Distance measurement system

• US 4,518,253 A
• Filed: 03/17/1981
• Issued: 05/21/1985
• Est. Priority Date: 03/19/1980
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Takahashi, Akira
• Primary Examiner(s): BUCZINSKI, STEPHEN C
• Application Number:
  US06/244,736
• Time in Patent Office: 1,526 Days
• Field of Search: 250/214 B, 354/25 A, 354/403, 356/1, 356/4, 367/99, 367/108, 367/111
• US Class Current: 356/4.07
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48

Abstract

A distance measurement system for measuring distance to an object by emitting light to the object and measuring the intensity of light reflected from the object.

Claims

1. A camera having a range detection system for determining whether an object to be photographed with said camera is within a predetermined distance from said camera, said camera comprising means for emitting energy towards said object, means including a single sensor receiving energy reflected from said object and developing a signal proportional to the intensity of energy received thereby, means for comparing said signal with a predetermined reference signal for producing a control signal, and means responsive to said control signal for determining whether said object is either within a predetermined range of said camera or beyond said predetermined range of said camera, said emitting means being operable intermittently, and said determining means including an element responsive to said energy land adapted to generate a level of current proportional to the intensity of energy received thereby, means operable when said emitting means is not operating for establishing the background level of current proportional to the intensity of energy received by said responsive element when said emitting means is not operating, means for draining said background level of current from said responsive element when said emitting means is operating to generate a current signal proportional to the intensity of the transmitted energy reflected by said object, and comparing means for comparing said current signal with a reference signal to activate said indicator means.

2. A camera according to claim 1, said determining means including a first display means giving a positive indication whenever said object is within said predetermined range from said camera, and a second display means giving a positive indication whenever said object is beyond said predetermined range.

3. A camera according to claim 1, said determining means including a first display means giving a positive indication when said object is within a predetermined range from said camera, a second display means giving a positive indication whenever said object is beyond said predetermined range but within a second predetermined range, and third display means giving a positive indication whenever said object is beyond said second predetermined distance.

4. A camera according to claim 1, said determining means including a first display means giving a positive indication when said object is within a predetermined range from said camera, a second display means giving a positive indication whenever said object is beyond said predetermined range but within a second predetermined range, and third display means giving a positive indication whenever said object is beyond said second predetermined range.

5. A camera according to claim 1, further including means responsive to said determining means for automatically focusing said camera.