JPS6196883A - Multiscan-type television receiver - Google Patents

Abstract

PURPOSE:To obtain a desired profile emphasis with respect to a picture by changing a profile emphasizing frequency corresponding to the horizontal frequency of an input signal in a television receiver using a converter for converting the number of scan lines twice as well as image receiving of normal television broadcasting. CONSTITUTION:When the horizontal frequency of the input signal is of about 15.75kHz, a high frequency component having a picture signal of 3MHz as a center is level- adjusted by a variable resistance 83 and supplied to an adder circuit 81 from which a picture signal obtained by executing the profile emphasis processing of a peaking frequency of 3mHz is supplied to a cathode ray tube 6. Then a picture whose frequency is emphasized by about 12cpd in conversion of space frequency at a visual distance 5H can be obtained. I the same manner the picture having a frequency component emphasized by about 12cpd can be obtained in case of about 31.5kHz horizontal frequency of the input signal. Thus, as the profile emphasizing frequency is changed in accordance with the horizontal frequency of the input signal, the space frequency with respect to the frequency except a horizontal frequency of about 15.75kHz, for instance, the input signal of about 31.5kHz, is emphasized, whereby a desired profile emphasis with respect to a picture can be carried out.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention can be used to increase the number of scanning lines to 2 in addition to normal television broadcast image reception.
The present invention relates to a multi-scan television receiver capable of receiving video signals of different horizontal frequencies from a converter or the like that performs double conversion.

[Conventional technology]

For example, in an NTSC television signal, an image is formed with a vertical frequency of approximately 6011 z and a horizontal frequency of approximately 15.75 KHz. In response, 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 approximately 60K and a horizontal frequency of approximately 31.5KH2.

In addition, some so-called high-resolution computer output signals have a horizontal frequency of about 24 KHz. Also, in so-called high-definition televisions, the horizontal frequency is about 33.
75KHz is planned.

Currently, a multi-scanning television receiver has been proposed which allows a single device to receive various signals having different horizontal frequencies.

First, a multi-scan television receiver proposed by the applicant of the present invention will be explained with reference to FIGS. 2 to 4.

Figure 2 shows the overall block diagram. In this figure, a typical television broadcast tuner or video tape recorder,
When receiving a normal video signal from a video disc player, satellite broadcast tuner, some personal computers, etc., the video signal supplied to the input terminal (1) passes through the video processing circuit (2) to the RGB processing circuit. (3) to form three primary color signals. In addition, the video/RGB switching signal supplied to the input terminal (4) is supplied to the RGB processing circuit (3), and the three primary color signals from the selected video signal are thereby output to the output circuit (5).
) is supplied to the cathode ray tube (6).

In addition, the video signal from the input terminal (1) is transferred to the sync separation circuit (
7), and the vertical and horizontal synchronization signals are separated.

Furthermore, the switching signal from the input terminal (4) is transmitted to the synchronous separation circuit (
7), whereby the vertical synchronizing signal from the selected video signal 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). be done. In addition, the horizontal synchronization signal from the video signal selected by the synchronization separation circuit (7) is transmitted to the AFC circuit QO.
) and the mode detection circuit (11), and this AFC
A signal from the circuit aω is supplied to the horizontal oscillation circuit 12), and a normal control signal from the mode detection circuit (11) is supplied to the horizontal oscillation circuit (12). The signal from this horizontal oscillation circuit (12) is transmitted to the horizontal deflection circuit (13).
), and the formed horizontal deflection signal is sent to the cathode ray tube (6
) is supplied to the horizontal deflection yoke (14). Further, the signal from the horizontal deflection circuit (13) is supplied to a surface pressure generation circuit (15) such as a fly bank transformer, and the generated high voltage is supplied to the high voltage terminal (16) of the cathode ray tube (6). A part of the signal is supplied to the AFC circuit GO+.

Furthermore, the commercial power from the power input (17) is connected to the power supply circuit (1
8), and a normal voltage according to the signal from the mode detection circuit (11) is supplied to the horizontal deflection circuit (13). Also, commercial power from the power supply 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, it receives digital or analog R, G, and B primary color signals (hereinafter referred to as RGB signals) from some personal computers, so-called captain demodulators, teletext demodulators, or scan converters. In this case, input terminal (20R) (20G) (2
The digital RGB signal supplied to the input terminal (21R) (21G'') (21B) is selected by the changeover switch (22) and supplied to the RGB process circuit (3). is selected by the switching signal from the input terminal (4) and the output circuit (5
).

