JPH07120793A - Diaphragm device and imaging device using the same - Google Patents

Abstract

PURPOSE:To appropriately adjust passing light quantity without deteriorating optical performance. CONSTITUTION:This device is provided with two diaphragm blades 1 and 2, and an electrochromic element filter 3 capable of optionally chaging transmissivity is attached to the blade 1. The filter 3 is attached to be positioned on an optical axis 4 when the diaphragm aperture diameter is made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm device capable of appropriately adjusting the amount of passing light and suitable for, for example, a video camera and an image pickup device using the diaphragm device.

[0002]

2. Description of the Related Art Conventionally, FIG. 6 shows a schematic view of a main part of a diaphragm device for adjusting the amount of passing light in an image pickup device such as a video camera. FIG. 6A shows the case where the diaphragm is opened, and FIG. 6B shows the case where the diaphragm aperture diameter is reduced. In FIG. 6, 6
Reference numerals 1 and 62 are diaphragm blades, 63 is an ND filter, and 64 is an optical axis.

The conventional diaphragm device has two diaphragm blades 61,
In addition to using 62, the ND filter 63 is attached to one diaphragm blade 61. Although the aperture diameter is controlled according to the brightness of the subject, when shooting a bright subject, as shown in FIG. 6B, the aperture opening diameter is not reduced from a predetermined value and is constant, and instead, the ND filter 63 is used. Is positioned on the optical axis 64 to adjust the amount of passing light. Thus, in the diaphragm device of the image pickup apparatus, it is possible to prevent the difficulty of mechanical control when the diaphragm aperture diameter is made small and the deterioration of the imaging performance due to the diffraction effect of the diaphragm aperture when the diaphragm aperture diameter becomes small. .

[0004]

However, various phenomena occur depending on the transmittance of the ND filter 63 attached to the diaphragm blade 61. For example, the ND filter 63
When an ND filter having a low transmittance is used as, the diffraction occurs at the aperture formed by the ND filter 63 and the aperture blade 62 not equipped with the ND filter, and the aperture opening diameter as when shooting a dark subject. Has a small effect on the imaging performance, but has a large effect when the aperture diameter is small, such as when shooting a bright subject, and the imaging performance deteriorates. Further, when an ND filter having a high transmittance is used as the ND filter 63, the effect of the diffraction effect of the aperture formed by the ND filter 63 and the diaphragm blade 62 without the ND filter is small, but a bright subject is photographed. At this time, it is necessary to reduce the aperture diameter of the aperture, which causes an adverse effect due to the constant transmittance of the ND filter 63. Further, when the ND filter 63 having a predetermined transmittance is attached to the diaphragm blade 61, there is a problem that the limit of the brightness of a subject that can be photographed is determined due to the diffraction effect of the diaphragm aperture.

An object of the present invention is to solve the above-mentioned conventional problems, and to prevent deterioration of the optical performance due to the diffractive action of the aperture formed by the filter and the diaphragm blade, and which is capable of appropriately adjusting the passing light amount. And to provide an image pickup apparatus capable of adjusting the amount of passing light without reducing the diaphragm aperture diameter from a predetermined value by using the diaphragm device and capable of photographing a subject with higher brightness.

[0006]

According to a first aspect of the present invention, there is provided a diaphragm device, wherein one or more of the plurality of diaphragm blades are provided with a variable transmittance filter positioned on the optical axis when the diaphragm aperture diameter is reduced. It is characterized by being attached. A diaphragm apparatus according to a second aspect of the present invention is the diaphragm apparatus according to the first aspect, wherein an electrochromic element filter is used as the variable transmittance filter.

An image pickup apparatus according to a third aspect uses the diaphragm apparatus according to the second aspect. According to a fourth aspect of the present invention, in the image pickup apparatus according to the third aspect, the brightness detection means for detecting the brightness on the image pickup surface, and the electrochromic element filter based on the value detected by the brightness detection means. And a transmittance control unit that changes the transmittance to a predetermined value.

