JPS63301935A - Image reader - Google Patents

Abstract

PURPOSE:To prevent the dirt due to dust mixed in sucked outside air by providing a blowing means with a dustproof filter, a shielding plate which is provided at the rear of the mirror unit of an optical system and faces the blowing direction of the blowing means, and a dustproof cover which covers an image pickup unit. CONSTITUTION:A blowing means 80 has a fan front chamber 82 where a dustproof filter 82 is attached to a front aperture part, and dust in outside air is removed by the dustproof filter 83. Outside air from which dust is removed is sent into a device by an electric fan 81 and is turned by a mirror back shielding plate 84 facing the blowing means 80 and a branched into two. One passes above the mirror back shielding plate 84 and under an original platen glass and is discharged out of the device through an aperture part 90a on the side face of a device frame. The other passes under the mirror back shielding plate 84 and along a dustproof cover 85 covering the image pickup unit and is discharged out of the device through the aperture part 90a. Thus, the blowing direction is changed to prevent outside air from directly acting upon respective members of the optical system, and sticking of dust to them is prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides an ff! system for use in, for example, facsimiles, copying machines, etc., in which an optical image of a document obtained by an exposure optical system that scans while irradiating the surface of the document is formed in an imaging unit.
ii. relates to an image reading device.

[Background of the invention]

In image reading devices, an optical image of the document surface obtained by exposure scanning is generally formed on a solid-state imaging device such as an image sensor installed with the optical axis as the center via an imaging system. There is. For example, in an image reading device of a multicolor image forming apparatus, a light image of the document surface obtained by exposure scanning is passed through an imaging lens system, and a lens system is provided on the optical axis of the document light image and behind it. After the light is separated by a light splitting means such as a prism, an image is formed on an image sensor that receives the light in each channel. The temperature of the document table glass on which the document is placed is raised by an exposure light source that illuminates the document. The standard value for the temperature rise of the original table glass is defined as room temperature +45°C. If the image reading device is operated continuously for a long time, the temperature of the document platen glass may rise and exceed the above-mentioned standard value. Therefore, means are usually provided to reduce the temperature within the device. The means for lowering the temperature inside the apparatus is often a blowing means that draws in outside air and blows it into the apparatus. Conventionally, when this kind of ventilation means blows outside air into the cabin of the machine, it also tills dust mixed in with the outside air, and the dust adheres to the mirrors, lenses, etc. of the optical system, impairing the image reading function. It had the disadvantage of 1.

[Problems to be solved by the invention]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is intended to reduce the amount of dust mixed in the outside air drawn into the image reading device, and to reduce the amount of dust drawn into each member of the optical system in the device. It is an object of the present invention to provide an image reading device that is configured so as not to be directly affected by the outside air that is drawn in, and can prevent contamination due to dust mixed in the outside air that is drawn in.

[Means to solve the problem]

The above object is to provide an image reading apparatus that scans and exposes a document on a document platen glass using an exposure light source of an optical system and forms a light image of the document in an imaging unit F. an air blowing means with a dustproof filter that sucks in outside air to lower the temperature inside the apparatus; a shielding plate facing the direction of air blowing from the air blowing means on the back of the mirror unit of the optical system; and a dustproof cover that covers the imaging unit. This is achieved by an image reading device characterized by the following.

