JPH11187203A - Image reader, image-forming device and image transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the image quality deterioration of a read image, even when an inexpensive motor under open loop control is used even through the reader has a configuration that can be miniaturized. SOLUTION: A lamp carriage 3 is arranged movably under a platen glass. A joint 27 is attached to the carriage 3 and locked to a cable 15 that is wound on a capstan pulley 25, etc. In this constitution, the carriage 3 is moved to the right, accompanying the cable 15 when a motor rotates the pulley 25 to scan an original. When it goes beyond a scan range, the carriage 3 hits against a regulation member 28 and stops. In such a case, the joint 27 allows the cable 15 to move although the carriage 3 stops. Then, transmission of a load that accompanies the sudden stop of the carriage 3 to a stepping motor 24 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus which optically scans an original to read an original, and an image forming apparatus and an image transmitting apparatus having the same.

[0002]

2. Description of the Related Art In a conventional image reading apparatus for optically scanning an original, the carriage started to decelerate after a carriage driven by a motor has finished scanning a scanning range. Then, after the carriage has once stopped, the return movement operation is started.

In such an apparatus, the carriage moves extra, that is, overruns, after the scanning of the scanning range is completed and before the carriage stops.
In a high-speed reading apparatus or when reading at a high speed in accordance with a reduction magnification at the time of reduction reading, the carriage moves at a high speed, so that the overrun amount becomes large, which is an obstacle to downsizing the apparatus.

As a method for reducing such an overrun amount of the carriage, the following method has conventionally been used. (1) By using a strong driving source (for example, a large-capacity motor), the time from exceeding the scanning range to stopping the carriage is shortened to reduce the overrun amount. (2) A stopper is provided on the rear end side of the scanning range of the carriage, and the carriage is abutted against the stopper, thereby restricting the movement of the carriage beyond the scanning range. (3) While the carriage is moving within the scanning range,
The overrun amount is reduced by starting the carriage deceleration.

[0005]

However, the method described in the above (1) requires a large drive source, which hinders downsizing of the apparatus, increases the price, and increases the power consumption. There is also a problem. In the method described in (2), when an inexpensive open-loop control motor is used as a drive source of the carriage, the motor loses synchronism when the carriage hits a stopper, which hinders the position control of the carriage. There is a problem that causes. Also,
In the method described in (3), the scanning speed of the carriage at the rear end of the scanning range becomes slow, and there is a problem that the image quality of the read image such as image expansion or image lack is reduced.

The present invention has been made in view of the above circumstances, and has a structure capable of reducing the size of a read image even when the carriage is driven by a drive source with a simple control. It is an object of the present invention to provide an image reading apparatus capable of reducing the deterioration, an image forming apparatus including the same, and an image transmitting apparatus.

[0007]

In order to solve the above-mentioned problems, an image reading apparatus according to the present invention is provided with a placing member on which a document is placed and a movable member along the placing member. A carriage that scans the original placed on the placing member over a scanning range, a driving unit that moves in conjunction with the carriage, and that moves the carriage by generating a driving force; and the carriage. A regulating member that regulates movement of the carriage when the carriage moves beyond the scanning range, and the carriage does not interlock with the driving unit when the movement of the carriage is regulated by the regulation member. And interlocking regulation means that can be configured as described above.

According to this structure, the carriage is moved by the driving force generated by the driving means. Then, when scanning of the document placed on the placing member over the scanning range is completed,
The movement of the carriage is regulated by the regulating member. This makes it possible to eliminate the overrun of the carriage while moving the carriage at a constant speed over the entire scanning range.
Therefore, it is possible to reduce the size of the apparatus without deteriorating the image quality of the read image. When the movement of the carriage is restricted by the restricting member, the interlock restricting means prevents the carriage from interlocking with the driving means. This suppresses the transmission of the load to the drive unit due to the restriction of the movement of the carriage. Therefore, even when an inexpensive open-loop control stepping motor or the like is used as the driving means, step-out of the motor can be reduced, so that there is almost no hindrance to the position control of the carriage.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. A. First Embodiment FIG. 1 is a side view showing an image reading apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a housing of the image reading apparatus. As shown in FIG. 1, a platen glass (mounting member) 2 on which an original D is mounted is attached to an upper plate of the housing 1. Below the platen glass 2, a lamp carriage 3 and a mirror carriage 4 are supported on a guide rail (not shown) so as to be reciprocally movable in the left-right direction.

