JPS6316207Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal display device that detects signals from a plurality of circuits under test having different frequencies and displays their waveforms on a display means.

Such signal display devices are used, for example, in devices for adjusting printed circuit boards of television receivers. That is, in recent television receivers, almost all the circuits of the television receiver are included in the printed circuit board, and when adjusting the printed circuit board, the frequency incorporated in the printed circuit board must be adjusted. This is because it is necessary to detect signals from a plurality of different circuits under test and display their waveforms on a display means for visual observation.

FIG. 1 shows a conventional signal display device in a system for conditioning such a printed circuit board. In FIG. 1, numeral 1 is a signal supply means for supplying test signals to the printed circuit board 2 under test, and numeral 3 is a switching circuit for switching the output path in response to a control signal from the system controller 4. Reference numeral 5 denotes a display unit, which includes a low-speed oscilloscope 5a, a high-speed oscilloscope 5b, a cathode ray tube 5c for displaying patterns, and a digital panel meter 5d for digitally displaying peak-to-peak values of measurement signals, etc. Display means are provided. In the signal display device, a predetermined test signal is applied from the signal supply means 1 to the printed circuit board 2 according to an instruction from the system controller 4, and at the same time, a display means optimal for displaying the characteristics is applied according to a selection signal from the system controller 4. The adjustment was performed by proceeding through adjustment steps for each unit phenomenon, and by having the operator manipulate the adjustment parts of the printed circuit board to obtain the desired characteristics.

However, in this display device, as the number of types of unit circuits included in the printed circuit board increases, the number of types of display means increases, resulting in an increase in cost and an undesirable increase in the floor area occupied by the device.

Furthermore, as an adjustment device for printed circuit boards, if the adjustment steps are switched for each unit circuit characteristic, the total number of adjustment steps will be large, and it will be necessary to repeat the adjustment steps to check the interaction on the characteristics of each unit circuit. However, this method was disadvantageous because it required an increase in man-hours and the skill level of the operator.

The present invention solves the above-mentioned drawbacks of the conventional art by simultaneously displaying multiple characteristics on a single cathode ray tube.

Hereinafter, the present invention will be explained in detail according to embodiments shown in the drawings.

In FIG. 2, 1 and 2 are printed circuit boards each incorporating a signal supply means and a plurality of types of circuits to be measured, as in FIG. 1, and 6a, 6b, 6c
are first means each comprising a detector for detecting a signal from the circuit under test in the printed circuit board, and 6a of these is a sweeper signal repeatedly applied from the signal supply means 1 to the circuit under test at a unit of vertical frequency. The signal obtained based on (e.g.
VIF signal) is detected, and 6b is, for example, R-Y,
Waveforms of color demodulated outputs such as G-Y and B-Y signals are detected in horizontal frequency units. Reference numeral 6c detects a test pattern, but it is actually formed by a switch, and when turned on, only connects a predetermined output end of the printed circuit board 2 to the cathode ray tube 11.
Although only one each of 6a and 6b is shown in the figure, a plurality of each may be provided as necessary.

7 is an arithmetic circuit that outputs the peak-to-peak values of each signal from the first means 6a and 6b, and this output is directly led to the color cathode ray tube 11 to display the peak-to-peak values in numbers at predetermined positions on the screen. represent

8 is a second means for converting the horizontal frequency signal from 6b into a vertical frequency signal, specifically 1
A horizontal period signal is extended to one vertical period. Note that since there is no need to frequency convert the vertical frequency signal, no second means for frequency conversion is provided at the output end of 6a. Reference numeral 9 denotes a third means for allocating portions of a plurality of signals aligned in vertical frequency to different positions in the horizontal scan and outputting a signal according to the size of the portion. Shown in Figure 3. In FIG. 3, 12a, 12
b,..., 12n are voltage comparators, and a sawtooth wave voltage with a horizontal frequency is commonly applied to their reference voltage input terminals, and a signal _E1 from 6a is applied to the first voltage comparator 12a for comparison. The second voltage comparator 12b receives a signal E ₂ (e.g. R-Y signal) from the second means 8 constituted by a frequency converter as a comparison signal input. Furthermore, the nth
Either signal 6a or 8 may be applied to the voltage comparator 12n, but here, for example, the signal B from 8 may be applied.
-Y signal is given as comparison signal input _Eo . In this case, if the voltages E ₁ , E ₂ , and E _o given as comparison signals are of similar magnitude, the first
Since the outputs of the voltage comparator 12a and the second voltage comparator 12b occur at approximately the same position in horizontal scanning, which is inconvenient for multiple display, it is necessary to delay one output for a certain period of time through a delay circuit. Even without using such a delay circuit, the comparison signals applied to each comparator 12a, 12b,..., 12n can be separated by a predetermined level by the volume VR ₁ , VR _{2 ,} . Bye.

