JPH06148593A - Optical system with light quantity adjusting device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain an optical system having a light amount adjusting device capable of widening a light amount adjusting range of a light flux passing through the optical system and obtaining a sufficient diaphragm effect. [Structure] A plurality of physical elements 9 and 16 capable of adjusting the transmittance are arranged in the optical path of the optical system to control the amount of passing light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system having a light quantity adjusting device, and in particular, by providing a plurality of physical elements capable of arbitrarily adjusting the transmittance (light transmittance) in the optical path of the optical system. The present invention relates to an optical system having a light amount adjusting device, which is suitable for a camera such as a video camera, an electronic still camera, a still camera, or the like, which is configured to widen a passing light amount adjusting range of the optical system.

[0002]

2. Description of the Related Art Conventionally, in a light quantity adjusting device used in an optical system such as a camera, diaphragm blades are mechanically moved to change the diaphragm diameter of the diaphragm to adjust the light quantity of a light beam incident on an image pickup surface.

In recent years, a video image is formed by converting an object image formed on the surface of the CCD into an electric signal by a photographing optical system using a photoelectric conversion element such as a CCD (line sensor) and recording it on a recording medium such as a magnetic tape. Camera devices such as cameras have become widespread.

This video camera (camera device) is required to be particularly miniaturized from the viewpoint of ease of use. Therefore, high density mounting of electric circuits constituting the camera, miniaturization of CCD and photographing optical system are required. The overall size of the camera is being reduced by downsizing.

Further, in such a video camera, in order to miniaturize the photographing optical system as a light quantity adjusting device for adjusting the quantity of light incident on the image pickup surface, for example, a liquid crystal element or an electro-optical device is used.
Attempts have been made to provide a physical property element such as a chromic (EC) element in the optical path of an optical system to control the light amount adjustment range of the optical system.

Further, in a camera using a silver salt film, it has been proposed to control the amount of light flux incident on the image pickup surface by utilizing a physical property element such as a liquid crystal element in order to electronicize a diaphragm device.

[0007]

A conventional diaphragm device for adjusting the light quantity by mechanically moving diaphragm blades to change the diaphragm aperture has 10 to 10 diaphragm stages in a video camera.
12 steps (light ratio (maximum transmitted light amount / minimum transmitted light amount) 1
000-4000). In cameras using silver salt film, the number of diaphragm steps is 5-8.
It is possible to adjust the light amount in steps (about 30 to 250 in light amount ratio).

The light amount adjusting devices used in these cameras can adjust the amount of transmitted light (transmitted light amount) in a relatively wide range, but on the other hand, there is a problem that the entire device becomes large and complicated. is there.

On the other hand, a single physical property element such as a liquid crystal element or an EC element is provided in the optical path of the optical system, and the transmittance of the physical property element is changed to adjust the amount of light incident on the image pickup surface. The device is suitable for downsizing of the photographing optical system, but on the other hand, it is difficult to adjust the light amount in a wider range than the mechanical light amount adjusting device (diaphragm device) described above. There is.

As a result, the light amount adjustment range becomes insufficient, and it is difficult to obtain a desired image.

Further, if an attempt is made to adjust the amount of light passing through the optical system by changing the transmittance (concentration) of a single physical property element, the diaphragm effect cannot be obtained sufficiently and the depth of field cannot be increased. There arise problems such as a problem that the harmful luminous flux cannot be effectively shielded.

According to the present invention, by disposing a plurality of physical property elements whose transmittance can be arbitrarily adjusted in the optical path of the optical system, a wider light amount adjustment range can be obtained and a sufficient diaphragm effect can be obtained. An object of the present invention is to provide an optical system having a small-sized light quantity adjusting device.

[0013]

In an optical system having a light quantity adjusting device of the present invention, a plurality of physical elements whose transmittance can be adjusted are arranged in the optical path of the optical system to control the passing light quantity. It is characterized by that.

Further, in the optical system having the light quantity adjusting device of the present invention, a plurality of physical property elements capable of adjusting the transmittance are disposed in the optical path of the optical system, and when the quantity of passing light is controlled, the plurality of physical property elements are arranged. At least one of the physical elements has a light-transmitting region divided into a plurality of regions, and at least one region of the divided plural regions is capable of adjusting the transmittance independently of other regions. Is characterized by.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential parts of a first embodiment when the present invention is applied to a video camera. FIG. 2 is a block diagram of essential parts showing a circuit configuration of the video camera shown in FIG. 1, and FIG. 3 is a flowchart diagram for controlling the operation of the video camera shown in FIG.

