JPH04330853A - Picture reader - Google Patents

Abstract

PURPOSE:To read original information with a high resolution in a stable state by using a timing belt with a skew gear, whose rigidity is improved, as a member which transmits a driving force from a driving device to a carriage device. CONSTITUTION:A housing 2 includes a carriage 3 which optical takes out information described on an original, and a carriage 4 which guides the information taken out by the carriage 3 to a desired direction. And also, the housing 2 is equipped with supporting members 33 and 34 which support the carriages 3 and 4 so as to be capable of being moved, and a driving member which moves them, that is, a timing belt 36 with the skew gear. As for the timing belt 36 with the skew gear, when a pitch between gears is defined as P, the width is as W, and the inclined angle of the gear towards a proceeding direction is as theta, it is inclined only at the angle fulfilling the following condition: 0.05P<=W X tantheta <=1.2P. And also, the extension percentage of this timing belt 36 for a 4 kg (f) load is defined to be less than 0.1%. Thus, the moving amount of the belt can be coincident with the position of the carriage.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is directed to inputting image information into an image forming apparatus such as a laser printer, or an image processing apparatus connected to a computer, etc. The present invention relates to an image reading device, and particularly relates to a fixed document type image reading device that reads an image while a document is fixed.

(Prior Art) Generally, image reading devices that input image information to an image processing device connected to a computer or the like are broadly classified into a moving original type and a fixed original type.

In a document moving type image reading device, information written on a document is usually read using, for example, a CCD contact line sensor. In this case, the documents that can be read are limited to those in sheet form. On the other hand, in a fixed document type image reading device, the document containing the information to be read is placed on a flat document table, so it is possible to read the information even if the document is three-dimensional. . In this case, information on the original placed on the original placing table is transmitted to the CC via the imaging lens system.
The image is formed on a photoelectric conversion device such as a D sensor and converted into an electrical signal. Therefore, the information written on the manuscript is read.

In the above-described fixed document type image reading device, the information written on the document is illuminated through the illumination device. The reflected light from the original is divided into elongated regions via a mirror extending in a first direction, that is, the main scanning direction, and is guided to a photoelectric conversion device. On the other hand, the lighting device and the mirror include a first
, that is, in the sub-scanning direction. Therefore, the information on the document divided into long and narrow areas is sequentially guided to the photoelectric conversion device, and all the information is read.

The reading device uses a moving mechanism for moving the illumination device and the mirror in the sub-scanning direction.

Generally, the illumination device and the mirror are moved using a wire rope made of twisted steel wires and coated with resin on the outer periphery, or a rubber belt with a steel wire core and gear-like teeth on the outer or inner periphery. A toothed timing belt is used. When the above-mentioned wire rope is used, the wire rope is fixed with a screw or the like to a drive pulley that transmits driving force from a drive device, that is, a motor, to prevent it from slipping. In addition, when a timing belt is used, the pulley is inserted into the shaft of the motor with the belt attached to the pulley on which the belt is stretched.
The pulley is fixed to the shaft.

(Problems to be Solved by the Invention) When a wire rope is used in the moving mechanism of the reading device, there is a risk of damaging the resin coating of the wire rope when screwing the wire rope to the drive pulley. be. Furthermore, since a wire rope having a length corresponding to the distance over which the illumination device and the mirror are moved must be wrapped around the pulley, there is a problem that assembly workability is poor.

On the other hand, even if a timing belt is used,
There is a risk of tooth skipping during acceleration and deceleration when moving the illumination device and the mirror, and there is also a problem in that speed fluctuations occur due to vibrations caused by tooth meshing. Furthermore, there is a problem in that high-speed driving is not possible because vibrations that occur during acceleration and deceleration are slow to attenuate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive transmission means that is suitable for sub-scanning drive for high-speed and accurate reading in a document-fixed image reading device and has good assembly workability.

