JPH0646785B2 - Multi-scan type receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable to the reception of television broadcasts of different broadcasting systems and the display of video signals from a computer or the like, in addition to the reception of ordinary television broadcasts. The present invention relates to a multi-scanning image receiver capable of receiving image 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 about 60 Hz and a horizontal frequency of about 15.75 kHz. On the other hand, in the so-called CCIR system, the vertical frequency is
It is 50Hz.

Further, there has been proposed a conversion device that doubles the number of scanning lines by an arithmetic process or the like to improve an image to be received. When this device is used, the signal output from this device has a vertical frequency of, for example, 60 Hz and a horizontal frequency of about 31.5 kHz.

In addition, there is a so-called high-resolution display computer output signal having a horizontal frequency of about 25 kHz. In so-called high-definition television, the horizontal frequency is about 3
3.75kHz is planned.

In this way, a multi-scanning type receiver has been proposed which enables various signals having different vertical and horizontal frequencies to be received by a single device.

By the way, in the conventional television receiver, the vertical deflection circuit generally uses a sawtooth wave having a constant slope to form the deflection current.

That is, for example, in FIG. 5, a vertical synchronizing signal is supplied to an input terminal (201), and this signal is supplied to a sawtooth wave oscillator (202), and a capacitor (203) is supplied with a current of a current source (204). It is charged and discharged to form a sawtooth wave with a constant slope. This signal is supplied to the vertical deflection yoke (206) through the output circuit (205). Further, a series circuit of an S-shaped correction capacitor (207) and a resistor (208) is connected in series to the deflection yoke (206).
) Is connected in parallel with a voltage dividing circuit including a vertical deflection volume (209), and this voltage dividing output is fed back to the output circuit (205).

According to this circuit, a vertical deflection signal having a constant inclination is formed and supplied to the vertical deflection yoke (206), and the volume (209) can be adjusted to control the vertical deflection width on the screen.

However, if this device later tries to receive NTSC and CCIR television broadcasts, the vertical frequency will be about 60.
It is changed from Hz to 50Hz. In this case, in the above device,
Due to the constant slope, the amplitude of the sawtooth wave is changed when the frequency is changed. That is, when the sawtooth wave as shown in FIG. 6A is formed at about 60 Hz, the amplitude becomes large at 50 Hz because of the constant slope as shown at B.
Therefore, conventionally, when the frequency was changed, the volume (209) had to be adjusted to re-adjust the screen size.

Also, for example, when displaying the output of a computer, so-called overscan is performed in order to display the display image on the full display surface in the case of receiving a conventional television broadcast, whereas in the output of a computer, every corner of the display screen is displayed. Underscan for full display. For this reason, in standard television broadcasting, the number of horizontal scanning lines is, for example, 26262.5 cycles, 229 images, and 5% overscan. While the vertical amplitude is determined so that the range of is the display surface, for example, in the output of a computer with a horizontal frequency of 25 kHz, the vertical scanning time is Must be the display surface and the vertical amplitude is changed.

Even in this case, it is necessary to readjust the vertical deflection width according to the input signal.

[Problems to be solved by the invention]

The multi-scanning type receiver as described above has been proposed. However, in this device, when vertical deflection is performed with the same configuration as used in a conventional television receiver, when the vertical frequency is different, or when the display range of the screen is changed, There was a problem that the vertical deflection volume had to be readjusted one by one.

[Means for solving problems]

The present invention, in a multi-scanning image receiver for receiving a plurality of video signals having different vertical frequencies, a sawtooth wave oscillating means (61) for inputting a vertical synchronizing signal to form a sawtooth wave, and this sawtooth wave. Detecting means (70) for detecting the level of amplitude, and first control means for controlling the amplitude of the sawtooth wave according to the output of this detecting means to be constant regardless of the frequency of the input vertical synchronizing signal. (71a), vertical deflection means (9) for inputting the sawtooth wave controlled to the constant amplitude, switching means (72) for switching the plurality of video signals, and the vertical deflection means according to the switching means. And a second control means (71b) for controlling the vertical deflection width of the multi-scanning type image receiving device.

