Apparatus to generate laser beam detect signal

• US 6,825,869 B2
• Filed: 11/12/2003
• Issued: 11/30/2004
• Est. Priority Date: 12/12/2002
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Bang, Doo-jin
• Primary Examiner(s): Tran, Huan
• Application Number:
  US10/704,918
• Publication Number:
  US 20040114029A1
• Time in Patent Office: 384 Days
• Field of Search: 347/235, 347/250
• US Class Current: 347/250
• CPC Class Codes: B41J 2/471 using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
• CPC Class Codes: G02B 26/125 Details of the optical system between the polygonal mirror and the image plane G02B26/123, G02B26/127 take precedence; F-Theta lenses G02B13/0005
• CPC Class Codes: G02B 26/127 Adaptive control of the scanning light beam, e.g. using the feedback from one or more detectors G02B27/0031 takes precedence

Abstract

An apparatus to detect a laser beam at a predetermined location within a light scanning unit of an image forming apparatus in order to synchronize a start position at which an electrostatic latent image is formed on a surface of a photosensitive body is disclosed. The apparatus includes laser beam detection optics, which may be formed of either a single unit lens or a cluster of one or more lenses that are placed in close proximity of each other. The laser beam detection optics receives the laser beam directed in the direction of the photosensitive body at a predetermined location relative to the start position on the photosensitive body, redirects the received laser beam towards a sensor, and focuses the laser beam on the sensing area of the sensor. The close proximity of, or the fact that the laser beam detection optics, minimizes the possibility of misalignment during the assembly that may result in the improper focusing of the laser beam on the sensor sensing area.

Claims

1. An apparatus for generating a laser beam detection signal in a light scanning unit that causes a laser beam to be scanned across a surface of a photosensitive body of an image forming device to form an electrostatic latent image on said photosensitive body, said laser beam being scanned across said surface of said photosensitive body in at least one scanning line that has a beginning point and an end point, said laser beam detection signal being used by said image forming apparatus to control said light scanning unit so that said beginning point occurs at a desired location, said laser scanning unit including at least a laser source and means for directing said laser beam emanating from said laser source towards a range of locations, said apparatus comprising:

a laser beam detecting sensor disposed at a sensor location that falls outside said range of locations; and

a single integrated optical element disposed at a predetermined location that falls within said range of locations, said single integrated optical element being arranged to receive said laser beam from said directing means, to deflect said received laser beam towards said laser beam detecting sensor, and to focus said deflected laser beam on said laser beam detecting sensor, said laser beam detecting sensor in response to said laser beam being focused thereon producing a signal indicative of said laser beam being detected at said predetermined location.

2. The apparatus according to claim 1, wherein the single integrated optical component comprises:

a first face having a reflective surface formed thereon; and

a second face having an incident surface and an emissive surface formed thereon, the incident surface having a first shape to direct laser beam received from said directing means to the reflective surface at an incident angle, and the emissive surface having a second shape to focus the laser beam reflected from the reflective surface on a sensing area of the laser beam detecting sensor.

3. The apparatus according to claim 2, wherein the reflective surface has at least one of a planar shape and a cylindrical shape.

4. The apparatus according to claim 2, wherein the first shape is at least one of a spherical shape and a cylindrical shape.

5. The apparatus according to claim 2, wherein the second shape is at least one of a spherical shape and a cylindrical shape.

6. The apparatus according to claim 1, wherein said predetermined location is located at an upstream of said beginning point of said at least one scanning line along said range of locations such that the laser beam received from said directing means is received by said single integrated optical element prior to said laser beam being incident on said beginning point of said at least one scanning line.

7. The apparatus according to claim 6, wherein said sensor location is located at an opposite side of said at least one scanning line from said predetermined location.