Further, the digital synchronization signal from the input terminal (20S) and the analog synchronization signal from the input terminal (21S) are selected by the changeover switch (23) and supplied to the synchronization separation circuit (7), and the input terminal (4) It is selected by a switching signal from , and is supplied to the vertical deflection circuit (8) and the AFC circuit 0ω. Furthermore, the signal from the synchronization separation circuit (7) is transmitted to the mode detection circuit (
11), a control signal corresponding to the frequency of the horizontal synchronization signal is formed, and the control signal is supplied to a horizontal oscillation circuit (12), a horizontal deflection circuit (13), and a power supply circuit (18).

As a result, digital or analog RGB signals are received. Furthermore, when performing so-called superimposed image reception in which RGB signals are displayed superimposed on the above-mentioned normal video signal, the switching signal supplied to the input terminal (4) is set to RGB mode, and the input terminal ( 24)
Ys times signal indicating the position of the superimposed signal supplied to Y and indicating the superimposed range
The m signal is supplied to the RGB processing circuit (3), and switching between the video signal and the RGB signal is performed between these Ys and Ym signals.

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 Figure 3, the synchronization separation circuit (
The horizontal synchronization signal from 7) is sent to the horizontal synchronization signal input terminal (7H
) through which the mode detection circuit (1■) is configured.
It is supplied to a voltage conversion circuit (FVC) (31) to form a voltage according to the horizontal frequency. A voltage controlled oscillator (VCO) (35) where the output voltage of this FVC (31) forms a horizontal oscillation circuit (12) through a buffer amplifier (34).
supplied to

The oscillation output of this VCO ('35) is supplied through a drive circuit (36) to a switching transistor (37) constituting a horizontal deflection circuit (13).

In addition, the voltage obtained at the movable contact (32a) of the changeover switch (32) passes through the gain control amplifier (38) to the power supply circuit (
18), for example, to a YZ type parametric power supply circuit (39). The output voltage of this power supply circuit (39) is passed through the voltage divider circuit (40) to the gain control amplifier (3
8) to stabilize the output voltage. This output voltage is supplied to a flyback transformer (41).

A switching transistor (37) is connected in series to this flyback transformer (41). Further, a series circuit of a damper diode (42), a resonant capacitor (43), a horizontal deflection yoke (14), and a figure-8 correction capacitor (44) is connected in parallel to this switching transistor (37).

Further, the horizontal synchronizing signal is supplied to the detection circuit (45) forming the AFC circuit Q[I, and the signal from the voltage dividing circuit (46) provided in series with the switching transistor (37) is supplied to the detection circuit (45). is supplied to form an AFC signal. This signal is passed through a low-pass filter (LPF) (4
7) to the control terminal of the VCO (35).

Furthermore, a switch circuit (
Capacitors (49) and (50) are connected through 48). In addition, the capacitor (52) (53) is connected in parallel to the figure 8 correction capacitor (44) through the switch circuit (51).
) are connected. In addition, the voltage from the FVC (31) is supplied to a comparator circuit (54) for binary comparison corresponding to voltages of 20 KHz and 30 KHz of the input horizontal frequency, for example.
A three-value comparison output corresponding to each range of 0 Kl (z or less, 20 to 30 KHz, and 30 KHz or more) is formed, and according to this comparison output, the two built-in switch circuits (4th) and (51) are Control is performed so that both switches are turned off or one of them is turned on.

As a result, in this horizontal deflection system, the VCO (35
), an oscillation signal that varies from 15 to 31 KHz in synchronization with the input horizontal synchronizing signal is formed to perform horizontal deflection, and at the same time, the power supply circuit (39) varies from 58 to 123 volts depending on the horizontal frequency. A voltage is generated to control the amplitude of the horizontal deflection to be constant. Also, the resonance capacitor (43) and the figure 8 correction capacitor (44)
) in parallel with the capacitor (4
9) (50), (52), and (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, the synchronous separation circuit (7
) is the vertical sync signal input terminal (7v)
The electric current is supplied to a sawtooth wave oscillator (61) constituting the vertical deflection circuit (8) via the sawtooth wave oscillator (61), and a sawtooth wave is formed by, for example, charging and discharging a capacitor (62) with the current from a current source (63).

This sawtooth wave is supplied to a comparator circuit (64) to form a three-value comparison output indicating a predetermined voltage range and lower or higher voltage ranges.
) (65) is supplied to the control terminal. This UDC (
A vertical synchronizing signal is supplied to the counting terminal of 65). This U
The count value of DC (65) is the DA converter circuit (DAC) (66
) is supplied to the current source (63
) is controlled.

Therefore, a sawtooth wave whose peak value (amplitude) is controlled within a predetermined voltage range is extracted from the sawtooth wave oscillator (61), regardless of the frequency of the vertical synchronization signal. This sawtooth wave is supplied to the vertical deflection yoke (9) through an output circuit (67).

