JPS5832820B2 - Television receiver adjustment method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention supplies a frequency shifting signal whose frequency changes at a predetermined repetition period to a television receiver having a circuit section whose frequency characteristics are to be adjusted, and adjusts the output of the circuit section. The present invention relates to a method and apparatus for adjusting a television receiver, in which a signal is supplied to the display means to form a display on the display means according to the frequency characteristics of the circuit portion.

Generally, as the final step in the assembly process of a television receiver, the assembled receiver is adjusted.

As part of this adjustment process, (a) adjusting a bandpass filter to separate the color subcarrier component (chroma component) modulated by the chromaticity signal from the color composite video signal; (b) adjusting the audio from the color composite video signal; (e) Adjustment of a frequency discriminator to demodulate the frequency modulated signal in the audio band; (d) Video IF to amplify the intermediate frequency of the video signal.
Adjustments to the amplifier circuit, etc. are made.

FIG. 1 is a block circuit diagram of a measurement system used in the adjustment process as described above.

Note that FIG. 2A is an output waveform diagram of the sweep generator 1 of FIG. 1.

FIG. 2B is a graph showing the frequency shift of the output of this sweep generator.

For example, when adjusting a bandpass filter for separating color subcarrier components (chroma band) from a color composite video signal, sweep generator 1 to 3.58
A frequency signal in the L band (color subcarrier band) is supplied to a test input terminal of the television receiver 2 (for example, an input terminal of a bandpass amplifier equipped with the above-mentioned bandpass filter).

The sweep generator 1 is a frequency oscillator whose output signal has a center frequency f as shown in FIG. 2A.

(For example, a constant frequency range f centered around 3.58 ME(z).

, ff (e.g., 3.58±I MHz).

That is, as shown in FIG. 2B, the frequency becomes f at a predetermined period.
.

-If to f. The sentence changes linearly up to +If.

The output signal of the sweep generator 1 is band-amplified by a band-pass amplifier equipped with the above-mentioned band-pass filter.

Then, the output frequency of the test output terminal of the receiver 2 (for example, the output terminal of the above-mentioned bandpass filter) is detected by the detection circuit 3,
When this detection signal is supplied to the oscilloscope 4, the band characteristics of the bandpass filter are displayed on the cathode ray tube of the oscilloscope 4.

FIG. 3A shows the band characteristics of a bandpass filter for separating chroma bands displayed on a cathode ray tube as described above.

As shown in FIG. 3A, the normal band characteristic of the bandpass filter has a peak at 3.58 MHz, and a band of about IMHz centered around this peak.

And the band characteristic displayed on oscilloscope 4 is 3A.
The bandpass filter of the image receiver 2 is adjusted so as to have the characteristics shown in the figure.

In this case, in order to easily perform the above adjustment, the third
Markers (for example, 3.08MHz, 3.58MHz
z, 4.08 MHz, and 4.5 ME (z position) are added.

This marker can be formed by providing a portion of the output signal of the sweep generator 1 at a predetermined frequency position with a locally varying amplitude as shown in FIG. 2A.

In addition, the audio band (4,5M
The same measurement and adjustment work as in the measurement system shown in FIG. 1 is also performed for the bandpass filter for separating frequency components in the Hz band).

In this case, the normal band characteristic of this bandpass filter is a characteristic curve characterized by 4.5 MHz, as shown in FIG. 3B.

Similarly, the frequency discriminator for demodulating the frequency modulated signal in the voice band is adjusted so as to have the frequency characteristics shown in FIG. 3C.

Regarding the video IF amplifier circuit, for example, in the UHF band, the tuning circuit of the amplifier is adjusted so as to have the band characteristics shown in FIG. 3D.

The above-mentioned adjustment work is necessary when mass-producing receivers.
A large number of oscilloscopes 4 are required to adjust a large number of receivers in parallel.

As a result, the amount of equipment required is enormous, and its maintenance is not easy.