[Action]

According to the above device, since the vertical deflection is performed using the signal from the sawtooth wave oscillator in which the amplitude of the sawtooth wave is controlled to be predetermined, the predetermined display signal is always obtained regardless of the vertical frequency. You can

〔Example〕

First, a multi-scanning image receiver proposed by the applicant of the present application will be described.

FIG. 3 shows an overall block diagram. In this figure, a normal TV broadcast tuner or video tape recorder,
When receiving a normal video signal from a video disc player, a satellite broadcast tuner, or some personal computers, the video signal supplied to the input terminal (1) is an RGB process circuit through the video process circuit (2).
It is supplied to (3) and the three primary color signals are formed. Further, the video / RGB switching signal supplied to the input terminal (4) is supplied to the process circuit (3), and the three primary color signals from the video signal selected by this are supplied to the cathode ray tube through the output circuit (5).
Supplied to (6).

Also, the video signal from the input terminal (1) is supplied to the sync separation circuit (7), and the vertical. The horizontal sync signal is separated. Furthermore, the switching signal from the input terminal (4) is supplied to the separation circuit (7),
The vertical synchronizing signal from the video signal selected by this is supplied to the vertical deflection circuit (8), and the formed vertical deflection signal is supplied to the vertical deflection yoke (9) of the cathode ray tube (6). Further, the horizontal synchronizing signal from the video signal selected by the separation circuit (7) is supplied to the AFC circuit (10), and this AFC circuit (10)
The signal from is supplied to the horizontal oscillation circuit (11),
A normal-time control signal from the mode detection circuit (12) is supplied to the oscillation circuit (11). Then, the signal from the oscillation circuit (11) is 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). Further, the signal from the deflection circuit (13) is supplied to a high voltage generation circuit (15) such as a flyback transformer, the generated high voltage is supplied to the high voltage terminal (16) of the cathode ray tube (6), and Parts are supplied to the AFC circuit (10).

Furthermore, commercial power from the power input (17) is the power circuit (18).
Is supplied to the horizontal deflection circuit (13) in the normal state according to the signal from the detection circuit (12). Further, commercial power from the power input (17) is supplied to the other power supply circuit (19), and the formed voltage is supplied to the other circuit.

As a result, a normal video signal is received. On the other hand, when receiving digital or analog RGB signals from some personal computers, so-called captain demodulators, teletext demodulators, scan converters, etc., the input terminals (20R) (20G) (20B) ) Digital RGB signal supplied to the input terminal (21R) (21G
) (21B) and the analog RGB signal are supplied to the changeover switch (22), selected by the analog / digital changeover signal from the input terminal (24) and supplied to the RGB process circuit (3). It is selected by the switching signal from the input terminal (4) and supplied to the output circuit (5).

Also, the digital sync signal from the input terminal (20S) and the analog sync signal from the input terminal (21S) are supplied to the changeover switch (23), and are selected by the changeover signal from the input terminal (24) to separate the sync. It is supplied to the circuit (7) and selected by the switching signal from the input terminal (4) to select the vertical deflection circuit (8) and the AFC.
It is supplied to the circuit (10). Further, the signal from the separation circuit (7) is supplied to the mode detection circuit (12), and a control signal corresponding to the frequency of the horizontal synchronizing signal is formed to generate a horizontal oscillation circuit (1
1) is supplied to the horizontal deflection circuit (13) and the power supply circuit (18).

As a result, an image of a digital or analog RGB signal is received. Furthermore, in the case of performing so-called superimpose image reception in which an RGB signal is displayed by being superimposed on the normal video signal described above, the switching signal supplied to the input terminal (4) is set to the RGB mode and the input terminal ( 25) Ys indicating the position of the superimposed signal supplied to
The signal and the Ym signal indicating the range to be superimposed are supplied to the RGB process circuit (3), and these Ys,
Switching between the video signal and the RGB signal is performed during the Ym signal.

As described above, images of various signals are received. Further, in the above-mentioned apparatus, the horizontal deflection system is specifically configured as follows. In FIG. 4, the frequency at which the horizontal sync signal from the separation circuit (7) constitutes the mode detection circuit (12)
The voltage is supplied to the voltage conversion circuit (FVC) (31) to form a voltage according to the horizontal frequency. A voltage controlled oscillator (VC) that constitutes a horizontal oscillation circuit (11) through a limiter circuit (32) that determines the lower limit of this voltage and a buffer (B) amplifier (33).
O) (34). The oscillation output of the VCO (34) is supplied to the switching transistor (36) forming the horizontal deflection circuit (13) through the drive circuit (35).

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

A transistor (36) is connected in series to the flyback transformer (41). A damper diode (42) and a resonance capacitor (43) are connected in parallel with the transistor (36).
And horizontal deflection yoke (14) and S-shaped correction capacitor (44)
And a series circuit with is connected.

Further, the horizontal synchronizing signal is supplied to the detection circuit (45) forming the AFC circuit (10), and the signal from the voltage dividing circuit (46) provided in series with the transistor (36) is supplied to the detection circuit (4).
5) and the AFC signal is formed. This signal is passed through the low pass filter (LPF) (47) to VCO (3
It is supplied to the control terminal of 4).

Furthermore, a switching circuit (4
Capacitors (49) and (50) are connected through 8). The capacitors (52) and (53) are connected in parallel to the S-shaped correction capacitor (44) through the switch circuit (51).
Further, the voltage from the FVC (31) is supplied to a comparison circuit (54) with a value corresponding to the input horizontal frequency of 20 kHz and 30 kHz, and corresponds to each range of 20 kHz or less, 20 to 30 kHz, 30 kHz or more. A three-valued comparison output is formed, and control is performed so that two respective switches incorporated in the switch circuits (48) and (51) are both turned off or one of them is turned on according to the comparison output. .

Therefore, in this horizontal deflection system, the VCO (34)
The oscillation signal which is changed to 15 to 34 kHz is formed in synchronism with the input horizontal synchronizing signal for horizontal deflection and is changed to, for example, 58 to 123 V depending on the horizontal frequency in the power supply circuit (39). Voltage is formed, and control is performed so that the amplitude of horizontal deflection is constant. Further, in parallel with the resonance capacitor (43) and the S-shaped correction capacitor (44), capacitors (49) (50) and (52) are provided depending on the horizontal frequency range.
(53) is connected and the characteristics are corrected respectively.

The vertical deflection system in the above device is constructed as follows. In FIG. 1, the vertical synchronizing signal from the separation circuit (7) is supplied to the sawtooth wave oscillator (61) constituting the vertical deflection circuit (8) through the input terminal (60), and the capacitor (62) is connected to the current source, for example. The current of (63) charges and discharges to form a sawtooth wave. This saw-tooth wave is supplied to the comparator circuits (64a) (64b) which detect when the amplitude is larger than the predetermined first and second amplitudes (first amplitude> second amplitude), respectively. The signal from the input terminal (60) is supplied to the counting terminal of the up / down counter (UDC) (65), and the output from the above-mentioned comparison circuit (64a) is supplied to the control terminal of the UDC (65). Further, the outputs of the comparison circuits (64a) (64b) are supplied to the air exclusive OR circuit (66), and this output is supplied to the inhibit terminal of the UDC (65). The count data of this UDC (65) is DA conversion circuit (DAC)
The current source (63) is controlled by the converted analog value supplied to (67).

As a result, the amplitude from the oscillator (61) is shown by the solid line a in FIG.
When it is below the comparison level of the comparison circuit (64b) like
The control signal for counting up is supplied to the UDC (65), the counting data is increased, the conversion output of the DAC (67) is increased, the current value of the current source (63) is increased, and the amplitude of the sawtooth wave is increased. To be done. When the amplitude from the oscillator (61) is in the middle of the comparison level of the comparison circuits (64a) (64b) as shown by the solid line b in the figure, the output of the exclusive OR circuit (66) is U.
It is supplied to the inhibit terminal of DC (65) to prohibit counting. Further, when the amplitude from the oscillator (61) is above the comparison level of the comparison circuit (64c) as shown by the solid line c in the figure, UD
The count down control signal is supplied to C (65), the count data is reduced, the conversion output of the DAC (67) is reduced, the current value of the current source (63) is reduced, and the amplitude of the sawtooth wave is reduced. To be done.

