JPS61190832A - Device for detecting disconnection of cathode during activation - Google Patents

Abstract

PURPOSE:To enable the detection of the disconnection of a cathode during an activation process, by connecting the input light emission diode of a photocoupler in series with the cathodes of a plurality of electron tubes put in the activation process, and by finding out the change in the turn-on state of the output phototransistor of the photocoupler. CONSTITUTION:The cathode heaters 3 of a plurality of camera tubes or the like are connected in series with each other. Activation work is performed on the tubes as gas is being evacuated therefrom. Dividing diodes 4A-4C and a photocoupler 5 are connected in series with the cathode heaters 3. Prior to the activation work, a switch 1 is turned on to cause an electrical current to flow through the cathode heaters 3 so that the disconnection of the cathode heater can be detected in terms of the change in the turn-on state of the output phototransistor of the photocoupler 5. Electricity is then supplied from an activation feeder 9 to perform the activation work as it is found out by the photocoupler 5 likewise whether the cathode heater 3 is disconnected or not. If the disconnection of the cathode heater is detected, a warning circuit 8 in a control section located at a distance is put into operation through a detection circuit 7. The disconnection during the activation work is thus enabled to enhance productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention provides a system for exhausting air by being attached to an automatic exhaust system, for example.
When one of the cathodes of a large number of electron tubes in the activation process breaks during this process, the fact of cathode breakage is sent to a central control department located away from the electron tube attached to the automatic exhaust system. The present invention relates to a cathode disconnection detection device during activation that displays and gives an alarm.

[Background of the invention]

Originally, in the manufacturing process of small receiver tubes, which were used and manufactured in large numbers before the practical use of transistors, there is a track record that the exhaust process and cathode activation process were carried out on automatic machines, but at this time, Automation is limited to the automation of the exhaust work itself and the work of switching the various voltages applied to the cathode in the activation process from manual to mechanical, and the discovery of abnormalities such as cathode disconnection is mainly due to the automation. It was detected by visual inspection by the worker in charge of the work process. Of course, attempts have been made to use relays to detect whether or not the cathode is energized, but for example, the contact state at the sliding contact part in the power supply path of an automatic machine fluctuates so much that the detection result is unreliable, or it is not reliable enough. Due to reasons such as the introduction of automated equipment, the equipment cost would exceed the labor cost, the cathode disconnection during the activation process was decided to be managed by a centralized department (in reality, each department has its own person in charge, so there is no need for centralized management). Monitoring was not carried out in practice.

Furthermore, while receiving tubes are mass-produced using automatic machines, so-called special tubes such as transmitting tubes and image pickup tubes require evacuation to a high degree of vacuum, and both the evacuation and activation processes are complicated. In addition, because the production volume was relatively small and there was some leeway in terms of price, production automation did not progress easily, but in recent years, the exhaust and activation processes of these special tubes have also been installed on automatic machines. It started to be done.

FIG. 2 is a diagram showing an example of conventional wiring connections during activation work (aging) during the evacuation process of the image pickup tube.

Activation is performed while 12 image pickup tubes are attached to one automatic exhaust stand and are being evacuated at the same time. First, the cathode is heated gradually to fully release the gas from the cathode oxide, and then the cathode temperature is gradually increased.Finally, the heater current is increased to, for example, 150% of the rated value, and after completion, the cathode Ensure that sufficient electron flow is obtained from the This is an activation process called activation, aging, etc.

In the case of the image pickup tube type shown in Figure 2, the activation work is carried out 12 times.
Heater current and electron current (thus the combination of electrode potentials) in stages
After changing the electron gun, each electrode of the electron gun is heated by induction using a bombarder to sufficiently remove gas, and then the exhaust pipe is tipped off to complete the exhaust process.

In the image pickup tube activation step shown in FIG. 2, the heaters 3 of the twelve image pickup tubes that are being evacuated at the same time are all connected in series, and the activation heater current is supplied from the activation feeder 9. There is. As mentioned above, in the activation process, a current considerably higher than the rated value is passed through the cathode, and a considerably high voltage is applied between the electrodes in the tube, where the degree of vacuum has not yet risen sufficiently, to generate an electron flow higher than the rated value. Because I let it flow,
During this process, the cathode heater may break. 12
If even one of the heaters connected in series is broken, if you continue the exhaust and activation process without noticing it, power will not be applied to the heaters in the other pipes that are not broken, so connect them in series. If all the tubes are evacuated at the same time, there is a great possibility that all the tubes will have poor activation, poor electron emission, poor gas ratio, etc. In order to prevent such a situation, in the conventional automatic exhaust machine activation circuit shown in FIG. Prior to the activation process (
At this time, no voltage is applied to the activation feeder)
, the above 12 heaters 3 and neon lamp 1 connected in series
0 are connected in parallel, switches LA and IB are closed and AC 200■ is applied. In this case, unless all 12 heaters 3 are disconnected, sufficient voltage will not be applied to the neon lamp 10, and the neon lamp 10 will not turn on.

