JPS6363275A - Reader - Google Patents

Abstract

PURPOSE:To prevent the entry of scattered light from a fluorescent tube and unnecessary light caused by irregular reflection on a platen glass, an original, a housing or the like to a solid-state image pickup element by providing a slit on a luminous flux path between the lighting fluorescent tube and a 1st mirror, and passing through only a necessary luminous flux. CONSTITUTION:A narrow paper tablet-shaped opening B41b transmitting the luminous flux on the original 2 to a 1st mirror 7 is provided on the lower surface of the housing 41. A lamellate light shielding material 42 obtained by opening the narrow paper tablet-shaped slit 42a is fitted on the housing 41 by adjusting a slit position. The width of the slit 42a is set slightly larger than that of the necessary flux in order to prevent miscellaneous light from entering the solid-state image pickup element. By setting such a slit 43a, the unnecessary light irregularly reflected in the housing 41 is practically blocked. The slit part of the light shielding material 43 is made into a groove-like slit 43a with a loading part along an optical axis toward the surface of the original, whereby the miscellaneous light obliquely making incident on the slit is reflected and absorbed by the slit leading part. When said light passes by the slit, its influence is substantially reduced.

Description

[Detailed description of the invention] [fr: Utilization field above]

The present invention relates to a reading device such as an image forming apparatus such as a facsimile machine or a copying machine, and more specifically, the present invention relates to a reading device such as an image forming apparatus such as a facsimile machine or a copying machine. The present invention relates to a reading device that reads an original image using a solid-state image sensor such as a sensor.

[Background of the invention]

In a reading device, an optical image of the document surface obtained by exposure scanning is generally formed by using an imaging lens system on a solid-state imaging device such as an image sensor located around the optical axis. . For example, in the reading device of a color image forming apparatus, the light image of the document surface obtained by exposure scanning is passed through an imaging lens system, and then separated by a light splitting means such as a prism installed behind it. The image is formed on an image sensor that receives light through the channels. In the exposure scanning of the reading device, in which the document table is fixed and the optical system is moved, the document placed on the platen plus is irradiated in the form of a strip by a moving light source, and the document image irradiated by the light source is The light is reflected and guided by a first mirror that moves with the light source, and second and third mirrors installed on the movable mirror unit nose, and is also fixed behind it through a fixed imaging lens. An image is formed on the image sensor. A rod-shaped halogen lamp or fluorescent tube is used as a light source. Fluorescent tubes are often used because halogen lamps generate a lot of heat when continuously lit. In addition to the light flux of the original image required to form an image on the line image sensor, the scanning optical system and imaging lens mentioned above are equipped with internal reflections and diffused reflections of indoor light from the platen glass and light from light sources such as fluorescent tubes. When unnecessary light (miscellaneous light) generated by other sources enters the line image sensor, it weakens the contrast of the image, further reduces the color balance in the case of color images, and lowers the image quality of the scanned document. It's so obvious.

[Problems to be solved by the invention]

The present invention provides a reading device that uses, for example, a fluorescent tube as a light source and reads an original image illuminated by a movable optical system, which prevents unnecessary light from entering a solid-state image sensor as much as possible, thereby obtaining good image quality. The purpose is to

[Means to solve the problem]

The present invention attempts to solve the above problems, and consists of a movable carriage composed of a light source for irradiating a document and a first mirror, and a movable carriage composed of two mirrors arranged in the shape of a letter . In the reading device, the reading device includes a movable mirror unit, a fixed imaging lens, and a solid-state imaging device provided behind the imaging lens, and the reading device is configured to form the document image on the solid-state imaging device. This is achieved by a reading device characterized by providing a shielding material having a slit between the two.

【Example】

Before explaining the reading device of the present invention, the image forming device will first be explained. FIG. 3 shows the configuration of an image forming apparatus equipped with the image reading device of the present invention, and a color image is formed in the following manner. In FIG. 3, A is a reading device, B is a writing unit,
C is an image forming section, and D is a paper feeding section. In the reading device, 1 is a platen glass, and a document 2 is placed on this platen glass 1. The document 2 is illuminated by fluorescent lamps 5 and 6 provided on a carriage 4 that moves on a slide rail 3. Movable mirror unit 8
mirrors 9 and 9' are provided, which move on the slide rail 3, and in combination with the tjSi mirror 7 provided on the carriage 4, capture the optical image of the document 2 on the platen glass 1 into a lens r=q scanning unit. 20. The carriage 4 and the movable mirror unit 8 are moved by pulleys 11, 12, 13, and 14 driven by a stepping motor 10 via a wire 15, respectively.
are driven in the same direction at a speed of v. Standard white plates 16 and 17 are provided on the back side of both ends of the platen plus 1, and are configured so that a standard white signal can be obtained before the start of original reading scanning and after the end of scanning. The lens reading unit 20 includes a lens 21 as a reading lens system, a prism 22 as a light decomposition means, a first reading board 24, and a red channel (hereinafter referred to as R-cl+) CCD 27.12 as a line image sensor.
Reading board 26, cyan channel (hereinafter C-cl+
) consists of 25 CCDs. first mirror 7,
The original light image transmitted by the mirrors 9 and 9' is focused by a lens:
A C-ch CCD 25 and a second VC removal substrate 26 are separated from each other and provided on the first reading substrate 24.
Each of the light receiving surfaces of the R-ah CCD 27 provided above is imaged. For the fluorescent lamps 5 and 6, commercially available warm white fluorescent lamps are used as light sources to prevent emphasis or attenuation of specific colors when reading color originals, and 40° C. fluorescent lamps are used to prevent flickering.
It is lit by a high-frequency Ti source from K Itz and is kept warm by a heater using a POSISTOR to maintain a constant temperature of the tube wall or to promote temperature-up. The C-cb CCD 25 and R-ch CCD 2
The image signal output from J! 7 passes through a signal processing section (not shown) and is sent to J! ! When a color signal divided into M colors according to the toner color is outputted and inputted to the writing unit B, each laser beam generated by the semiconductor laser is sequentially projected onto the circumferential surface of the photoreceptor drum 31. , a color image (X') is formed using three-color toner through development processing for each projection. Next, the color image on the circumferential surface of the photoreceptor drum 31 is transferred to a recording layer conveyed from the paper feed section at a transfer separation waterfall 32. After being transferred to paper, the recording paper is separated and ejected from the apparatus through a fixing device 33 to complete the duplication of the color image. Figure f54 shows the main part of the structure of the image reading device A described above. The machine frame that houses the reading device A is constructed as follows: The bottom part of the reading device A has a vertical plane facing forward and backward in the direction of movement of the moving optical system. The side plates 51 and 52 are integrally formed, and a pair of left and right frame plates 53 are symmetrically attached and fixed to the bent portions 51a and 52a provided at the left and right ends respectively, and are attached to the reading device together with the bottom portion. On the other hand, a pair of left and right substrates 54, each having a U-shaped space 54a formed by bending, is in a state in which the space 54a protrudes to the outside of the machine frame. It is fixed to the bent portions 51b, 52b of the side plates 51, 52 and to the inner surface of the frame plate 53 by screws X, and the platen glass 1 is placed and fixed on the upper surface thereof. The carriage 40, which is a movable mirror unit, and the movable mirror unit F80 are housed inside the substrate 54, and both wing portions 40a, 80a of each are attached to a slide point (not shown) made of polyacetal or PPT resin, etc. attached to the bottom surface. The carriage 40 and the movable mirror unit 80 are placed so as to be slidable on a slide rail 3 made of high-density polyethylene or the like laid on the bottom surface of the space 54a. It is formed by a separate member (not shown) from the rail 3. Furthermore, notches 54b and 54c are provided at both ends of the board 54.
A fixed boot 912 is provided facing the notch 54b, while a boo 912 is fixed in a position facing the notch 54c and is pushed counterclockwise by a tension lever 13a pivoted to the front J frame [53]. pulleys 13 are disposed on the outside of the substrate 54, respectively. Further, on the frame 4i53 facing the outside of the substrate 54, a stepping motor 10 for moving a moving optical system rotates a pulley 11, which is a driving J pulley, which is also pivoted on the frame plate 53 via a timing belt 10a. The installation is supported as possible. In this way, the wire 15 for moving and controlling the moving optical system is fixed on both wing sections 40a of the carriage 40 after going around the pulley 12, and one end thereof is fixed on both wing sections 40a of the movable mirror unit 80. After going around the lower pulley 14 above the pulley 80a and inverting it, the third pulley 80a is fixed to the board 54 at its end, whereas the other end around which the pulley 11 is wound is Said boo 1
After going around the upper pulleys 14 on both wings of the movable mirror unit 80 from J13 and being reversed, it is fixed on the substrate 54 at S2. That is, since the wire 15 is always maintained at a predetermined tension by the action of the tension lever 13a, when the stepper motor 10 is operated and the boo Ull is rotated counterclockwise, the movable mirror is moved along with the carriage 74 by the amount 172. The unit 80 is the space 54a of the substrate 54.
The exposure scanning of the entire surface of the document 2 is performed while satisfying the imaging conditions of the optical system by moving to the left inside the document 2. Figure fjS1 shows a side sectional view of the optical system in the above reading device. The document 2 placed on the platen glass 1 is illuminated by a pair of fluorescent tubes 50 provided in a carriage 40 that moves on a slide rail. The optical image of the original i product 2 is reflected by the first mirror 7 integrally provided on the carriage 40 and the mirrors 9 and 9'' provided in a V-shape in the movable mirror unit 80 to the lens reading unit 20. The lens reading unit 20 covered by the cover 60
is an image forming lens 21, a color separation prism 22 bifurcated behind it, and a C-ell CCD 25, which is a solid-state image sensor provided at the image forming position, and R-c! ＋C
Comprised of CD 27. The light flux reflected and transmitted by the first mirror 7, mirror 9, and mirror 9' is focused by the imaging lens 21, and the prism 2
C-ah
The image is separated into an image and a R-ah image, and the images are formed on the light receiving surfaces of the C-cb CCD 2'J and the R-cl+ CCD 27. FIG. 2 CaHb') shows a cross-sectional view of the interior of the tube 40 according to the present invention, and a pair of fluorescent tubes 50 for illumination used in this ninth embodiment have a part of the tube wall oriented in the longitudinal direction. This is a so-called 7 part 7 type fluorescent tube having an opening 50b to which no fluorescent material is applied. The fluorescent tube 5
Since the opening 50b is placed opposite to the document surface to be irradiated, the document surface in the scanning section can be efficiently irradiated in a similar shape. Further, since a pair of fluorescent tubes 50 are provided symmetrically with respect to the vertical light flux in the direction perpendicular to the document surface in the scanning section, a sufficient amount of light is irradiated onto the document surface in the scanning section. Furthermore, since the fluorescent tube 50 generates significantly less heat than a halogen lamp, it can be installed close to the platen plus 1, making it possible to illuminate the surface of the scanned document with high intensity. Solid-state imaging device C-cl+ CCD used in this example
25 and R-ah CCD 27 are line sensors constructed with pixel elements with a pixel width of about 7 μm, and the imaging lens 21 has a focal length of 45 mm and a pupil diameter of 11.2 mm, with a reduction ratio of 0.112. is set to read images. Therefore, the distance between the pair of fluorescent tubes 50 used in the embodiment is approximately I
It is installed at I and has the effect of a slit. The carriage 40 is provided with a housing 41 whose inner surface is coated with black anti-reflection treatment and surrounds the pair of fluorescent lights W50 arranged at the above-mentioned interval from four sides. The upper surface of the housing 41 has fluorescent LR! An opening ^41a is provided for the light emitted from the document 2 to illuminate the document 2, and a strip-shaped opening 841b is provided on the lower surface of the housing 41 for transmitting the light beam of the document 2 to the first mirror 7.
is the provision. The first embodiment of the present invention is shown in FIG.
As shown in a), a plate-shaped shielding material 42 with a strip-shaped slit 7) 42a opened at the opening 841b on the lower surface of the housing 41 is attached to the housing 41 after adjusting the slit position. The slit width of the pickpocket 7) 42a is such that the miscellaneous light is solid wt(
In order to prevent the light from penetrating the two elements, the required light flux is set to slightly exceed the required light flux. If the width is approximately .1+am, it is sufficient to allow the light flux to pass through, but in this embodiment, the width is set to 1 ml1, which is set wide to allow for some margin. As shown in this embodiment, a slit 42a that is treated to prevent reflection in the luminous flux is set in an extremely narrow part of the luminous flux reaching the mirror 7, thereby eliminating unnecessary diffused reflection within the housing 41. Most of the light will be blocked. FIG. 2(b) shows a carriage 4 according to a second embodiment of the present invention.
0 is shown. This embodiment is the same as the first embodiment with respect to the fluorescent tube 50, housing = $1, carriage 40, etc. In this embodiment, the slit portion of the shielding material 43 installed on the lower surface of the housing 41 is a groove-shaped s') y) 43a with a rising portion along the optical axis toward the document surface, and the opposing groove portion is treated with anti-reflection treatment. The necessary light flux from the document that is effective for forming an image on the solid-state imaging element, which is incident directly on the groove part, passes through the slit 7F, but the light flux that is incident on the slit obliquely passes through the slit 7F. When the light is reflected and absorbed by the rising edge of the slit and passes through the slit, its influence is greatly attenuated. In the first embodiment of the fjS2 described above, the shielding members 42 and 43 with the long slits are both separate members from the housing 41, but of course they are the same member, and the slits are provided directly on the housing 41. There is no problem. In addition, the shielding materials 42 and 43 are each made of two members, and the slit width is i1! It is also possible to permanently install it after it has been adjusted.

