JPH0638535Y2 - camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a camera for high sensitivity in which a photomultiplier tube is arranged in an optical system block.

SUMMARY OF THE INVENTION The present invention relates to a camera in which a photomultiplier tube covered with an insulating case is fixed to a conductive optical system housing, and the insulating case and the optical system housing are electrically connected to the outer surface of the insulating case. By providing a conductive part connected to the optical system block, it is possible to keep the size and weight of the optical system block small and reduce the discharge noise caused by the electric charge on the outer surface of the insulating case sparking and discharging to the optical system housing. .

[Prior Art] Some cameras, such as video cameras and electronic still cameras, which take pictures by photoelectric conversion have high sensitivity for taking pictures even in a low light environment. The optical system block of such a camera is provided with a photomultiplier tube and an image pickup element arranged on the exit light side of the photomultiplier tube, and the photomultiplier tube and the image pickup element are fixed to a conductive optical system housing. Has been done. In the photomultiplier tube, the photomultiplier is covered with an insulating case. When a high voltage (about -9KV) is applied to the photomultiplier,
Incident light of the photomultiplier tube is increased several times and emitted, and the emitted light is applied to the image pickup element, so that an image is captured even in a low light amount environment.

[Problems to be Solved by the Invention] However, since the photomultiplier tube applies a high voltage to the photomultiplier, surface charges are charged in the insulating case, and the surface charges are electrically conductive in the vicinity of the optical system housing or the like. Spark and discharge the parts. Then, there is a drawback that noise is added to the output signal of the image pickup device due to the discharge due to the spark.

In order to prevent this discharge, it is conceivable to configure the outside of the photomultiplier tube with a conductive case instead of an insulating case. However, when the case is made of a conductive case, the gap between the photomultiplier and the case must be increased to prevent discharge between the case and the case. Then, the size of the photomultiplier tube itself becomes large, and the optical system block becomes large and heavy,
Contrary to smaller and lighter cameras.

Therefore, an object of the present invention is to provide a camera that can keep the size and weight of the optical system block small and can reduce the discharge noise due to the photomultiplier tube.

[Means for Solving the Problems] In order to achieve the above object, in a camera of the present invention, a photomultiplier tube in which a photomultiplier is covered with an insulating case is fixed to a conductive optical system housing. In a camera in which an image pickup device is arranged on the exit light side of a multiplier tube, a conductive portion that electrically connects the insulating case and the optical system housing is provided on the outer surface of the insulating case.

[Operation] When a high voltage is applied to the photomultiplier, electric charges are charged in the insulating case. Since the electric charges flow into the optical system housing through the conductive parts, an optical system housing or the like arranged around the insulating case is used. The conductive member will not be discharged by sparks. In addition, since the outside of the photomultiplier tube can be configured with an insulating case, the photomultiplier tube itself is small and lightweight.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an optical system block of a camera to which the present invention is applied. In FIG. 1, the optical system housing 1 comprises a front surface portion 1a and a mounting body 1b fixed to the front surface portion 1a. Both the front surface 1a and the mounting body 1b are made of a conductive member, and the optical system housing 1 serves as a ground member. A hole 2 is formed in the front surface portion 1a, and a lens mounting member 3 is fixed around the hole 2. A lens system (not shown) is mounted through the lens mounting member 3, and a hole 4 is formed in the lens mounting member 3. The light passing through the lens system passes through the hole 4 and enters the optical system housing 1. Mounting body in the optical system housing 1
The optical prism 5 fixed to 1b is arranged, and the light incident on the optical system housing 1 is incident on the optical prism 5. The optical prism 5 splits the incident light into three paths and emits the light from the three emission surfaces 5a to 5c.
A color filter (not shown) is fixed to 5c. Further, mounting holes 6a to 6c are formed at three places in the mounting body 1b, and the photomultiplier tube 8 and the blocks 7a to 7c of the image pickup device 9 are arranged by utilizing these mounting holes 6a to 6c, respectively. . In each of the blocks 7a to 7c, the photomultiplier tube 8 and the image pickup device 9 have a holding metal fitting 10
, And the holding metal fitting 10 is formed of a conductive member. Each holding metal fitting 10 is attached to each mounting hole 6a
Each of the holding metal fittings 10 and the mounting main body 1b are in surface contact with each other at a contact point by being fastened with screws 11 around the to 6c. Each photomultiplier tube 8
A photomultiplier 14 having a photoconductor 12 and a phosphor 13 is arranged inside, and the photomultiplier 14 is covered with an insulating case 15.
Holes 16 are formed in two places in the insulating case 15, and each of these holes 16
A glass body 17 is provided in. Each one glass body 17 is arranged at a position facing the three exit surfaces 5a to 5c of the optical prism 5, and each one glass body 17 is configured as an incident surface of each photomultiplier tube 8. The other glass body 17 is configured as an exit surface of each photomultiplier tube 8. In addition, the outer surface of the insulating case 15 is entirely covered with the conductive portion 18.
Is provided. The conductive portion 18 is made of, for example, silicone rubber having a resistance value of 50 Ω / cm ³ . Each image pickup element 9 is arranged on the exit surface side of each photomultiplier tube 8. The image pickup device 9 is composed of a charge-coupled image pickup device (CCD) in this embodiment, but may be any device that performs photoelectric conversion such as an image pickup tube.

The operation of the above configuration will be described below.

When light from a lens system (not shown) is incident on the optical prism 5, the incident light is incident on each photomultiplier tube 8 from the three emission surfaces 5a to 5c. Photomultiplier 14 of each photomultiplier tube 8
A high voltage is applied to the photomultiplier tube 8 to multiply the amount of light incident on each photomultiplier tube 8 and irradiate each image pickup element 9. Each of the image pickup devices 9 converts the irradiation light into a corresponding charge amount and outputs, for example, red, green, and blue video signals.

Insulation case when high voltage is applied to the photomultiplier 14
The electric charge is charged in 15, and the charged electric charge is discharged from the conductive portion 18 through the holding metal fitting 10 to the mounting body 1b of the optical system housing 1. Therefore, the conductive member such as the optical system housing 1 arranged around the insulating case 15 is not discharged by the spark.

Further, since the outside of the photomultiplier tube 8 is constituted by the insulating case 15, the space gap between the photomultiplier part 14 and the insulating case 15 can be made small, and the photomultiplier tube 8 itself can be made compact and lightweight.

[Advantages of the Invention] As described above, according to the present invention, in a camera in which a photomultiplier tube covered with an insulating case is fixed to a conductive optical system housing, the insulating case and the insulating case are provided on the outer surface of the insulating case. Since the conductive part that electrically connects to the optical system housing is provided, the size and weight of the optical system block can be kept small, and the electric charge on the outer surface of the insulating case sparks and discharges to the optical system housing, etc. This has the effect of reducing noise.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical system block of a camera to which the present invention is applied. 1 ... Optical system housing, 8 ... Photomultiplier tube, 9 ...
Image sensor, 14 …… Light multiplier, 15 …… Insulation case, 18 ……
Conductive part.

Claims (1)

[Scope of utility model registration request] 1. A camera in which a photomultiplier tube having a photomultiplier part covered with an insulating case is fixed to a conductive optical system housing, and an image pickup device is arranged on the exit light side of the photomultiplier tube. A camera, comprising: a conductive portion that electrically connects the insulating case and the optical system housing to each other on an outer surface of the insulating case.