8. An apparatus for generating a laser beam detection signal in a light scanning unit that causes a laser beam to be scanned across a surface of a photosensitive body of an image forming device to form an electrostatic latent image on said photosensitive body, said laser beam being scanned across said surface of said photosensitive body in at least one scanning line that has a beginning point and an end point, said laser beam detection signal being used by said image forming apparatus to control said light scanning unit so that said beginning point occurs at a desired location, said laser scanning unit including at least a laser source and means for directing said laser beam emanating from said laser source towards said photosensitive body, said apparatus comprising:

a laser beam detecting sensor; and

one or more closely arranged optical element clustered together at a predetermined location that is at least one of a first predetermined location and a second predetermined location, said first predetermined location being upstream of said beginning point of said at least one scanning line such that the laser beam received from said directing means is received by at least one member of said one or more closely arranged optical element prior to said laser beam being incident on said beginning point of said at least one scanning line, said second predetermined location being downstream of said end point of said at least one scanning line such that the laser beam received from said directing means is received by at least one member of said one or more closely arranged optical element after to said laser beam being incident on said end point of said at least one scanning line, said one or more closely arranged optical element being configured to receive said laser beam from said directing means, to deflect said received laser beam towards said laser beam detecting sensor, and to focus said deflected laser beam on said laser beam detecting sensor, said laser beam detecting sensor in response to said laser beam being focused thereon producing a signal indicative of said laser beam being detected at said predetermined location.

9. The apparatus according to claim 8, wherein:

said one or more closely arranged optical element comprises a single integrated optical element having a first face having a reflective surface formed thereon and a second face having an incident surface and an emissive surface formed thereon, the incident surface having a first shape to direct laser beam received from said directing means to the reflective surface at an incident angle, and the emissive surface having a second shape to focus the laser beam reflected from the reflective surface on a sensing area of the laser beam detecting sensor.

10. The apparatus according to claim 9, wherein the reflective surface has at least one of a planar shape and a cylindrical shape.

11. The apparatus according to claim 9, wherein the incident surface has at least one of a spherical shape and a cylindrical shape.

12. The apparatus according to claim 9, wherein the emissive surface has at least one of a spherical shape and a cylindrical shape.

13. A light scanning unit for scanning a laser beam across a surface of a photosensitive body of an image forming device to form an electrostatic latent image on said photosensitive body, comprising:

a laser source for generating said laser beam;

means for directing said laser beam emanating from said laser source towards a range of locations, at least a portion of said range of locations being at least one scanning line across said surface of said photosensitive body, said at least one scanning line having a beginning point and an end point;

a laser beam detecting sensor mounted in said light scanning unit at a sensor location that falls outside said range of locations; and

one or more closely arranged optical element clustered together at a predetermined location that falls within said range locations, said predetermined location being at least one of a first predetermined location and a second predetermined location, said first predetermined location being upstream of said beginning point of said at least one scanning line such that the laser beam received from said directing means is received by at least one member of said one or more closely arranged optical element prior to said laser beam being incident on said beginning point of said at least one scanning line, said second predetermined location being downstream of said end point of said at least one scanning line such that the laser beam received from said directing means is received by at least one member of said one or more closely arranged optical element after to said laser beam being incident on said end point of said at least one scanning line, said one or more closely arranged optical element being configured to receive said laser beam from said directing means, to deflect said received laser beam towards said laser beam detecting sensor, and to focus said deflected laser beam on said laser beam detecting sensor, said laser beam detecting sensor in response to said laser beam being focused thereon producing a signal indicative of said laser beam being detected at said predetermined location.

14. The light scanning unit according to claim 13, wherein:

said one or more closely arranged optical element comprises a single integrated optical element having a first face having a reflective surface formed thereon and a second face having an incident surface and an emissive surface formed thereon, the incident surface having a first shape to direct laser beam received from said directing means to the reflective surface at an incident angle, and the emissive surface having a second shape to focus the laser beam reflected from the reflective surface on a sensing area of the laser beam detecting sensor.

15. The light scanning unit according to claim 13, wherein:

said sensor location is near said first predetermined location if said one or more closely arranged optical element is positioned at said second predetermined location, and is near said second predetermined location if said one or more closely arranged optical component is positioned at said first predetermined location.

16. The light scanning unit according to claim 14, wherein the reflective surface has at least one of a planar and a cylindrical shape.

17. The light scanning unit according to claim 14, wherein the incident surface has at least one of a spherical and a cylindrical shape.

18. The light scanning unit according to claim 14, wherein the emissive surface has at least one of a spherical and a cylindrical shape.

19. The light scanning unit according to claim 14, wherein the reflective surface comprises a reflective film formed on the first face.

20. The light scanning unit according to claim 14, wherein the reflective surface comprises a mirror member attached to the first face.