JPH09146185A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the overshooting of a traveling object caused by sudden acceleration after the traveling object escapes from a home position. SOLUTION: A material whose coefficient of friction is comparatively high is used for the approach run range AP between a position 16 corresponding to the home position of the traveling object and a position 17 corresponding to the lead edge (an image reading start position), of a sliding rail 11. Further, a thing made of the material whose coefficient of friction is lower than that of the approach run range AP is used for the range from the position 17 to a position 18, which corresponds to an image reading range. The overshooting caused by the sudden acceleration after the traveling object escapes from the home position is made little by great frictional force in the approach run range AP and in the image reading range, the traveling object runs with small frictional force, so that nonuniformity of speed and vibration are not generated because unnecessary force is not exerted at the time of traveling at a fixed speed.

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 for reading a document while traveling a first traveling body and a second traveling body, each holding a mirror, at a predetermined speed ratio.

[0002]

2. Description of the Related Art In a stationary original type image reading apparatus,
A first traveling body including a lamp for irradiating the original with light and a first mirror for reflecting the reflected light from the original, and second and third mirrors for sequentially reflecting the reflected light from the first mirror The second traveling body is provided, and the document is read while the first traveling body and the second traveling body are traveling at a speed ratio of 2: 1.

The structure of such a fixed document type image reading apparatus is shown in FIGS. As shown in FIG. 1, this image reading apparatus holds a contact glass 2 on an upper surface of a housing 1, and near a lower surface of the contact glass 2, a first traveling body 3 so as to be movable along the contact glass 2. Place and
Further, a second traveling body 4 that moves in the same direction at a moving speed that is half that of the first traveling body 3 is arranged, and when the first and second traveling bodies 3 and 4 reciprocate. A slide rail 11 serving as a guide member is provided. The first traveling body 3 holds a lamp 5 as a light source and a first mirror 6, and
The traveling body 4 holds a second mirror 7 and a third mirror 8. The first mirror 6 and the second mirror 7 are on the same horizontal plane, and the second mirror 7 and the third mirror 8 are on the same vertical plane. The home positions 9a and 9b are the positions of the first and second traveling bodies 3 and 4 when the traveling bodies 3 and 4 are closest to each other, and the positions when the traveling bodies 3 and 4 are farthest from each other are the home positions 9a and 9b. Each return position 10a, 10
b.

FIG. 2 shows the drive units of the first and second traveling bodies 3 and 4.
Shown in Drive motor 12 and drive belts 13a to 13c
As a result, the first and second traveling bodies 3 and 4 are reciprocally driven. Since the structure of the drive system itself in FIG. 2 is well known, detailed description thereof will be omitted. Further, at a predetermined position of the apparatus main body, a home position sensor 14 having a reflection type photo interrupter functioning as a detecting means is provided at a reference position of the optical system, and reaches the home position 9b of the second traveling body 4. A home position shielding plate 15 is provided which can shield the sensor portion of the home position sensor 14 at the time.

Further, the slide rail 11, which serves as a slide guide member when the first and second traveling bodies 3 and 4 perform a moving operation, has a sliding resistance as small as possible when traveling at a constant speed during image reading. , A material with a low coefficient of friction is used.

The first on the slide rail 11,
Regarding the sliding position of the second traveling bodies 3 and 4, for example, as shown in FIG. 3, a method in which the first and second traveling bodies 3 and 4 slide on the same straight line 1 in the sub-scanning direction DS, or in FIG. First, as shown
(2) The widths of the traveling bodies 3 and 4 in the main scanning direction DM are made different from each other, and even on the same slide rail 11, a different position is slid on parallel straight lines l1 and l2 along the sub scanning direction DS. There is also a system in which the first traveling body 3 slides in the first stage and the second traveling body 4 slides in the second stage in two stages. The shaded portions in FIGS. 3 and 4 are sliding portions.

