Image reading apparatus

• US 4,658,303 A
• Filed: 04/08/1985
• Issued: 04/14/1987
• Est. Priority Date: 04/09/1984
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nagano, Fumikazu
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US06/720,712
• Time in Patent Office: 736 Days
• Field of Search: 358/75, 358/78, 358/80, 358/293, 358/294, 358/213, 358/214
• US Class Current: 358/483
• CPC Class Codes: H04N 1/40056 Circuits for driving or energising particular reading heads or original illumination means H04N1/401, H04N1/407 take precedence
• CPC Class Codes: H04N 1/484 with sequential colour illumination of the original

Abstract

An image reading apparatus comprising a lighting control means, an analog shift means, a transfer control means and a clock pulse control means. According to the controlling operation of a lighting control means for lighting the light source during a given time period, the output of the CCD sensor is prohibited from being fed to the analog shift means while the light source is turned on, with the output of the CCD sensor being adapted to be fed to the analog shift means and to shift to an output circuit while the light source is turned off, thus preventing the accumulation of light electric-charges, caused by light leakage within a light-source lighting period, and preventing mixed color reading through the remaining electric charges, with the result that the color resolution of the red, green, blue can be performed with accuracy.

Claims

1. An image reading apparatus which detects, by the use of a CCD sensor the lights from a light source reflected by images, comprising:

lighting control means for lighting said light source only during a given period;

analog shift means for receiving a plurality of analog signals in parallel from said CCD sensor for output to an output circuit, and shifting said analog signals in accordance with a clock pulse;

transfer control means for prohibiting said analog signals from being provided to said analog shift means while said light source is turned on, and for providing said analog signals to said analog shift means while said light source is turned off;

clock pulse control means for providing said clock pulse to said analog shift means to control the shifting of the contents of said analog shift means to said output circuit while said light source is turned off.

2. An image reading apparatus in accordance with claim 1, wherein said clock pulse control means includes, means for controlling said clock pulse to be provided to said analog shift means so as to discharge light electric charges, which are caused by light leakage and are accumulated on said analog shift means while prohibiting the provision of said analog signals from said CCD sensor to said analog shift means for a given time period after said light source is turned off.

3. An image reading apparatus in accordance with claim 2, wherein said clock pulse control means further includes means for shortening the period of said clock pulse to be provided to said analog shift means during said given time period.

4. An image reading apparatus in accordance with claim 1, wherein said lighting control means includes control means for performing a control operation to light said light source at the timing of a scanning period T and performing a control operation to provide to said analog shift means said analog signals from said CCD sensor in accordance with a first timing period T+1, but not to provide to said analog shift means said analog signals from said CCD sensor in accordance with a second timing period T+2.