JPS5923079B2 - X-ray irradiation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A conventional X-ray tube drive circuit includes a switch circuit that turns on and off a power supply path to the high voltage generation circuit, upstream of a high voltage generation circuit that applies a high voltage to the X-ray tube. This switch circuit is turned on and off by an exposure time setting circuit activated by a starting operation circuit to operate the X-ray tube for a set time and perform X-ray exposure.

However, the high voltage generation circuit did not have any protection measures when a voltage higher than the standard value was input, and if the power supply voltage fluctuated to a higher level, there was a risk of exposing the human body to X-rays exceeding the permissible amount. .

The present invention relates to an X-ray irradiation device capable of preventing the above-mentioned trouble from occurring due to overvoltage, and the present invention will be described in detail below with reference to embodiment figures.

A voltage regulating circuit 2 made of a slider or the like is connected in parallel through a main switch 1 between terminals a and b connected to a commercial AC power supply, and normally open contacts 3a, 4a are connected to the sliding terminal 2a of the voltage regulating circuit 2. Switch circuits consisting of series circuits are connected in series, and this switch circuit 5 is
It is connected via a half-wave rectifier diode 6 to a primary winding T1 of a high voltage transformer T constituting a high voltage generating circuit 7.

Thus, FIG. 8 is an X-ray tube.

Further, a primary winding PT of a transformer PT is connected in parallel to the connection point between the voltage adjustment circuit 2 and the switch circuit 5,
This constitutes an inductive coupling circuit 9.

A transistor switching circuit 11 is coupled to the secondary winding PT2 of the transformer PT via a full-wave rectifier circuit 10, and this transistor switching circuit 11 has the following characteristics:
A relay 13 and a constant voltage diode 14 are connected to the collector and emitter of the transistor 12, respectively, and predetermined bias resistors 16 and 17 are connected to the emitter and base, respectively.

18 is a lamp, and 19 is a current limiting resistor.

Reference numeral 20 denotes a starting operation circuit, which has a starting switch 22 for manual operation connected in series after the full-wave rectifying circuit 21, and a relay 23 connected to this starting switch 22.

Reference numeral 24 denotes an exposure time setting circuit, which is composed of an exposure start circuit A and an exposure stop circuit B.

Thus, the exposure starting circuit A connects the relay 4 that drives the contact 4a of the switch circuit 5 to the anode of the control rectifying element 25, and connects a timer capacitor 27 between the gate and the cathode. By charging the capacitor 27 through the charging resistor 28, the control rectifying element 25 is triggered, thereby energizing the relay 4.

The exposure stop circuit B connects a relay 30 in series to the anode of the control rectifier 29, and
A circuit consisting of an N-gate controlled rectifier 31 and a time constant charging circuit 32 is connected to the gate of the circuit, and the circuit is supplied with power by the normally closed contact 30a of the relay 30.

3 is a relay that drives one contact 3a of the switching circuit 5; 13a is a normally closed contact driven by the relay 13 of the transistor switching circuit 11; 36 to 39 are relay protection diodes; 23a is a normally closed contact of the relay 23; 32a is a time limit capacitor.

Next, the operation will be explained.

First, when the voltage set by the voltage adjustment circuit 2 is within a predetermined value, the voltage input to the transistor switching circuit 11 via the inductive coupling circuit 9 and the full-wave rectifier circuit 10 turns on the transistor 12. Therefore, the relay 13 remains demagnetized and its normally closed contact 13a remains on.

When the start switch 22 is turned on in this state, the relay 3 is first excited and its contact 3a is turned on.

Next, charging of the capacitor 27 of the exposure starting circuit A progresses, and when the control rectifying element 25 is triggered, the relay 4 is energized and the normally open contact 4a of the switch circuit 5 is closed.

When the normally open contacts 3a and 4a are closed as described above, the power supply voltage is applied to the high voltage generating circuit 5, the X-ray tube 8 is driven, and the X-ray exposure operation is started.

On the other hand, when the start switch 22 is turned on, the relay 23
is excited and its normally closed contact 23a is opened, so that the time capacitor 32a constituting the CR time constant charging circuit 32 connected to the N-gate control rectifier 31 is charged in accordance with the charging time constant.

