JPH0313797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a tuning inspection device used for tuning adjustment during the manufacture of television receivers and video tape recorders.

(b) Conventional technology As a conventional example of a synchronization inspection device, for example,
There is a description in Publication No. 58-16787. In such equipment, tuning is adjusted by displaying the tuning status on the screen of the television receiver, but this method does not have good adjustment efficiency and the configuration of the inspection equipment itself is complicated. be. There is also a method of measuring the local signal by directly reading it with a frequency counter, but since the signal level of local signals generally decreases as the frequency increases, it is not possible to measure the frequency, and this method also However, the measurement requires a large amount of time, and the adjustment efficiency is poor.

(c) Problems to be Solved by the Invention In view of the above-mentioned drawbacks of the conventional example, the present invention seeks to provide a tuning inspection device that can improve the efficiency of tuning adjustment with a simple configuration.

(d) Means for solving the problem The tuning test device of the present invention beats down the intermediate frequency to obtain a first frequency and a second frequency lower than the first frequency. The first and second frequencies are each converted into a binary signal by an analog-to-digital conversion means, and the tuning voltage applied to the tuner is controlled based on the binary signal. It is something that will be done.

(E) Effect Since the intermediate frequency is beat down as described above to obtain the first frequency and the second frequency lower than the first frequency, coarse tuning adjustment can be performed based on the first frequency. Fine tuning of the tuning can be done based on the second frequency.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows an embodiment of a tuning test device embodying the present invention, and 1 is a tuner (not shown).
2 is a programmable RF oscillator that supplies RE signals corresponding to channels 1, 2, etc. of television broadcasting to the antenna terminal (ANT) of the printed board 1, and 3 is the printer board of the television receiver. 1 is a buffer amplifier that amplifies the IF (intermediate frequency) signal output, 4 is an impedance conversion amplifier, 5 is NTSC,
A beatdown oscillator that oscillates different frequencies according to PAL and SECAM systems, and 6 takes the difference (osc ₁ - IF) between the first oscillation frequency osc ₁ of the oscillator 5 and the IF signal IF and converts it to the first frequency. First thing to do
mixer 7 is the second oscillation frequency of the oscillator 5;
A second mixer 8 takes the difference (osc ₂ −IF) between osc ₂ and the IF signal IF and converts it to a second frequency ₂ ;
A 1/10 frequency divider that divides the frequency by 1/10, and 9 is a first frequency divider that converts the output frequency ( ¹ ') of the frequency divider 8 into a voltage.
A frequency/voltage converter [first FV converter]; 10 is a second frequency/voltage converter [second FV converter] that converts the output frequency of the second mixer 7 into voltage; 11 is a plurality of window comparators 11a to 11c; A first analog-to-digital converter (first
1A/D converter), 12 is a plurality of window comparators 12a to 12d, and the second FV converter 1
A second analog-to-digital converter converts the output voltage of 0 into a binary signal, 13 is a frequency divider 14, FV
An image frequency detection circuit consisting of a converter 15 and a comparator 16; 17 is an amplifier 18;
An IF level detection circuit consisting of a two-peak detector 19 and a comparator 20; 21 indicates each of the comparators 11a-11c, 12a-12d and
The controller 21 is configured with a microcomputer or the like, and controls the tuning voltage applied to the tuner in response to the binary output signals of the programmable RF signals 6 and 20.
It also controls the oscillator 2, etc.

Next, the adjustment operation of the synchronization testing device of the present invention is performed in a second manner.
A flowchart showing the adjustment procedure in Figure 3 and a flowchart showing the adjustment procedure in Figure 3.
Referring to a characteristic diagram of an FV converter, a case will be described in which a television receiver equipped with an NTSC voltage synthesizer type channel selection device is tested.

First, first set the tuning position (for example, 1ch) and set the RF oscillator 2 to Japan's 1ch frequency of 91.25MHz, then check whether the predetermined band reception status is set.
Set a predetermined tuning voltage. After this, tuning adjustment begins.First, the image frequency detection circuit 13 detects whether the IF signal is not an image frequency, and the IF level detection circuit 17 detects whether the IF signal has a sufficient level. do. Note that this detection is performed by inputting the outputs of the window comparators 16 and 20 to the controller 21, and when it is determined that the image frequency is present or that there is no IF output level, tuning is performed. Increase or decrease the voltage. The first oscillation frequency osc ₁ (63.75MHz) is supplied from the oscillator 5 to the first mixer 6, where the IF signal is beat down and supplied to the 1/10 frequency divider 8 at the next stage. The oscillation frequency of 2 (59.25MHz) is supplied to the second mixer 7, and the IF
Beat down the signal. If the above IF signal is a normal value, the first
Frequency ¹ becomes 5MHz, output of 1/10 frequency divider 8
¹ ′ becomes 500KHz. Further, the second frequency ² output from the second mixer 7 is 500KHz. These first and second frequencies ¹ ' and ² are supplied to first and second FV converters 9 and 10 having the same performance. The first and second FV converters 9 and 10 output voltages of 0 to 10 V in proportion to frequency changes of 0 to 1 MHz. Therefore, if the first frequency is 5MHz, that is, ¹ ' is 500KHz, the IF frequency is 58.75MHz, so if you set the output voltage to 5V, the solid straight line i in Figure 3 as shown in
Outputs voltage from 0 to 10V in the range of 58.75±5MHz. In this way, the 1/10 frequency divider 8 has the function of converting the first FV converter 9 into voltage over a substantially 10 MHz range. Also, if the second frequency is 500KHz, the IF frequency is 58.75MHz, so if the output voltage at this time is set to 5V, the third
As shown by straight line B in the figure, it outputs a voltage of 0 to 10V in the range of 58.75±0.5MHz. Therefore, the first mixer 6, 1/10 frequency divider 8, first FV converter 9, first A/D
The converter 11 forms a coarse tuning adjustment section A, and the second mixer 7, the second FV converter 10, and the second A/D converter 1
2 forms a fine tuning adjustment section B. Furthermore, 2nd A/D
The number of window comparators in the converter 12 is greater than that in the first A/D converter 11 in order to improve resolution.

To explain the adjustment operation again with reference to FIG. 2, when it is determined that there is an IF signal level instead of an image frequency, the controller 21 detects the outputs of the window comparators 12a to 12d of the fine tuning adjustment section B, and Check whether the IF signal is within 58.75±0.2MHz, and if it is within this range, no adjustment is necessary and the process ends. Above 58.75
If the IF signal is not within ±0.1MHz, 85.75
Check whether it is within ±5MHz, and if it is not within that range (±5MHz), use the window comparators 11a to 11c of the coarse tuning adjustment section A.
Adjust the tuning voltage so that the IF signal falls within the range of 58.75±5MHz while detecting the output.

If the IF signal is within the range of 58.75±5MHz, then the window comparators 12a to 1 of the fine tuning adjustment section B are adjusted so that the IF signal is within the range of 58.75±0.5MHz.
Adjust the tuning voltage while detecting the 2d output, and adjust the tuning voltage in the same way so that the IF signal falls within the range of 58.75±0.2MHz.Finally, if the IF signal falls within the range of 58.75±0.2MHz, this The tuning data at that time is stored in the memory of the channel selection device, and the adjustment is completed.

The adjustment is completed by performing the above adjustment for each band and channel in this manner.

As described above, the tuning test device of the present invention includes a coarse tuning adjustment section and a fine tuning adjustment section, and the controller changes the tuning voltage based on the binary signals from these adjustment sections. High efficiency and speed of work can be achieved.

Another advantage is that when adjusting PAL or SECAM television receivers other than the NTSC system, it is only necessary to change the first and second oscillation frequencies.

(g) Effects of the invention As described above, according to the synchronization testing device of the present invention,
With a simple configuration, high efficiency and high speed tuning adjustment can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a synchronization testing device embodying the present invention, FIG. 2 is a flowchart for explaining its adjustment operation, and FIG. 3 is a main part of the device of the present invention. FIG. 5... Beatdown oscillator, 6, 7... First and second mixers, 9, 10... First and second frequency/voltage converters, 11, 12... First and second analog/digital converters, 21... controller.

Claims (1)

[Claims] 1. First and second frequency converting means that beat down an intermediate frequency to obtain a first frequency and a second frequency lower than the first frequency, and converting the outputs of the first and second frequency converting means into voltages. first and second frequency/voltage conversion means for converting the first and second frequencies;
a first converting the output of the voltage converting means into a binary signal;
A tuning inspection device comprising a second analog-to-digital conversion means and a control means for controlling a tuning voltage applied to the tuner based on the outputs of the first and second analog-to-digital conversion means.