JPS62112469A - Image reader - Google Patents

Abstract

PURPOSE:To prevent an image sensor from the rise of temperature and to output an always normal image signal by using the return driving of an optical system to rotate a cooling fan. CONSTITUTION:An one-way clatch 41 capable of transmission of the rotational motion of a rotary shaft 11a to a sleeve member 42 only when the rotary shaft 11a is rotated in the clockwise direction is formed on the outer periphery of the rotary shaft 11a. A cross flow fan 43 is fixed on the sleeve member 42 as a cooling fan so as to be rotated only when a stepping motor 10 is reversely rotated. When the stepping motor 10 is reversely rotated after the end of exposure scanning, a carriage 4 and a movable mirror unit 8 start forward movement at a speed corresponding to approximately 10 times the reciprocation simultaneously with the OFF of fluorescent lamps 5, 6. Consequently, the fan 43 is rotated at a high speed, air of low temperature is carried from the outside of a machine frame 50 to a prism 22, an R-chCCD 25 and C-chCCD 27 arranged on the back of a lens 21 through a suction hole 44 arranged on the machine frame 50 to prevent the image sensor from temperature rise.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exposure optical device in an image reading device,
In particular, the present invention relates to an image reading device with improved image reading performance of an image sensor.

[Conventional technology]

In an image reading device in a color image forming apparatus,
The light image 3 of the document surface obtained by exposure scanning is focused by an optical system, separated into colors, and imaged on a photographing element that receives each spectral light, which is then output as an image signal for each color. Color images are reproduced using the original color-based image forming process.

In recent years, CCDs have been widely used as such photographic elements, which have been mass-produced using LSI manufacturing technology and are inexpensive and compact, as well as consume less power, have stable performance, and have a long life.

[Problem that the invention seeks to solve]

However, when a CCD is energized and left in an active state for a long period of time, the temperature of the element rises, and as a result, it is no longer able to output a normal image signal even if it receives a spectrum of light images.
As a result, it has the disadvantage that an accurate color image signal cannot be obtained.

As a result of solving this problem and improving the present invention, it is an object of the present invention to provide an image reading device that suppresses the temperature rise of the image sensor and always outputs a normal image signal, thereby obtaining an image with excellent color balance. This is the purpose.

[Means for solving problems]

The above object is achieved by an image reading device that reads a document on a document table using an image sensor by optical scanning, and is characterized in that a cooling fan is rotated using return drive of an optical system. Ru.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1-3.

FIG. 1 shows the configuration of an image forming apparatus equipped with an image reading device of the present invention, and a color image is formed in the following manner.

In FIG. 1, 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 A, a platen glass is used, 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
The optical image of the document 2 on the platen glass l is transferred to the lens reading unit 20 by moving on the mirror 9 and the sliding slide rail 3, and in combination with the first mirror 7 provided in the carriage 4. Derive.

The carrier, gear 4 and movable mirror unit 8 are driven by pulleys 11, 12, 13, and 14 driven by a stepping motor 10 via a pulley 15, respectively.
They are driven in the same direction at a speed of 2. Standard white plates 16 and 17 are provided on the back side of both ends of the platen glass 1, and are configured so that a standard white signal can be obtained before the start of document 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-e11') CCD as a line image sensor. '5,
Second reading board 26, cyan channel (hereinafter 0-ch
) consists of 27 CCDs. first mirror 7,
The optical image of the original transmitted by the mirrors 9 and 9' is focused by the lens 21 and 1. The dichroic and mirror images provided in the prism 22 separate the R-ch image and the knee-ch image, and the R-ch image provided on the first reading board 24
The light receiving surfaces of the ch CCD 25 and the C-eh CCD 27 provided on the second reading board 26 are respectively imaged.

The fluorescent lamps 5 and 6 are commercially available warm white fluorescent lamps used as light sources to prevent emphasis or attenuation of specific colors when reading color documents, and 40I fluorescent lamps are used to prevent flickering.
It is lit by a high-frequency power supply of G (z) and kept warm by a heater using a POSISTOR to maintain a constant temperature of the tube wall or promote warm-up.

Said R-ch CCD 25 and C-ch CCD 2
The image signal output from 7 is subjected to signal processing through a signal processing section (not shown), and a color signal separated according to the color of the toner is output and input to writing unit (B).
Images by laser beams generated by a semiconductor laser are sequentially projected onto the circumferential surface of the photoreceptor drum 31, and each projection is subjected to development processing by a developing roller to form a color image using three colors of toner.

Next, the color image on the circumferential surface of the photoreceptor drum 31 is transferred to a recording paper conveyed from the paper feed section at a transfer separation pole 32, and then the recording paper is separated and ejected to the outside of the apparatus via a fixing device 33. to end the color image duplication.