[Structure of the Invention] (Means for Solving the Problems) This invention has been made based on the above-mentioned problems, and includes a carriage means having an optical means for optically extracting information, and a means for moving the carriage means. a driving means;
disposed between the drive means and the carriage means;
A transmission mechanism having a helical-teeth transmission member is provided for transmitting a driving force to the carriage means, and the transmission member has a tooth-to-tooth pitch of P, a width of W, and an inclination of the teeth with respect to the traveling direction. When the angle is θ, 0.05P≦W×tan
The present invention provides an image reading device that is tilted by an angle θ that satisfies θ≦1.2P. Further, according to the present invention, a carriage means having an optical means for optically extracting information, a drive means for moving the carriage means, and a drive means disposed between the drive means and the carriage means, the carriage means being disposed between the drive means and the carriage means, An image characterized in that the transmission mechanism includes a helical-toothed transmission member that transmits a driving force to the means, and the transmission member has an elongation rate of 0.1% or less with respect to a load of 4 kgf. A reader is provided.

(Function) According to the present invention, a timing belt having helical teeth is used as a transmission member disposed between the carriage device and the drive device and transmitting the driving force from the drive device to the carriage device. The impact force generated when the belt and pulley mesh is dispersed temporally and positionally.

Furthermore, since the core material used in the belt has improved steel properties, the deflection, vibration, etc. that exist in the belt itself during acceleration or deceleration are reduced. Furthermore, even when the carriage device is repeatedly reciprocated, the amount of movement of the belt and the position of the carriage device can be accurately matched.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of the image reading device in the sub-scanning direction.

The image reading device 1 includes a document mounting table 12 on which a document G is placed.
A housing 2 with
It includes a document holder 14 for bringing the document into close contact with the document. The document mounting table 12 is a transparent plate that transmits the information written on the document, and is a flat plate with a thickness of 2 to 3 mm made of glass, polycarbonate, acrylic, or the like. The document presser 14 can be opened and closed with respect to the document placement table 12, and has an elastic body such as a sponge mat or a polyurethane mat 16 on the side that contacts the document G to press the document G toward the document placement table 12. are doing.

The housing 2 includes a first carriage 3 that extends in a first direction, that is, the main scanning direction, and optically extracts information written on a document; The second carriage 4 is arranged parallel to the first carriage 3 and guides the information retrieved by the first carriage 3 in a desired direction. The housing 2 also supports an image reading unit 5 that photoelectrically converts information transmitted via the second carriage 4 and replaces the information with electrical signals, and the first and second carriages 3 and 4. It also includes a carriage drive mechanism, which will be described later, which moves the first and second carriages 3 and 4 at a desired speed.

The first carriage 3 includes a lamp 20 which is formed to be longer than at least the short side length of the readable original G and illuminates the original G along the main scanning direction.
a reflection plate 21 that focuses the light rays from the source onto the information surface of the document G;
22, and a first reflecting mirror 24 that guides reflected light from an elongated illuminated area of the document G in the main scanning direction to the second carriage 4.

The second carriage 4 is mounted with second and third reflecting mirrors 26 and 28 that each return the reflected light from the first carriage 3 by 90 degrees and guide it to the image reading unit 5.

The image reading unit 5 includes an imaging lens 30 that forms an image of information from a document G, a photoelectric conversion element such as a CCD sensor 32 that reads the image information formed by this imaging lens 30, and this CCD sensor 32. The reading apparatus 1 includes a control section 6, which will be described later, which processes the information photoelectrically converted by a predetermined process and controls the operation of the reading device 1.

FIG. 2 schematically shows a driving device in the sub-scanning direction of the image reading apparatus shown in FIG.

The housing 2 includes a support member 33 that movably supports the first carriage 3, a support member 34 that movably supports the second carriage 4, and a drive member that moves the first and second carriages 3, 4, that is, a toothed timing. A belt 36 is provided. The housing 2 further includes a drive pulley 40 that urges the timing belt, a support pulley 42 that supports the toothed belt 36, a spring 44 that applies a desired tension to the timing belt 36, and a state in which the first carriage 3 is moved. It is equipped with a home position switch 52 for detection, a start switch 54, a return switch 56, and a drive motor (not shown).

The first carriage 3 has connecting members 46 at both ends that are formed long in the main scanning direction and are used for connecting with the timing belt 36. Further, the first carriage 3 is supported by a first support member 33 so as to be movable at a desired height, that is, to be able to scan.

Like the first carriage 3, the second carriage 4 has driven pulleys 47 and 48 at both ends to receive drive from the timing belt 36 at 1/2 the moving speed of the first carriage 3. . Further, the second carriage 4 is supported by a second support member 34 so as to be movable at a different height than the first carriage 3, that is, to be able to scan.