When the charging voltage of the time capacitor 32a reaches a value sufficient to turn on the N-gate controlled rectifier 31,
First, the N-gate controlled rectifier 31 is turned on, and then the controlled rectifier 29 is turned on.

Then, the relay 30 is energized, so its normally closed contact 30a
is turned off and relays 3 and 4 are de-energized, so
Contacts 3a and 4a constituting the switch circuit 5 are opened, and the exposure operation of the X-ray tube 8 is stopped.

Next, when the voltage set by the voltage adjustment circuit 2 corresponds to an overvoltage higher than a predetermined value, the following operation is performed.

First, although the base potential of the transistor 120 constituting the transistor switching circuit 11 becomes high, the potential of the emitter is kept constant by the constant voltage diode 14, so the potential between the base and emitter of the transistor 12 becomes high. As a result, the transistor 12 becomes conductive, and the relay 13 connected to the collector is excited.

As a result, the normally closed contact 13a is opened by the relay 13,
The power supply path to the relay 3 is opened.

Therefore, the contact 3a constituting the switch circuit 5 remains open, and power supply to the high voltage generation circuit 7 is stopped.

Even if the starting switch 22 of the starting operation circuit 20 is pressed to operate the exposure time setting circuit 24 and the contact 4a is closed, the state does not change.

When the transistor 12 becomes conductive, the indicator lamp 18 lights up, so that it can be confirmed that there is an overvoltage state.

After confirming that the lamp 18 is lit, the voltage adjustment circuit 2 is operated to lower the voltage.

Turn on the start switch 22 again at the position where the indicator lamp 18 goes out.
By operating , the normal exposure cycle described above is formed.

Furthermore, since the exposure time setting circuit 24 is separate from the X-ray tube 80 circuit, even if the switch circuit 5 is activated due to overvoltage, the exposure time setting circuit 24 can operate normally. As soon as the voltage is restored, the entire X-ray exposure device can be returned to its normal operating state.

Furthermore, since the transistor switching circuit 11 detects the output terminal voltage of the voltage adjustment circuit 2, which is the primary winding side of the high voltage generation circuit 70 using a transformer, an overvoltage is generated on the secondary side of the high voltage generation circuit 70. Even in this case, only a voltage sufficient to make the transistor 12 conductive is applied to the transistor switching circuit 11, and the transistor switching circuit 11 is protected from the high voltage.

Further, if sufficient voltage is applied to the primary side to generate an overvoltage to the secondary side of the high voltage generation circuit 70, the transistor will remain conductive, so the contact 3a will continue to be open to the X-ray tube 8. power supply is cut off.

Since the X-ray irradiation device according to the present invention is configured as described above, the X-ray tube can be driven within a predetermined voltage range and has the effect of preventing adverse effects on the human body due to overvoltage irradiation. .

[Brief explanation of the drawing]

The figure is an electric circuit diagram showing an example of an X-ray irradiation device according to the present invention. In the figure, 1... Main switch, 2... Voltage adjustment circuit, 5... Switch circuit, 7... High voltage generation circuit, 8
... X-ray tube, 9... Inductive coupling circuit, 11... Transistor switching circuit, 20... Starting operation circuit,
24... Exposure time setting circuit, PT... Transformer.

Claims (1)

[Claims] 1. A normally open contact 3a that connects in series a voltage adjustment circuit 2 that adjusts an input terminal and an output end of the voltage adjustment circuit. 4b, the output of the voltage adjustment circuit is branched to a full-wave rectifier circuit 10, and the output terminal of the full-wave rectifier circuit is connected to the collector of a transistor 12. The output of the full-wave rectifier circuit is connected to the base of the transistor via a relay 13 via a bias resistor 16, and a manual operation start switch 22 is connected to one end of the power supply. Relay 2 energized by closing start switch 22
3, the relays 3 and 4 close the normally open contacts 3a and 4b when the relay 23 is energized; A relay 30 opens the open contact 4a, and the normally open contact 3a opens when the relay 13 is energized.
Exposure time setting circuit 2 having a normally closed contact 13a that opens
4. An X-ray irradiation device comprising: