Image sensing system including a light source

• US 5,883,987 A
• Filed: 06/06/1995
• Issued: 03/16/1999
• Est. Priority Date: 06/08/1994
• Status: Expired due to Term

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Noda, Atsuhiro, Ono, Takeshi, Tanimoto, Tetsuyuki, Nanba, Katsuyuki, Ogoshi, Takeshi
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Do, Anh Hong
• Application Number:
  US08/471,370
• Time in Patent Office: 1,379 Days
• Field of Search: 382/312, 382/319, 382/321, 382/274, 348/68, 348/96, 348/195, 348/221, 348/266, 348/104, 355/83, 356/474, 356/475, 362/4, 362/5, 362/260, 362/321, 386/4, 386/117
• US Class Current: 382/312
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10752 Exposure time control

Abstract

An image sensing system is provided with a fluorescent lamp which performs AC lighting to irradiate an object, an inverter power source which supplies currents to the fluorescent lamp, a lighting frequency changing circuit which changes the frequency of the current supply, a lens which images an image onto a film, and a CCD image sensing device which is capable of changing the period of exposure by the formed image and which outputs the image of the object as an electric signal through photoelectric conversion. The exposure period of the CCD image sensing device is controlled by a microcomputer and a timing generator. The lighting frequency changing circuit is controlled so that the phase of the exposure period and the phase of the current supply to the fluorescent lamp are in synchronism with each other.

Claims

1. An image reading apparatus comprising:

image projecting means for performing alternating current lighting to project light including image information of an original;

a power source which supplies an alternating current to the image projecting means;

an image reading member having photoelectric conversion devices arranged in a line, said image reading member reading out the image information;

a scanner which moves the original and the photoelectric conversion devices relatively to each other in a direction perpendicular to the line in which the photoelectric conversion devices are arranged; and

a control circuit which controls a start timing of reading of each line by the image reading member, said control circuit controlling the power source so that a phase position of the alternating current is substantially the same for the start timing of reading of each line so that an output level of said image reading member its-substaritially the same for each line.

2. An image reading apparatus as claimed in claim 1, wherein relative movement between the original and the photoelectric conversion devices by the scanner is made by a movement of the original.

3. An image reading apparatus as claimed in claim 1, wherein said scanner includes a pulse motor, and wherein an amount of the relative movement between the original and the photoelectric conversion devices is decided by a pulse number of driving of said pulse motor, and wherein a start timing of reading of each line is controlled by the pulse number.

4. An image reading apparatus as claimed in claim 1, wherein said image projecting means has a mirror for directing the projected light to the image reading member and wherein relative movement between the original and the photoelectric conversion devices by the scanner is made by a movement of the image projecting means.

5. An image sensing apparatus comprising:

a light source which performs alternating current lighting to irradiate an original;

an inverter power source which supplies an alternating current to the light source, said inverter power source being capable of changing a period of the supplied alternating current;

an image sensing device whose exposure period is changeable, said image sensing device performing image sensing of light irradiated by the light source; and

a control circuit for controlling an exposure timing and an exposure period of the image sensing device and for controlling the period of the alternating current from the inverter power source so that a phase of the exposure period of the image sensing device and a phase of said alternating current to the light source are synchronized so that an output level of said sensing device is substantially the same regardless of said exposure timing.

6. An image sensing apparatus as claimed in claim 5, wherein said control circuit controls the alternating current from the inverter power source so that the exposure period of the image sensing device coincides with one period of the alternating current for lighting the light source.

7. An image sensing system comprising:

a light source which performs alternating current lighting to irradiate an original;

an inverter power source which supplies an alternating current to the light source;

an image sensing device which performs image sensing of light irradiated by the light source;

detecting means for detecting a lighting period of the light source;

processing means for processing an image signal transmitted from the image sensing device; and

controlling means for controlling a processing timing of the processing means based on a detection signal from the detecting means so that a phase of said processing timing of the processing means and a phase of said light source are synchronized so that a level of said image signal transmitted from the image sensing device for said processing does not substantially vary based on said phase of said light source.

8. An image sensing system as claimed in claim 7, wherein said processing means has an image processing circuit which converts the image signal transmitted from the image sensing device into an electric signal which can be printed out, and wherein said image sensing system has a printer for recording an image on a recording medium based on an output signal from the image processing circuit, and wherein said controlling means controls an image recording timing of the printer.

9. An image reading apparatus comprising:

a projecting optical system which performs alternating current lighting to project light including image information of a predetermined line of an original;

a power source which supplies an alternating current to the projecting optical system;

an image reading member having photoelectric conversion devices, said image reading member reading out the image information of the predetermined line projected by the photoelectric conversion devices;

a scanner which moves the original and the photoelectric conversion devices relatively to each other in a direction perpendicular to the predetermined line projected by the projecting optical system;

a sensing circuit which senses a light receiving period of the photoelectric conversion devices for reading of each line by the image reading member; and

a control circuit which controls a frequency of the power source based on an output of the sensing circuit so that for reading of each line, a phase of the light receiving period of the photoelectric conversion devices and a phase of the power source have a constant phase relationship therebetween so that an output level of said image reading member is substantially the same for each line.

10. An image reading apparatus as claimed in claim 9, wherein relative movement between the original and the photoelectric conversion devices by the scanner is made by a movement of the original.

11. An image reading apparatus as claimed in claim 10, wherein said scanner includes a pulse motor, and wherein an amount of the relative movement is decided by a pulse number of driving of said pulse motor, and wherein a start timing of reading of each line is controlled by the pulse number.

12. An image reading apparatus as claimed in claim 9, wherein said control circuit controls the power source so that the light receiving period of the photoelectric conversion devices and the period of the alternating current coincide with each other.

13. An image sensing system including a light source, comprising:

a light source which irradiates an object by performing alternating current lighting;

a current supplying circuit which supplies a current to turn on the light source;

a lens which forms an image of the object irradiated by light from the light source;

an image sensing device capable of changing a period of exposure by light formed into an image by the lens, said image sensing device outputting the image of the object as an electric signal through photoelectric conversion;

an exposure period controller which controls an is exposure period of the image sensing device; and

a lighting frequency controller which controls a frequency of a current supplied to the light source so that a phase of the exposure period and a phase of the lighting are synchronized by using an output of the exposure period controlling means so that a level of said electrical signal outputted by said image sensing device does not substantially depend on exposure timing.

14. A method of providing uniform exposure between lines in an image reading operation comprising the steps of:

supplying alternating current to a light source to irradiate an object;

forming an image of the object irradiated by light from the light source;

sequentially reading lines of image information in the formed image; and

controlling a phase position of the alternating current supplied to the light source so that a phase position of the alternating current is substantially the same at the start timing of reading of each line of image information so that an amount of light received during is the reading of each sequential line of image information is substantially the same.