The present invention has been made in view of the above-mentioned problems, and includes:
Displays the frequency characteristics of the television receiver's circuitry that should be adjusted without using an oscilloscope on the receiver's screen.
Based on this display, the frequency characteristics of the circuit portion are adjusted.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a block circuit diagram showing an embodiment in which the present invention is applied to a measurement system for various adjustments of a television receiver.

Note that FIG. 5A is a graph showing the frequency spectrum of a test signal formed by this measurement system, and FIG. 5B is a waveform diagram showing waveforms at various parts in FIG. 4.

6 is a front view showing the screen of the television receiver of FIG. 4 on which the band characteristic curve is displayed by the measurement system of FIG. 4.

The measurement system in Figure 4 replaces the oscilloscope 40 in Figure 1.
A cathode ray tube 20 of the television receiver 2 to be adjusted is used to display the band characteristic curve.

In FIG. 4, the synchronizing signal generator 5 is composed of a clock pulse generator that generates clock pulses CP of a predetermined frequency and a counter that counts the clock pulses CP.

This counter detects the horizontal synchronizing signal H (15,7 KHz) and vertical synchronizing signal V for the television signal.
(60Hz) is formed.

The clock pulse CP, horizontal synchronization signal H and vertical synchronization signal V generated by the synchronization signal generator 5 are supplied to a pattern signal generator 6.

The vertical synchronization signal V is also supplied to the sweep generator 1.

The pattern signal generator 6 includes, for example, a ROM,
In this pattern signal generator 6, markers 13a and 13b as shown in FIG.

13c, a pattern signal for displaying a frequency display 14, a zero level display 15, etc. on the television screen 12 is formed.

These displays serve as a reference for adjustment and are intended to facilitate the adjustment work. Figure 6 shows a bandpass filter for separating color subcarrier components (chroma components) from the color composite video signal. A pattern display used for adjustment is shown.

That is, the pair of markers 13a and 13b correspond to each frequency of the band characteristic (3.08 MHz, 3.58 MHz).

4.08 MHz), the range of levels through which the characteristic curve should pass is displayed.

Note that the position of 4.5 ME (z is the frequency band where the audio band exists, so 4.5 ME (marker 13 of z
c indicates a predetermined level below which the characteristic curve should be set.

Further, the frequency display displays the frequencies (MHz) at the positions where the markers 13a, 13b, and 13c are displayed.

Note that this frequency display may be a symbol such as A, B, or C.

Further, the zero level display 15 is for displaying the zero level of the band characteristic curve, and in FIG. 6, the level is indicated by a dotted line.

A horizontal synchronization signal H and a vertical synchronization signal V are added to the pattern signal for displaying the markers 13a, 13b, 13c, etc. in the pattern signal generator 6, and this added pattern signal is sent to the mixer as a video signal. 7.

The output signal of the sweep generator 1 is supplied to the mixer 7.

This sweep generator 1 may be identical to the sweep generator 1 of FIG.

As shown in Fig. 2A, when the output signal is used for adjusting a bandpass filter for chroma band separation, for example, the frequency is centered around 3.58 MHz, and the output signal is Changes periodically.

The period of this transition is set to be the period of the vertical synchronizing signal supplied from the synchronizing signal generator 5.

The output signal of the sweep generator 1 fed to the mixer 7 is mixed with the output signal of the pattern signal generator 6;
The signal is supplied to a modulator 8.

This modulator 8 is supplied with a video carrier wave in the UHF band, and this carrier wave is modulated according to the output signal of the mixer 7, and sent by radio waves or wires to each part of the television receiver assembly factory.

The frequency spectrum of this modulated signal (hereinafter referred to as test signal) is shown in Figure 5A, where the output of the sweep generator 1 (3.5 MHz
±IMHz band) are obtained.

The above-mentioned markers 13a and 13b are placed in bands other than the chroma signal band of 3.5ME (z±IMHz).
.

13c, a video signal for displaying a frequency display 14, etc. is superimposed.

A test signal sent wirelessly or by wire is supplied to the UHFHF input terminal of the receiver 2 to be adjusted.

This television receiver 2 generally has a configuration as shown in FIG.

That is, an input signal from an input terminal A (for example, an antenna terminal) is supplied to a video IF amplification circuit 22 via a tuner 21, where intermediate frequency amplification is performed.

