Optical writing head such as organic EL array exposure head, method of manufacturing the same, and image forming apparatus using the same

• US 7,081,912 B2
• Filed: 03/10/2003
• Issued: 07/25/2006
• Est. Priority Date: 03/11/2002
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Seki, Hideya, Yonekubo, Masatoshi
• Primary Examiner(s): PHAM, HAI CHI
• Application Number:
  US10/383,865
• Publication Number:
  US 20040021762A1
• Time in Patent Office: 1,233 Days
• Field of Search: 347/237, 347241-245, 347/247, 347256-258, 347/130, 347/238, 347/134, 347/137, 399/186, 399/379, 313/506, 313/509, 257/88, 362/555, 362/612, 362/613
• US Class Current: 347/244
• CPC Class Codes: B41J 2/451 Special optical means therefor, e.g. lenses, mirrors, focusing means

Abstract

The present invention relates to a small optical writing head, such as an organic EL array exposure head, having long work distance with little crosstalk, a method of manufacturing the same, and an image forming apparatus using the same. The optical writing head is an optical writing head which projects fluxes of modulated light from light-emitting parts 2 of a light-emitting element array such as an organic EL array or fluxes of modulated light transmitted through shutter parts 2 of an optical shutter element array onto an image carrier 11 to form a predetermined pattern on the image carrier 11. The optical writing head comprises ball lenses 10 which are arranged such that the alignment of the ball lenses 10 corresponds to the alignment of the light-emitting parts 2 of the light-emitting element array or the shutter parts 2 of the optical shutter element array.

Claims

1. An image forming apparatus comprising:

an organic EL array exposure head for writing an image on an image carrier, said organic EL array exposure head comprising;

a long transparent substrate,

an array of organic EL elements aligned just like pixels aligned in at least one row, and

a barrier plate formed with optical holes for preventing crosstalk of light, where crosstalk of light is a phenomenon that fluxes of light emitted from the light-emitting parts of adjacent organic EL elements are immixed at the condensing position of light from the light-emitting part of either organic EL element,

wherein

said barrier plate is arranged on the output side of said array of the organic EL elements on a side of said transparent substrate that is opposite to a side where said array of the organic EL elements is arranged,

plus lenses are arranged at positions of said holes of said barrier plate, respectively,

said image forming apparatus is a color image forming apparatus of a tandem type having at least two image forming stations each comprising a charging means, an exposure head, a developing means with toner, and a transfer means which are arranged around an image carrier, wherein said color image forming apparatus forms a color image by passing a transfer medium through the respective stations, and

said image forming apparatus satisfies both the following relations;

$\begin{array}{cc}<br><br>{\mathrm{\Phi <br><br>}}_T-{\mathrm{\Phi <br><br>}}_L<br><br>\le <br><br>0.2<br><br><br><br>\mathrm{eV}& \left(1\right)\\ <br><br>{\mathrm{\Phi <br><br>}}_T-{\mathrm{\Phi <br><br>}}_B<br><br>\ge <br><br>0.5<br><br><br><br>\mathrm{eV}& \left(2\right)\end{array}$

wherein φ

_L is the work function of the material for said plus lenses, φ

_B is the work function of the material of said barrier plate, and φ

_T is the work function of the material of toner.