JPH0644004Y2 - Image intensifier - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application This invention relates to an image intensifier that converts an incident X-ray image or an invisible light image into a visible light image, and in particular, a vacuum degree in the image intensifier. The present invention relates to a technique for controlling the operation of a getter having a pump action provided for maintaining the above.

B. Prior art Image intensifier is a sealed tube whose inside is evacuated to a high vacuum, but gas is released from the electrodes and the tube wall during its operation, which may deteriorate the internal vacuum degree. Are known. Therefore, by providing a pumping element called a getter inside the tube, a current of several amperes is periodically supplied to the getter to generate heat.
The released gas in the tube is efficiently adsorbed to maintain the degree of vacuum in the tube.

When a current is passed through the getter, a magnetic field is generated around the getter. Therefore, when the getter is operated during the operation of the image intensifier, the electric field distribution of the electron lens for converging the electron flow in the tube is disturbed by the magnetic field, so that the image quality of the converted light image is deteriorated. Therefore, conventionally, in the device using the image intensifier,
The getter does not work while the image intensifier has an input.

An example of conventional getter operation control will be described below with reference to FIG.

In the figure, 10 is an X-ray image intensifier,
20 is a getter control circuit for driving and controlling the getter, and 30 is an X for irradiating the X-ray image intensifier 10 with X-rays.
An X-ray controller 40 controls the application of high voltage to the X-ray tube 30.

When X-rays are emitted from the X-ray tube 30 while the getter is operating, the X-ray controller 40 simultaneously causes the getter control circuit 20 to operate.
A signal for notifying X-ray irradiation is output to. Getter control circuit
The 20 interrupts the getter operation by inputting this signal.

C. Problems to be Solved by the Invention However, according to the above-described conventional apparatus, the X-ray controller
It is necessary to lay a cable for transmitting a signal notifying the X-ray irradiation from 40 to the getter control circuit 20, and
Since it is usual that the X-ray controller 40 and the getter control circuit 20 are installed at a great distance from each other, laying such a cable is complicated and causes a cost increase.

The present invention has been made in view of such circumstances, and when an input is made to the image intensifier, that is, the fact that the image intensifier is in operation is notified from the external device to the image intensifier. An object of the present invention is to provide an image intensifier capable of automatically detecting this by the image intensifier itself and interrupting the getter operation without notifying.

D. Means for Solving the Problems This invention has the following configurations in order to achieve the above object.

That is, the image intensifier of the present invention comprises a detecting means for detecting that the image intensifier is in operation, and a getter control means for operating the getter operation by a signal from the detecting means. is there.

The detection means detects a cathode current or a change in the amount of output visible light, and thereby detects that the image intensifier is in operation.

E. Action When the X-ray etc. is input to the image intensifier, the cathode current and the output visible light intensity change more greatly than when not operating. Therefore, the cathode current and the output visible light intensity change. It is possible to detect that the image intensifier is in operation by detecting.

The detection means detects a cathode current or a change in the amount of output visible light, and produces an output signal when the image intensifier is in operation.

The getter control means is activated by the output signal of the detection means, and interrupts the getter operation.

Therefore, since the image intensifier itself detects that it is in operation, no external device is required to inform the getter control circuit that it is in operation.

F. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a block diagram showing the outline of the configuration of the first embodiment of the present invention.

In the X-ray image intensifier 10, 11 is a closed tube, 12 is an input window through which X-rays are incident, and 13 is an output window through which visible light is emitted. There is a cathode electrode 14 on the side of the input window 12 inside the tube, and the side surface of the input window of the cathode electrode 14 is the input fluorescent surface and the opposite side is the cathode electrode surface.
Focusing electrodes 15a and 15b for forming an electron lens are provided along the tube axis, and an anode electrode 16 and an output fluorescent surface 17 are provided on the output window 13 side in the tube. Reference numeral 18 is a getter for maintaining the inside of the tube at a high degree of vacuum, and is formed of, for example, a bulk made of a zirconium-based material.

The getter 18 is electrically connected to the getter control circuit 20, and is configured to generate heat by the current supplied from the getter control circuit 20 and adsorb the gas released in the tube.

The getter control circuit 20 has a timer function for supplying a current to the getter 18 for a certain period of time, and is configured to interrupt the current supply to the getter 18 by a signal from a current detection circuit 50 described later.

