 34 kHz is formed to perform horizontal deflection, and at the same time, a voltage that changes from 58 to 123 volts depending on the horizontal frequency is generated in the power supply circuit 39, so that the amplitude of the horizontal deflection is constant. Control is performed to ensure that In addition, in parallel with the resonance capacitor 43 and the S-shaped correction capacitor 44, capacitors 49, 50, and 52 are installed depending on the horizontal frequency range.
53 are connected, and the characteristics of each are corrected.

Further, in the above-described apparatus, the vertical deflection system is specifically configured as follows. In FIG. 4, a vertical synchronizing signal from a separation circuit 7 is supplied to a sawtooth wave oscillator 61 constituting a vertical deflection circuit 8, and a sawtooth wave is formed by, for example, charging and discharging a capacitor 62 with a current from a current source 63. Ru. This sawtooth wave is supplied to a comparison circuit 64 to form a three-value comparison output indicating a predetermined voltage range and lower or higher voltage ranges, and this comparison output is supplied to a control terminal of an up-down counter UDC 65. A vertical synchronizing signal is supplied to the counting terminal of this UDC 65. The count value of this UDC 65 is supplied to the DA conversion circuit DAC66, and the current source 63 is controlled by the converted analog value.

Therefore, a sawtooth wave whose peak value (amplitude) is controlled within a predetermined voltage range is extracted from the oscillator 61 regardless of the frequency of the vertical synchronizing signal. This sawtooth wave is supplied to the vertical deflection yoke 9 through an output circuit 67. Furthermore, a series circuit of a capacitor 68 and a resistor 69 is connected in series to this deflection yoke 9, and a voltage dividing circuit 70 is connected in parallel to this resistor 69.
The divided voltage output of this voltage dividing circuit 70 is supplied to the output circuit 67.

This ensures that vertical deflection always has a constant amplitude even if the vertical frequency changes. Furthermore, the voltage dividing circuit 70
By making one of the resistors variable, the amplitude of the vertical deflection can be arbitrarily controlled.

Furthermore, another set of circuits (oscillator 71 to DAC76) including an oscillator 61 to DAC66 is provided, and the output value of the DAC 76 of this circuit is supplied to a pin distortion correction signal forming circuit 77. A vertically synchronized parabolic wave signal from the connection midpoint is supplied to a forming circuit 77 to form a pin distortion correction signal. This signal is supplied to the pin distortion correction circuit.

In this manner, in the above-described apparatus, the necessary horizontal and vertical deflections are performed in accordance with various different horizontal and vertical frequencies, and various signals are received.

However, in this device, when performing the above-mentioned superimposition, the synchronization separation circuit 7 is supplied with a video signal from a tuner or the like. Therefore, for example, the horizontal frequency of the video signal fluctuates due to disturbances in the synchronization signal when switching channels with a tuner, tracking drift due to a weak electric field, or malfunction of the tracking system due to fast-forward playback on a video tape recorder. If such fluctuations occur, the output voltage of the FVC 31 described above may fluctuate and the image may be distorted. Furthermore, in composite video signals, the output voltage is disturbed by the equalization pulse of the vertical synchronizing signal, and there is a risk that so-called vertical ripples and tracking errors may occur.

[Problems to be Solved by the Invention] A multi-scanning receiver as described above has been proposed. However, the above-mentioned apparatus has a problem in that images are distorted, especially when superimposed display is performed.

[Means for solving problems]

The present invention performs horizontal deflection according to the horizontal frequency of video signals having different horizontal frequencies, and performs frequency-voltage conversion 31 on the horizontal frequency,
In a multi-scanning receiver, the horizontal amplitude amplitude is controlled according to the converted voltage, and when the video signal is a composite video signal, the converted output voltage of the frequency-voltage converter 31 is set to a predetermined value. 102 is provided with fixing means 101, and when the video signal is an arbitrary RGB signal, predetermined conditions are determined 103 to 108 to fix the converted output voltage. It is a scanning type receiver.

