Photosensor apparatus with light integration control

• US 4,547,676 A
• Filed: 01/24/1983
• Issued: 10/15/1985
• Est. Priority Date: 01/25/1982
• Status: Expired due to Fees

• Current Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Original Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha
• Inventors: Hashimoto, Isamu, Ishibashi, Kenzo, Suzuki, Takeomi
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US06/460,627
• Time in Patent Office: 995 Days
• Field of Search: 250/201, 250/204, 250/216, 250/578, 250/208, 250/209, 358/212, 358/213, 354/402-408
• US Class Current: 250/208.3
• CPC Class Codes: G02B 7/36 using image sharpness techniques , e.g. image processing techniques for generating autofocus signals image data processing per se G06T; in cameras having a solid state image sensor H04N23/67

Abstract

A photosensor apparatus for detecting focal position or the like, which uses a plurality of light-receiving elements arranged in a matrix array, is disclosed. Simultaneous light integration is started with respect to all the light-receiving elements, while all the outputs of the light-receiving elements are progressively scanned immediately after the start of the simultaneous light integration. When at least one of the outputs reaches a first reference level, all the outputs are held. If at least one of the held outputs is above a second reference level of a different level, check as to whether all the outputs are below the second reference level is repeatedly done for progressively reducing light integration periods until all the outputs of the light-receiving elements are at a fixed level.

Claims

1. A photosensor apparatus comprising:

a light-receiving element array consisting of a plurality of light integration type light-receiving elements;

memory means consisting of plural memory elements each connected to a respective one of said light-receiving elements via a respective one of a plurality of switches for, after the light-receiving elements start the light integration, storing an output signal of the said respective one of the light-receiving elements while the one switch is closed to thereby perform sampling, and said memory means holding the output signal of said light-receiving elements substantially simultaneously when said switches are opened at any instant;

scanning means for scanning the memory elements corresponding to at least some of said light-receiving element array during the sampling or after the holding and for progressively obtaining the outputs of these light-receiving elements;

comparing means for comparing the output signals of the light-receiving elements progressively obtained by said scanning means with a first of two reference levels, and said comparing means comparing said output signals with a second of said two reference levels dependent upon a control signal, said second reference level corresponding to a greater degree of received light than said first reference level;

time counting means for counting the light integration time period during which said light-receiving elements are producing a charge due to the light received thereby and during the storage of the charges from the start of the light integration;

control means for controlling the switches connecting respective memory means and light-receiving elements and for controlling said scanning means, said control means coupled to said comparing means and being effected thereby, said control means including;

a means for closing said switches and starting said time counting means simultaneously with the start of light integration by said light-receiving elements;

a first means for timed actuation of said scanning means after the closure of said switches by said first means;

means for opening said switches thereby causing said memory means to hold all the output signals from the light-receiving elements substantially simultaneously and for stopping the counting of said time counting means when one of said output signals exceeds said first reference level based upon said comparing means;

a second means for actuating said scanning means and for generating said control signal to effect the comparison each of the output signals to said second reference level in said comparing means;

means for identifying the output signals as effective detection signals when none of the output signals exceeds said second reference level based upon said comparing means;

means for restarting the light integration period;

means for reducing the timed actuation of said scanning means and reducing the light integration time period when any one of said outputs exceeds said second reference level based upon the comparison in said comparing means, said means for reducing obtaining a ratio of the count in said time counting means and effecting the timed actuation of said scanning means in accordance with said ratio;

means for further restarting the light integration period utilizing the reduced light integration time period and for further reducing the light integration time period until all of the outputs do not exceed said second reference level based upon said comparison means.