In either method, the
The second traveling bodies 3 and 4 move along the document placed on the contact glass 2 during the operation of the image reading device reading the image information of the document, and the home positions 9a and 9 are formed.
After starting b, the drive motor 12 accelerates to reach a certain speed before the lead edge in the image reading range, starts image reading from the lead edge, and decelerates after reading a predetermined document size from the lead edge. Enter, enter a certain overrun distance, stop, and then return.

The first and second traveling bodies 3 and 4 are, specifically,
Scanning is driven by the speed control diagram as shown in FIG.
First, the two traveling bodies 3 and 4 that have left the home positions 9a and 9b start forward traveling, and accelerate to a linear velocity V corresponding to the scaling ratio within the approach distance range AP to the lead edge (image reading start position) E. After that, the speed becomes constant, image reading is started from the lead edge E, and a constant speed operation is performed within a distance according to the paper size of the original on the contact glass 2, that is, within the image reading range. Then, for example, if it is 100% (at the same magnification), after traveling within the image reading range X1 shown by the upper line in FIG. After the traveling is completed, the vehicle decelerates to stop the traveling and travels the distance until the traveling speed becomes 0 (overrun distance, XR1 at 100%, XR2 at 25%). After traveling the overrun distance XR1 or XR2 and the forward traveling speed becomes 0, the reverse traveling of the drive motor 12 causes a return traveling opposite to the forward traveling. That is, the vehicle accelerates until it reaches the return speed RV, and when it reaches the return speed RV, it travels at a constant speed, and further decelerates near the home positions 9a and 9b.
When the home position shield plate 15 of the second traveling body 4 shields the home position sensor 14, the rotation of the drive motor 12 becomes 0, and the speeds of both traveling bodies 3 and 4 become 0. Of course, the traveling distances of the first traveling body 3 and the second traveling body 4 are different, but in FIG. 5, the traveling distances are disregarded and different scales are drawn in the same diagram.

[0009]

In the above-described surface image reading apparatus, immediately before the first and second traveling bodies 3, 4 that have left the home positions 9a, 9b reach the lead edge E, overshoot due to acceleration is caused. Is settled. However, recently, as the machine becomes smaller and lighter, the distances from the home positions 9a and 9b to the lead edge E and the overrun distances XR1 and XR2 are inevitably very short.

Therefore, for example, in the case of a low variable magnification such as 25%, as shown in the speed control diagram of FIG. 6, the approaching distance AP becomes long because the traveling speed of the traveling bodies 3 and 4 is high, As a result, there is a problem that the lead edge is reached before the overshoot OS is settled, and the read image is deteriorated at the image front end. By increasing the friction coefficient of the slide rail 11, it is possible to increase the frictional force and reduce the overshoot OS, but in this case, the frictional force within the image reading range after the lead edge E is also increased. There is also a problem that unnecessary force is applied in that range, the traveling stability of the traveling bodies 3 and 4 is impaired, speed unevenness and vibration occur, and the read image deteriorates.

Furthermore, overrun distances XR1 and XR2
In order to shorten the acceleration, it is necessary to accelerate the falling acceleration, and in order to accelerate the acceleration, energy corresponding to that is required, and the current or voltage of the drive motor 12 must be increased before use. In addition, the temperature of the drive motor 12 rises, and the power consumption increases.

The present invention has been made in view of the above problems of the prior art. It is possible to reduce the overshoot of the running body due to the sudden acceleration after leaving the home position, and the read image deteriorates at the leading edge of the image. It is an object of the present invention to provide an image reading apparatus that can obtain a good image without causing unevenness in speed and vibrations.

[0013]

According to a first aspect of the present invention, there is provided a light source for irradiating a document placed on a document table with light to achieve the above object. A first traveling body that holds a first mirror that reflects the reflected light from the document, a second mirror that reflects the reflected light from the first mirror, and a reflected light from the second mirror. The second traveling body that holds the third mirror to be driven is connected to each other so as to operate in a mutually related manner, and a drive device for reciprocating these traveling bodies in the sub-scanning direction and a slide rail that serves as a guide member for reciprocating movement are provided. In the image reading device provided, the coefficient of friction of the slide rail is
It is characterized in that the range before the start of reading is set higher than the range of image reading when the second traveling body reciprocates.