Reference E is a voltage source for applying a predetermined voltage to each electrode of the image intensifier described above.
A current detection circuit 50 for detecting the cathode current is provided in the middle of the path connecting the voltage source E and the cathode electrode 14.

As shown in FIG. 2, the current detection circuit 50 includes a current amplifier 51 for amplifying a minute cathode current, and a low pass filter (LPF) for cutting off a pulsed current due to incidence of cosmic rays. 52, a comparator 53, a reference voltage source V _REF and the like. In the reference voltage source V _REF , a leak current may flow between the electrode of the X-ray image intensifier and the tube wall, so that the cathode current flowing by a normal X-ray input is distinguished from the leak current. Therefore, the voltage value is appropriately set according to the level of the leak current.

The operation of the embodiment will be described below.

When X-rays enter the X-ray image intensifier 10 while the getter 18 is operating, a cathode current flows. The cathode current is amplified by the current amplifier 51 and then input to the comparator 53 via the low pass filter 52. When this input voltage is higher than the other reference voltage V _REF , the output of the comparator 53 is inverted. By providing this output to the getter control circuit 20, the getter control circuit 20
Interrupts the getter operation.

Second Embodiment FIG. 3 is a block diagram of the essential parts according to the second embodiment of the present invention. In the figure, the parts designated by the same reference numerals as those in FIG.

The feature of the present embodiment is that the output visible image is generated on the output phosphor screen 17 during operation when the image intensifier has an input, and that the operation is detected based on the change in the amount of output visible light. It is something that is done. In particular,
Output window 13 and TV camera for capturing output visible light
A reflecting mirror 62 for branching a part of the output visible light is provided in the optical system 60 interposed between the optical system 60 and 61, and a part of the output visible light reflected by the reflecting mirror 62 is collected by an optical system 63. The light is emitted and detected by the photo sensor 64. The output signal of the photo sensor 64 is given to the current detection circuit 50 similar to that of the first embodiment,
When the X-ray is incident during the getter operation, the getter operation is interrupted.

In the above configuration, the reflecting mirror 62, the optical system 63, the photo sensor 64, and the current detection circuit 50 constitute the light amount detection means.

Although the X-ray image intensifier has been described as an example of the image intensifier in the above-described embodiments, the present invention can be applied to a night-vision image intensifier.

G. Effect of the Invention As is clear from the above description, the invention detects the fact that the image intensifier is in operation as the cathode current or the change in the output visible light intensity by the image intensifier itself, and obtains the getter. Since the operation is automatically interrupted, it is not necessary to give a signal for interrupting the getter operation to the getter control circuit from an external device. Therefore, like the conventional device, between the X-ray controller and the getter control circuit,
It is not necessary to lay a signal cable for informing that the image intensifier is in operation, and the installation cost of the device can be reduced.

Also, during operation when the image intensifier has an input, the image intensifier detects it,
Since the getter operation is automatically interrupted, it is not necessary to consider the timing of performing the getter operation (performing the getter operation while there is no input to the image intensifier), and generating X-rays at any timing. Since X-ray fluoroscopy can be performed, the timing of fluoroscopy is not missed, which is useful for X-ray diagnosis.

[Brief description of drawings]

1 and 2 are explanatory views of a first embodiment of the present invention, FIG. 1 is a schematic block diagram of the apparatus, and FIG. 2 is a block diagram showing a concrete configuration of a current detection circuit. . Third
The figure is a schematic block diagram of a second embodiment of the present invention. FIG. 4 is a schematic block diagram of the conventional device. 10 …… X-ray image intensifier 14 …… Cathode electrode 18 …… Getter 20 …… Getter control circuit 50 …… Current detection circuit 64 …… Photo sensor

Claims (2)

[Scope of utility model registration request] 1. An image intensifier having a getter, wherein a getter operation is performed based on a signal from the current detecting means for detecting that the image intensifier is operating by a change in cathode current, and a signal from the detecting means. An image intensifier having a getter control means for interrupting the image intensifier. 2. An image intensifier equipped with a getter, based on a signal from the light amount detecting means for detecting that the image intensifier is in operation by a change in the amount of output visible light, and a signal from the detecting means. An image intensifier comprising: getter control means for interrupting a getter operation.