Therefore, a sawtooth wave whose crest value (amplitude) is controlled within a predetermined voltage range is extracted from the oscillator (61) regardless of the frequency of the vertical synchronizing signal. The sawtooth wave is supplied to the vertical deflection yoke (9) through the output circuit (68). Further, a series circuit of a capacitor (69) and a resistor (70) is connected in series with the deflection yoke (9), and preset volumes (71a) (71b) are connected in parallel with the resistor (70). The divided voltage output of the potentiometers (71a) (71b) is selected by the changeover switch (72) and supplied to the output circuit (68).

Further, a switching signal from the input terminals (4) (24) is supplied to the selection control circuit (73). Here, the switching signal supplied to the input terminal (4) is, for example, "1" when selecting a video signal,
It is set to "0" when selecting an RGB signal, and the switching signal supplied to the input terminal (24) is set to "1" when selecting an analog signal and "0" when selecting a digital signal. . Therefore, in this selection control circuit (73), R
The state where the GB signal is selected and the analog signal or the digital signal is selected is determined.

Further, a switch (74) for presetting an analog signal and a switch (75) for presetting a digital signal are provided, and the states of these switches (74) (75) match the contents determined by the selection control circuit (73). Then, the selection control circuit (73) outputs a control signal. This signal is supplied to the control terminal of the changeover switch circuit (72).

Therefore, in this apparatus, the switch circuit (72) is normally switched to, for example, the volume (71a) side, and the vertical deflection width is the size set by the preset volume (71a). On the other hand, if the analog signal and / or the digital signal set by the switches (74) (75) and the signal that discriminates the signal from the input terminals (4) (24) match, the switch circuit ( 72) is the volume (71b)
And the vertical deflection width is set to a second size in which the display range is 90% or more.

This allows the vertical deflection width to be deflected when, for example, an analog or digital signal supplied by a computer is selected, and this change is made only for analog signals, only for digital signals, or both. It can be set arbitrarily. Further, this change can be automatically made in association with the selection of the video signal by setting the switches (74) (75) in advance.

In the above example, there are two vertical change widths, overscan and underscan, but the volume (71b
) May be provided so that three or more of them can be set, and these can be switched according to the selection of the video signal.

In this way, the vertical deflection width is always adjusted to a predetermined value. According to the above circuit, however, the amplitude control is divided into two parts, so that the amplitude characteristic with respect to frequency becomes constant, and the input of the output circuit (68) is changed. Has a constant amplitude, a desired peculiar display ratio can be obtained with a relatively small change in the voltage-current gain of the output circuit (68), and the operation is stabilized. Further, in the case of the relaxation oscillation type oscillator, a good cycle cannot be obtained unless the vertical hold is moved according to the change of the input frequency, but the above-mentioned circuit allows the vertical hold to be removed.

〔The invention's effect〕

According to the present invention, since the vertical deflection is performed by using the signal from the sawtooth wave oscillator in which the amplitude of the sawtooth wave is controlled to be predetermined, it is possible to always obtain a predetermined display image regardless of the vertical frequency. I can do it now.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, FIGS. 2 to 4 are diagrams for explaining the same, and FIGS. 5 and 6 are diagrams for explaining a conventional device. (60) is an input terminal, (61) is a sawtooth wave oscillator, (64a)
(64b) is the comparison circuit, (65) is the up / down counter,
(67) is a D / A conversion circuit, and (68) is an output circuit.

Claims (1)

[Claims] 1. A multi-scanning image receiver for receiving a plurality of video signals having different vertical frequencies, wherein a sawtooth wave oscillating means for inputting a vertical synchronizing signal to form a sawtooth wave and an amplitude of the sawtooth wave. Detection means for detecting the level; first control means for controlling the amplitude of the sawtooth wave according to the output of the detection means to be constant regardless of the frequency of the input vertical synchronizing signal; and the constant amplitude. The vertical deflection means for inputting the sawtooth wave controlled by the above, the switching means for switching the plurality of video signals, and the second control means for controlling the vertical deflection width of the vertical deflection means according to the switching means. A multi-scanning image receiver characterized in that