JPH02142029A - Protective device for electronic tube - Google Patents

Abstract

PURPOSE:To perform the protective operation for tublar bulb assuredly by providing a threshold control circuit by which threshold is set to a first value during the rise time of accelerating electrode voltage and to a second value after the rise time. CONSTITUTION:During the rise time of accelerating electrode voltage Ea, threshold of delay wave circuit current Ib is set to a first value that is slightly higher than its peak value Ib1, and after the rise time of the accelerating electrode voltage Ea, threshold of the delay wave circuit current Ib is set to a second value that is slightly higher than its constant value Ib2. Protection of a tublar bulb can thus be performed assuredly for extraordinary delay wave circuit current during the rise time of accelerating electrode voltage Ea as well as for extraordinary delay wave circuit current after the rise time of the accelerating electrode voltage Ea.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Industrial Application Field) The present invention relates to an electron tube protection device suitable for an electron tube such as a traveling wave tube.

(Prior Art) As is well known, in electron tubes such as traveling wave tubes, excessive slow wave circuit current can cause damage to the tube.
Therefore, in this type of power supply device for city f, when the detected i-wave circuit current value exceeds the threshold (lI'j), the accelerating electrode voltage output circuit is short-circuited and the accelerating electrode voltage is applied. There is a protective device for the electron tube that stops the operation.

Figure 2 shows a small diagram of an example of a power supply connection in a traveling wave tube, and Figure 3 shows the relationship between the slow-wave circuit current and acceleration voltage over time and the conventional wave circuit current threshold. -This is a diagram.

In Fig. 2, 1 is the slow wave circuit, b is the 8-wave circuit voltage, Ec is the collector voltage, [2a is the accelerating electrode voltage, E
W is the focusing electrode voltage, and Ef is the heak voltage -C.

When operating the traveling wave tube, as shown by -C symbol 4 in FIG.
The accelerating electrode voltage Fa is gradually increased until
After time t2, the accelerating electrode voltage "a" is fixed at a constant value.

In other words, the slow wave circuit current 1b reaches the peak value 1b1 - once during the rising period (t1 x t x t2) of the accelerating electrode voltage Ea, and then reaches the peak value 1b1 after time t2 (t>t2), as indicated by the symbol 2. ) is fixed at - constant value 1b2.

Therefore, conventionally, the threshold value 1bth of the slow wave circuit current is set to infinity (Ibth=oo) from time t1 to time t3, which includes the rising period of the accelerating electrode voltage Ea, as shown by reference numeral 3. On the other hand, after time t3, l bo (I b2<lbo <Ib1)
By doing so, the bulb protection operation is enabled only after the accelerating electrode voltage Ea rises.

This is the rising period of the accelerating electrode voltage Ea (jl < t
<t2) is a short period of time, and the possibility of an abnormality occurring during that time is considered to be extremely low, and the threshold value 1b was set considering the protection of the tube during such a rising period.
The reason for determining the value of th was that the threshold value for the steady-state value 1b2 after rising would be too high.

However, for example, changes in the state of the tube or the slow wave circuit voltage E
b. Considering the case where the voltage value such as the collector voltage EC deviates from the specified value, it is also assumed that the value of the slow wave circuit current 1b becomes excessive during the rising period of the accelerated N-pole voltage Ea, and in this case, the normal The peak value itself is high (fbl)>
In addition to I b2), this would further increase, creating a very dangerous situation for the tube, and in fact, such a condition could sometimes cause damage to the tube.

(Problem to be Solved by the Invention) As described above, in the conventional electron tube protection device, the protective operation is not performed during the rising period of the accelerating electrode voltage Ea, so that, for example, the state of the tube Considering the possibility that the voltage values of the slow-wave circuit voltage Eb, collector voltage Ec, etc. may deviate from the specified values, the value of the R-wave circuit current rb may become excessive during the rising period of the accelerating electrode voltage Ea. is also assumed, in which case the normal peak value itself is high (
In addition to Ib1>>1b2), this will further increase, creating a very dangerous situation for the tube.
In fact, there was a problem in that such conditions could cause damage to the tube.

This defense was made in view of the above problems,
Its purpose is of course to protect the tube against abnormal slow wave circuit current after the accelerating electrode voltage has risen.
It is an object of the present invention to provide a protection device for an electron tube that can reliably protect the tube even against an abnormal slow wave circuit current during the rising of the accelerating electrode voltage.

(Structure of the Invention) (Means for Solving the Problems) In order to achieve the above object, the present invention detects a slow wave circuit current, and when the current value exceeds a threshold value, the accelerating electrode voltage is The electron tube protection device is configured to stop the application of the voltage, and includes a threshold control circuit that sets the threshold to a first value while the accelerating electrode voltage is rising and to a second value after the accelerating electrode voltage rises. It is characterized by:

(Function) According to such a configuration, during the rise of the accelerating electrode voltage, the threshold value of the wave circuit current is set to the first value slightly higher than its peak value, and J3< By setting the threshold of the slow wave circuit current to a second value slightly higher than its steady value, after the accelerating electrode voltage has risen, the accelerating electrode voltage has risen. It is possible to reliably protect the bulb not only against abnormal slow-wave circuit currents that occur later, but also against abnormal slow-wave circuit currents during the rise of the accelerating electrode voltage.
(Embodiment) FIG. 1 is a block diagram showing an embodiment of an electron tube protection device according to the present invention.