One end of the toothed timing belt 3B is fixed to a desired position of the housing 2. The direction of the timing belt 36 is reversed via the pulley 47 of the second carriage 4, and at the same time it is positioned at the same height as the connecting portion of the first carriage 3.

The first carriage 3 is directly fixed to a desired position via a connecting member 46 to the belt 36 whose height is aligned with the connecting portion with the first carriage 3 . The height and direction of the belt 36 are changed again via the drive pulley 40, and one end of the belt 36 is guided below the fixed position.

The belt 36 whose direction has been reversed at the drive pulley 40 is further changed in height and direction via the support pulley 42 and guided to a pulley 48 which is disposed close to the pulley 47 of the second carriage 4 . Belt 3 guided to pulley 48
6 is again changed in height and direction and connected to spring 44.

The first carriage 3 has a drive pulley 40 which is directly connected to the timing belt 36 and which transmits the drive from the drive motor.
is moved at a predetermined speed V through the .

Further, the second carriage 4 follows the movement of the first carriage 3, and since the belt 36 is folded back by the pulley 47, the second carriage 4 moves by a distance 1/2 of the moving speed V of the belt 36. That is, when the first carriage 3 is moved at a speed V, the moving speed of the second carriage 4 is V/2.

The switches 52 and 5 are located at the home position, reading start position, and reversal position of the first carriage 3, respectively.
4 and 56, the position to which the first carriage 3 has been moved can be detected.

According to FIGS. 1 and 2, in the image reading device 2, a document G on which information to be read is written is placed on the document placement table 12 with the information side facing the document placement table 12. This document G is brought into close contact with the document placement table 12 by closing the document holder 14.

When a reading start switch (not shown) is turned on, the first carriage 3 and the second carriage 4 are moved in the sub-scanning direction. As the carriage 3 moves, the home position switch 52 is turned off (or turned on) and the lamp 20 is turned on. Light from lamp 20 and reflecting plate 21
, 22, the information surface of the document G is illuminated.

In this case, as already explained, the first carriage 3, the lamp 20, and the reflectors 21 and 22 extend in the main scanning direction, so that the information surface of the original G is displayed in the main scanning direction (not shown). An elongated illumination area is formed. This illumination area is sequentially moved as the carriage 3 is moved in the sub-scanning direction.

The reflected light from the original G is bent by the first reflecting mirror 24 and guided to the second reflecting mirror 26 disposed on the second carriage 4 . The reflected light guided to the second reflecting mirror 26 is bent by 90°, guided to the third reflecting mirror 28, and further bent by 90°. This reflected light is imaged from the third reflection mirror 28 to the CCD sensor 32 via the imaging lens 30.

The reflected light guided to the CCD sensor 32, that is, the information written on the document G, is photoelectrically converted and replaced with an electrical signal. Since the illumination area on the original G is sequentially moved by the movement of the first and second carriages 3 and 4 in the sub-scanning direction, the information written on the original G is sequentially transferred to the CC.
It is guided to the D sensor 32. Therefore, all information written on the document G is converted into electrical signals.

Note that the carriage 3 moves and the start switch 54 is turned on.
As a result, reading of information, that is, photoelectric conversion of reflected light in the image reading unit 5, which will be described later, is started. Also,
When the carriage 3 reaches the return switch 56 located at the position corresponding to the maximum document size that can be read, the photoelectric conversion is completed and the carriage 3 is moved in the opposite direction. The carriage 3 is moved until it touches the home position switch 52, and the switch 5
2 is turned ON (or OFF) and waits until the next instruction is received from the control section 6.

FIG. 3A shows the structure of a timing belt used in the carriage drive mechanism in the image reading apparatus shown in FIGS. 1 and 2. FIG.

The timing belt 36 is made of core wires 62 (for example, formed by twisting glass fiber, aramid fiber, Tetron fiber, steel wire, etc.) arranged at intervals, and a chloroprene rubber or polyurethane rubber 64. It is formed by molding. This belt 36 is formed with teeth having a desired tooth pattern, which will be described later, during the molding process. The belt 36 has a nylon canvas 66 on its surface, which protects the teeth and reinforces its strength.

Specifically, the timing belt 36 is manufactured by the following method. First, the core wire 62 is spirally wound at desired intervals around a cylindrical inner mold (not shown) having an outer diameter equal to the minimum length used in the reading device. Second
Then, the rubber 64, the canvas 66, and an outer mold (not shown) having teeth of a desired pitch are stacked in order and vulcanization molded.

Third, the inner and outer molds are removed and cut to a desired width to form an endless belt. During this cutting,
For example, by cutting the long endless belt 36 into a spiral shape, the timing belts 37 and 38 having the above-mentioned minimum length can be obtained by cutting the long endless belt 36 perpendicularly to the central axis of the cylinder.

Table 1 shows data regarding the toothed timing belt.

The toothed timing belt of the present invention utilizes a core wire having a diameter approximately three times that of conventionally used general belts. This shows that the steel is three times stronger than commonly used toothed belts.

Therefore, the belt is prevented from vibrating as if it were an elastic body in response to rapid acceleration or deceleration required for high-speed driving. More specifically, when compared with a general belt with the same belt width, the timing belt has 1/3 the number of core wires per belt cross section, but the cross-sectional area of the core wires is 3 x 3 x 1/3. 3 = 3 times. Therefore,
It has approximately three times the strength of steel compared to conventional belts.

Furthermore, the timing belt is formed with a pitch of 1 mm, which is half the pitch of teeth of 2 mm used in conventional belts. This means, for example,
If the moving speed in the sub-scanning direction is 200 mm/sec, the pitch vibration frequency depending on the tooth pitch is 2.
This shows that it can be doubled. Therefore, the vibration amplitude of the belt is reduced, and speed fluctuations when the carriages 3, 4 are moved are significantly reduced.

FIG. 4 shows a graph showing the steel properties of the timing belt shown in FIG.

The line ■ is a belt that has been used conventionally, for example, a width of 5
mm, the tooth pitch is 2 mm, and the steel property of the belt is formed into a round tooth shape. In this belt, for example, the elongation rate is 0.3% at a tension of 7.2 kgf. On the other hand, according to the timing belt of the present invention, the elongation rate is significantly improved to 0.1% at a tension of 7.2 kgf, for example (line ■). Therefore, it can be confirmed that the belt shown in FIG. 3 has approximately three times the steel strength as compared to the conventional belt. Furthermore, the above growth rate is
This is an index that compares the total length of the belt when no load is applied to the total length of the belt when a specified load is applied. In addition, for the wire ■, for example, the outer diameter of 1.2 mm (
Measurement results are shown under the same conditions regarding the steel properties of a wire rope with a wire diameter of 0.1 mm x 36 strands. As is clear from the graph, wire ropes have conventionally been superior to belts in terms of steel properties, but the timing belt of the present invention has greater steel properties than wire ropes.

Here, the steel properties of the timing belt 36 and vibrations when the first and second carriages 3 and 4 are sub-scanned will be considered.

Generally, if the maximum size of a document that can be read is A3, the first and second carriages 3 and 4 are at least A3
Since it is necessary to have an effective reading width larger than the short side length of the document, that is, 297 mm, the carriage 3 is a combination of the structure of the carriages 3 and 4 and a mirror or lamp.
, 4 each weigh approximately 1 kg. on the other hand,
Since the length of the A3 document in the long side direction is 420 mm, the carriages 3 and 4 must be moved at least about 500 mm. Therefore, the drive mechanism for moving the carriages 3 and 4, ie, the timing belt 36, has a weight that is 1/2 of the weight of the first carriage 3 and 1/2 of the weight of the second carriage 4.
is given as a load. That is, the timing belt 36 has a total load of 1.5 kgf (an inertial load of 10-4 to 1
0-3 kgf・m2) is given. On the other hand, as is clear from FIG. 2, in this embodiment, the first and second carriages 3 and 4 are driven via two timing belts, so the load applied to each belt is It is approximately 0.75 kgf. Here, the readable resolution of the reading device is 400 dpi (dots/inch).
) = 16 lines/mm, the reading width per reading area on the document in the sub-scanning direction is 0.0625
It becomes mm. In addition, in the main scanning direction, at least 5,000 yen (because the readable original size is A3)
A CCD sensor with approximately 0 pixels is used, and the minimum readable area on the document (document pixel size) is 0.06
It will be 25mm square. In this case, if the maximum vibration amplitude allowed for the timing belt 36 that drives the first and second carriages 3 and 4 is less than or equal to the size of one pixel, then The maximum elongation is 0.0625mm/500mm
=1.25×10-4. This value is the maximum permissible elongation value for the load applied to one belt, that is, 0.75 kgf, so if the total load on the drive mechanism shown in FIG. 2 is 4 kgf, the elongation in the timing belt 36 is The maximum value of is 6.67×10−4
becomes. When this maximum elongation value is converted into the maximum elongation rate allowable for the timing belt 36, it is approximately 0.1%.

In addition, it is generally known that when a toothed timing belt is used, the steel properties are lowered during driving force transmission compared to a wire rope. On the other hand, when a wire rope is used, there is a problem that the diameter of the pulley cannot be reduced because the wire rope has a relatively large bending resistance. On the other hand, when the above-mentioned timing belt is used, since the belt itself includes a vibration damping function, if the above-mentioned elongation rate is maintained, sufficient driving force transmission characteristics are achieved. can get.

Also, the diameter of the pulley can be made smaller.

According to FIG. 3B, the timing belt 36 has teeth shaped at a certain angle with respect to the traveling direction of the belt.
A helical tooth belt is used. This causes problems when the teeth of the belt mesh with the pulley, such as undesired contact or rubbing between the teeth of the belt and the teeth of the pulley, and the air caught between the teeth being compressed and rapidly Vibration of the belt due to extraction and the opposite problem to the above-mentioned meshing problem that occurs when the teeth of the belt separate from the pulley, etc., are reduced.

In other words, by using a helical tooth belt, the impact force that occurs when meshing is dispersed in time or position, so it is different from the belt that has been used in the past, where only the grip force is increased. In comparison, a belt with less vibration is provided without sacrificing grip strength. As a result, the mechanical vibrations existing between the belt and the pulleys and the vibrations of the belt generated due to these vibrations are reduced during high-speed driving. Therefore, the first and second carriages 3, 4 driven by the belt
vibrations or speed changes are reduced.

Here, the tooth angle and tooth pitch in the helical tooth belt will be considered.

When the angle of the teeth in the above-mentioned helical timing belt is θ, the pitch of the teeth is P, and the width of the belt is W, then W×tan
If θ>P is satisfied, the impact force during meshing can be completely dispersed. However, if the above W×tanθ is too large compared to the pitch P, for example, W×tanθ
When >1.2P is satisfied, the thrust load that causes the belt itself to move in a direction parallel to the teeth, that is, in the direction of the tooth trace increases. In this case, the belt tends to ride on the pulley flange of the pulley that drives the belt or is driven by the belt, and the end surface of the belt is abraded due to friction between the flange and the belt. From this, the above W×tan θ is preferably W×t with respect to the pitch P.
It is defined that anθ≦1.2P or less. Furthermore, since it is a helical belt, at least θ=0 is excluded.

Therefore, 0.05P≦W×tanθ is defined as the lower limit.

Generally, the belt pulley disposed in the drive mechanism and the carriage has teeth with an angle equal to the tooth angle specified in the helical timing belt. A pulley without one may be used. In this case, the transmission of driving force between the timing belt and the pulley is determined only by the adhesive force between the rubber used in the belt and the surface of the pulley. On the other hand, since the thrust load caused by the engagement between the teeth of the pulley and the teeth of the belt is removed, substantially sufficient driving force is transmitted.

FIG. 5 shows details of the speed reducer that transmits the driving force to the carriage drive device shown in FIG. 2.

The driving force of the drive motor 39 is transmitted to the timing belt 38 via a motor pulley 39a. The driving force of the motor is decelerated (
or speed-up) and is supplied to the pulley 38b. This reduced (or increased) driving force is further transmitted to the pulley 37a via the belt 37.

The pulley 37a is arranged coaxially with the drive pulley 40 that drives the first carriage 3, and further reduces (or speeds up) the drive force of the motor 39 to rotate the drive pulley 40 that drives the timing belt 36. The driving force from the motor 39 that has been sequentially decelerated in this manner is converted from a rotational force to a propulsive force for the belt 36 via the drive pulley 40, causing the first carriage 3 to reciprocate.

Note that the belts 38 and 37 each have the third A
A high steel helical timing belt shown in Figures 4 through 4 is utilized. That is, 0.0 for pitch P
A timing belt satisfying 5P≦W×tanθ≦1.2P is used.

FIG. 6 simply shows the configuration of the control section 6 of the image reading apparatus shown in FIGS. 1 and 2. As shown in FIG. Control unit 6
The image information signal from the CCD sensor 32 supplied to
This information is temporarily stored in the RAM 73, which is used as a working buffer memory for the CPU 71. This image information signal is sent to the CPU according to fixed data, ie, a control program, etc. stored in advance in the ROM 72, which is a read-only memory.
Predetermined processing is performed via 71. The image information signal that has undergone the desired processing via the CPU 71 is sent via the interface 87 to, for example, a card connector and a RAM.
The data is output or transferred to an external storage device or external output device (not shown) such as an auxiliary unit such as a card.

More specifically, the image information signal from the CCD sensor 32 is amplified to a predetermined gain by the amplifier circuit 76, and converted to a white or black signal with a certain level as the boundary via the binarization circuit 77. RAM via I/O bus 81
73.

Further, for the above-mentioned desired processing, the input/output of data or signals at each input/output port, circuit, terminal, etc. as described below is controlled by the CPU 71. The input/output port 82 is used, for example, to exchange data with an operation panel (not shown), that is, to read information from the document D by the reading device 2. The input/output port 83 is
For example, a motor drive circuit 74 that controls a motor for moving the first and second carriages 3 and 4 in the sub-scanning direction.
It is used for supplying motor drive signals from the CPU 71 to the CPU 71. The input/output port 84 is connected to a home position switch 52 that detects the home position of the first carriage 3.
, a start switch 54 that detects the reading start position, and a return switch 56 that detects the reversal position, respectively.
For example, when the position signal is turned ON/OFF, the CPU
71. The input/output port 85 is used to transfer a CCD sensor control signal from the CPU 71 to the CCD drive circuit 75 to drive the CCD sensor 32.

The input/output port 86 is used, for example, to monitor the voltage in the secondary battery 78.

Another embodiment of the invention is shown in FIG.

Components that are the same as those shown in FIG. 1 are designated with the same reference numerals.

The image forming apparatus 90 includes a document placing table 1 on which a document G is placed.
2 on the upper part, and the document G is placed on the document mounting table 1.
2, a paper feed section 92 that includes a paper cassette 91, which is disposed at one end of the housing 2, and supplies a transfer material to which a visualized image is transferred;
, and a fixing unit 93 that is disposed at the other end of the housing 2 and heat-fixes the image transferred to the transfer material.

The housing 2 includes a first carriage 3 that extends in a first direction, that is, the main scanning direction, and optically extracts information written on the document, and a first carriage 3 that extends in the main scanning direction and is parallel to the first carriage 3. a second carriage 4 which is arranged in a direction and guides the information taken out by the first carriage 3 in a desired direction; a lens 94 which optically shapes the information transmitted via the second carriage 4; an image forming unit 97 having a photoreceptor 96 on which information is recorded as a charge distribution pattern, that is, an electrostatic latent image is formed; and a carriage drive mechanism (not shown) that supports the second carriages 3, 4 and moves the first and second carriages 3, 4 at a desired speed, and a control unit (not shown). The carriage drive mechanism described in detail in FIG. 3A, FIG. 3B, and FIG.
．． A helical-toothed timing belt having teeth defined by 05P≦W×tanθ≦1.2P is used.

The first carriage 3 includes a lamp 20 that illuminates the original G along the main scanning direction, and a light beam from this lamp 20 is attached to the original G along the main scanning direction.
A reflecting plate 22 that focuses light on the information surface of the document G, and a first reflecting mirror 24 that guides reflected light from the original G to the second carriage 4 are mounted.

The second carriage 4 is equipped with second and third reflecting mirrors 26 and 28 that each return the reflected light from the first carriage 3 by 90 degrees and guide it to the image forming unit 97.

The image forming unit 97 includes a developing unit 98 that visualizes the electrostatic latent image formed on the photoreceptor 96.

Further, around the photoreceptor 96, there is a main charger 97a that charges the photoreceptor 96, and a developed image is transferred to a transfer material, that is, a transfer paper fed from the cassette 91 or an O
A transfer charger 97b for transferring the image to a HP sheet or the like, a static eliminator 97c for returning the electrical characteristics of the photoreceptor 96 to the initial state for the next image formation, a cleaner 97d, etc. are arranged.

A long and narrow region of the document G placed on the document table 12 is illuminated in the main scanning direction by a lamp 20 and a reflector 22 . The reflected light from the original G is bent by the first reflecting mirror 24 and guided to the second reflecting mirror 26 disposed on the second carriage 4 . The reflected light guided to the second reflecting mirror 26 is bent by 90 degrees, and then directed to the third reflecting mirror 28.
It is then bent further by 90 degrees. This reflected light is optically shaped through the lens 94 and reflected by the fourth reflecting mirror 95 toward the image forming unit 97 . In synchronization with the series of operations up to this point, the first and second carriages 3 and 4 are simultaneously moved in the sub-scanning direction via the drive mechanism as in FIG. 2. Further, the photoreceptor 96 included in the image forming unit 97 rotates its own image forming surface in the direction of the arrow via a photoreceptor drive device (not shown) at the same speed as the speed at which the first carriage 3 is moved. be done. Therefore, all the information written on the document G is sequentially optically read out and recorded as an electrostatic latent image on the image forming surface of the photoreceptor 96.

The information of the document G recorded on the photoreceptor 96 is visualized through the developing unit 98 and transferred onto the transfer material fed from the paper feed section 92 by the transfer device 97b. The image is fixed on the transfer material via the fixing unit 93, and the material is discharged to the outside of the image forming apparatus 90.

(Effects) As explained above, since a timing belt with helical teeth and high steel properties is used as a transmission member that transmits the driving force from the drive device to the carriage device, vibrations when the carriage device is driven;
Fluctuations in movement speed, etc. are removed. Furthermore, the carriage device can be driven at high speed. Therefore, an image reading device is provided that can read information on a document with high resolution and in a stable state. Furthermore, an image reading device with a high reading speed is provided. Furthermore, color separation filters etc. are used,
When incorporated into a color image reading device that reads a single document multiple times, the reading accuracy for each color is improved, making it possible to read images without color shift.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an image reading device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a driving method and drive mechanism in the sub-scanning direction of the image reading device shown in FIG. 1. 3A is a schematic diagram showing the structure of the timing belt used in the drive mechanism shown in FIG.
Figure B is a partially enlarged view showing the characteristics of the timing belt shown in Figure 3A, Figure 2 is a graph showing the steel properties of the timing belt shown in Figures 3A and 3B, and Figure 5. is a schematic diagram showing a deceleration mechanism that transmits drive to the drive mechanism shown in FIG. 2, and FIG. 6 is a schematic diagram showing a signal processing circuit of the image reading device shown in FIG. 1 and controlling the entire device. FIG. 7 is a block diagram schematically showing the control circuit, etc., and is a sectional view showing an image forming apparatus according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Image reading device, 2... Housing, 3... First carriage, 4... Second carriage, 5... Image reading unit, 12
...Original placing table, 14...Document holder, 20...Illumination lamp,
24...first reflecting mirror, 26...second reflecting mirror, 28...
Third reflecting mirror, 30...imaging lens, 32...CCD sensor.

Claims (2)

[Claims] Claims: 1. Carriage means having optical means for optically extracting information; driving means for moving the carriage means; disposed between the driving means and the carriage means, with respect to the carriage means; a transmission mechanism having a helical tooth transmission member that transmits the driving force,
The transmission member has a tooth-to-tooth pitch of P, a width of W, and
An image reading device characterized in that the teeth are tilted by an angle θ that satisfies 0.05P≦W×tanθ≦1.2P, where θ is the inclination angle of the teeth with respect to the direction of movement. 2. A carriage means having an optical means for optically extracting information, a drive means for moving the carriage means, and a drive means disposed between the drive means and the carriage means, with respect to the carriage means. a transmission mechanism having a helical tooth transmission member that transmits the driving force,
The transmission member has an elongation rate of 0.0 with respect to a load of 4 kgf.
An image reading device characterized in that it is defined as 1% or less.