FIG. 2 shows a main part 3 of the structure of the image reading device A. When a document 2 is placed on the platen glass 1 located at the top of the machine frame 50 of the reading device shown by a dashed line, , the image plane is illuminated by the fluorescent lamp 5.6 of the carriage 4, is reflected by the first mirror 7 and the mirrors 9 and 9' of the movable mirror unit 8, and is incident on the lens 21 as a slit-shaped light image. It has become.

The carrier 4 and the movable mirror unit 8 reciprocate in the optical axis direction of the lens 21 inside a pair of front and rear substrates 51, which are also shown with dashed lines and broken surfaces, to expose and scan the entire image surface of the original 2. The drive is performed by a pulley 11 driven by a pin motor 10 mounted on the side of the machine frame 50, and a pulley 12, 1
The power is obtained from pulling 15 wires through 3.

That is, one end of the wire 15 wound around the pulley 1 goes around the boo IJ 12 and is fixed to the carrier and the jig 4, and then goes around the lower pulley of the pulley 14 and is fixed to the board 51 at the SL. , and the other end goes around the pulley 13 and around the upper boob of the boo 914, and is similarly fixed to the substrate 51 at S2.

Therefore, when the stepping motor 10 rotates and the boo 911 rotates counterclockwise, the pulley 11 pulls the wire 15 to move the movable mirror unit 8 to the left, and at the same time the boo 911 on the movable mirror unit 8 By pulling the carriage 4 to the left at twice the speed, the optical path length between the surface of the document and the lens 21 is kept constant, and the entire surface of the document is exposed and scanned.

This wire pulley device is also arranged symmetrically on the outside of the substrate 51 provided on the opposite side (not shown), so that the carriage 4 and the movable mirror unit 8 can be simultaneously moved in a well-balanced manner at the left and right ends of each. Therefore, the rotating shaft 11a of the boo 911 is mounted so as to pass through the left and right boards 51, and the pulleys 11 are provided at the ends of the shafts on the outside of the boards 51, respectively.

In the present invention, a sleeve member 42 fitted onto the outer periphery of the rotating shaft 11a transfers rotational movement only when the rotating shaft 11a rotates clockwise.
A one-way clutch 41 is provided, and a cross-flow fan 43 as a cooling fan is fixed to the sleeve member 42, and the cross-flow fan 43 is activated only when the stepping motor 10 rotates clockwise, that is, reversely. It has a configuration that allows it to rotate.

Therefore, as shown in FIG. 3, the stepping motor 10 is rotating in the normal direction, and at the same time the fluorescent lamp 5.6 of the carriage 4 is turned on, the carriage 4 and movable mirror unit 8 move forward to perform exposure scanning of the document surface. During this time, the one-way crank 41 does not work and the cross flow fan 43 is stopped. However, when the exposure scan is completed and the stepping motor 10 starts rotating in reverse, the fluorescent lamps 5 and 6 are turned off. At the same time as the lights go out, the carriage 4 and the movable mirror unit 8 begin to move backward at a speed ten times greater than the forward movement, and at this time, the cross flow fan 43 rotates at high speed due to the action of the one-way clutch 41. Low-temperature air outside the machine frame 50 is passed through a filter or the like from an intake hole 44 provided between the machine frames to the prism n and R-ch CCD 25 arranged behind the lens 21.
, C-ch CCD 27 to prevent its temperature from rising.

Note that in order to further increase the cooling effect, the rotating shaft 11a
It is also possible to install shafts whose rotation speed is increased by gears or belts in parallel, and to rotate the cross flow fan 43 at a higher speed by attaching the cross flow fan 43 to the shaft. is also possible.

〔Effect of the invention〕

The present invention realizes a device that prevents a rise in temperature of an image sensor that receives an optical image obtained by the optical system by using the rotation of a motor that moves the moving optical system backward, thereby always providing a normal image signal. An image reading device equipped with an image sensor that outputs 100% and has improved durability has now been provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a color image forming apparatus. FIG. 2 is a perspective view of the main parts of the image reading device of the same apparatus. Figure 3 is the time chart. 4... Carriage 8... Movable mirror unit 10... Stepping motor 11, 12.13.14... Pulley 11
a...Rotating shaft 15...Wire 25 (27)...R-ch (C-ch)
CCD41...One-way clutch 42...Sleeve 43...Cross flow fan 44...Filter 50...Machine frame

Claims (1)

[Claims] What is claimed is: 1. An image reading device that uses an image sensor to optically scan a document on a document mounting table, the image reading device being characterized in that a cooling fan is rotated by using a return drive of an optical system.