The output signal of the video IF amplification circuit 22 is detected by the video detection circuit 23 and then supplied to the first video amplification circuit 24 .

The video signal containing the chroma component amplified by the first video amplification circuit 24 is supplied to the cathode ray tube 20 after its luminance component is amplified by the second video amplification circuit 25 .

The output signal of the first video amplifying circuit 24 is supplied to a band amplifying circuit 26 equipped with a chroma band bandpass filter, where the chroma component (3,58 L band) is separated.

The chroma signal output from the band amplification circuit 26 is supplied to a color demodulation circuit 27 and a color synchronization circuit 28, and the chromaticity signal output from the color demodulation circuit 27 is supplied to a cathode ray tube 20.

Further, the output signal of the first video amplification circuit 24 is transmitted to the synchronous separation circuit 2.
9, where the horizontal synchronizing signal H and vertical synchronizing signal V in the video signal are separated.

The separated horizontal and vertical synchronizing signals are sent to the horizontal deflection circuit 3.
0 and vertical deflection circuit 31, where horizontal and vertical deflection is performed.

On the other hand, video I including audio band components (4,5 MHz band)
The output signal of the F amplifier circuit 22 is supplied to a 4.5 MHz detection and band pass filter 32, where the audio band components are separated.

This audio band component passes through an audio IF amplifier circuit 33 and is FM demodulated by an audio FM detection circuit 34 equipped with an equal wave number discriminator.

The FM demodulated audio signal is then amplified and then reproduced by the speaker 35.

The test signal supplied to the television receiver 2 configured as described above is transmitted to the tuner 21 . A mixed signal of the output signal of the sweep generator 1 and the output signal of the pattern signal generator 6 is reproduced through the video IF amplifier circuit 2, the video detection circuit 23, and the first video amplifier circuit 24.

and markers 13a and 13b. A pattern signal forming a display such as 13c is supplied to the cathode ray tube 20 via the second video amplification circuit 25.

As a result, the marker 13a shown in FIG. 13b, 13
c, a frequency display 14, a zero level display 15, etc. are displayed on the screen.

On the other hand, the output signal of the first video amplification circuit 24 is supplied to a band amplification circuit 26 including a chroma band bandpass filter.

The output signal of this band amplification circuit 26 is led out from the test output terminal T of the receiver 2.

The output signal of this test output terminal T1 is then supplied to the measurement signal forming circuit 9.

The measurement signal forming circuit 9 converts the band characteristics of the band pass filter into the receiver (2) based on the output signal of the band amplification circuit 26.
) is a circuit for forming signals to be displayed on a cathode ray tube.

The measurement signal forming circuit 9 includes a detection circuit 3, a pulse phase modulation circuit 10, and a differentiation circuit 11.

In this detection circuit 3, the envelope of the output signal of the band amplification circuit 26 is detected.

The output signal of the detection circuit 3 shows the band characteristics of the band pass filter as shown in FIG. 58a.

The output signal of the detection circuit 3 is supplied to a pulse phase modulation circuit 10.

The pulse phase modulation circuit 10 is supplied with a horizontal synchronization signal H (FIG. 5B b) from the synchronization signal separation circuit 29 of the receiver 2 from a test terminal T2.

A triangular wave signal C (C in FIG. 5B) synchronized with this horizontal synchronizing signal H is then formed.

This triangular wave signal C is superimposed on the inverted signal of the output signal a of the above-mentioned detection circuit 3 in the pulse phase modulation circuit 10, as shown in FIG. 5B d.

Then, this superimposed signal d is set at a predetermined level (Fig. 5B d).
If the signal is clipped at the level shown by the dashed line in FIG. 5B, a pulse phase modulation signal as shown in FIG. 5B is obtained.

The rising phase of this pulse phase modulation signal e is delayed from the horizontal synchronizing signal H according to the level of the detection output signal a, as shown in FIG. 5B e.

This pulse phase modulation signal e is supplied to the differentiating circuit 11,
Here, the differential pulse f at the rising position of the signal e (Fig. 5B f
) is formed.

The differential pulse f is supplied to the video check terminal T3 of the television receiver 2.

This video check terminal T3 is, for example, an input terminal of the first video amplification circuit 240 of the receiver 2, and the differential pulse f is supplied to the cathode ray tube 20 via the first video amplification circuit 24 and the second video amplification circuit 25.

As shown in FIG. 6, the band characteristic curve 16 of the band pass filter is
, 13c, etc. are displayed in a superimposed manner on the screen 12.

In the adjustment work, the bandpass transformer, tuning circuit, etc. of the bandpass filter are adjusted so that the band characteristic curve 16 passes through a predetermined range indicated by the markers 13a, 13b, and 13c.

Regarding the adjustment of the bandpass filter 32 for separating frequency components in the audio band from the Naorikai video signal and the adjustment of the audio FM detection circuit 34 equipped with a frequency discriminator for demodulating the frequency modulated signal in the audio band This is also carried out by displaying the characteristic curve on the cathode ray tube 20 of the receiver 2 in the same manner as in the above case.

In this case, although not shown, the pattern signal generator 6 and sweep generator 1 similar to those shown in FIG. Formed for bandpass filter adjustment.

After these signals are mixed in a mixer different from that shown in Fig. 4, they are mixed into the U for the chroma band test signal mentioned above.
It is modulated with a UHF carrier wave of a different frequency from the HF' carrier wave and sent as a test signal to the assembly plant.

Similarly, the test signal for adjusting the frequency discriminator is sent to another U.
It is formed by being modulated with an HF carrier wave.

In the assembly factory, the channels of the receiver 20 are sequentially switched and the above-mentioned adjustments of each part are sequentially performed.

Note that the pattern signal for displaying markers etc. formed by the pattern signal generator 6 mentioned above and the output signal of the sweep generator 1 are recorded in a recording/reproducing means such as a VTR, and the recorded signals are It may also be reproduced and supplied to the television receiver 2.

Next, adjustment of the video IF amplification circuit of the television receiver 2 will be explained.

FIG. 7 is a block circuit diagram of a measurement system for adjusting the video IF amplifier circuit 22.

The video IF amplifier circuit 22 is a circuit for converting a signal modulated by a video carrier wave and sent to the receiver 2 into a video signal.

Therefore, if a pattern signal such as a marker is included in the test signal modulated by the UHF carrier wave as shown in Fig. 4, a normal IF output will not be obtained if the video IF amplifier circuit 22 is not adjusted. , a pattern such as a normal marker will not be displayed on the screen 12 of the receiver 2.

To prevent this, in FIG. 1, the output signal of the pattern signal generator 6 is transmitted to the receiver 2 without being modulated by the UHF carrier wave.
We are trying to supply it to

That is, in FIG. 1, in the same manner as in FIG.
Vertical motion signals V are respectively supplied to pattern signal generators 6.

This pattern signal generator 6 generates pattern signals for displaying markers 13a, 13b, 13c, zero level display 15, etc. on the screen 12 as shown in FIG.

This pattern signal is supplied to the assembly factory nomixer 17 by wire.

On the other hand, sweep generator 1 is UH
It is an F-band sweep generator whose output frequency varies periodically and continuously from, for example, 54 MHz to 61 MHz.

This transition period is set to be the period of the vertical synchronization signal V supplied from the synchronization signal generator 5.

The output signal of the UHF band of the sweep generator 1 is supplied as a test signal to the television receiver 2 to be adjusted, either wirelessly or by wire.

The test signal supplied to the receiver 2 is supplied to the video IF amplifier circuit 22 to be adjusted via the tuner 21 of the receiver 2.

The output of the video IF amplifier circuit 22 is supplied from the IF test terminal T4 of the receiver 2 to the measurement signal forming circuit 9 having the same configuration as that shown in FIG.

The output signal of the video IF amplification circuit 22 is detected here and further subjected to pulse phase modulation.

This pulse phase modulation signal is then differentiated and the video IF
A video signal for displaying the band characteristic curve of the amplifier circuit 22 on the cathode ray tube of the receiver 2 is formed.

This video signal is supplied to the mixer 17 described above.

In the mixer 17, the video signal of the characteristic curve described above and the pattern signal for displaying the markers 13a, 13b, 13c, etc. are mixed.

The mixed signal of the mixer 17 is then supplied to the video check terminal T3 of the receiver 2 (ie, the input terminal of the first video amplification circuit 240).

The pattern signal and the video signal of the characteristic curve are
The signal is supplied to the cathode ray tube 20 via the video amplification circuit 24 and the second video amplification circuit 25.

In this case, since the pattern signal includes horizontal and vertical synchronization signal components, these synchronization signal components are passed through the first video amplification circuit 24 and the synchronization separation circuit 29 to the horizontal deflection circuit 30 and the vertical deflection circuit 31. Supplied.

As a result, even when the video IF amplifier circuit 22 is not adjusted,
Since the synchronization system of the receiver 2 operates normally, the band characteristic curve 16 of the video IF amplification circuit as shown in FIG. 8, the adjustment markers 13a, 13b, 13c, the frequency display 14,
A zero level display 15 and the like are displayed on the screen 12.

Adjustment of bandpass filter for Naori Roma band separation,
Regarding the adjustment of the bandpass filter for audio band separation and the adjustment of the audio frequency discriminator, the measurement system for these adjustments may have a configuration similar to that shown in FIG. 7.

For example, the frequency band swept by the sweep generator 1 in FIG. 7 is the audio band, and the output signal of the sweep generator 1 is directly supplied to the audio band bandpass filter 32.

Then, the output signal of the bandpass filter 32 is detected, pulse phase modulated, further differentiated, and this differentiated output is displayed on the screen of the receiver 2 via the video amplification section. is displayed on the screen.

Further, the adjustment of the chroma band bandpass filter and the audio frequency discriminator can be similarly performed using the measurement system shown in FIG.

Although the above description has been made regarding a receiver used in the UHF band, the invention is equally applicable to the VHF band.

Since the present invention has the above-described configuration, it is possible to form a display on the screen of a television receiver according to the frequency characteristics of the circuit section to be adjusted, without using an oscilloscope as in the conventional case. Therefore, the frequency characteristics of the circuit portion can be easily adjusted based on the display corresponding to the frequency characteristics.

Further, the invention described in claim 4 is such that a marker display serving as a reference for the frequency characteristic is also formed on the screen of the television receiver on which a display corresponding to the frequency characteristic is formed. .

Therefore, the frequency characteristics of the circuit portion can be reliably and easily adjusted using this marker as a reference.

[Brief explanation of the drawing]

Figure 1 is a block circuit diagram of a measurement system used in the conventional adjustment process of television receivers. Figure 2A is the output waveform of the sweep generator in Figure 1. Figure 2B is the sweep generator in Figure 1. Figure 3A is a graph showing the frequency shift of the output of the color composite video signal. Figure 3A is a graph showing the band characteristics of the bandpass filter of the television receiver shown in Figure 1 for separating the chroma band components from the color composite video signal. Figure 3B is the color graph. The first method for separating audio band components from a composite video signal
FIG. 3C is a graph showing the band characteristics of the bandpass filter of the television receiver shown in FIG. 3, and FIG. 3C shows the frequency characteristics of the frequency discriminator of the television receiver shown in FIG. Graph, Figure 3D is Image I
It is a graph which shows the band characteristic of an F amplifier circuit. FIG. 4 is a block circuit diagram showing an embodiment in which the present invention is applied to a measurement system for various adjustments of a television receiver;
Figure 5A is a graph showing the frequency spectrum of the test signal. Figure 5B is a waveform diagram showing the waveforms of each part in Figure 4. Figure 6 is a diagram showing the band characteristic curve by the measurement system in Figure 4. FIG. 3 is a front view showing the screen of the television receiver of FIG. FIG. 7 is a block circuit diagram of a measurement system for adjusting the video IF amplifier circuit, and FIG. 8 is a front view similar to FIG. 6 showing the band characteristic curve of the video IF amplifier circuit. In the symbols used in the drawings, 1 is a sweep generator, 2 is a television receiver, 3 is a detection circuit, 4 is an oscilloscope, 5 is a synchronization signal generator, 6 is a pattern signal generator, 7 is a mixer, 8 is a modulator, 9 is a measurement signal forming circuit, 10 is a pulse phase modulation circuit, 11 is a differentiation circuit, and 12 is a television screen.

Claims (1)

[Claims] 1. A frequency shifting signal whose frequency changes at a predetermined repetition period is supplied to a television receiver having a circuit section whose frequency characteristics are to be adjusted, and based on the output signal of the circuit section. In a method for adjusting a television receiver in which the frequency characteristics of the circuit section are displayed on a display means, the following steps include: (a) supplying the frequency shift signal to the circuit section; (b) an integer multiple of the horizontal synchronizing signal; (e) supplying this phase modulated pulse to an image intensifying section of the television receiver to obtain a phase modulated pulse in which a periodic signal is phase-modulated according to an output signal of the circuit section; A method for adjusting a television receiver comprising: forming a display according to frequency characteristics on the screen of the television receiver. 2. A frequency shifting signal whose frequency changes at a predetermined repetition period is supplied to a television receiver having a circuit part whose frequency characteristics are to be adjusted, and the frequency characteristics of the circuit part are adjusted based on the output signal of the circuit part. An adjustment device for a television receiver configured to display on a display means: (a) an oscillator for supplying the television receiver with a frequency shifting signal whose frequency varies with the repetition period of the vertical synchronizing signal; b) A detection circuit for detecting the output signal of the above circuit portion; (e) A phase modulation pulse that is obtained by modulating the phase of the horizontal synchronization signal supplied from the television receiver according to the output level of the above detection circuit. a phase modulation circuit for supplying the phase modulation pulse to the video intensifying section of the television receiver to display a display on the screen of the television receiver according to the frequency characteristics of the circuit section. An adjustment device for a television receiver. 3. The television set forth in claim 2, further comprising a modulator that modulates a predetermined video carrier wave with a frequency-shifted signal output from the oscillator and transmits the modulated video carrier wave to the television receiver. Receiver adjustment device. 4. A frequency shifting signal whose frequency changes at a predetermined repetition period is supplied to a television receiver having a circuit part whose frequency characteristics are to be adjusted, and the frequency characteristics of the circuit part are adjusted based on the output signal of the circuit part. An adjustment device for a television receiver configured to display on a display means: (a) an oscillator for supplying the television receiver with a frequency shifting signal whose frequency varies with the repetition period of the vertical synchronization signal; b) a pattern signal forming circuit that forms a pattern signal to be supplied to the television receiver in order to display a marker serving as a reference for the frequency characteristic of the circuit portion on the screen of the television receiver; (c) the above. a detection circuit for detecting the output signal of the circuit portion; (d) a phase for outputting a phase-modulated pulse obtained by phase-modulating the horizontal synchronizing signal supplied from the television receiver according to the output level of the detection circuit; Modulation circuit. and supplying the phase modulation pulse to the video amplifying section of the television receiver to display a display according to the frequency characteristics of the circuit section and a display of the marker on the screen of the television receiver. An adjustment device for a television receiver. 5. A patent characterized in that a modulator is provided for modulating a predetermined video carrier wave with a frequency shift signal output from the oscillator and a pattern signal output from the pattern signal forming circuit and transmitting the modulated video carrier wave to the television receiver. Claim 4
The adjustment device for the television receiver described in Section 1. 6. The pattern signal forming circuit includes a synchronizing signal adding circuit, and the pattern signal including a horizontal synchronizing signal and a vertical synchronizing signal is supplied to the television receiver from the output of the pattern signal forming circuit. An adjustment device for a television receiver according to claim 4. 7. Claim No. 7, further comprising a mixer for mixing the output of the phase modulation circuit and the output of the pattern signal forming circuit, and the output of the mixer is supplied to the video amplification section of the television receiver. The adjustment device for a television receiver described in item 4.