[0008]

According to the diaphragm device of the present invention, when there is an aperture formed by the filter and the diaphragm blade, it is possible to suppress the deterioration of the optical performance due to the diffraction effect of the aperture by increasing the transmittance of the filter. . Further, when there is no aperture formed by the filter and the diaphragm blade, the amount of passing light can be properly adjusted by reducing the transmittance of the filter without reducing the aperture diameter of the diaphragm.

Further, according to the image pickup apparatus having the diaphragm device using the electrochromic element filter as the variable transmittance filter, the transmittance of the electrochromic element filter can be changed according to the size of the diaphragm aperture diameter. When shooting a bright subject etc., deterioration of optical performance can be prevented by appropriately changing the transmittance of the electrochromic filter located on the optical axis without reducing the aperture size from a certain size. It is possible to appropriately adjust the amount of passing light while preventing it.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 3 are schematic views of a main part of a diaphragm device according to an embodiment of the present invention. 1 to 3, reference numerals 1 and 2 are diaphragm blades, 3 is an electrochromic element, and 4 is an optical axis. 1 to 3 show the case where the diaphragm blades 1 and 2 are moved to control the diaphragm aperture diameter. FIG. 1 shows the case where the diaphragm is released, FIG. 2 shows the case where the diaphragm is slightly closed, and FIG. This is the case of the minimum aperture.

This diaphragm device is provided with two diaphragm blades 1 and 2, and an electrochromic element filter 3 whose transmittance can be arbitrarily changed is attached to the diaphragm blade 1. This electrochromic element filter 3 is provided. Is mounted so as to be located on the optical axis 4 when the aperture diameter of the diaphragm is reduced. An example of the configuration of this electrochromic element filter 3 is shown in FIG. In FIG. 4, 40 and 41 are transparent electrodes, 42 is an electrochromic material, 43 is a power supply device, and 44 is a voltage control device for controlling voltage. In this example, the electrochromic material 42 is sandwiched between the transparent electrodes 40 and 41 to form a thin film layer.
The voltage of 3 is controlled to a voltage of about 1 to 2 V by the voltage control device 44, and the redox reaction occurs in the electrochromic material 42 by applying it to the transparent electrodes 40 and 41,
The transmittance will change.

According to this embodiment, as shown in FIGS. 1 and 2, the electrochromic element filter 3 and the diaphragm blade 2 are provided.
When there is an opening formed in step 1, the deterioration of the optical performance due to the diffraction effect of the opening can be suppressed by increasing the transmittance of the electrochromic element filter 3.
Further, as shown in FIG. 3, when there is no aperture formed by the electrochromic element filter 3 and the diaphragm blade 2, the electrochromic element filter 3 located on the optical axis 4 is not reduced in size of the diaphragm aperture. The amount of light passing through can be properly adjusted by lowering the transmittance of.

Next, FIG. 5 is a schematic configuration diagram of an embodiment of an image pickup apparatus in which the diaphragm apparatus of the present invention is arranged in a part of a photographing system. In FIG. 5, reference numeral 50 denotes a photographing lens group,
It is composed of a front group 51 and a rear group 52. The front group 51 includes a focus lens group, a variable power lens group (variator, compensator), an afocal lens group, and the like, and the rear group 5
Reference numeral 2 has an image forming lens group (relay lens group). 5
A diaphragm device 3 is disposed between the front group 51 and the rear group 52. This diaphragm device 53 has two diaphragm blades 1 and 2, for example, as shown in FIG. 1, and the electrochromic element filter 3 is mounted on the diaphragm blade 1.
Reference numeral 54 denotes an image pickup section, the image pickup surface of which is composed of a CCD 55 or the like, and an object image formed by the photographing lens group 50 is formed on the surface of the CCD 55. Reference numeral 56 denotes a signal processing circuit, which performs signal processing on the video signal sent from the imaging unit 54 and sends the signal to a television receiver or a video signal recording device (not shown). Further, the signal processing circuit 56 (brightness detecting means) detects the brightness of the subject from the level of the video signal, and the diaphragm drive control section 57 and the transmittance control section (transmittance control means) 58.
The control signal is sent to the to adjust the video signal level. 5
Reference numeral 9 denotes a switch, which serves as means for changing the transmittance of the electrochromic element filter 3, and switches between the transmittance changing section 60 and the transmittance control section 58 which are manually changed.

