JPS639279B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device for displaying abnormal conditions in plants such as power plants and factories, and particularly to a display device suitable for inspection work.

At electrical stations such as power plants and factories, we constantly monitor the status of the plant, and in the event that an abnormality occurs, we respond quickly and appropriately to prevent it from leading to a major accident. A display device is provided to display abnormalities in each part of the plant.

Normally, this display device has a large number of indicators arranged on a panel corresponding to each part of the plant, and each of these indicators is divided into multiple blocks, and the blinking operation is performed by multiple drive circuits. It is configured as follows.

By the way, this display device always needs to be on standby in a normal operating state, and sometimes
It will be necessary to carry out inspection work. Moreover,
Since this inspection work is often carried out during plant operation, it is necessary to carry out it quickly so as not to interfere with the operation.

For this reason, in the past, display devices were inspected by operating each drive circuit of the display device at the same time and causing each display to blink all at once, but due to variations in the characteristics of the elements in each drive circuit, However, the blinking operations of the display lamps were not synchronized, and the indicators blinked in a jumbled manner, making it impossible to quickly inspect the display device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display device that eliminates the drawbacks of the conventional devices and allows quick and comprehensive inspection of each display device.

In order to achieve this objective, the present invention proposes that one of each drive circuit constituted by a thyristor type flip-flop.
The display device is characterized in that each indicator is synchronously blinked all at once by controlling the activation of gate trigger time constant circuits of a plurality of other drive circuits using the blinking signal as a reference. .

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of the main parts of a display device showing an embodiment of the present invention, in which FLR ₁ and FLR ₂ are used to blink a plurality of displays L ₁₁ to _{L 1o} and L ₂₁ to _{L 2o} , respectively. Drive circuit, T is inspection switch, P, N are DC power supply,
SW is switch. However, this switch SW
is originally unnecessary and was added for convenience of explanation.

Each of the drive circuits FLR ₁ and FLR ₂ is configured similarly, and S
is the thyristor, G is the thyristor gate circuit, U
is a unidirectional transistor, C is a capacitor, R is a resistor, VR is a variable resistor, ZD is a Zener diode, and TP is a photocoupler. Further, A is an external connection terminal of the drive circuit.

Now, when inspection switch T is closed and a DC voltage is applied between P ₂ and N ₂ , capacitor C ₁ starts charging, but capacitor C ₂ is charged because the voltage across resistor R ₁ is lower than the dynamic pressure of Zener diode ZD. , in a no-dynamic pressure state. When the charging voltage of C ₁ exceeds the peak voltage of unidirectional transistor U ₁ , C ₁ and
discharge through U ₁ to the gate G of thyristor S ₁ ,
Turn on _S1 . When S ₁ turns ON, the time constant circuit of C ₁ is short-circuited by S ₁ , so charging stops. Furthermore, due to the ON of S ₁ , the zero voltage across R ₁ becomes higher than the Zener voltage, and C ₂ starts charging, and discharges to the gate G _{2 of the thyristor S 2 via} the unidirectional transistor U ₂ similarly to C ₁ above. and turn on _S2 . When S ₂ turns ON, commutation capacitor C ₃ , which had been charged by S ₁ until now, is applied as a reverse voltage to S ₁ , so S ₁ turns OFF, and C ₃ is then reverse charged by S ₂ . Ru. And S ₁ is
By turning OFF, C ₁ starts charging, and C ₂ becomes a no-voltage state and enters the initial operating state. Next, when S ₁ turns ON, S ₂ turns OFF, as shown in Fig. 2 below. Repeat the same action as shown.

At this time, the repetition period is mainly determined by the variable resistor VR _1.
is determined by the time constants of capacitors C ₁ and VR ₂ and C ₂ .
In addition, the display L lights up when S ₂ is turned ON.
When _S1 is turned on, a so-called blinking display is performed, which turns off the light.

The above is the operation of the drive circuit FLR ₂ , and the drive circuit
FLR ₁ has the same configuration and operates in the same way as FLR ₂ . However, even if the time constants of the drive circuits FLR ₁ and FLR are the same, due to slight differences in the characteristics of the unidirectional transistor U, thyristor S, etc., the display gradually changes.
A shift occurs in the blinking timing of L ₁₁ to L _1o and L ₂₁ to L _2o .

In order to eliminate this timing discrepancy,
In this embodiment, a photocoupler TP is provided that short-circuits the charging circuit of the capacitor _C2 only when an external signal is received in the drive circuit FLR. For example, when the blinking cycle of the drive circuit FLR ₁ is used as a reference, the output terminal A ₂ of the FLR ₁ is connected to the input terminal A ₄ of the FLR ₂ via the switch SW.

