JPH0457277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical device, and particularly to an optical device such as a high-speed television camera that intermittently exposes the imaging surface of an imaging means using a shutter.

[Conventional technology]

Conventionally, in this type of optical device, as shown in FIG. A shutter disk 6 provided, a motor 12 for rotating the shutter disk 6, and a three-color separation prism 1 provided on the side opposite to the shutter disk 6 of the rear lens group 14.
5, and three image pickup tubes 13 provided above, below, and to the right of the three-color separation prism 15 in the figure. Here, the shutter disk 6
is a disc in which a plurality of shutter openings are provided at equal intervals in the circumferential direction, and is rotated by a motor 12 to intermittently transmit the light beam emitted from the front lens group 11. be.

In such an optical device, since the shutter disk 6 is arranged in the optical system of the imaging lens, the light flux emitted from the front lens group 11 is transmitted during the blanking period ( It is necessary to rotate the shutter disk 6 so that the light passes through the shutter opening during the vertical retrace period.

As shown in FIG. 3, the scanning order of the scanning lines 3 in the image pickup tube 13 is from the top left in the figure to the bottom right in the figure, and since the shutter disk 6 is arranged in the image pickup lens system, Even if the aperture position of the tadisk 6 changes, the brightness across the entire imaging surface changes uniformly on the imaging surface. Therefore, even if exposure is performed outside the blanking period (that is, while the image plane is being scanned), double exposure will result. That is, in order to avoid double exposure, it is desirable to perform exposure using the shutter disk 6 during the blanking period when the image plane is not scanned.

[Problem to be solved by the invention]

However, in the conventional optical device described above, since the shutter disk 6 is rotated so that the light beam emitted from the front lens group 11 is transmitted through the shutter opening during the blanking period, each image pickup tube 13 by the light beam is rotated. The exposure time is a short period of time called the blanking period (approximately 1/60× in the NTSC system)
35/525).

Furthermore, depending on the position where the shutter disk 6 is placed in the optical system of the imaging lens, the optical path of the light beam on the optical axis is different from the optical path of the light beam off the optical axis, resulting in the problem of uneven light amount. be.

Furthermore, when the imaging lens is a zoom lens, the diameter of the light flux also changes due to changes in the zoom state, which further causes the problem of unevenness in the amount of light.

An object of the present invention is to provide an optical device that can arbitrarily set the exposure time without causing unevenness in the amount of light.

[Means to solve the problem]

The optical device of the present invention is an optical device that intermittently exposes the imaging surface of an imaging means using a shutter, and includes a first optical system that forms an intermediate image, which is provided in order from the object side, and a first optical system that forms an intermediate image. a second optical system that is inverted and re-images on the imaging surface; a shutter having an opening provided at or near the position where the intermediate image is formed; and a scanning line on the imaging surface. A drive mechanism is included for driving the shutter so that the scanning position and the opening do not overlap with each other.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of an optical device of the present invention.

The optical device of this embodiment has intermediate images 17 provided sequentially from the side of an object (not shown) on the left side of the figure.
A first lens system 16 and an intermediate image 17 forming
A second lens system 18 that inverts the image pickup tube 13 and re-images it on the imaging surface 2 (see FIG. 3) of each image pickup tube 13, and a shutter that functions as a shutter and is provided near the position where an intermediate image is formed. a shutter disk 6, a motor 12 for rotating the shutter disk 6,
A three-color separation prism 15 provided on the opposite side of the shutter disk 6 of the second lens system 18, and three image pickup tubes provided above, below, and to the right of the three-color separation prism 15 in the drawing, respectively. 13, and the imaging surface 2 of each image pickup tube 13 is intermittently exposed using a shutter disk 6.

Here, as shown in FIG. 2, the shutter disk 6 is a disk in which a plurality of shutter openings 7 are provided at equal intervals in the circumferential direction. lens system 16
The light beam emitted from the shutter opening 7 is intermittently
It allows the light to pass through. Note that the motor 12
As will be described later, the position where the scanning line 3 scans the imaging surface 2 of each image pickup tube 13 and the shutter opening 7 are
To rotate a shutter disk 6 without overlapping each other.

Furthermore, in each image pickup tube 13, as shown in FIG.
By scanning the imaging surface 2 in the manner of 1a→1a', 1b→1b', . . . 1f→1f' and reading out the electrical signals, one field worth of image of the object is taken out. In FIG. 3, the horizontal retrace line 4 and the vertical retrace line 5 are shown by broken lines.

Next, rotation control of the shutter disk 6 in the optical device of this embodiment will be explained in detail.

Since the second lens system 18 inverts the intermediate image 17 and re-images it on the imaging surface 2 of each image pickup tube 13, the scanning order of the scanning lines 3 in each image pickup tube 13 is as follows for the intermediate image 17. As shown in FIG. 2, it goes from the lower right in the figure to the upper left in the figure. At this time,
The motor 12 rotates the shutter disk 6 so that the position where the scanning line 3 scans the imaging surface 2 of each image pickup tube 13 and the shutter opening 7 do not overlap with each other. While scanning 1f', multiple shutter openings 7
One of the shutter openings 7a and the intermediate image 17
have a positional relationship as shown in Figure 2, and
The upper edge of the shutter opening 7a in the figure rotates the shutter disk 6 in the direction of the arrow 8 in the figure at a rotational speed that does not cause the scanning line 3 to scan from 1f to 1f'.

Therefore, in each image pickup tube 13, the scanning line 3 always follows the exposed portion of the image pickup surface 2, so that there is no double exposure even during periods other than the blanking period, and each image pickup tube 13 can be exposed to light.

Furthermore, by replacing the shutter disk with a shutter disk having shutter openings with different opening areas, the exposure range can be set arbitrarily. the result,
It is possible to select the optimal exposure time corresponding to the amount of light per unit time without being limited to shooting conditions like with conventional optical devices, so it is possible to avoid large F-numbers that could not be avoided with conventional optical devices. It can also prevent falling. Note that for objects moving at high speed, each shutter opening 7 is closed to limit the exposure time.
It is possible to suppress the occurrence of afterimages that are generally seen in optical devices that do not have a shutter.

In the above explanation, when the scanning line 3 scans from 1f to 1f', one shutter opening 7a of the plurality of shutter openings 7 and the intermediate image 17 appear as shown in FIG. The shutter disk 6 was rotated so that the positional relationship was established. However, when the scanning line 3 scans a portion other than the shutter opening 7a shown by diagonal lines in the figure, the shutter opening 7a and the intermediate image 17 are arranged in a positional relationship as shown in FIG. The shutter disk 6 may also be rotated.

Further, a method of synchronizing the rotation of the shutter disk 6 with the scanning line 3 is, for example, by using a pulse motor or a motor attached with a pulse control device as the motor 12, and controlling the motor 12 with a vertical synchronization signal of a television signal. You can use the method to do so.

Further, although the image pickup tube 13 is used as an image pickup means, an image pickup element such as a charge coupled device (CCD) may also be used.

〔Effect of the invention〕

Since the present invention is configured as described above,
The following effects are achieved.

(1) In the imaging means, since the scanning line always follows the exposed part of the imaging surface,
Since the imaging surface of the imaging means can be exposed without double exposure even during periods other than the blanking period, unevenness in the amount of light does not occur.

(2) By replacing the shutter with a shutter having openings with different opening areas, the exposure range can be set arbitrarily.

(3) Since the optimum exposure time corresponding to the amount of light per unit time can be selected without being limited by photographing conditions, a large drop in the F number can be prevented.

(4) For objects moving at high speed, the occurrence of afterimages can be suppressed by narrowing the aperture and limiting the exposure time.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the optical device of the present invention, FIG. 2 is a diagram showing the shape of the shutter disk shown in FIG. 1, and the positional relationship between the shutter opening and the intermediate image. FIG. 3 is a diagram showing sequential scanning of the imaging surface of each image pickup tube shown in FIG. 1 by scanning lines, and FIG. 4 is a schematic diagram showing a conventional example of this type of optical device. 2...imaging surface, 3...scanning line, 4...horizontal retrace line, 5...vertical retrace line, 6...shutter disk,
7, 7a... Shutter opening, 12... Motor,
13... Image pickup tube, 15... Three color separation prism, 1
6...First lens system, 17...Intermediate image, 18...
...Second lens system.

Claims (1)

[Scope of Claims] 1. An optical device that intermittently exposes the imaging surface of an imaging means using a shutter, comprising: a first optical system that forms an intermediate image, which is provided in order from the object side, and a first optical system that forms an intermediate image; a second optical system that is inverted and re-images on the imaging surface; a shutter having an opening provided at or near a position where the intermediate image is formed; and a scanning line that forms a scanning line on the imaging surface. An optical device comprising: a drive mechanism that drives the shutter so that the scanning position and the opening do not overlap with each other.