In FIG. 2, for example, only one signal transmission path from 6b to 8, one signal transmission path from 8 to 9, and one transmission path from 6a to 9 are shown, but these are actually A plurality of them may be provided as necessary.

FIG. 4A shows the comparison signals E ₁ , E ₂ , ..., as described above.
The relationship between these signals and the reference voltage (horizontal sawtooth voltage) S is shown when E _o is separated by a predetermined level.
Then, a pulse P ₁₁ having a width corresponding to the comparison signal portion smaller than the sawtooth wave voltage S serving as the reference voltage is obtained as shown in FIG _. Each of the n comparators 12n obtains a pulse P _o1 . In the second scanning period, P ₁₂ , P ₂₂ , P _o2 are sequentially applied to each voltage comparator 12a, 1
2b, 12n, and in the third horizontal scanning period
P ₁₃ , P ₂₃ , P _o3 , P _1n , P _2n , in the m-th horizontal scanning period
P _on is obtained respectively. These pulses can also be made into pulses synchronized with the falling edge (FIG. 4C) through an appropriate differentiation and shaping circuit (not shown), and if they are led to the cathode ray tube 11, the pulses shown in FIG. The waveforms of each signal are displayed simultaneously on the same screen. In FIG. 5, the waveforms represented by a ₁ , a ₂ , a ₃ ... _an , the waveforms represented by b ₁ , b ₂ , b ₃ ...b _n , and the waveforms c ₁ , c ₂ , c ₃ ...c The position on the screen of the waveform displayed by _n (and therefore the time relationship of multiple display) is determined by the volumes VR ₁ , VR ₂ , VR _o in FIG. 3.

As mentioned above, in the embodiment of FIG.
A horizontal sawtooth wave voltage is supplied to the reference signal input terminals of 2a, 12b...12n under the same conditions, and each signal voltage to be compared is supplied with a certain level shift. Add various signal voltages for comparison as they are without level shifting,
Even if the horizontal sawtooth voltage is individually shifted for each comparator, the waveforms of each signal can be displayed multiplexed on the same screen in substantially the same way.

Returning again to FIG. 2, numeral 10 is a hue decoder circuit for determining the hue of each signal waveform displayed on the screen, and a specific example of its configuration is shown in FIG.

In FIG. 6, the signal from the third means 9 is applied to the input terminal 13 of the decoder section 10a, where the decoder section is controlled by a multiple selection time signal separately supplied to address terminals 14, 15, 16. 1
An output is selectively generated at one or more of the output terminals 0, 1, 2, . . . , 7 of the output terminal 0a. The diode matrix section 10b is the decoder section 10a.
The cathode R of a predetermined electron gun depending on the output content of
The lines of the color output circuit and the cathode are electrically coupled so that G and B are activated.

The hue decoder circuit 10 allows multiplexed signal waveforms to be displayed on the screen in different hues.

FIG. 7 shows the configuration of the circuit 17 for forming the multiple selection time signal and the decoder section 10a. Signals Tk and Tk+ ₁ are given. These signals Tk and Tk+ ₁ , as shown in FIG. 8B, fall within a predetermined range W ₁ , of the sawtooth voltage waveform S of the horizontal frequency shown in FIG.
It has a negative polarity pulse with a width matching W ₂ .

Now, if we think about displaying data within range W ₁ ,
The signal Tk given to the first terminal 18 is low level,
Since the signal Tk+ ₁ applied to the second terminal 19 is at a high level, the line _L1 is at a high level "1" due to diode _D2 being turned off, and the lines _L2 and _L3 are at a low level when diodes _D1 and _D2 are on. It becomes “0”.
Therefore, the address terminals 14 of the decoder section 10a,
[1,0,0] is given to 15 and 16. When the decoder IC 20 receives [1, 0, 0], the first output terminal O1 becomes " ₁ " and all other output terminals become "0".
Therefore, in the AND gates Q ₁ , Q ₂ ... Q ₇ to which each output terminal O ₁ , O ₂ ... O 7 is connected individually, only _{Q 1 is} conductive,
The data given from the input terminal 13 is sent to the decoder section 1.
It is output to output terminal 0 of 0a.

