Recording medium discrimination apparatus and method

• US 7,646,479 B2
• Filed: 06/07/2005
• Issued: 01/12/2010
• Est. Priority Date: 06/11/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kokubo, Yoshitaka
• Primary Examiner(s): Toatley, Jr.; Gregory J
• Assistant Examiner(s): Ton; Tri T
• Application Number:
  US11/146,080
• Publication Number:
  US 20050276198A1
• Time in Patent Office: 1,680 Days
• Field of Search: 356/239.1, 356/239.7, 3562371-2376, 369/53.22, 369 471- 4716, 369 531- 532, 369/275.3, 369/59.25, 369/94, 369/47.51, 369/13.24, 369/84
• US Class Current: 356/239.1
• CPC Class Codes: B41J 11/009 Detecting type of paper, e.g. by automatic reading of a code that is printed on a paper package or on a paper roll or by sensing the grade of translucency of the paper
• CPC Class Codes: H04N 1/00681 Detecting the presence, position or size of a sheet or correcting its position before scanning H04N1/047 takes precedence; mode signalling H04N1/333; skew detection or correction in image signals H04N1/3878
• CPC Class Codes: H04N 1/00689 Presence
• CPC Class Codes: H04N 1/00724 Type of sheet, e.g. colour of paper or transparency
• CPC Class Codes: H04N 1/00734 Optical detectors
• CPC Class Codes: H04N 1/0075 Detecting a change in reflectivity
• CPC Class Codes: H04N 1/00779 Adjusting settings, e.g. mode, feeding rate or type of paper

Abstract

An apparatus can correctly discriminate between types of a recording medium, and obtain good fixed image by performing fixing in the optimum fixing conditions for a variety of different types of recording media. The apparatus includes an LED 101 serving as a first irradiation section, an LED 104 serving as a second irradiation section, a phototransistor 103 serving as a first reading section, and a phototransistor 102 serving as a second reading section. The light output from the LED 101 operating as the light source and passing through a slit 111 illuminates a surface of recording paper P on a recording paper conveyance guide 105. Besides, the recording paper conveyance guide 105 has a window opened for illuminating the recording paper from its underside in the present embodiment. The reflected light from the recording paper P is gathered via slits 112 and 113 and is received by the phototransistors 102 and 103.

Claims

1. A recording medium discrimination apparatus comprising:

a first irradiation section for illuminating a recording medium to obtain reflected light from a surface of the recording medium;

a second irradiation section for illuminating the recording medium to obtain transmitted light from the recording medium;

a plurality of reading sections for reading regularly reflected light and diffusely reflected light reflected from the recording medium illuminated by said first irradiation section, and for reading regularly transmitted light and diffusely transmitted light transmitted through the recording medium illuminated by the second irradiation section; and

a discrimination section for discriminating a type of the recording medium by using a reflected light ratio defined as a ratio of a regularly reflected light quantity and a diffusely reflected light quantity obtained by said plurality of reading sections, and a transmitted light ratio defined as a ratio of a regularly transmitted light quantity and a diffusely transmitted light quantity obtained by said plurality of reading sections.

2. The recording medium discrimination apparatus as claimed in claim 1, wherein said first irradiation section and said second irradiation section each radiate at a plurality of different predetermined light quantities, and said discrimination section discriminates the type of the recording medium by using the reflected light ratio and transmitted light ratio each obtained from the plurality of different predetermined light quantities by said first irradiation section and second irradiation section.

3. The recording medium discrimination apparatus as claimed in claim 2, further comprising a reference plate that has a predetermined reflection characteristic and a predetermined transmission characteristic for light rays radiated from said first irradiation section and said second irradiation section, and is placed at a reading position of the recording medium.

4. The recording medium discrimination apparatus as claimed in claim 1, wherein said first irradiation section and said plurality of reading sections are placed on one side of the recording medium, and said second irradiation section is placed on opposite side of said first irradiation section with respect to the recording medium.

5. The recording medium discrimination apparatus as claimed in claim 1, wherein

said plurality of reading sections comprises a first reading section and a second reading section, and wherein

said second irradiation section and said second reading section are placed at positions opposing via the recording medium, and said first irradiation section and said first reading section are placed at positions having line symmetry with respect to a line connecting said second irradiation section to said second reading section.