When starting up this device, first Eb (slow wave circuit voltage)
On signal 14 arrives first, and slightly later, Ea
(Accelerating electrode voltage) ON signal 15 arrives.

When the Eb-on signal 14 arrives, the wave circuit voltage output circuit 5 is activated and application of the R-wave circuit voltage Eb is started.

Next, when the Ea-on signal 15 arrives, the accelerating electrode voltage photogenerating circuit 7 is activated and application of the accelerating electrode voltage is started.

As described above, the value of the accelerating electrode voltage Ea is fixed to a steady value after a certain period of time after rising.

Then, during this rising period, the slow wave circuit current tb
reaches a predetermined peak value and stabilizes after a certain period of time.

The comparator 13 is connected to the wave circuit current equivalent voltage v b sent from the slow wave circuit current detection circuit 6 and the wave circuit current threshold voltage equivalent voltage v b th sent from the threshold control circuit 17 (described later). A magnitude comparison is made, and when the slow wave circuit current Ib exceeds the threshold value 1bth, an excessive 1b alarm signal 16 is output.

The Ea output short-circuit switch 8 short-circuits the accelerating electrode voltage output circuit 7 in response to the excessive alarm signal 16, and stops applying the accelerating electrode voltage [a.

Next, details of the threshold control circuit 17, which is the main part of the present invention, will be explained.

In the figure, the delay circuit 9 transmits the Ea ON signal 15 to the time required for the accelerating electrode voltage Ea to rise (+3-t in Figure 2).
l).

The switch 10 is operated by the output of the delay circuit 9,
When the output of the delay circuit 10 is on, it is Δ-on, and when it is off, it is off.

The variable resistor 11 and the fixed resistor 12 constitute a voltage dividing circuit, and the voltage taken out from the variable resistor 11's initial terminal is equal to the threshold current equivalent voltage v b th.

In addition, the above-mentioned switch 10 is connected in such a way that both ends of the fixed resistor 12 are short 18, so that the value of the threshold current equivalent voltage vbth is during the rise of the accelerating electrode type L. is set to the first value V b th (+1), which is slightly higher than the value corresponding to the slow wave circuit current peak, but in the afternoon, after the slow wave circuit current rises, the d wave Second #IV b slightly higher than the circuit steady current equivalent value
th(L).

According to the above configuration, for example, due to a change in the state of the bulb or voltage values such as R-wave circuit voltage Eb and collector voltage [C, etc., deviating from the specified values, the slow-wave circuit current changes during the rising period of the accelerating electrode type LtFa. If (F?1 of 1b is too large, J3 is input to the comparator 13 and V b > V b t
When h(11) is detected, an excessive 1b alarm signal 16 is output, and the a output short-circuit switch 8 is activated, and the application of the normal electrode voltage [a is immediately stopped to protect the bulb. is achieved.

Furthermore, if the value of the d-wave circuit current ib becomes excessive after the accelerating electrode voltage rises, the comparator 13 detects V b > V b th (L), indicating that it is excessive! The b-alarm signal 16 is output, the Ea output short-circuit switch 8 is operated, and the application of the pass-through electrode voltage Ea is immediately stopped, thereby achieving protection of the bulb.

Therefore, according to the device of this embodiment, not only can the bulb be protected against abnormal slow-wave circuit current after the accelerating electrode voltage rises, but also against abnormal η-wave circuit current during the rising of the accelerating electrode voltage. It is possible to perform tube protection operations reliably.

In addition, the threshold value in the steady state, that is, the second (self v
Since b th ([) is sufficiently lower than the first value V b th (I+), it is possible to overlook an abnormality in the slow wave circuit current in a constant state. do not.

In the above embodiments, the present invention was applied to a traveling wave tube, but it is of course possible to widely apply it to other electron tubes.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, it is possible to not only protect the bulb against the abnormal "wave circuit current" in J3 after the accelerating electrode voltage rises, but also protect the accelerating electrode voltage from rising. The tube protection operation can be performed reliably even against abnormal slow wave circuit current inside the tube.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the electron tube protection device according to the present invention, FIG. 2 is a diagram showing an example of power supply connection in a traveling wave tube, and FIG. 3 is a block diagram showing an example of a power supply connection in a traveling wave tube. It is a diagram showing the relationship between the transition between electrode voltages and the conventional slow wave circuit current threshold. 1... slow wave circuit, 2... slow wave circuit current, 3... excessive rb protection Threshold (conventional value), 4... Accelerating electrode voltage, 5... Slow wave circuit voltage output circuit, 6... Rational wave circuit current detection circuit, 7... Accelerating electrode voltage output circuit, 8...
・lea output short circuit switch, 9...delay circuit, 10・
...Switch, 11...Variable resistor, 12...Fixed resistor, 13...Comparator, 14...Eb on signal, 15...[a on signal, 16...Excessive alarm signal, 17 ...Threshold control circuit. c h f Figure 2 Figure 1 Figure 3

Claims (1)

[Scope of Claim] An electron tube protection device that detects a slow wave circuit current and stops application of an accelerating electrode voltage when the current value exceeds a threshold value, comprising: 1. A protection device for an electron tube, comprising a threshold control circuit that sets the electrode voltage to a first value while it is rising and to a second value after it rises.