That is, as shown in FIG. 3a, the indicators L ₁₁ to L _1o
If the timing at which the display devices L ₂₁ to _{L 2o} turn on is α ₁ hour earlier than that, for example, if the switch SW is closed at point V and the cycle is applied, at this time L ₁₁ to L _1o will be OFF, that is, the synchronization from the drive circuit FLR ₁ will be delayed. Since the output a is 0,
The drive circuit FLR ₂ has no effect. However, when the W point is reached, the photocoupler TP is turned ON by the synchronized output a, short-circuiting the charging circuit of _C2 (between the bases of _U2 ) and prohibiting the start of charging at the X point. α at point X ₁ hour later, synchronous output a becomes 0 again at point Y
Therefore, TP is also turned off, and C ₂ is started at this point.
starts charging. Next, when the Z point is reached, the synchronous output a rises, and as a result, TP turns ON, short-circuiting the charging circuit of _C2 , discharging _C2 via the unidirectional transistor _U2 , and _S2 ( _L21 ~ _L2o ) ON
let

At this time, if C ₂ completes charging earlier than the Z point, there will be a slight difference in the lighting start timing of indicators L ₁₁ - _{L 1o} and L ₂₁ - _{L 2o} , but C ₂ will start charging. The timing is always determined at the falling edge of the synchronous output a, so the deviation is never accumulated.
The indicators L ₁₁ to _{L 1o} and L ₂₁ to _{L 2o} always blink in synchronization with the difference. Moreover, since the deviation is due to an extremely small difference in the charging time constant between FLR ₁ and FLR ₂ , it does not have any effect on the actual inspection work.

On the other hand, if C ₂ completes charging later than point Z,
As mentioned above, since discharge is forcibly performed at the Z point via the unijunction _U2 , _S2 is always turned on at the rise of the synchronous output a, and the indicators _L21 to _L2o are
Blinks in synchronization with L ₁₁ to L _1o .

Next, as shown in FIG. 3b, the indicators L ₁₁ to L _1o
If the timing of turning on L ₂₁ to _{L 2o} is α ₂ hours later than that, when synchronization is applied at point V, the photocoupler TP turns on at point W, and the charging circuit of C ₂ is short-circuited. At this time, C ₂ starts charging at point V'. Since the voltage of v ₁ is charged, this is discharged through U ₂ , but since this voltage v ₁ is a very small value, S ₂ I can't get it to turn on. Therefore, S ₁ is
The ON state continues, and conversely, _S2 continues the OFF state. Then, when the synchronous output a reaches point Y where it falls, charging of _C2 starts. After that, the third
It operates in the same way as in Figure a, and the indicators L ₂₁ to L _2o are
Blinks in synchronization with L ₁₁ ~ L _1o .

In this way, in this embodiment, by utilizing the characteristic that the conduction voltage changes due to the voltage change between the base of the unidirectional transistor, _C2 is forcibly charged and discharged by the synchronous output a of FLR ₁ , and S ₂ of
Since the ON and OFF operations are synchronized,
Even if there are some variations in the characteristics of the elements in the FLR, the FLR ₂ output can always be synchronized with the FLR ₁ output, and the indicators L ₁₁ to _{L 1o} and L ₂₁ to _{L 2o} can be operated in synchronized blinking mode. Can be done.

Incidentally, in the above embodiment, the case where there are two drive circuits has been explained, but of course there is no need to limit the number to two.
By setting one of the plurality of drive circuits as a reference and sending a synchronous output a from the reference drive circuit FLR _x to each of the drive circuits FLR ₁ to FLR _o in parallel as shown in FIG. It is possible to make all the indicators connected to the machine flash simultaneously. Further, as shown in FIG. 5, even if the drive circuits FLR _x , FLR ₁ to FLR _o are connected in series, the same effects as described above can be obtained. Furthermore, in this case, even if the reference FLR _x stops, the next FLR ₁ becomes the reference, and other FLRs can be synchronized.

In addition, the display device in each of the above embodiments synchronizes each drive circuit only during inspection operation, turns off the synchronization signal a except during inspection, and blinks in its own synchronization regardless of other blocks. It is also possible to use it without any effect even if other blocks fail.

As described above, according to the present invention, each drive circuit is configured with a thyristor type flip-flop, and a short circuit is provided that shorts between the bases of the unijunction transistors that control the gates of the drive circuits, and one drive circuit is used as a reference. Since the short circuit is operated by the output, the thyristors in other drive circuits operate in synchronization with the output of the reference drive circuit, and this causes all indicators connected to each drive circuit to operate simultaneously. It can be operated in synchronization with the flashing. As a result, a large number of indicators can be inspected in a short time.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a main part of a display device showing an embodiment of the present invention, FIG. 2 is a time chart for explaining the flip-flop operation of a drive circuit in the display device, and FIGS. A time chart for explaining the operation of the display device, and FIGS. 4 and 5 are block diagrams of the display device showing other embodiments of the present invention, respectively. FLR ₁ , FLR ₂ ... each drive circuit, L ₁₁ ~ L _1o , L ₂₁
~L _2o ...Display, T...Inspection switch, P, N
...DC power supply, SW ... switch, S ... thyristor, G ... gate circuit, U ... unidirectional transistor, C ... capacitor, R ... resistor, VR ... variable resistor, ZD ... Zener diode, TP...Photocoupler, A...External connection terminal.

Claims (1)

[Claims] 1. In a display device comprising a plurality of drive circuits for blinking a plurality of display devices, the drive circuit includes a thyristor, a unidirectional transistor connected to the gate of the thyristor, and a unidirectional transistor that operates at a predetermined timing. The structure uses a thyristor-type flip-flop consisting of a time constant circuit and a short-circuit circuit that shorts between the bases of the unijunction transistors. A display device characterized by operating the short circuit described above.