Furthermore, a capacitor (88) is connected in series with this deflection yoke (9).
), a series circuit of a resistor (69) is connected, 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 an output circuit (67).

This provides a constant amplitude vertical deflection even if the vertical frequency changes. Furthermore, by making one of the resistors constituting the voltage dividing circuit (70) variable, the amplitude of the vertical deflection can be arbitrarily controlled.

Furthermore, another set of sawtooth wave oscillator (61) to DAC (66) circuits (oscillator (71) to DAC (76)) is provided, and the output value of the DAC (76) of this circuit forms a pin distortion correction signal. In addition to being supplied to the circuit (77), for example, a parabolic signal with a vertical period from the connection midpoint between the deflection yoke (91 and the capacitor (68)) is also supplied to the formation circuit (77) to form a bin distortion correction signal. This signal is supplied to the bin 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.

[Problem that the invention seeks to solve]

By the way, in conventional television receivers, the sharpness deteriorates due to insufficient characteristics of the image pickup tube, transmission system, signal system, cathode ray tube, etc., and the so-called contour that adjusts the outline of the image due to visual characteristics. An emphasis circuit is provided. In this contour enhancement circuit, in order to compensate for the deterioration in sharpness described above, in the case of a rectangular video signal as shown in FIG. 5A, a television signal of the type shown in FIG. 5B is converted into a horizontal frequency component. The frequency is about 3 MHz. ) frequency components are emphasized. In this case, if frequencies lower than 12 cpd are emphasized, the outline will be unnaturally emphasized and the three-dimensional effect will be lost, and conversely, if frequencies higher than 12 cpd are emphasized, the sharpness will fade.

In this contour enhancement circuit, the high-frequency component (approximately 3 Mt(z
) is added to the original signal, and in the vertical direction, a high frequency component extracted by a transversal filter using a field delay, line delay, etc. is added to the original signal. In this case, the frequency to be emphasized, the so-called peaking frequency, is fixed regardless of the image signal. However, when such edge enhancement is performed in the multi-scanning television receiver described above, the spatial frequency to be emphasized changes depending on the deflection frequency. Therefore, for example, if the horizontal deflection frequency is 15.75 KIIz and the image signal is strongly rotated around 3 MHz, a spatial frequency of about 12 cpd will be emphasized at a viewing distance of 5 H, but the same effect will be obtained when the horizontal deflection frequency is 31.5 KHz. Approximately 6 depending on the signal processing of
cpd, which has the disadvantage that desired contour enhancement cannot be performed on the image.

In view of these points, the present invention aims to propose an apparatus in which an optimal spatial frequency is emphasized according to the horizontal frequency of an input signal, and a desired outline of an image can be emphasized.

[Means for solving problems]

The present invention detects the horizontal frequency of an input signal, converts it into a voltage, applies this voltage to a horizontal deflection circuit, and switches the horizontal deflection frequency of the horizontal deflection circuit to receive input signals of different horizontal frequencies. The present invention is a multi-scan television receiver in which the frequency for contour-enhancing HIM is changed according to the horizontal frequency of an input signal.

[Effect]

According to such a configuration, the frequency for edge enhancement is changed according to the horizontal frequency of the input signal, the optimum spatial frequency is emphasized, and the desired edge enhancement is performed on the image.

〔Example〕

Hereinafter, an embodiment of the multi-scan television receiver of the present invention will be described with reference to FIG. This first
In the figure, parts corresponding to those in FIGS. 2 to 4 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, as shown in FIG. The output signal of this variable center frequency band pass filter (82) is grounded via a variable resistor (83).
) of the movable element (84) is added to the adder circuit (81).
supply to the other end.

The cutoff frequency of this variable cutoff frequency low pass filter (80) is varied by the voltage supplied to its control terminal. Further, the center frequency of the variable center frequency band pass filter (82) is varied by the voltage supplied to its control terminal.

The addition output of the addition circuit (81) is supplied to the cathode ray tube (6) via the output circuit (5).

On the other hand, the FVC (31
) with variable cutoff frequency IJlft! 1 low-pass filter (80) and one control terminal of each of the variable center frequency band-pass filter (82).

In this case, the output voltage obtained when an NTSC horizontal synchronizing signal with a horizontal frequency of approximately 15.75KIIz is supplied to the input side of the FVC (31) is determined by the variable cutoff frequency low-pass filter (80) and the variable center frequency band. When supplied to the pass filter (82), the cutoff frequency and center frequency are each 3 MHz, and the FVC
(31) When a horizontal synchronizing signal with a horizontal frequency of about 31.5 KHz of the NTSC system is supplied to the input side of the variable cutoff frequency low-pass filter (80) and the variable center frequency band-pass filter (82),
), the cutoff frequency and center frequency are respectively 6 MH! Do as it is done.