In the figure, reference numeral 1 denotes a photographing optical system, which is a focus adjusting lens 1a, two zoom adjusting lenses 1b1,
1b2 and a fixed lens 1c.

Reference numeral 2 denotes a focus lens holding frame, which has a gear portion 2a and holds a focus adjusting lens 1a. A fixing portion 3 has a screw portion 3a at one end and is screwed with a screw portion 2c of the focus lens holding frame 2. Reference numeral 4 is a cam barrel, and two zoom adjusting lenses 1b1 and 1b
It has a cam groove for determining the position of No. 2 and is rotatably held inside the fixed portion 3.

Lens frames 5 and 6 respectively hold zoom adjusting lenses 1b1 and 1b2. A focusing motor 7 rotates the focus lens holding frame 2. Reference numeral 7a denotes a gear of the motor output shaft, which is engaged with the gear portion 2a of the focus lens holding frame 2. A zoom motor 8 rotates the cam barrel 4. 8a
Is a gear of the motor output shaft, and is engaged with the gear portion 4a of the cam barrel 4.

Reference numerals 9 and 16 denote physical elements according to the present invention, which are liquid crystal elements and electrochromic (EC) elements (for example, conductive metal such as transition metal oxide on the surface of a glass plate having a thickness of about 0.3 to 1 mm). Membrane (IrOx, Ta ₂ O ₅ , WO ₃
Etc.) formed)) etc. The physical property elements 9 and 16 have the function of arbitrarily controlling the transmittance and the amount of transmission of the element by applying a voltage in a known manner.

In the present embodiment, the physical property element 9 is provided near the diaphragm in the optical path between the zoom adjusting lens 1b2 and the fixed lens 1c, and the physical property element 16 is provided in the front optical path of the focus adjusting lens 1a. ing. As a result, the amount of light passing through the optical system (photographing optical system 1) (amount of transmitted light) is arbitrarily adjusted by the two physical elements 9 and 16, and the light amount adjustment range is widened to perform appropriate exposure.

Reference numeral 10 denotes an image pickup element, which is composed of, for example, a CCD (line sensor) or the like. Reference numeral 11 is an optical axis of the photographing optical system. Reference numeral 12 is an electronic viewfinder, and 13 is an eyepiece for enlarging and observing an image displayed on the electronic viewfinder. Reference numeral 14 is a power switch of the video camera, and 15 is a zoom operation unit of the video camera. Further, the video camera shown in the figure has a camera control circuit 17 and a recording section 1 electrically connected to the camera control circuit 17.
8 and a power source 19.

Further, the focusing motor 7, the zoom motor 8, the two physical elements 9, 16, the image pickup element 10, the electronic viewfinder 12, the power switch 14, and the zoom operating section 15 are electrically connected to the camera control circuit 17, respectively. Connected to each other.

Next, the operation of the video camera of this embodiment will be described with reference to FIGS.

First, when the power switch 14 of the video camera is operated and the power is turned on, the focus adjusting lens 1a moves in a predetermined direction on the optical axis so that the high frequency component of the video signal from the image pickup device 10 becomes maximum.

In order to move the focus adjusting lens 1a, the focus motor 7 is driven (rotated) based on a signal from the camera control circuit 17. The gear 7a of the motor output shaft is the gear portion 2a of the focus lens holding frame 2.
Since the screw portion 2c of the focus lens holding frame 2 is engaged with the screw portion 3c of the fixed portion 3, the focus adjustment lens 1a can be moved in a predetermined direction on the optical axis. . Thereby, the focusing operation is performed.

Next, the exposure amount is controlled so that the light amount of the light beam incident on the image pickup device 10 becomes substantially constant, and the two physical property elements 9,
The passing light amount (transmission amount) of the light flux passing through 16 is controlled by the exposure amount control circuit. Thereafter, the image captured by the image sensor 10 is displayed on the electronic viewfinder 12 via the camera control circuit 17 and is observed by the photographer through the eyepiece lens 13. This state is called a standby state.

When the zoom operation section 15 is operated by the photographer, the zoom motor 8 is driven (rotated) based on a signal from the camera control circuit 17. Since the gear 8a of the motor output shaft and the gear portion 4a of the cam barrel 4 are engaged with each other, the cam barrel 4 rotates, which causes the two zoom adjusting lenses 1b1 and 1b2 to follow the cam groove of the cam barrel 4. And moves in a predetermined direction on the optical axis to perform a zoom operation.

The zoom operation section 15 is provided with two zoom switches 31, 32 for the tele direction and the wide direction. For example, when the zoom switch 31 is turned on, the zoom motor 8 rotates in the normal direction and the two zoom switches are operated. Adjustment lens 1b
1, 1b2 moves to the wide-angle side. Also zoom switch 32
When is turned on, the zoom motor 8 is rotated in the reverse direction, and the two zoom adjusting lenses 1b1 and 1b2 are moved to the telephoto side.
The two zoom switches 31 and 32 are turned on at the same time.
It cannot be configured.

When the photographer presses a photographing button (not shown), the photographing switch is turned on. When the camera control circuit 17 confirms that the photographing switch is turned on, the photographing operation is started and the image pickup device 10 operates. The video signal is transferred to the recording unit 18 by the camera control circuit 17 and recorded on the recording medium by the recording unit control circuit.

At this time, the focusing operation and the adjustment of the exposure amount have already been performed as described above, and the image is displayed on the electronic viewfinder 12 via the camera control circuit 17.

When the photographer releases the photographing button (not shown), the photographing switch is turned off, and the camera control circuit 17
When it is confirmed that this photographing switch has been turned off, the photographing operation is stopped and the camera returns to the standby state again. Video recording is sequentially performed by repeating the above-described photographing operation procedure.

Next, the two physical property elements 9 and 1 according to the present embodiment.
The optical action when 6 is used will be described.

For example, the minimum transmittance and the maximum transmittance of the physical property element 9 are respectively set to A _MIN and A _MAX, and the amount of transmitted light (transmitted light amount) of the physical property element 9 can be adjusted from the minimum transmittance A _MIN to the maximum transmittance A _MAX. It can be done. At this time, the following relational expression holds between the minimum transmittance A _MIN and the maximum transmittance A _MAX .

[0034] 0 <A _MIN <A _MAX <1 ‥‥‥‥‥(1) Matasaidaitokaritsu_A _MAX Tosaishotokaritsu_A _MIN Tonohi_(hikariryohi)R1wa R1=A _MAX /A _MIN (> 1) It becomes (2).

Similarly, the same can be said for the physical property element 16 as for the physical property element 9 described above. For example, it is assumed that the minimum transmittance and the maximum transmittance of the physical property element 16 are B _MIN and B _MAX , respectively, and that the physical property element 16 can adjust the passing light amount from the minimum transmittance B _MIN to the maximum transmittance B _MAX . At this time, the following relational expression holds between the minimum transmittance B _MIN and the maximum transmittance B _MAX .

0 <B _MIN <B _MAX <1 ‥‥‥‥‥‥ (3) Also, the ratio of the maximum transmittance B _MAX and the minimum transmittance B _MIN (light quantity ratio).
R2 becomes _{R2 = B MAX / B MIN (} > 1) ‥‥‥‥‥ (4).

Here, the transmittance of the optical system (adjustment range of the amount of transmitted light) when the physical property element 9 and the physical property element 16 are combined is A
_{From MIN} / B _MIN to A _MAX / B _MAX .

Further, the ratio (light amount ratio) R of the maximum transmittance and the minimum transmittance is R = (A _MAX · B _MAX ) / (A _MIN · B _MIN ) = (A _MAX / A _MIN ) · (B _MAX / B _MIN) = R1 · R2 is ‥‥‥‥‥ (5), the light quantity ratio R values above equation (5) as is clear from, for example, than when only the physical properties element 9 R2 (B _MAX /
B _MIN (> 1) times.

That is, rather than adjusting the quantity of light passing through the optical system by using the physical element 9 alone, the adjustment of the quantity of light using a plurality of physical elements can make the light quantity adjustment range much wider.

Therefore, in this embodiment, as described above, the two physical elements 9 and 16 are arranged in the optical path of the optical system so that the adjustment range of the passing light amount is widened, whereby the desired optical performance is obtained. Is getting

The two physical property elements 9 and 16 in this embodiment may be physical property elements having the same characteristics (transmittance), or the physical property elements having different characteristics may be applied to the present invention.

Further, in the present embodiment, the two physical property elements 9 and 16 are arranged with the optical members (lenses 1a, 1b1 and 1b2) sandwiched therebetween, but the physical property elements 9 and 16 are not limited to this arrangement position, for example, the two physical property elements 9 and 16. May be arranged adjacent to each other. Further, the number of physical property elements is not limited to two and may be three or more. As a result, the amount of passing light can be adjusted in a wider range.

FIGS. 4 (A) and 4 (B) are a side view and a front view of one of a plurality of physical property elements according to the second embodiment of the present invention.

The present embodiment differs from the above-described first embodiment in that at least one of the two physical elements is provided near the stop position of the optical system, and the area of the physical element at this time is a plurality of concentric circular areas. That is, the transmittance is adjusted so that at least one of the divided areas can be adjusted independently of the other areas. Other configurations and optical functions are substantially the same as those in the first embodiment.

That is, in this embodiment, one physical property element 20 is divided into a plurality of concentric pattern regions 20a to 20g as shown in FIG.
Although it is divided into two areas, the number of divisions is not limited to this. ) The transmittance of each of the divided regions 20a to 20g is independently adjusted as shown in, for example, FIGS. 5A to 5H, whereby the effect of narrowing down (for example, deepening or shallowing the depth of field). To obtain the desired image).

In FIG. 5, the shaded area shows the case where the transmittance is smaller than that of other areas. As shown in the figure, the physical property element 20 is independently controlled for each of the regions 20a to 20g so that the transmittance is gradually reduced (from the depth of field to be gradually increased) from (A) to (H). is doing. This makes the depth of field deeper or shallower to obtain the diaphragm effect.

FIG. 6 is a side view of the third embodiment of the light quantity adjusting device of the present invention.

This embodiment is different from the above-described first embodiment in that the light quantity adjusting device is unitized by providing the physical property elements 22 and 23 on the light incident surface 21a side and the light emitting surface 21b side of the transparent substrate 21 such as glass. That is, it is arranged at an arbitrary position in the optical path of the optical system. Other configurations and optical functions are substantially the same as those in the first embodiment.

That is, by providing one of the two physical property elements 22 and 23 on the light incident surface 21a side of the transparent substrate 21 and the other physical property element 23 on the light emission surface 21b side, The same effect as that of the first embodiment can be obtained, and the light quantity adjusting device can be unitized, thereby simplifying and downsizing the structure of the entire device.

At least one of the two physical property elements 22 and 23 is divided into a plurality of concentric regions as shown in FIG. 4 of the second embodiment, and the divided regions are independently passed. The amount of light may be adjusted. As a result, the diaphragm effect can be obtained as in the second embodiment.

7A and 7B are a side view and a front view, respectively, of a fourth embodiment of the light quantity adjusting device of the present invention.

The present embodiment differs from the above-mentioned third embodiment in that the physical property element 26 is provided only on the area 28 outside the area (hatched area) of the circle 27 centered on the optical axis on at least one surface of the transparent substrate 24. It is provided. Other configurations and optical functions are substantially the same as those in the third embodiment.

For example, if two physical elements having a maximum transmittance that are not so large are used to adjust the amount of light passing through the optical system, the maximum transmittance of the optical system may be considerably lowered. For example, when two physical elements having a maximum transmittance of 90% are used, the combined maximum transmittance of this optical system is about 81.
However, when two physical elements having a maximum transmittance of 50% are used, the combined maximum transmittance of this optical system is about 25%.
It will decrease to%.

Therefore, in this embodiment, as shown in FIG.
As shown in (B), the physical property element 25 is formed in the region on the light incident surface 24a side of the transparent substrate 24 such as glass as in the third embodiment.
Is provided on almost the entire surface, and the physical property element 26 is provided only on the area 28 outside the area (hatched area) of the circle 27 centered on the optical axis on the light exit surface 24b side to increase the amount of light passing therethrough.

As a result, even if a plurality of physical elements having a low maximum transmittance are used, the maximum transmittance of the composite is not significantly reduced, and the adjustment range of the amount of transmitted light can be widened to some extent. The element 26 can obtain a diaphragm effect to some extent.

The light exit surface 2 on which no physical property element is formed
The area of the circle 27 of 4b may be arbitrarily set according to the characteristics (transmittance) of the physical element used.

Also in this embodiment, the physical property element 25 may be divided into a plurality of concentric regions, and the amount of light passing through each of the divided regions may be adjusted independently, as in the second embodiment. . Alternatively, the physical property element 26 may be divided into a plurality of regions by concentric circles centering on the optical axis, and the respective divided regions may be adjusted in the amount of passing light independently.

