JP2005148246A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such an image reading apparatus, while attaining the miniaturization, that can prevent a noise when a scanning optical system is stopped. <P>SOLUTION: Regarding the image reading apparatus provided with a placing part for placing an original, a 1st mirror table (scanning optical system) 20 for reading the original placed on the placing part, and a guide rail (supporting means) 30 for supporting the 1st mirror table 20 so that it can freely slide, a cushioning member 31 is arranged on the surface supporting the 1st mirror table 20 of the guide rail 30. That is, a plurality of sliders (sliding members) 28 and 29 coming in contact with the guide rail 30 are arranged on the 1st mirror table 20, and the sliders 28 and 29 are arranged in an offset state in a direction orthogonal to the scanning direction, and also, the cushioning member 31 is arranged in a position where the slider 29 passes by when the 1st mirror table 20 is moved in one direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus such as a copying machine, a facsimile machine, and a scanner.

  The configuration of a conventional image forming apparatus is shown in FIG.

  That is, FIG. 6 is a cross-sectional view of a conventional image forming apparatus. The image forming apparatus main body A has a scanner section B as an image reading means for reading image information of a book document at the upper part, and image forming at the lower part. It has an image forming unit C as a means, and a sheet deck D is assembled to the lower part thereof.

  The scanner unit B includes a platen glass 202, an original platen plate 203 that can be opened and closed with respect to the apparatus main body A, a first mirror table 20, a second mirror table 21, a lens barrel 22, a CCD sensor 23, an image processing unit, and the like. It consists of The first mirror table 20 includes an exposure lamp 24 that irradiates the document surface, a reflection shade 25, and a first mirror 26 that deflects the reflected light of the irradiated document 45 degrees and guides it to the second mirror table 21. It has been.

  Further, the second mirror table 21 is provided with a second mirror 27 and a third mirror 28 that turn back the reflected light incident from the first mirror table 20 by 180 degrees. The reflected light reflected by the second mirror base 21 passes through the lens barrel 22 and forms an image with the CCD sensor 23.

  Here, the first mirror base 20 and the second mirror base 21 are supported by a guide rail (not shown) and are movable along the guide rail. The first mirror base 20 and the second mirror base 21 are driven by a wire, a drive shaft, a pulley, a stepping motor, etc. (not shown) so that the optical path length from the document surface to the CCD sensor 23 is always constant. .

  Thus, when the original is placed on the platen glass 202 with the reading surface facing downward, the back surface of the original is pressed by the pressure plate 203 and set in a stationary state, and a reading start key (not shown) is pressed, the exposure lamp 24 scans the lower part of the platen glass 202 in the direction of the arrow a (hereinafter referred to as the scanning direction) to read image information on the document surface. The document image information read by the exposure lamp 24 is processed by an image processing unit, converted into an electrical signal, and transmitted to the laser scanner 111.

  Here, the image forming apparatus main body A functions as a copying machine when an image reading unit reading signal is input to the laser scanner 111, and functions as a printer when a computer output signal is input. The image forming apparatus main body A also functions as a facsimile apparatus if it receives a signal from another facsimile apparatus or transmits a signal from the image processing unit to another facsimile apparatus.

  FIG. 7 shows a cross section of the first mirror base 20.

  In the first mirror base 20, as shown in FIG. 7, a first mirror 26, an exposure lamp 24 and a reflection shade 25 are attached to the mirror base 19, and guide rails 30 are provided at both ends of the mirror base 19. Sliders 28 and 29 are provided which slide in contact with each other. These sliders 28 and 29 are respectively provided at two locations on the FWD side and the REV side along the traveling direction of one guide rail 30, and the sliders 28 and 29 are provided at a total of four locations of one first mirror base 20. Is provided.

  By the way, in recent years, image forming apparatuses such as copying machines tend to be further downsized, and accordingly, the width of the image reading apparatus tends to be narrow. Thus, when the width of the image reading device is reduced, the movable range of the mirror table is inevitably reduced. However, since the size of the original to be read is not different from the conventional one, the width of the mirror table is reduced and the run-up distance and braking distance are reduced. To meet the demand for miniaturization.

  On the other hand, there is a demand for higher reading speed as opposed to downsizing. Therefore, as a result, it is necessary to accelerate the mirror base moving at a higher speed at a shorter distance and to decelerate and stop at a shorter distance.

  However, as shown in FIG. 7, the main parts such as the exposure lamp 24, the reflection shade 25, and the first mirror 26 are arranged above the surface of the guide rail 30 on the first mirror base 20 that moves at the highest speed. In many cases, the center of gravity G of the first mirror base 20 is located above the guide rail 30. Therefore, when the reading is finished and stopped, a moment M in the direction indicated by the arrow in FIG. 7 acts to lift the REV-side slider 29, and when the slider 29 once lifted falls, a metal guide rail is dropped. There was a problem that a large impact sound was generated by colliding with 30.

  With respect to such a problem that noise is generated due to the mirror table jumping at the time of stop, in Patent Document 1, arms are extended from the mirror table to both sides in the scanning direction, and sliders are provided at both ends of the arm to provide a wide span. A proposal has been made to prevent the mirror table from jumping by supporting the mirror table.

JP-A-6-282013

  However, as proposed in the above-mentioned Patent Document 1, if an attempt is made to prevent the mirror table from jumping by increasing the distance between the sliders, an extremely wide slider distance is actually required, and the image forming apparatus can be downsized. It becomes difficult to achieve both.

  FIG. 8 is a diagram for explaining the proposal of Patent Document 1. In FIG.