If even one heater is broken, sufficient voltage will be applied to the neon lamp 10 and it will turn on.

However, in this circuit, when no voltage is applied to the activated feeder 9, the series connection.

It is possible to detect whether any of the 12 connected heaters are disconnected, but during the activation process (
At this time, switches IA and IB are open, and power is supplied to the series-connected heater group by the activation feeder 9), and the activation feeder is directly connected to the neon lamp 10 regardless of whether or not the series-connected heater group is disconnected. When a voltage is applied from 9 and a heater current that far exceeds the rated value is attempted to flow as described above, the neon lamp 10 lights up, giving an inconvenient indication that the cathode is disconnected. .

In order to prevent such inconvenience from occurring, it is possible to use a meter relay, current transformer detection method, or compensating transformer method. In addition, since the coupling transformer method has a large loss current and a small activation current value of about several tens of milliamperes, it is disadvantageous in terms of accuracy.

[Purpose of the invention]

The purpose of the present invention is to use an automatic exhaust machine as described above, in which the cathodes of a large number of electron tubes are connected in series, and when a cathode breakage occurs during simultaneous evacuation, the fact is immediately reported to the management department, and the cathode is immediately removed. To provide a cathode disconnection detection device during activation which can prevent a situation in which parts other than the cathode tube become involved and waste man-hours.

[Summary of the invention]

In order to achieve the above object, in the present invention, the input side LED of a photocoupler is connected in series with the cathode of a plurality of electron tubes in the activation process, and the potential caused by the change in the conduction state of the output side phototransistor of the photocoupler is The cathode disconnection is detected by the change, and the fact of the cathode disconnection is displayed and alerted to a central control department located far away from the location where the electron tube is located. By using a photocoupler, the input side and output side can be made electrically independent, and there is sufficient margin in terms of output, making circuit design easier.
There are almost no restrictions on the insertion point of the photocoupler or the distance to the management department where disconnections should be reported. Moreover, there is currently no problem in terms of cost performance.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which 4A, 4B, and 4C are shunt diodes for suppressing the current flowing through the LED of the photocoupler within the absolute maximum rated current value, 5 is a photocoupler, and 6 is a rectifier circuit (2A12B 7 is a cathode disconnection detection circuit (comparator) that detects changes in the photocoupler output, 8 is a cathode disconnection display alarm circuit, and other symbols are the same as in Figure 2. It is. In this embodiment as well, the switch LA is
, close the IB and apply 200V AC to the series-connected heater group.
When this is applied, if there is no disconnection in any of the heaters 3, the input side LED of the photocoupler 5 emits light, the output side phototransistor of the photocoupler becomes conductive, and its collector potential drops almost to the ground potential. In this state, the cathode disconnection detection circuit 7 does not output the same output, and the cathode disconnection display alarm circuit 8 does not operate. However, if any of the heaters 3 connected in series is disconnected, the LED of the photocoupler 5 does not emit light, the output side phototransistor of the photocoupler is cut off, and its collector potential is set to the power supply potential Vcc. rise to This collector potential is compared with a predetermined standard voltage value at the time of cathode disconnection by the cathode disconnection detection circuit 7, and if it is equal to or higher than this standard value, the cathode disconnection detection circuit 7 outputs a cathode disconnection. The display alarm circuit 8 displays and alarms the fact of cathode disconnection.

The operation of the above photocoupler 5 is that the power supply is not AC200V,
The same is true even when power is being supplied from the activation feeder 9, and any cathode disconnection that occurs during exhaust or activation work will be accurately reported to the management department. It is possible to avoid the situation where the evacuation and activation work is continued for the electron tubes that are not disconnected, wasting man-hours and producing many defective products.

〔Effect of the invention〕

As explained above, according to the present invention, even a management department located far away from the exhaust area can detect if the cathode of any one of multiple electron tubes is disconnected during the exhaust or activation process. This eliminates the waste of producing many defective products by continuing to evacuate and activate other tubes that were being evacuated together with the tube that has the disconnected cathode.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a diagram showing a conventional connection when activating a cathode in an automatic exhaust machine.

Claims (1)

[Claims] An LED on the input side of a photocoupler is connected in series with the cathodes of multiple electron tubes in the activation process, and cathode disconnection is detected by a change in potential caused by a change in the conduction state of the phototransistor on the output side of the photocoupler, and it is detected that an electron tube is present. A cathode disconnection detection device during activation, characterized in that the fact of cathode disconnection is displayed and an alarm is issued to a central control department installed at a location remote from the current location.