Although not shown in the figure, the G and B signals of the RGB process circuit (3) are also supplied to the output circuit (5) via a signal processing circuit similar to that for the R signal described above. The other horizontal deflection systems, vertical deflection systems, etc. are constructed in the same manner as shown in FIGS. 2 to 4 above.

According to such a configuration, the horizontal frequency of the input signal is about 15.
In the case of 75KIIz, a low-J variable cutoff frequency low-pass filter (80) whose cutoff frequency is set to 3 MHz depending on the output voltage of the FVC (31), and a variable frequency band-pass filter (80) whose center frequency is set to 3 MHz or a variable frequency band-pass filter (80) whose cutoff frequency is set to 3 MHz are used.
82) are supplied with the image signals from the RGB processing circuit (3), and the low-frequency components of the image signals are supplied from the variable cutoff frequency low-pass filter (80) to the adder circuit (81), and the variable center frequency band Pass filter (
The high-frequency component centered around 3M)lz of the image signal from 82) is level-adjusted by a variable resistor (83) and supplied to the adder circuit (81). The image signal subjected to the enhancement processing is supplied to the cathode ray tube (6) via the output circuit (5), and an image with enhanced frequency components of approximately 12 cpd in spatial frequency is obtained at a viewing distance of 1iItt5H.

Also, if the horizontal frequency of the input signal is approximately 31.5KHz,
The cutoff frequency is 6 depending on the output voltage of FVC (31).
The image signals from the RGB processing circuit (3) are supplied to a variable cutoff frequency low-pass filter (80) with a MHz frequency and a variable center frequency bandpass filter (82) with a center frequency of 6KHz, respectively. The low-frequency components of the image signal are supplied from the off-frequency low-pass filter (80) to the adder circuit (81), and the high-frequency components of the image signal centered around 6 MHz are supplied from the variable center frequency bandpass filter (82) to the variable resistor. Vessel (83)
The image signal is level-adjusted and supplied to the adder circuit (81), and the adder circuit (81) performs contour enhancement processing at a peaking frequency of 6 Mllz, and the image signal is supplied to the cathode ray tube (6) via the output circuit (5). At a viewing distance of 5H, an image with enhanced spatial frequency components of about 12 cpd is obtained.

As described above, according to this example, the horizontal frequency of the human input signal is detected and converted into a voltage, and this voltage is converted into a horizontal deflection circuit (13
), in a multi-scan television receiver that receives input signals of different horizontal frequencies by switching the horizontal deflection frequency of the horizontal deflection circuit (13), the frequency for edge enhancement is adjusted according to the horizontal frequency of the input signal. Because the horizontal frequency is changed, the viewing distance HIE can be maintained even for input signals with frequencies other than approximately 15.75 KHz, for example, approximately 31.5 KHz.
5H enhances a spatial frequency of approximately 12 cpd, which has the advantage of providing desired contour enhancement to the image.

Furthermore, in the above embodiment, a case has been described in which a variable center frequency band pass filter (82) is used to extract the high J8 component of the image signal, but even if a variable cutoff frequency bypass filter is used, the same effect as in the above embodiment is achieved. It is easy to understand that similar effects can be obtained.

However, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, an optimal spatial frequency is emphasized according to the horizontal frequency of an input signal, and there is an advantage that desired contour enhancement can be performed on an image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the essential parts of a multi-scan television receiver according to the present invention, FIG. 2 is a block diagram showing an example of a multi-scan television receiver, and FIG. FIG. 4 is a block diagram showing the horizontal deflection system extracted from the figure, FIG. 4 is a block diagram showing the vertical deflection system extracted from FIG. 2, and FIG. 5 is a diagram for explaining outline enhancement. (3) is the RGB process circuit, (5) is the output circuit, (6
) is a cathode ray tube, (7) is a sync separation circuit, (11) is a mode detection circuit, (31) is an FVC, (80) is a variable cut-off frequency low-pass filter, (81) is an addition circuit, (
82) is a variable center frequency bandpass filter, (83)
is a variable resistor.

Claims (1)

[Claims] A multi-scan television receiver that detects the horizontal frequency of an input signal, converts it into a voltage, applies the voltage to a horizontal deflection circuit, and switches the horizontal deflection frequency of the horizontal deflection circuit to receive input signals of different horizontal frequencies. A multi-scan television receiver characterized in that a frequency for edge enhancement is changed depending on the horizontal frequency of the input signal.