JPH0391365A - Image sensor unit - Google Patents

Abstract

PURPOSE:To obtain an image sensor having the large depth of focus by employing a light emitting diode array light source having the illuminance distribution of the 4th power of cosine function taking the numerical aperture efficiency of a lens into account for an illuminating light source of an image sensor unit. CONSTITUTION:A light emitting diode array light source 2 having the illuminance distribution of the 4th power of cosine function in the main scanning direction taking the numerical aperture efficiency of a picture reduction lens 1 into account irradiates an original face 3 in a line. A reflected light from the original face 3 is reflected in a mirror 4 and the image is formed onto an image sensor 5 by the picture reduction lens 1. Through the structure above, since a light having the illuminance distribution of the 4th power of cosine function taking the numerical aperture efficiency of the picture reduction lens 1 into account irradiates in the main scanning direction of the original face, a picture without shading distortion is formed on the image sensor, thus a light shielding plate for shading correction is not required, the unit is more miniaturized than that of a conventional reduction system. Moreover, since the reflection mirror 4 is arranged in the inside of a same unit case 7, the unit is immune to vibration and the adjustment at every device is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image sensor unit that can be used in an image reading section of a facsimile machine, digital copying machine, etc.

Conventional technologyThe image reading method of some image scanners such as facsimiles and digital copiers is the same size (contact) type (Figure 2)
and reduction systems (Figure 3). As shown in the perspective view of FIG. 2, in the 1-magnification image sensor, light is irradiated onto the document 9 in a straight line from a light emitting diode aligned light source 8 having a uniform illuminance distribution in the main scanning direction, and a SELFOC lens array 10
This is a mechanism in which image information decomposed into minute pixels of the image sensor 11 arranged in a straight line is extracted as an electric signal for each pixel density on a 1:1 ratio. This 1x image sensor has already been realized as a 1x image sensor unit in which the light emitting diode array light source 8, the SELFOC lens array 10, and the image sensor 11 are arranged in the same interior. On the other hand, in the reduction type image sensor, as shown in the perspective view of FIG. Ru. The image formed on the image sensor 15 is taken out as an electrical signal for each pixel density. In this case, shading distortion is corrected by providing a light shielding plate 16 in the middle of the optical path.

Problems to be Solved by the Invention Among image reading systems, unitization has already been realized as a single-magnification image sensor. This same-size image sensor unit has advantages such as being compact as an image reading device and easy to assemble since no adjustment is required, but has a disadvantage that it requires precision in document feeding due to its small depth of focus. On the other hand, reduction type image sensors have a large depth of focus and can read originals with irregular heights, and have advantages such as being lower in price than the same magnification type. but,
It has drawbacks such as being unsuitable for use in a vehicle because it is susceptible to vibration, requiring a light shielding plate for shading correction to be provided in the middle of the optical path, resulting in a large size, and furthermore requiring adjustment for each device.

The present invention is weak against vibrations of a reduction type image sensor.
It is an object of the present invention to provide a reduced-size image sensor unit that has all disadvantages such as large size and the necessity of adjustment for each device being improved.

Means for Solving the Problems The image sensor unit of the present invention uses a COS fourth law illuminance distribution that takes into account the aperture efficiency of the lens, instead of using a fluorescent lamp that has a uniform illuminance distribution as an illumination light source for reading a document. We achieved miniaturization by using a light emitting diode aligned light source. Furthermore, the mirror for returning the light emitting diode aligned light source 1, the lens for image reduction, and the image sensor are fixedly arranged in the same interior and made into a unit, thereby improving vibration and eliminating the need for adjustment for each device.

Function: This image sensor unit is a compact and vibration-resistant image reading device that has a large depth of focus, is lower in price than the same magnification type, and has been improved from being large and susceptible to vibrations.

Embodiment An embodiment of the image sensor unit of the present invention will be described with reference to the sectional view of FIG. This structure takes into account the aperture efficiency of the image reduction lens 1, and uses a light emitting diode aligned light source 2 with an illuminance distribution according to the fourth power law of COS in the main scanning direction to illuminate the original surface.
is irradiated in a straight line. The reflected light from the document surface 3 is reflected by a mirror 4, and an image is formed on an image sensor 5 by an image reduction lens 1. According to this structure, light having an illuminance distribution based on the fourth power law of COS in consideration of the aperture efficiency of the image reduction lens 1 is irradiated in the main scanning direction on the document surface, so that the image sensor receives an image without shading distortion. imaged. Therefore, since a light shielding plate for shading correction is not required, the size can be reduced compared to conventional reduction systems. Furthermore, since the reflecting mirror is fixedly arranged inside the same unit case 7, it is resistant to vibration and does not require adjustment for each device.

Effects of the Invention According to the image sensor unit of the present invention, a light emitting diode aligned light source having an illuminance distribution according to the COS fourth law considering the aperture efficiency of the lens, a fixed reflection mirror, an image reduction lens, and an image signal converted into an electrical signal are provided. By placing the image sensors to be converted into a unit inside the same unit, we have created a reduced image sensor with a large depth of focus, which is smaller than conventional reduced image sensors, is resistant to vibration, and does not require adjustment for each device. can.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the image sensor unit of the present invention, Fig. 2 is a perspective view showing the optical system of the same-magnification (contact) type image reading system, and Fig. 3 is a perspective view showing the optical system of the reduction type image reading system. It is a diagram. 1... Image reduction lens, 2... Light emitting diode alignment light source, 3... Document, 4...
... Reflection mirror, 5... Image sensor, 6.
...Glass, 7...Unit case, 8
・・・・・・Light emitting diode alignment light source, 9・・・・・・
Manuscript, 10... SELFOC lens array, 1
1... Image sensor, 12... Fluorescent lamp, 13... Document, 14... Lens,
15... Image sensor, 16... Light shielding plate.

Claims (1)

[Claims] An image sensor unit characterized by optically arranging and integrating a light emitting diode aligned light source with a COS fourth law illuminance distribution, a reflecting mirror, an image reduction lens, and an image sensor that converts an image signal into an electrical signal. .