Next, regarding the display of the range _W2 part shown in FIG. 8, since the signal Tk applied to the first terminal 18 of the circuit 17 is at a high level and the signal Tk+ ₁ applied to the second terminal 19 is at a low level, the diode
When D ₃ and D ₄ are turned on, lines L ₁ and L ₃ are set to “0”, and when diode D ₁ is turned off, line L ₂ is set to “1”.
Address terminals 14, 15, 1 of decoder section 10a
6 is given [0, 1, 0]. At this time,
Since the second output terminal _O1 of the decoder IC20 is "1" and all others are "0", the data applied to the input terminal 13 is outputted to the output terminal ₁ through the AND gate Q2.

Thus _, in the case of FIGS _. 6 to 8, the image formed by a ₁ , a ₂ , _{a 3 .} . . a _na shown in FIG. The image formed by _n is red,
The image formed by c ₁ , c ₂ , c _{3 .} . _.
Lines L ₁ , L ₂ , L ₃ depending on the combination of Tk and Tk+ ₁
It is easy to understand that a desired color can be selected by freely selecting the level of color.

In FIG. 2, 4 is a system controller;
Multiplex display of signal waveforms with different frequencies and pattern generation are performed by switching. That is, as mentioned above, the pattern detector 6c is composed of a switch, and when the pattern is not displayed, the switch is turned off to cut off a predetermined output terminal of the printed circuit board 2 and the cathode ray tube 11. 6a, 6b,
When 7, 8, 9, and 10 are activated, a display as shown in FIG. 5 mentioned above is produced. On the other hand, when displaying a pattern, when the switch of the pattern detector 6c is turned on, a predetermined output terminal of the printed circuit board 2 is coupled to the cathode ray tube 11, and a test pattern is displayed on the cathode ray tube 11. At this time 6a, 6b, 7, 8, 9, 10
Set it to off. 6c and 6 like this
A, 6b, 7, 8, 9, and 10 are switched by the system controller 4.

As explained above, according to the present invention, the waveforms of a plurality of different signals detected from a plurality of circuits under test incorporated in a printed circuit board can be displayed simultaneously on a common cathode ray tube, thereby reducing the number of display means. Since only one signal display device is required, the cost is much lower than that of conventional signal display devices, and the device occupies less floor space, making it very convenient.
Furthermore, when adjusting the circuit under test while looking at the signal waveform, the adjustment can be done at the most appropriate point for multiple types of interconnected circuits at once, so there is no need to repeat the adjustment steps as in the conventional case. be.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a conventional signal display device. FIG. 2 is a block circuit diagram of a signal display device embodying the present invention, FIG. 3 is a circuit diagram showing a specific example of one of its constituent means, and FIGS. 4 and 5 are explanatory diagrams of FIG. be. FIG. 6 is a diagram showing a specific example of another constituent means in FIG. 2. FIG. 7 is a circuit diagram specifically showing the main part of FIG. 6 together with related circuits, and FIG. 8 is an explanatory waveform diagram thereof. 1...Signal supply means, 2...Printed circuit board, 6a, 6b, 6c...first means, 8...second
Means, 9...Third means, 11...Cathode ray tube.

Claims (1)

[Claims for Utility Model Registration] (1) In a device that detects a plurality of signals from a circuit under test and displays their waveforms on a display means, a signal that supplies a predetermined signal to the circuit under test. a first means having a supply means, a means for detecting a vertical frequency signal among the signals from the circuit under test, and a means for detecting a horizontal frequency signal among the signals output from the first means; a second means for stretching the signal to become a signal of a vertical frequency; and a second means for allocating a plurality of types of signals aligned to the vertical frequency to different positions in the horizontal scanning of the television, and adjusting the magnitude of the signals. A signal display device comprising a third means for outputting a corresponding signal, and a cathode ray tube for displaying a plurality of groups of images on a screen according to the output of the third means. (2) The third means converts the magnitude of the signal in the horizontal sawtooth wave voltage into a pulse width by comparing a plurality of types of signals aligned at vertical frequencies with a reference voltage at different parts of the horizontal sawtooth voltage. The signal display device according to claim 1, wherein the cathode ray tube displays a plurality of groups of images on a screen corresponding to the plurality of groups of signals converted into the pulse width.