【Effect of the invention】

According to the present invention, by installing a shield member having a slit that allows only the necessary light to pass through the path of the light flux between the fluorescent tube for illumination and the first mirror, the scattered light emitted from the fluorescent tube can be removed from the platen glass. It is now possible to provide a reading device that prevents unnecessary light reflected from documents, housings, etc. from entering the solid-state image sensor, and that can obtain images with good contrast and, in the case of color, good color balance. Ta.

[Brief explanation of drawings]

Figure vJ1 is a cross-sectional view of the optical system of the reading device according to the present invention.
FIG. 2(,) shows a sectional view of the carriage of the fjS1 embodiment, and FIG. 2(b) shows a sectional view of the carriage of the second embodiment. ! Figure @3 is a configuration diagram of an image forming apparatus to which the present invention is applied, and Figure PIS4 is a perspective view of a reading device. 1... Platen glass 2... Document 7... First mirror 9, 9''... Mirror 20... Lens reading unit 21... Imaging lens 22... Prism 25-
C-ah CCD 27- R-ah CCD
40... Carriage 41... Housing 41
a...Opening A 41b...Opening B421
．． 43... Shielding material 42a-... Slit 43a
... Groove-shaped slit 50 ... Fluorescent tube 80 ... Movable mirror unit Fig. 2 (OL) 1゛7 j) nB between 1b

Claims (3)

[Claims] (1) A movable carriage consisting of a light source for illuminating a document and a first mirror, a movable mirror unit consisting of two mirrors arranged in a V-shape, a fixed imaging lens, and A reading device comprising a solid-state image pickup device provided at the rear and configured to form an image of the document on the solid-state image pickup device, wherein a shielding material having a slit is provided between the light source and the first mirror. A reading device characterized by: (2) The reading device according to claim 1, wherein the slit is a groove-shaped slit having a rising portion along the optical path. (3) The reading device according to claim 1 or 2, characterized in that a light splitting member is provided between the imaging lens and the solid-state image sensor.