According to this embodiment, when the diaphragm drive control section 57 controls the diaphragm aperture diameter based on the signal from the signal processing circuit 56, the electrochromic element filter 3 is controlled in accordance with the diaphragm aperture diameter. The transmittance is controlled, and when photographing a bright subject, the aperture diameter of the diaphragm is not reduced from a certain size, and instead the electrochromic element filter 3 is positioned on the optical axis 4. , The transmittance control unit 58 selected by the switch 59 or the transmittance changing unit 60 that is manually changed.
Thus, by appropriately changing the transmittance of the electrochromic element filter 3, it is possible to appropriately adjust the amount of passing light while preventing deterioration of optical performance.

In the above embodiment, the two diaphragm blades 1,
The electrochromic element filter 3 is attached to one of the diaphragm blades 1 by using 2
An electrochromic element filter may be attached to each diaphragm blade using more than one diaphragm blade, and thereby the diaphragm aperture diameter can be made into a shape close to a circle. That is, it is only necessary to use a plurality of diaphragm blades and attach the electrochromic element filter to one or more diaphragm blades among the plurality of diaphragm blades. Further, when a plurality of electrochromic element filters are overlapped with each other when the diaphragm diameter is made small, the value of the minimum transmittance can be lowered, and a brighter subject can be photographed. Instead of the electrochromic element filter, a filter such as a liquid crystal filter whose transmittance can be arbitrarily changed may be used.

[0016]

As described above, according to the diaphragm device of the present invention, one or more of the plurality of diaphragm blades have variable transmittance filters positioned on the optical axis when the diaphragm aperture diameter is reduced. When the filter is attached and there is an opening formed by the filter and the diaphragm blade, it is possible to suppress the deterioration of the optical performance due to the diffraction effect of the opening by increasing the transmittance of the filter. Further, when there is no aperture formed by the filter and the diaphragm blade, the amount of passing light can be properly adjusted by reducing the transmittance of the filter without reducing the aperture diameter of the diaphragm.

Further, according to the image pickup apparatus including the diaphragm device using the electrochromic element filter as the variable transmittance filter, the transmittance of the electrochromic element filter can be changed according to the size of the diaphragm aperture diameter. When shooting a bright subject etc., deterioration of optical performance can be achieved by appropriately changing the transmittance of the electrochromic filter located on the optical axis without reducing the aperture size from a certain size. Since the amount of passing light can be adjusted appropriately while preventing, a brighter subject can be photographed.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a diaphragm device according to an embodiment of the present invention when a diaphragm is released.

FIG. 2 is a schematic view of a main part when the diaphragm of the diaphragm device of one embodiment of the present invention is slightly narrowed.

FIG. 3 is a schematic view of a main part when the diaphragm of the diaphragm apparatus according to the embodiment of the present invention is set to the minimum diaphragm.

FIG. 4 is a schematic configuration diagram of an electrochromic element filter according to an embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an image pickup apparatus according to an embodiment of the present invention.

FIG. 6 is a schematic view of a main part of a conventional diaphragm device.

[Explanation of symbols]

 1, 2 diaphragm blades 3 electrochromic element filter 4 optical axis 53 diaphragm device 55 CCD 56 signal processing circuit (brightness detecting means) 57 diaphragm drive control section 58 transmittance control section (transmittance control means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Park Kazutake, 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A diaphragm device for adjusting a passing light amount by changing a diaphragm aperture diameter using a plurality of diaphragm blades, wherein one or more of the plurality of diaphragm blades have a small diaphragm aperture diameter. A diaphragm device equipped with a variable-transmittance filter located on the optical axis. 2. The diaphragm device according to claim 1, wherein an electrochromic element filter is used as the variable transmittance filter. 3. An imaging device using the diaphragm device according to claim 2. 4. Brightness detection means for detecting the brightness on the imaging surface, and transmittance control means for changing the transmittance of the electrochromic element filter to a predetermined value based on the value detected by the brightness detection means. The image pickup apparatus according to claim 3, further comprising: