Catadioptric lens system with light transmission control means

• US 4,256,372 A
• Filed: 10/02/1978
• Issued: 03/17/1981
• Est. Priority Date: 10/03/1977
• Status: Expired due to Term

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Camera Kabushiki Kaisha
• Inventors: Iida, Takashi, Kawamura, Kunio, Yoshida, Nobuo, Kiten, Hiroshi, Yasukuni, Mitsuo
• Primary Examiner(s): Clark, Conrad J.
• Application Number:
  US05/947,737
• Time in Patent Office: 897 Days
• Field of Search: 354/227, 354/271, 350/357, 350/195, 350/199, 350/196, 350/205, 350/314
• US Class Current: 359/275
• CPC Class Codes: G02B 17/0808 on-axis systems with at least one of the mirrors having a central aperture
• CPC Class Codes: G02B 17/0852 having a field corrector only
• CPC Class Codes: G02B 17/0856 comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
• CPC Class Codes: G02B 17/0884 having a pupil corrector

Abstract

A catadioptric light system such as a module lens system capable of being mounted on a camera is provided. A plurality of light reflecting and refracting optic members are designed to provide a desired image forming light path through the lens system. Disposed within the lens system is an electrochromic device that is responsive to an applied voltage to provide a predetermined degree of light transmission intensity through the lens system. The electrochromic device can be a thin film mounted on a transparent plate or on a reflective surface. The housing of the lens system can be advantageously designed to contain its own power source.

Claims

1. A self-contained electronic light attenuating catadioptric lens system for a camera comprising:

a lens barrel;

means for exchangeably mounting the catadioptric lens system on a camera;

a plurality of light reflecting surfaces mounted in the lens barrel;

a plurality of light refracting surfaces mounted in the lens barrel;

an electrochromic device in the lens barrel for variably attenuating the light transmission through the lens system, whereby the light reflecting and refracting surfaces define an optical path for forming an image of an object and the electrochromic device operatively interfaces with the optical path; and

electric circuit means including a power source for controlling the electrochromic device, the electric circuit means being located in the lens barrel.

2. The invention of claim 1 further comprising means for applying voltage to the electrochromic device and means for variably determining a time during which the voltage is applied.

3. The invention of claim 1, wherein the catadioptric lens system includes a ring shaped lens with a central aperture, a main mirror for reflecting light rays toward the object side and a second mirror for reflecting the light rays from the main mirror toward the image side, and wherein the electric circuit means is located at a space next to the rear side of the second mirror within the central aperture.

4. The invention of claim 3, wherein the film of electrochromic device is mounted on the second mirror.

5. An improved self-contained electronic catadioptric lens system adapted for removable mounting as a lens module on a camera housing comprising;

a lens barrel body member of approximately the configuration of a conventional camera lens non-electronic catadioptric lens system;

a plurality of light reflecting and refracting optical elements forming a non-linear optical path through the lens module for transmitting the image of an object including a first ring-shaped lens with a central aperture, a first mirror member having an object side reflecting surface and a second mirror member having an image side reflecting surface adjacent the first ring-shaped lens;

an electrochromic device, uniformly intersecting the effective image forming light path and mounted within the body member, having a variable light transmission characteristic;

circuit means for varying the light transmission characteristic of the electrochromic device to a predetermined value of light intensity passing therethrough including control means mounted on the body member for providing a plurality of predetermined values of light intensity and a battery receptacle mounted directly in the body member for receiving at least one battery to power the circuit means.

6. The invention of claim 5 further comprising a light transmitting plate, the electrochromic device being formed on a surface of the light transmitting plate.

7. The invention of claim 6, wherein the light transmitting plate is an exchangeable chromatic filter.

8. The invention of claim 6, wherein the light transmitting plate is a transparent plate for compensating the back focal distance of the lens system.

9. The invention of claim 5 wherein the control means are mounted concentrically on the object side of the ring-shaped lens to extend within the ring-shaped lens aperture.

10. The invention of claim 9 wherein the control means includes a variable resistor for adjusting the quantity of light transmitted through the electrochromic device.

11. The invention of claim 9 wherein the battery receptacle is mounted within the ring-shaped lens aperture and on the object side of the second mirror member.

12. The invention of claim 5 wherein the control means is mounted on the lens barrel body member on the image side of the first mirror member.

13. The invention of claim 5 wherein the control means further comprises means for applying voltage to the electrochromic device and means for variably determining a time during which the voltage is applied.