That is, the friction coefficient of the slide rail, which serves as a guide member when the first and second traveling bodies reciprocate, is changed between before the reading is started and within the reading range. Increase the frictional force, and use the frictional force to reduce the overshoot of the moving body due to sudden acceleration after exiting the home position. Also, within the reading range,
The frictional force between the slide rail and the traveling body is reduced so that unnecessary force is not applied during constant-speed steady traveling, and speed unevenness and vibration do not occur within the reading range.

According to a second aspect of the image reading apparatus of the present invention, the sliding positions of the first and second traveling bodies are different in the main scanning direction, and the first traveling body slides in the above range. The friction coefficient of the slide rail is different from the friction coefficient of the slide rail in a range in which the second traveling body slides. That is, if the moving speed ratio of the first traveling body and the second traveling body is, for example, 2: 1, the acceleration of the rising of the second traveling body after leaving the home position is half that of the first traveling body, The overshoot at the tip is not so severe and it is better to use a slide rail that does not have a high coefficient of friction, so you can obtain a running condition suitable for each of the first and second running bodies, and do not impair running stability for both running bodies. To

According to a third aspect of the image reading device of the present invention, the coefficient of friction of the range after the start of reading of the slide rail is set higher than the coefficient of friction of the image reading range. That is, in the range after the image is read, the overrun distance of the traveling body is shortened by a large frictional force so that the traveling body can be used without increasing the current or voltage of the drive motor.

According to a fourth aspect of the image reading apparatus of the present invention, the coefficient of friction of the range of the slide rail before the start of reading is increased as it approaches the image reading range in the sub-scanning direction. It is characterized by gradually changing. That is, the friction coefficient of the slide rail in the range before the start of reading is changed stepwise in the sub-scanning direction, and the friction coefficient in the range immediately after leaving the home position is lowered so that a large torque is not required by the drive motor. In addition, gradually increasing the friction coefficient to prevent the running body from becoming unstable,
Make sure that the load on the drive motor is not shocking.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of the present invention will be described below with reference to FIGS. 7 to 12. In the following, description will be made by assigning common reference numerals to parts common to the related art.

FIG. 7 is a perspective view showing a first embodiment of the image reading apparatus according to the present invention, and FIG. 8 is a perspective view of a slide rail used in the same embodiment. In the slide rail 11 of the present embodiment, the range of the diagonal line sandwiched between the position 16 indicated by the alternate long and short dashed line corresponding to the home position 9a of the first traveling body 3 and the position 17 indicated by the alternate long and short dashed line corresponding to the lead edge E is shown. In the approach distance range AP, its range 16 to 17 and position 17
To, for example, double-letter (432 mm) reading range X
Range 17 up to the position 18 indicated by the alternate long and short dash line that is 1, X2
The coefficient of friction of ~ 18 is changed. The arrow DS in FIG.
F indicates the forward operation direction of the traveling bodies 3 and 4 in the sub-scanning direction.

For example, the approach distance range AP at positions 16 to 17
Use a material with a relatively high friction coefficient for
In the image reading ranges X1 and X2, a material having a friction coefficient lower than that of the approach distance range AP is used. For this reason,
The first and second traveling bodies 3 and 4 are home positions 9a and 9b.
The overshoot due to the sudden acceleration after exiting the vehicle becomes small by utilizing the high frictional force in the approach distance range AP. In the image reading ranges X1 and X2, the slide rail 11
Since the frictional force between the two traveling bodies 3 and 4 becomes small, unnecessary force is not applied during constant speed traveling, and speed unevenness and vibration do not occur.