6. A recording medium discrimination method comprising:

a reflected light reading step of illuminating a recording medium to obtain reflected light from a surface of the recording medium, and of reading regularly reflected light and diffusely reflected light obtained from the recording medium;

a transmitted light reading step of illuminating the recording medium to obtain transmitted light through the recording medium, and of reading regularly transmitted light and diffusely transmitted light transmitted through the recording medium; and

a discrimination step of discriminating a type of the recording medium by using a reflected light ratio defined as a ratio of a regularly reflected light quantity and a diffusely reflected light quantity which are read, and a transmitted light ratio defined as a ratio of a regularly transmitted light quantity and a diffusely transmitted light quantity which are read.

7. The recording medium discrimination method as claimed in claim 6, wherein the reflected light reading step and the transmitted light reading step radiate a plurality of different predetermined light quantities each, and read reflected light and transmitted light, respectively, and the discrimination step discriminates the type of the recording medium by using the reflected light ratio and the transmitted light ratio each obtained from the plurality of different predetermined light quantities.

8. The recording medium discrimination method as claimed in claim 7, wherein the reflected light reading step or the transmitted light reading step radiates in descending order of emitted light quantities.

9. The recording medium discrimination method as claimed in claim 6, wherein the reflected light reading step or the transmitted light reading step is carried out during conveyance of the recording medium.

10. An image forming apparatus including a image bearing member for bearing a latent image, a developing section for visualizing the latent image as a developed image by providing the image bearing member with a developing agent, a transfer section for transferring the developed image by said developing section to a recording medium conveyed in a predetermined direction, and a fixing section for fixing the developed image on the recording medium by heating and pressing the recording medium, to which the developed image is transferred by the transfer section, in predetermined fixing conditions, said image forming apparatus comprising:

a first irradiation section for illuminating the recording medium to obtain reflected light from a surface of the recording medium;

a second irradiation section for illuminating the recording medium to obtain transmitted light from the recording medium;

a plurality of reading means for reading regularly reflected light and diffusely reflected light reflected from the recording medium illuminated by said first irradiation section, and for reading regularly transmitted light and diffusely transmitted light transmitted through the recording medium illuminated by said second irradiation section; and

a discrimination section for discriminating a type of the recording medium by using a reflected light ratio defined as a ratio of a regularly reflected light quantity and a diffusely reflected light quantity obtained by said plurality of reading means, and a transmitted light ratio defined as a ratio of a regularly transmitted light quantity and a diffusely transmitted light quantity obtained by said plurality of reading means, wherein

the developed image is fixed on the recording medium by said fixing section in the fixing conditions corresponding to the type of the recording medium discriminated.

11. The image forming apparatus as claimed in claim 10, wherein said first irradiation section and said second irradiation section each radiate at a plurality of different predetermined light quantities, and said discrimination section discriminates the type of the recording medium by using the reflected light ratio and transmitted light ratio each obtained from the plurality of different predetermined light quantities by said first irradiation section and second irradiation section.

12. The image forming apparatus as claimed in claim 11, further comprising a reference plate that has a predetermined reflection characteristic and a predetermined transmission characteristic for light rays radiated from said first irradiation section and said second irradiation section, and is placed at a reading position of the recording medium.

13. The image forming apparatus as claimed in claim 10, wherein said first irradiation section and said plurality of reading sections are placed on one side of the recording medium, and said second irradiation section is placed on opposite side of said first irradiation section with respect to the recording medium.

14. The image forming apparatus as claimed in claim 10, wherein

said plurality of reading sections comprises a first reading section and a second reading section, and wherein

said second irradiation section and said second reading section are placed at positions opposing via the recording medium, and said first irradiation section and said first reading section are placed at positions having line symmetry with respect to a line connecting said second irradiation section to said second reading section.

15. The image forming apparatus as claimed in claim 10, further comprising post-processing control means for varying a number of sheets to be supplied to a post-processing unit in response to the type of the recording medium decided by said discrimination means.

16. The image forming apparatus as claimed in claim 15, wherein said post-processing unit has a staple stacker.

17. The image forming apparatus as claimed in claim 15, wherein said post-processing unit has a paper foldout function.

18. An image forming apparatus including an image bearing member;

a developing section for developing a latent image by providing a developing agent to the latent image formed on said image bearing member;

a transfer section for transferring the developed image developed on the recording medium by said developing section; and

a fixing section for fixing the developed image transferred on the recording medium by said transfer section, said image forming apparatus comprising;

a first irradiation section for illuminating the recording medium to obtain reflected light from a surface of the recording medium;

a second irradiation section for illuminating the recording medium to obtain transmitted light from the recording medium; and

a plurality of reading means for reading regularly reflected light and diffusely reflected light reflected from the recording medium illuminated by said first irradiation section, and for reading regularly transmitted light and diffusely transmitted light transmitted through the recording medium illuminated by said second irradiation section, wherein

the developed image is fixed on the recording medium by setting fixing conditions of said fixing section in accordance with a reflected light ratio defined as a ratio of a regularly reflected light quantity and a diffusely reflected light quantity obtained by said plurality of reading means, and a transmitted light ratio defined as a ratio of a regularly transmitted light quantity and a diffusely transmitted light quantity obtained by said plurality of reading means.

19. The image forming apparatus as claimed in claim 18, wherein said first irradiation section and said second irradiation section each radiate at a plurality of different predetermined light quantities, and said discrimination section discriminates between the types of the recording medium by using the reflected light ratio and transmitted light ratio each obtained from the plurality of different predetermined light quantities by said first irradiation section and second irradiation section.

20. The image forming apparatus as claimed in claim 18, wherein said first irradiation section and said plurality of reading sections are placed on one side of the recording medium, and said second irradiation section is placed on opposite side of said first irradiation section with respect to the recording medium.

21. The image forming apparatus as claimed in claim 18, wherein

said plurality of reading sections comprises a first reading section and a second reading section, and wherein

said second irradiation section and said second reading section are placed at positions opposing via the recording medium, and said first irradiation section and said first reading section are placed at positions having line symmetry with respect to a line connecting said second irradiation section to said second reading section.

22. A recording medium discrimination apparatus comprising:

an irradiation section for illuminating a recording medium;

a first photodetecting section for receiving regularly transmitted light passing through the recording medium illuminated by said irradiation section;

a second photodetecting section for receiving diffusely transmitted light passing through the recording medium illuminated by said irradiation section; and

a discrimination section for discriminating a thickness of the recording medium by using a ratio of an output obtained from said first detecting section and an output obtained from said second detecting section,

wherein said discrimination section discriminates the thickness of the recording medium on a basis of a plurality of said ratios obtained when illuminating the recording medium from said irradiation section at a plurality of different predetermined light quantities multiple times.

23. The recording medium discrimination apparatus as claimed in claim 22, wherein said discrimination section determines whether to illuminate the recording medium from said irradiation section at a second light quantity different from a first light quantity the recording medium on a basis of a ratio obtained when illuminating the recording medium from said irradiation section at said first light quantities.

24. A recording medium discrimination method comprising:

a step of illuminating a recording medium;

a step of receiving regularly transmitted light passing through the recording medium;

a step of receiving diffusely transmitted light passing through the recording medium; and

a step of discriminating a thickness of the recording medium on a basis of a ratio of the regularly transmitted light and the diffusely transmitted light which are received,

wherein said step of discriminating discriminates the thickness of the recording medium on a basis of a plurality of said ratios of lights transmitted when illuminating the recording medium at a plurality of different light quantities multiple times.

25. An image forming apparatus including an image bearing member;

a developing section for developing a latent image by providing a developing agent to the latent image formed on said image bearing member;

a transfer section for transferring the developed image developed on the recording medium by said developing section; and

a fixing section for fixing the developed image transferred on the recording medium by said transfer section, said image forming apparatus comprising;

an irradiation section for illuminating a recording medium;

a first detecting section for receiving regularly transmitted light passing through the recording medium illuminated by said irradiation section; and

a second detecting section for receiving diffusely transmitted light passing through the recording medium illuminated by said irradiation section;

a discrimination section for discriminating a thickness of the recording medium by using a ratio of an output obtained from said first detecting section and an output obtained from said second detection section,

wherein said discrimination section discriminates the thickness of the recording medium on a basis of a plurality of said ratios obtained when illuminating the recording medium from said irradiation section at a plurality of different light quantities multiple times,

wherein the developed image is fixed on the recording medium by setting fixing conditions of said fixing section on a basis of said discriminated thickness.