Further, in this embodiment, two physical property elements 2 are used.
5, 26 are provided integrally on the light incident surface 24a side and the light emitting surface 24b side of the transparent substrate 24, respectively, but the present invention is not limited to this, and each physical property element is the same as in the first embodiment, for example. 25 and 26 may be provided at different places.

FIG. 8 is a schematic view of the essential portions of Embodiment 5 when the present invention is applied to a video camera. In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

The present embodiment differs from the above-mentioned first embodiment in that the light incident surface of an optical member such as a plurality of lenses constituting the photographing optical system 1, the optical low-pass filter 37, and the protective glass for protecting the image sensor 10 is formed. That is, the physical property elements are formed on a plurality of surfaces of the light emitting surface. Other configurations and optical functions are substantially the same as those in the first embodiment.

That is, in this embodiment, the fixed lens 1c is used.
The physical property element 9 is provided on the light exit surface of the optical path, and the physical property element 16 is provided on the light entrance surface of the optical low-pass filter 37. As a result, the same effect as that of the above-described first embodiment is obtained, the light amount adjusting device is downsized, and the entire optical system is downsized.

Although the present invention is applied to a video camera in the above embodiments, the present invention is not limited to the video camera but may be applied to any optical system such as an optical system of a still camera using a silver salt film. Also, the present invention can be applied similarly to the above-mentioned embodiments.

[0063]

According to the present invention, as described above, by disposing a plurality of physical elements whose transmittance can be arbitrarily adjusted in the optical path of the optical system, a simple structure and a wider light amount adjustment range can be obtained. In addition, it is possible to achieve an optical system having a small light quantity adjusting device that can obtain the above-mentioned effect and a sufficient diaphragm effect.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment when the present invention is applied to a video camera.

2 is a block diagram of a main part showing a circuit configuration of the video camera shown in FIG.

FIG. 3 is a flowchart for controlling the operation of the video camera shown in FIG.

FIG. 4 is a side view and a front view of the physical property element according to Example 2 of the present invention.

5 is an explanatory view showing a method of adjusting the transmittance of the physical property element shown in FIG.

FIG. 6 is a side view of a light amount adjusting apparatus according to a third embodiment of the present invention.

FIG. 7 is a side view and a front view of a light amount adjusting device according to a fourth embodiment of the present invention.

FIG. 8 is a schematic view of the essential portions of Embodiment 5 when the present invention is applied to a video camera.

[Explanation of symbols]

 1 Photographic optical system 1a Focus adjustment lens 1b1, 1b2 Zoom adjustment lens 1c Fixed lens 2 Focus lens holding frame 2a Gear part 2c, 3a Screw part 3 Fixed part 4 Cam barrel 4a Gear part 5, 6 Lens frame 7 Focus motor 8 Zoom Motor 8a Gear 9,16 Physical Device 10 Image Sensor 11 Optical Axis 12 Electronic Viewfinder 13 Eyepiece 14 Power Switch 15 Zoom Operation Section

Claims (7)

[Claims] 1. An optical system having a light quantity adjusting device, wherein a plurality of physical elements capable of adjusting the transmittance are arranged in the optical path of the optical system to control the quantity of passing light. 2. At least one of the plurality of physical property elements
The light transmission region of one physical property element is divided into a plurality of regions, and at least one region of the plurality of divided regions can adjust the transmittance independently of the other regions. An optical system having a light amount adjusting device. 3. At least one divided into the plurality of regions
3. An optical system having a light quantity adjusting device according to claim 2, wherein one physical property element is provided near the stop position of the optical system. 4. An optical device having a light quantity adjusting device according to claim 1, wherein optical elements each having the physical property element on the light incident surface side and the light emitting surface side are arranged in the optical path of the optical system. system. 5. The physical property element is provided on the entire surface of at least one of the light incident surface and the light exit surface of the optical element,
An optical system having a light quantity adjusting device according to claim 4, wherein the physical property element is provided only on a ring zone of a circle centered on the optical axis on the other surface. 6. An optical system having a light quantity adjusting device according to claim 1, wherein the physical property element is formed on at least one surface of an optical member constituting the optical system. 7. When a plurality of physical elements capable of adjusting the transmittance are arranged in the optical path of the optical system and the amount of passing light is controlled, at least one of the plurality of physical elements transmits light. An optical system having a light quantity adjusting device, characterized in that a region is divided into a plurality of regions, and at least one region of the plurality of divided regions can be adjusted in transmittance independently of other regions. .