[Effect]

According to the above-mentioned device, a predetermined condition is determined when using an arbitrary RGB signal such as superimposed,
Since the output voltage of the frequency-voltage conversion circuit 31 of the horizontal deflection system is fixed at a voltage corresponding to the horizontal frequency of a predetermined composite video signal, even if the horizontal frequency fluctuates as described above, the image will not change. undisturbed.

〔Example〕

In FIG. 1, the output voltage of the FVC 31 is supplied to one fixed contact of the switch circuit 101, and the horizontal frequency of about 15.75kHz of the NTSC system is supplied to the other fixed contact of the switch circuit 101.
A voltage from voltage source 102 corresponding to the voltage generated when supplied to FVC 31 is supplied.
A signal from the movable contact of the switch circuit 101 is supplied to the limiter circuits 32, 37, the comparator circuit 54, etc.

Further, a video/RGB switching signal (manual signal) formed by a manual switch (not shown) or the like and supplied to the input terminal 3 is supplied to the NOR circuit 103, and this output signal is passed through the inverter 104 to the above-mentioned switch circuit. 2 and RGB switch circuit 5, as well as the digital signal from input terminal 24.
The analog switching signal and the AV signal from the input terminal 25 are supplied to the NOR circuit 105, and this output signal is supplied to the NOR circuit 103.

As a result, the inverter 104 supplies a digital or analog RGB signal, and outputs a switching signal for switching to RGB only when RGB is selected by the signal supplied to the input terminal 3.

Furthermore, a signal that becomes 0 level when a superimposed image is received from a manual switch (not shown) or the like is supplied to the input terminal 106, and this signal and the signal from the input terminal 24 are supplied to the OR circuit 107. , this output signal is supplied to the NAND circuit 108. Further, the output signal of the NOR circuit 103 is supplied to the NAND circuit 108, and the switch circuit 101 is switched by the output signal of the NAND circuit 108.

As a result, the switch circuit 101 selects video when the signal supplied to the input terminal 3 is selected, and when the signal supplied to the input terminal 3 selects RGB.
is selected, and the signal supplied to the input terminal 24 is analog, and furthermore, when the signal supplied to the input terminal 106 is at 0 level (superimposed), the switch circuit 101 is connected to the fixed voltage source 102.
A control signal to switch to the side is output.

Therefore, according to this device, a predetermined condition is determined in the case of an arbitrary RGB signal such as a superimposed signal, and the output voltage of the frequency-voltage conversion circuit 31 of the horizontal deflection system is adjusted to the horizontal frequency of the predetermined composite video signal. Since the voltage is fixed according to the
Even if the horizontal frequency changes as described above occur, the image is not disturbed.

In the above device, the signal supplied to the input terminal 106 may be linked to an intensity terminal in a microcomputer manufactured by IBM, for example.

〔Effect of the invention〕

According to the present invention, a predetermined condition is determined in the case of an arbitrary RGB signal such as a superimposed signal, and the output voltage of the frequency-voltage conversion circuit 31 of the horizontal deflection system is adjusted according to the horizontal frequency of the predetermined composite video signal. Since the voltage is fixed at a certain voltage, the image is not disturbed even if the horizontal frequency fluctuates as described above.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an example of the present invention, Figures 2 to 4
The figure is a diagram for explaining a conventional device. 31 is a frequency-voltage conversion circuit, 101 is a switch circuit, 102 is a voltage source, and 106 is an input terminal.

Claims (1)

[Claims] 1. Perform horizontal deflection according to the horizontal frequency of video signals having different horizontal frequencies, perform frequency-voltage conversion on the horizontal frequency, and control the horizontal deflection amplitude according to the converted voltage. In the multi-scanning receiver, when the video signal is a composite video signal, or when the video signal is an arbitrary RGB signal and the arbitrary RGB signal is at least an analog signal, the frequency - What is claimed is: 1. A multi-scanning type television receiver, characterized in that a means for fixing the converted output voltage to a predetermined value is provided so that the converted output voltage can be fixed.