【Example】

Prior to a detailed description of the present invention, general functions of the image reading device will be described. FIG. 3 is a configuration diagram of the image reading device. In the same figure,
Reference numeral 1 denotes an original platen glass, and the original MA2 is placed on this original platen glass. The original 2 is illuminated by fluorescent lamps 5 and 6 provided in an exposure light source unit 40 that moves on the slide rail 3. The movable mirror unit 70 is provided with mirrors 9a and 91) that move on the slide rail 3, and the first mirror 7 provided in the exposure light source unit 40 is configured to adjust the light of the original 2 on the original platen glass 1 in which combination. The image is guided to the imaging unit 20. The exposure light source unit 40 and the movable mirror unit 70 are driven by a driving device (not shown) consisting of a stepping motor, a pulley, a wire, etc., respectively.
are driven in the same direction at a speed of A standard white plate 16 is provided on the back side of the front end of the document platen glass 1, and is configured to obtain a standard white signal before starting the document reading scan. The imaging unit) 20 includes a lens 21 as an imaging lens system.
, a prism 22 as a photolysis means, and a first reading substrate 24
, red channel (hereinafter referred to as R), which is a line image sensor
-cl+) CC [127], second reading board 26, and cyan channel (hereinafter referred to as C-cl+) CCD 25. First mirror 7, mirror 9a, mirror 91
] is focused by a lens 21, and separated into a C-cl+ image and an R-cl+ image by a microink mirror provided in a prism 22. The C-011 image is then
-eh Imaged on the light receiving surface of CCD 25, R-cl+
The image is R-cl+C provided on the second reading substrate 26
An image is formed on the light receiving surface of the CD 27. As the fluorescent lamp 5.6 for illuminating the document, a commercially available warm white fluorescent lamp is used to prevent emphasis or attenuation of specific colors based on the light source when reading a color document. Also, to prevent flickering, the lights are powered by a 40Ktlz high frequency power source. The fluorescent lamps 5 and 6 are heated by a heater (not shown) using a POSISTOR in order to maintain a constant temperature of the tube wall or to increase the ohm. Imaging lens 21 and photolysis prism 2 of imaging unit 20
2 is attached by a mounting member or the like. Solid-state image sensor C-ch CCD 25 and R-ch CCD
27 are fixed to the photoresolving prism 22 with adhesive or the like after highly accurate position adjustment. Solid-state image sensor C-cl+ CCD25 and R-ch C
The CD 27 is a line image sensor composed of pixel elements with a pixel width of approximately 7 μm. Figure #1 is a perspective view of the main parts of an image reading device showing an embodiment of the present invention, and Figures 2a and 2b are side sectional views of the image reading device showing the relationship between the movable mirror unit and the air blowing means. . In these figures, 80 is a ventilation means, 81 is an electric fan, 82 is a 7-amp front chamber, 82a is a suction opening, 83 is a dustproof filter, 84 is a mirror rear shielding plate, 85 is a dustproof cover, and 85a is an entrance opening. . The air blowing means 80 is composed of an electric fan 81, a fan front chamber 82, and a dust filter 83, and is installed on the side plate 90 of the machine frame of the image reading device so as to face the back of the movable mirror unit 70. The blowing means 80 installed on the side plate 90 of the machine frame sucks in outside air and blows it into the device to lower the temperature inside the device. The air blowing means 80 has a fan front chamber 82 on the suction side, and the blown outside air passes through this fan front chamber 82 once. The curved opening of the fan front chamber 82 is formed to have a larger diameter than the effective diameter of the electric 7T fan 81, and a dust filter 83 is installed in the front opening. The mirror rear shielding plate 84 is a shielding member provided on the rear surface of the movable mirror unit 70. Mirror back shielding plate 8
4 faces the air blowing means 80, and therefore the direction of the outside air from the air blowing means 80 is changed by the mirror rear shielding plate 84. The outside air whose direction of blowing has been changed is divided into two by this mirror back shielding plate 84. One of them goes around above the mirror back shielding plate 84, passes through the lower surface of the document table glass 1, and is exhausted to the outside of the NFI through an opening 90a on the side of the machine frame opposite to the side where the air blowing means of the image reading device is installed. be done. The other part goes around below the mirror back shielding plate 84 and reaches the dustproof cover 85 that covers the imaging unit 20, and is exhausted out of the machine from the opening 90a along the dustproof cover 85. The dustproof cover 85 is a dustproof member that covers the imaging unit 20. The dust-proof cover 85 has an entrance opening 85a that does not prevent the light image of the original 2 from entering, and the light image of the original 2 passes through the entrance opening 85a and enters the imaging unit 20.
and forms an image on the solid-state image sensor. The embodiment of the present invention is constructed as described above, and its operation will be explained below. When the image reading device is continuously used, the temperature of the document table glass rises due to the irradiation of the exposure light source that scans the document. The upper limit of the temperature rise of the document table glass is determined to be room temperature +45°C, and when the temperature reaches a predetermined temperature set lower than this upper limit, the air blowing means 80 is activated. The air blower 80 has a fan front chamber 82 with a dustproof filter 83 attached to its front opening, and the dustproof filter 83 removes dust in the outside air. Fan front chamber 82
The one section between the front surfaces is formed to have a larger diameter than the effective air diameter of the electric fan 81 to prevent the air blowing efficiency from decreasing due to the frictional force of the filter 83 passing through the outside air. The outside air from which dust has been removed is sent into the apparatus by an electric 7-amp 81, and the direction of the air is changed by a mirror rear shielding plate 84 facing the air blowing means 80. The outside air whose direction of blowing has been changed is divided into two by this mirror back shielding plate 84. One of them goes around above the mirror back shielding plate 84, passes through the lower surface of the document table glass 1, and exits the machine through an opening 90a on the side of the machine frame opposite to the side where the air blowing means of the image reading device is installed. is exhausted to. The other one goes around below the mirror back shielding plate 84 and reaches the dustproof cover 85 that covers the imaging unit 120.
5 to the outside of the machine through the opening 90a. 2a and 2b show each member of the optical system and the air blowing means 80.
It shows the positional relationship with Figure 2a shows the exposure light source unit 40 and the movable mirror unit 7 at the start of scanning exposure.
FIG. 2b shows the operating positions of the exposure light source unit 40 and the movable mirror unit 70 at the end of scanning exposure. In either case, the first mirror 7, mirror 9
a, 9b, the imaging unit 20 is connected to the mirror rear shielding plate 8;
4 from the direct blowing action of the blowing means 80.

【Effect of the invention】

According to the present invention, it is possible to take outside air from which dust has been removed into the device without reducing the blowing efficiency, and the direction of the taken outside air can be changed once by a shielding plate behind the mirror unit. It is possible to provide an image reading device that can prevent dust from adhering to each member of the optical system by preventing it from directly acting on each member of the optical system, and that can obtain clear and accurate image information. It became a thing.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of an image reading device showing an embodiment of the present invention, FIGS. FIG. 1 is a configuration diagram of an image reading device. 1... Original table lath 2... Original 40... Exposure light source unit 70... Movable mirror unit

Claims (3)

[Claims] (1) In an image reading device that scans and exposes a document on a document platen glass using an exposure light source of an optical system and forms a light image of the document in an imaging unit, outside air is applied to the side plate of the machine frame of the image reading device. An image reading device comprising: a blowing device for lowering the internal temperature of the device by sucking in air; and a shielding plate arranged at the back of the mirror unit of the optical system and facing in the direction of air blown by the blowing device. (2) A front chamber having a suction opening having a diameter larger than the effective diameter of the air blowing means is provided on the suction side of the air blowing means, and a dustproof filter is attached to the suction opening. The image reading device according to item 1. (3) The image reading device according to claim 1 or 2, characterized in that the imaging unit is provided with a dustproof cover having an entrance closure that does not prevent the incidence of the original optical image.