FIG. 9 is a perspective view showing a slide rail used in the second embodiment of the image reading apparatus according to the present invention.
The present embodiment is intended for an image reading apparatus having a configuration in which the sliding ranges of the first traveling body 3 and the second traveling body 4 as shown in FIG. 4 are different. A portion in the figure is an approach distance range AP1 of the first traveling body 3,
The section B is the approach distance range AP2 of the second traveling body 4,
Corresponding to the speed ratio of the traveling body 3 and the second traveling body 4 (for example, 2: 1), the length of the B portion in the sub-scanning direction is 1/2 of that of the A portion.
It is. Further, the C section is the image reading range of the first traveling body 3, and the D section is the image reading range of the second traveling body 4. Each of these parts has the highest coefficient of friction of the part A, the part B has a lower coefficient of friction than the part A, and the parts C and D have a higher coefficient of friction. Use a material with a low coefficient of friction that minimizes the sliding resistance when reading at a constant speed.

That is, the second traveling body 4 is at the home position 9
The rising acceleration after leaving b is the same as that of the first traveling body 3 and the second traveling body.
If the traveling speed ratio of the traveling body 4 is 2: 1, the traveling speed ratio is half that of the first traveling body 3, and the overshoot does not have to be considered so severely. Therefore, the friction coefficient of the portion B is not increased so much that a traveling state suitable for the second traveling body 4 is obtained and traveling stability is not impaired.

FIG. 10 shows a third image reading apparatus according to the present invention.
3 is a perspective view showing a slide rail used in the embodiment of FIG. In the slide rail 11 of this embodiment, a range 18 to 19 of oblique lines sandwiched between a position 18 indicating the end position of the reading range and a position 19 indicated by a dashed line corresponding to the end position of the overrun of the first traveling body 3 is provided. Overrun range XR1,
In XR2, the range 18 to 19 and the image reading range X1,
The friction coefficient in the range 17 to 18 that is X2 is changed. For example, a material having a relatively low coefficient of friction is used in the ranges 17 to 18, and a material having a higher coefficient of friction is used in the ranges 18 to 19. As a result, in the range 18 to 19, the frictional force between the slide rail 11 and the traveling bodies 3 and 4 becomes large, and the overrun distance becomes short. Further, it is not necessary to increase the current or voltage of the drive motor for use.

FIG. 11 shows a fourth embodiment of the image reading apparatus according to the present invention.
5 is a graph showing a change in friction coefficient within the approach distance range of the slide rail used in the embodiment of FIG. That is, in the range immediately after leaving the home positions 9a and 9b (home position to position P1), the friction coefficient of the slide rail is set small in order to reduce the required torque of the drive motor, and the range of positions P1 to P2 is set. Then, the friction coefficient is gradually increased, and the friction coefficient is increased from the position 2 to the lead edge E near the lead edge E.

Here, the reason why the friction coefficient is gradually increased is that, for example, when the friction coefficient is rapidly changed from a low coefficient to a high coefficient as shown in the graph of the comparative example of FIG. The traveling body 3 due to the change in the frictional force,
The running state of No. 4 becomes unstable, and the load on the drive motor also becomes shocking due to this rapid change in frictional force, which may cause the drive motor to step out.
When the friction coefficient is changed stepwise in the sub-scanning direction as in the present embodiment, the running body does not become unstable, a large torque is not required in the drive motor, and the load applied to the drive motor does not become shock. .

[0026]

As described above, in the image reading apparatus according to the first aspect of the present invention, the coefficient of friction of the slide rail, which serves as a guide member when the traveling body is reciprocated, is set before the reading starts from the image reading range. Since the range of is increased, overshoot of the running body due to sudden acceleration after leaving the home position can be reduced by using frictional force, and the read image does not deteriorate at the image tip, There is an effect that a good image can be obtained. In addition, since the frictional force between the slide rail and the traveling body can be reduced within the reading range, unnecessary force is not applied during steady running at a constant speed, and uneven speed and vibration do not occur within the reading range, which is good. There is also an effect that it is possible to obtain various read images.

In the image reading apparatus according to the second aspect,
Since the friction coefficient of the slide rail in the range in which the first traveling body slides and the friction coefficient of the slide rail in the range in which the second traveling body slides are different, in addition to the common effects described above, The friction coefficient is changed to the sliding range of the two traveling bodies, and there is an effect that a traveling state suitable for each of the traveling bodies can be obtained and traveling stability is not impaired.