An exposure device 16 for irradiating the lower surface of the original D placed on the platen glass 2 to the lamp carriage 3
And a mirror 17a for receiving the reflected light from the document D. The mirror carriage 4 includes a mirror 17.
Mirrors 17b and 17c that receive the reflected light of a are provided. Further, an image sensor 18 for receiving the reflected light from the mirror 17c converged by a lens (not shown) is provided.

Next, a drive mechanism (drive means) for driving the lamp carriage 3 and the mirror carriage 4 will be described. As shown in FIG. 2, a drive shaft 21 is rotatably supported in parallel with the lamp carriage 3 and the mirror carriage 4 on the right end side in the drawing in the housing 1. One end of the drive shaft 21 protrudes outside the housing 1, and a timing pulley 22 is fixed to the protruding end, and a stepping motor 24 is connected to the timing pulley 22 via a timing belt 23. When the stepping motor 24 operates, its rotation is controlled by the timing belt 23.
The drive shaft 21 is transmitted to the drive shaft 21 via the timing pulley 22, and the drive shaft 21 rotates.

Capstan pulleys 25 are fixed to both ends of the drive shaft 21 in the housing 1, respectively. An idler pulley 11 is rotatably supported on the left end side of the housing 1. Further, idler pulleys 12 and 13 are mounted on both ends of the mirror carriage 4 so as to be freely rotatable.

One end of a coil-shaped spring 14 that expands and contracts in the left-right direction is fixed above and below the left inner surface of the housing 1, and one end of a cable 15 is connected to the other end. These two cables 15
Along the movable direction of the lamp carriage 3 and the mirror carriage 4, first, it is wound around the idler pulley 12 of the mirror carriage 4 and then the idler pulley 1.
1. The capstan pulley 25 is wound in this order. Next, after being wound around the idler pulley 13 of the mirror carriage 4, it is drawn rightward, and the other end is fixed to a fixing portion 26 near the center of the housing 1. Cable 15
Pulley 25 and idler pulley 13
A joint (interlocking regulation means) 27 attached to the lamp carriage 3 is locked at a portion between the two.

FIG. 3 is a view showing the vicinity of the joint 27 attached to the lamp carriage 3. As shown in FIG. As shown in the figure, a housing 31 is fixed to the lamp carriage 3. Through holes 32 are formed on the left and right sides of the housing 31, respectively.
5 are inserted.

A disk-shaped stopper 34 is fixed to one portion of the cable 15 by caulking. A coil-shaped spring 33 that expands and contracts in the left-right direction is disposed between the stopper 34 and the right side of the housing 31. Under this configuration, the stopper 34 is normally pressed to the left side of the housing 31 by the urging force of the spring 33, so that the cable 15 and the joint 27 move integrally. That is, the lamp carriage 3 moves as the cable 15 moves. On the other hand, the stopper 34
When a force exceeding the pressing force of the spring 33 is applied rightward, the stopper 34 moves to the right in the figure (see FIG. 4).

As shown in FIG. 2, regulating members 28 are attached to the upper and lower portions of the right inner surface of the housing 1, respectively. When the lamp carriage 3 moves to the right side in the figure, it abuts on the regulating member 28,
Further movement to the right is restricted.

B. Next, an operation of the image reading apparatus according to the above-described embodiment will be described. Here, a case will be described in which the image reading apparatus reads a document D of a maximum size that can be read in the left-right direction in FIG.

First, the original D
Is placed on the platen glass 2 and image reading is started. Then, a pulse signal of a predetermined frequency is input from a control device (not shown) to the stepping motor 24, and the stepping motor 24 rotates at a predetermined speed. Thereby, the capstan pulley 25 rotates clockwise in FIG. 1, and the lamp carriage 3 and the mirror carriage 4 move to the right in the figure.

While the lamp carriage 3 is moving, the exposure device 16 irradiates the lower surface of the document D, and the image sensor 18 receives the reflected light from the document D via mirrors 17a, 17b, and 17c to form an image. Read. At this time, the idler pulleys 12 and 13 serve as a moving pulley, and the mirror carriage 4 moves at half the speed of the ramp carriage 3. As a result, the reflected light from the document D is always received by the image sensor 18 with a constant optical path length. Thus, the image of the entire document D is read by the lamp carriage 3 moving over the entire scanning range of the document D.

When the reading of the document D is completed,
That is, when the lamp carriage 3 exceeds the scanning range,
The lamp carriage 3 comes into contact with the regulating member 28 and stops. Further, the stepping motor 24 starts decelerating from the time when the lamp carriage 3 exceeds the scanning range.

Here, FIG. 4 shows a state of the joint 27 when the lamp carriage 3 abuts on the regulating member 28.
As shown in the figure, in this state, the stepping motor 24 is rotating even though the lamp carriage 3 is stopped, so that the cable 15 linked to the rotation of the stepping motor 24 is connected to the housing 31 in FIG. Moving to the right, the stopper 34 compresses the spring 33.

Then, the stepping motor 24 temporarily stops and then rotates in the reverse direction, whereby the lamp carriage 3 starts the reciprocating operation. At this time, the joint 27 returns to the state shown in FIG. Thereafter, the stopper 34 presses the left side of the housing 31 and the lamp carriage 3
With the movement of 5, it moves to the left.

C. Next, effects of the image reading apparatus according to the present embodiment will be described in comparison with a conventional apparatus. FIGS. 5, 6 and 7 are graphs showing the operation of the lamp carriage, where the horizontal axis represents time,
The vertical axis indicates the scanning distance of the lamp carriage. FIG.
6 shows the operation of the lamp carriage in the conventional image reading apparatus, and FIG. 7 shows the operation of the lamp carriage in the image reading apparatus according to the present embodiment.

First, in the case of the image reading apparatus shown in FIG. 5, after the ramp carriage has moved at a constant speed and finished scanning the scanning range, deceleration is started. Therefore, the lamp carriage moves excessively beyond the scanning range until it stops, that is, overruns. In particular, when performing reduced reading or the like, the lamp carriage moves at a high speed, so that the overrun amount increases. In such an apparatus, it is necessary to consider the amount of overrun, so it is difficult to reduce the size of the apparatus.

Next, in the case of the image reading apparatus shown in FIG. 6, deceleration is started while the lamp carriage is moving in the scanning range. In this case, the overrun of the lamp carriage can be eliminated, but since the ramp carriage starts decelerating at the rear end side of the scanning range, the read image may have an image extension or an image missing.

On the other hand, in the image reading apparatus according to the present embodiment shown in FIG. 7, the ramp carriage 3 moves at a constant speed within the scanning range, hits the restricting member 28 and stops at the same time as it exceeds the scanning range. Runs can be eliminated. Therefore, it is possible to reduce the size of the apparatus without deteriorating the image quality of the read image.

In the conventional apparatus, an apparatus for suddenly stopping the lamp carriage using a regulating member has been developed. In such an apparatus, the motor connected to the lamp carriage is caused by the sudden stop of the lamp carriage. The motor may step out due to an overload condition. When an inexpensive open-loop control stepping motor or the like is used as a drive source, the motor loses synchronism and may hinder the position control of the lamp carriage.

In the image reading apparatus according to the present embodiment, the stopper 34 fixed to the cable 15 moves to the right with respect to the housing 31 after the lamp carriage 3 suddenly stops by hitting the regulating member 28 as described above. (See FIG. 4). By providing the joint 27 in this way, even if the lamp carriage 3 stops suddenly, the cable 1
5 would be allowed. As a result, the stepping motor 24 can perform a predetermined deceleration while the movement of the cable 15 is permitted, so that a large load is not applied to the stepping motor 24. Therefore, it is possible to reduce the possibility of the motor stepping out, and it is possible to hardly hinder the position control of the lamp carriage 3 even when using an inexpensive open-loop control motor as in the present embodiment. .

D. Modified Example In the above-described embodiment, a joint (an interlocking restriction unit) 80 shown in FIG. 8 may be provided instead of the joint 27. As shown in the figure, a magnet 81 is fixed to the left side of the housing 31 of the joint 80. On the other hand, the cable 15 inserted into the housing 31 has a magnet 8
2 is fixed. The magnet 81 and the magnet 82 are arranged such that different poles face each other.
1 and the magnet 82 come into close contact with each other due to the attraction force, and the cable 15 and the joint 80 move integrally. That is,
The lamp carriage 3 moves as the cable 15 moves.

On the other hand, when the lamp carriage 3 is suddenly stopped by hitting the regulating member 28 as in the above-described embodiment, the magnet 81 and the magnet 82 are separated from each other and the magnet 8
2 moves to the right in the figure. Therefore, even if the lamp carriage 3 stops suddenly, the movement of the cable 15 is allowed, and the same effect as in the above-described embodiment can be obtained.

As another modified example of the above-described embodiment, as shown in FIG.
A joint (interlocking regulation means) 90 may be provided between the drive shaft 21a and the drive shaft 21b. The joint 90 includes a disk-shaped drive unit 91 fixed to a drive shaft 21 a that rotates with the rotation of the timing pulley 22, and a disk-shaped transmission unit 92 fixed to a drive shaft 21 b that rotates the capstan pulley 25.
It is composed of

FIG. 10 is a view taken along line XX of FIG. As shown in the figure, two concave portions 93 are formed on a surface 92 a of the transmission portion 92 facing the drive portion 91. On the other hand, as shown in FIG.
1 has a projection 94 on a surface 91a facing the transmission portion 92.
Are formed, and the concave portion 93 of the transmitting portion 92 shown in FIG.
The projections 94 of the drive unit 91 are respectively made to enter therein. Further, a spring 95 is arranged in a compressed state between one side surface of the concave portion 93 of the transmitting portion 92 and the protrusion 94 which is inserted into the concave portion 93.

Under this configuration, the projection 94 is pressed against the side surface of the recess 93 by the pressing force of the spring 95 in the direction of the arrow in the figure. Are designed to rotate together.

On the other hand, when the lamp carriage 3 is suddenly stopped by hitting the regulating member 28 as in the above-described embodiment, the projection 94 moves by compressing the spring 95 in the direction opposite to the arrow direction, that is, The driving unit 91 rotates in the direction opposite to the direction of the arrow. In this way, the rotation of the drive unit 91 that is linked to the motor is allowed even though the transmission unit 92 that is linked to the ramp carriage 3 is stopped, so that the possibility of the motor stepping out can be reduced. Becomes

As shown in FIG. 12, a projection 101 formed of a magnet may be provided on the drive unit 91 instead of the projection 94. In this case, the magnet 102 is buried in one side surface of the concave portion 93, and the magnet 101 and the magnet 102 are normally brought into close contact with each other by the attraction force, so that the drive unit 91 and the transmission unit 92 are integrated. To rotate.

When the lamp carriage 3 stops suddenly, the magnet 101 and the magnet 102 separate and move in the direction of the arrow in the figure. Will be allowed.

E. FIG. 13 illustrates an example of a copier including the image reading apparatus according to the above-described embodiment. In the figure, reference numeral 60 indicates the image reading apparatus according to the above-described embodiment. Image reading device 6
0 reads the document D and generates an image reading signal as described above. The image processing unit 61 includes the image reading device 6
Then, the image reading signal generated by 0 is corrected to generate an image writing signal, and the image writing signal is supplied to a latent image writing device (ROS) 62 described later.

Next, the image forming unit 63 for forming an image based on the above-described image writing signal will be described. Reference numeral 64 denotes a photosensitive drum. Around the photosensitive drum 64, a charged corotron 65, a latent image writing device 62, a developing device 66, a transfer roll 67, a cleaner 68, and a charge removing roll 69 are provided.
Is arranged. The photoreceptor drum 64 is rotated in the direction indicated by the arrow in FIG.
5, the surface of the photosensitive drum 64 is uniformly charged.

The latent image writing device 62 irradiates a laser beam onto the photosensitive drum 64 in response to the image writing signal. As a result, the latent image corresponding to the image of the original D is
Written on the surface. Then, the developing device 66
The toner supplied from is electrostatically attached to form a visible toner image.

A sheet S such as paper or an OHP sheet is transported between the photosensitive drum 64 and the transfer roll 67 by a transport mechanism described later. Then, the toner image on the photosensitive drum 64 is electrostatically transferred to the sheet S by the electric field generated by the transfer roll 67. Note that a two-dot chain line in FIG. 13 indicates a path along which the sheet S is conveyed.

Thereafter, the sheet S is conveyed to the heat fixing device 70. The heat fixing device 70 includes a heating roll 70a and a pressure roll 70b that are arranged substantially in parallel with each other, and the toner image is heated and pressed by passing the sheet S through the nip therebetween. Is fixed on the sheet S. On the other hand, without being transferred to the sheet S, the photosensitive drum 6
The toner remaining on the surface 4 is removed by a cleaner 68 such as a blade, and thereafter, the surface of the photosensitive drum 64 is neutralized by the neutralization roll 69 for the image forming process again.

Reference numeral 71 denotes a sheet storage tray for storing sheets S first. Sheet storage tray 7
1, the sheet S is pulled out toward the main transport path 72. The main transport path 72 is provided with a plurality of pairs of transport rollers 73, which transport the sheet S toward a nip between the photosensitive drum 64 and the transfer roll 67. A discharge roller 75 for discharging the sheet S to the outside of the cabinet of the copying machine or to a discharge tray 74 is provided downstream of the heat fixing device 70.

As shown in FIG. 14, the image reading apparatus 60 according to the above embodiment can be provided in a facsimile apparatus. As shown in the figure, an image reading signal generated by the image reading device 60 is input to a controller (transmission unit) 77 through an input / output port 76. Then, the controller 77 transmits image data based on the input image reading signal to the outside.

[0044]

As described above, according to the present invention,
Despite the configuration capable of miniaturization, even when an inexpensive open-loop control motor is used as a drive source of the carriage, it is possible to reduce the deterioration in the image quality of the read image.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a plan sectional view showing the image reading apparatus.

FIG. 3 is a view showing a structure of a joint attached to a lamp carriage of the image reading apparatus.

FIG. 4 is a diagram showing a state of the joint when the lamp carriage of the image reading device hits a stopper.

FIG. 5 is a graph showing an operation of a lamp carriage in a conventional image reading apparatus.

FIG. 6 is a graph showing another example of the operation of the lamp carriage in the conventional image reading apparatus.

FIG. 7 is a graph showing an operation of a lamp carriage in the image reading apparatus according to the embodiment.

FIG. 8 is a view showing a structure of a joint in a modification of the image reading apparatus according to the embodiment.

FIG. 9 is a view showing the vicinity of a joint in another modification of the image reading apparatus according to the embodiment.

FIG. 10 is a view taken along line XX in FIG. 9;

FIG. 11 is a diagram showing a driving unit which is a component of another modification of the image reading apparatus.

FIG. 12 is a view showing still another modification of the image reading apparatus according to the embodiment.

FIG. 13 is a diagram illustrating a mechanical configuration of a copier including the image reading apparatus according to the embodiment.

FIG. 14 is a block diagram illustrating a schematic configuration of a facsimile including the image reading device according to the embodiment.

[Explanation of symbols]

D: Original, S: Sheet, 1: Housing, 2: Platen glass (mounting member), 3: Lamp carriage, 4: Mirror carriage, 15: Cable, 21: Drive shaft, 24: Stepping motor, 25: Cap Stan pulley, 27 joint (interlocking regulation means), 28 regulation member, 31 housing, 34 stopper, 63 image forming unit, 77
... Controller (transmission means) 80 ... Coupling (interlocking restriction means), 81, 82 ... Magnet, 90 ... Coupling (interlocking restriction means)

Claims (3)

[Claims] A mounting member for mounting an original, a carriage movably arranged along the mounting member, and scanning the original mounted on the mounting member during the movement over a scanning range; A driving unit configured to interlock with the carriage and move the carriage by generating a driving force; and a restriction unit configured to restrict movement of the carriage when the carriage moves beyond the scanning range. An image, comprising: a member; and an interlocking restricting unit configured to prevent the carriage from interlocking with the driving unit when the movement of the carriage is restricted by the restricting member. Reader. 2. An image forming apparatus, comprising: the image reading apparatus according to claim 1; and an image forming unit that forms an image on a sheet based on an image read by the image reading apparatus. 3. An image transmission device comprising: the image reading device according to claim 1; and a transmission unit that transmits a read signal based on an image read by the image reading device.