Title:
TEMPERATURE COMPENSATING DEVICE FOR FOCUS POSITION
Document Type and Number:
Japanese Patent JPH0387801
Kind Code:
A
Abstract:
PURPOSE:To compensate a shift in the focus position of an image forming lens with temperature and obtain the best focus position by calculating focal length corresponding to current temperature from data on the distances between the image forming lens, and a subject and an image formation plane, focal length data on the image forming lens, and temperature data. CONSTITUTION:A temperature sensor 4 is embedded in the lens barrel, etc., of the image forming lens to detect the temperature of the image forming lens. As the temperature of the image forming lens varies, the temperature sensor 4 detects that and its detection signal is converted into a digital signal, which is inputted to an arithmetic part 7. The arithmetic part 7 inputs the data on the distance between the image forming lens and subject, the data on the distance between the image forming lens and image formation plane, the focal length data on the image forming lens, and data on the quantity of focal length variation of the image forming lens per constant variation quantity of the temperature corresponding to specific magnification in advance and calculates the shift in the focus position with the temperature according to those data, and an original setting table 14 and a platen 15 are driven according to the result to correct the focus position to the best focus position.
Inventors:
YAMASHITA KOJI
Application Number:
JP22512089A
Publication Date:
April 12, 1991
Filing Date:
August 31, 1989
Export Citation:
Assignee:
HIRAKAWA KOGYOSHA KK
International Classes:
G02B7/28; G03B27/34; G02B7/09; (IPC1-7): G02B7/09; G02B7/28
Domestic Patent References:
| JP58062344B | ||||
| JPS61133912A | 1986-06-21 | |||
| JPS5397418A | 1978-08-25 |
Attorney, Agent or Firm:
Yoshiyuki Ishibashi
Next Patent: JPH0387802