In the image reading apparatus according to claim 3,
Since the friction coefficient of the slide rail is increased in the range after image reading compared to the image reading range, in addition to the common effects described above, uneven speed and vibration can be achieved without unnecessary force being applied during steady running at a constant speed within the reading range. The effect is that the overrun distance can be shortened by utilizing a high frictional force in the range after the image is read.

In the image reading apparatus according to the fourth aspect,
By gradually changing the friction coefficient of the slide rail in the range before the reading starts in the sub-scanning direction, the friction coefficient in the range immediately after leaving the home position is lowered, and then the friction coefficient is gradually increased. Since the frictional force is increased, in addition to the common effects described above, there is an effect that the overshoot of the running body due to the sudden acceleration after exiting the home position can be reduced before the image reading area.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a fixed document type image reading apparatus.

FIG. 2 is an enlarged perspective view showing a drive unit of a traveling body of the apparatus shown in FIG.

FIG. 3 is a perspective view showing an example of a traveling body and slide rails of the apparatus of FIG.

FIG. 4 is a perspective view showing another example of a traveling body and slide rails of the apparatus of FIG.

5 is a speed control diagram of the traveling body in the apparatus shown in FIG.

FIG. 6 is a speed control diagram in the approach distance range of the traveling body in the device of FIG.

FIG. 7 is a perspective view showing a first embodiment of an image reading apparatus according to the present invention.

FIG. 8 is a perspective view of a slide rail used in the embodiment of FIG.

FIG. 9 is a perspective view showing a slide rail used in a second embodiment of the image reading apparatus according to the present invention.

FIG. 10 is a perspective view showing a slide rail used in a third embodiment of the image reading apparatus according to the present invention.

FIG. 11 is a graph showing a change of a friction coefficient within a run-up distance range of a slide rail used in a fourth embodiment of the image reading apparatus according to the present invention.

12 is a graph showing a comparative example with the embodiment of FIG.

[Explanation of symbols]

 1 Case 2 Contact Glass 3 First Traveling Body 4 Second Traveling Body 5 Lamp 6 First Mirror 7 Second Mirror 8 Third Mirror 9a, 9b Home Position 10a, 10b Return Position 11 Slide Rail 12 Drive Motors 13a-13c Drive Belt 14 Home position sensor 15 Home position shielding plate E Lead edge (image reading start position) AP Running distance range X1, X2 Image reading range XR1, XR2 Overrun distance OS Overshoot DM Main scanning direction DS Sub scanning direction DSF Forward operation direction

Claims (4)

[Claims] 1. A first traveling body holding a light source for irradiating a document placed on a document table with light, and a first mirror for reflecting light reflected from the document, and the first mirror. A second mirror that holds a second mirror that reflects the reflected light from the second mirror and a third mirror that reflects the reflected light from the second mirror
An image reading apparatus comprising: a driving device for connecting a traveling body to each other so as to perform a relative movement, and a drive device for reciprocating the traveling body in a sub-scanning direction; and a slide rail serving as a guide member for the reciprocating movement. Friction coefficient of
An image reading apparatus characterized in that a range before starting reading is made higher than an image reading range when the first and second traveling bodies reciprocate. 2. The frictional coefficient of the slide rail in a range in which the first traveling body slides and the second traveling body slides when the sliding positions of the first and second traveling bodies differ in the main scanning direction. 2. The image reading apparatus according to claim 1, wherein the friction coefficient of the slide rail in a moving range is different. 3. The image reading apparatus according to claim 2, wherein a coefficient of friction in a range after the reading of the slide rail is started is made higher than a coefficient of friction in the image reading range. 4. The friction coefficient in the range before the reading of the slide rail is started is gradually changed so as to become higher as it approaches the image reading range in the sub-scanning direction. An image reading device according to any one of 3 to 3.