JPS59175174A - Light emitting diode array - Google Patents

Abstract

PURPOSE:To make the photoelectric conversion output signal uniform by a method wherein the arrangement of a diode array is made coarse to dense from the center to the end. CONSTITUTION:The arrangement of light emitting diodes is so performed that the array end becomes in dense pitch, the center in coarse one, and the medium part in the intermediate one between dense and coarse, thus making the amount of image-forming light in an optical image forming plane uniform at a necessary part. As a result, the photoelectric conversion output signal becomes uniform because of obtaining the amount of uniform image forming light in said plane, therefore a uniform reproduced picture image can be obtained. Accordingly, the shading as conventional that the amount of image forming light by the uniform amount of light becomes large at the center of said plane and smaller toward the periphery can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to shape ink correction of a photoelectric conversion unit that converts a document into an electrical signal in a facsimile machine or the like.

[Prior art]

In the photoelectric conversion section of most facsimile machines, a difference in the amount of light occurs between the center and the periphery of the optical image due to unevenness in the amount of light and spherical aberration of the lens, which affects the electrical output signal (this is called shading). ). Various methods have been used in the past to obtain uniform reproduced images.

FIG. 1 shows an example in which the amount of light incident on a lens is corrected by a light shielding plate. FIG. 2 is a sectional view of the light shielding plate.

FIG. 3 shows an example in which a reflected light amount correction plate is provided near the original reading surface to correct the amount of light incident on the lens.

[Purpose of the invention]

The present invention differs from conventional methods in that it provides a method for uniformizing photoelectric conversion output signals by considering the amount of light from the light source itself, including the shading of the lens system, in advance. In addition, conventional facsimile machines and other devices use fluorescent lamps as light sources, but a special lighting device is required to drive the fluorescent lamps, and fluorescent lamps cannot be used continuously or intermittently. Regardless of the problem with lifespan,
There was also an economic problem as they had to be treated as consumables.

The present invention has been made in view of these points, and the present invention aims to extend the lifespan and simplify the drive circuit by using a light emitting diode array, which is a semiconductor light emitting element, as a light source. The purpose is to perform shading correction and obtain a uniform reproduced image by performing the following steps.

[Embodiments of the invention]

FIG. 4 shows an embodiment of a photoelectric conversion section in which the light emitting diode play of the present invention is used.

2 is a document, 3 lenses, 4 photoelectric conversion elements, 5 is a preamplifier that amplifies the output signal of the 4 photoelectric conversion elements, 7 is an optical axis of the lens, 8 is an optical imaging plane of the photoelectric conversion element 4, 11 is a 1 is a light emitting diode array that is a light source of the present invention. The light from the light emitting diode play is reflected by the original 2, passes through the optical axis 7, and is imaged by the lens 3 on the optical imaging surface 8 of the photoelectric conversion element 4. This imaged optical signal is converted into an electrical signal by a photoelectric conversion element 4 and amplified by a preamplifier 5. The light emitting diode array 11 used here is shown in Fig. 5 (α).
Assuming that the diode array is as shown in Figure 5 (hl), the amount of light in the play direction, that is, the amount of light on the document reading surface is as shown in Figure 5 (hl). The amount of light formed on the image plane 8 is as shown in FIG. 5(C), where the center is bright and the amount of light is small at the periphery, so that the output signal of the photoelectric conversion element 4 is no longer uniform. Therefore, we arranged the individual diodes of the light emitting diode array as shown in Figure 6 (al), and calculated the amount of light as shown in Figure 6 (al).
By setting it as A+, it becomes possible to make the amount of imaging light on the optical imaging surface 8 uniform in the necessary portion.

〔Effect of the invention〕

As described above, according to the present invention, since a uniform amount of imaging light is projected on the optical imaging surface, the photoelectric conversion output signal becomes uniform, so that a uniform image on the reproduction surface J can be obtained.

[Brief explanation of the drawing]

In Figure 1, the amount of light incident on the lens is supplemented by a light shielding plate. 2 is a sectional view showing an example of a light shielding plate, and FIG. 3 is an explanatory view showing an example of correcting the amount of light incident on the lens by installing a reflected light amount correction plate near the document reading surface. , FIG. 4 is an explanatory diagram of the operation of the male light emitting diode of the present invention. 1... Fluorescent light 2... Original 3... Lens 4... Photoelectric conversion element 5... Preamplifier 6... Light shielding plate 7... Optical axis of lens 8... Photoelectric conversion element 4. Optical imaging surface 9...Reflection plate 10...Reflected light amount correction plate 11...Light emitting diode array, 4. Figure 1 Figure 2 Figure 3V Figure 5 2

Claims (1)

[Claims] t In facsimile machines and other devices that use a light emitting diode array as a light source in a photoelectric conversion section, the light emitting diodes are arranged densely at the playing edges, sparsely in the center, and with a pitch between dense and coarse in the middle. A light emitting diode array characterized in that seeding correction in an optical system is performed by performing the following steps.