In FIG. 8, 20 is the first mirror base, P is the fixing point of the wire that pulls the first mirror base 20, G is the center of gravity of the first mirror base 20, and 1 is the distance between the wire fixing point P and the center of gravity G. , L is the distance between the center of gravity G and the sliders 28 and 29. Although detailed description is omitted here, in Patent Document 1, when the acceleration when the first mirror base 20 stops in FIG. 8 is a and the gravitational acceleration is g,
L ≧ 2al / g (1)
It is explained that jumping of the first mirror base 20 can be prevented if the above is satisfied.

A specific numerical value is substituted into the above formula (1). As an example, when the first mirror base reading at a speed of 460 mm / s is to be stopped at a braking distance of 5 mm, the acceleration is a = 21 m / s 2.
It becomes. If the center of gravity G of the first mirror base 20 is located 15 mm above the wire fixing point P, according to the equation (1), L is required to be 60 mm or more on one side, and the image reading apparatus can be downsized. It becomes difficult.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image reading apparatus capable of preventing noise when the scanning optical system is stopped while reducing the size.

  In order to achieve the above object, the invention described in claim 1 is a placement unit for placing a document, a scanning optical system for reading a document placed on the placement unit, and a sliding optical system. In the image reading apparatus having the supporting means for supporting the scanning optical system, a buffer member is provided on a surface of the supporting means for supporting the scanning optical system.

According to a second aspect of the invention, in the first aspect of the invention, the scanning optical system is provided with a plurality of sliding members that come into contact with the support means, and the sliding members are offset in a direction perpendicular to the scanning direction. 2. The image reading apparatus according to claim 1, wherein the buffer member is disposed at a position where at least one of the sliding members passes when the scanning optical system moves in one direction. .
According to a third aspect of the present invention, in the first or second aspect of the present invention, the buffer member is provided at at least one preset stop position of the scanning optical system.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the stop position is a position after the scanning optical system reads a document of a maximum size.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, characterized in that the buffer member is provided at a position outside the image reading area.

  The invention according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the coefficient of friction of the buffer member is set larger than that of the support means.

  According to the first aspect of the present invention, in the image forming apparatus in which the braking distance of the scanning optical system is shortened along with the downsizing of the image reading apparatus, after the scanning optical system that has read at high speed has finished reading. Even when the scanning optical system jumps and stops due to a short braking distance, the scanning optical system that jumps and floats falls on the buffer member, so that a large impact sound as in the conventional case is not generated and the image is not generated. Generation of noise when the scanning optical system is stopped can be prevented while downsizing the reading apparatus.

  According to the second aspect of the present invention, the sliding member of the scanning optical system is offset in the direction orthogonal to the scanning direction, and only one of the offset sliding members is out of the reading range and then on the buffer member. Since the sliding member passes through the joint between the buffer member on the supporting means and the other sliding surface, the read image does not blur.

  According to the third aspect of the invention, similarly to the reading operation, the buffer member is also arranged at the stop position after the returning operation, thereby preventing the generation of noise due to the jumping of the scanning optical system even during the returning operation. Is possible.

  According to the fourth aspect of the present invention, since the buffer member is provided at the stop position after the scanning optical system reads the maximum size document, the reading of the scanning optical system is completed when the document other than the maximum size is read. By setting a long braking distance later, the moment generated in the scanning optical system can be suppressed to a small value, and jumping of the scanning optical system when stopped can be prevented.

  According to the fifth aspect of the present invention, since the buffer member is provided at a position outside the image reading area, the scanning optical system does not pass through the joint between the buffer member and the support means during the image reading, and the step of the seam The scanned image does not blur.

  According to the sixth aspect of the present invention, since the friction coefficient of the buffer member is set larger than that of the support means, the motor torque required at the time of stop is reduced, and the optical drive motor is less likely to step out at the time of stop. .

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a perspective view of an image reading apparatus according to Embodiment 1 of the present invention. Note that the description of the configuration of the image reading apparatus that overlaps the conventional example is omitted.

  In the image reading apparatus shown in FIG. 1, the first mirror base 20 and the second mirror base 21 read an image by the same operation as the conventional image reading apparatus shown in FIG. The first mirror base 20 is provided with two sliders 28 and 29 (see FIG. 2) per one guide rail 30. In the present embodiment, as shown in FIG. A slider 28 on the FWD side and a slider 29 on the REV side are disposed along the width direction perpendicular to the scanning direction by an offset e.

  Further, as shown in FIG. 2, on the outer line through which the REV-side slider 29 passes and at a position immediately after the REV-side slider 29 passes through the image reading region, a resin-made buffer member 31 is provided. Is provided. The material of the buffer member 31 is required to have wear resistance and oil resistance (grease is often applied on the guide rail 30 to improve the slidability). For example, POM and TPU (urethane elastomer) ) Etc. are conceivable. In particular, it is considered that TPU is suitable when the buffer performance for preventing the generation of impact sound is emphasized. Of course, as long as the material can exhibit a desired buffer performance, a resin other than those exemplified here or a material other than the resin may be used.

  As a method of attaching the buffer member 31, a method such as screwing or bonding may be considered. However, in the present embodiment, the buffer member 31 is snapped as shown in FIG. A method of attaching to the guide rail 30 in a fitted shape is adopted.

  That is, in FIG. 3, the dimensions of a, b, and c of the buffer member 31 are each set to be about 0.2 mm larger than the dimensions of A, B, and C of the corresponding guide rail 30. The buffer member 31 having the slightly larger dimensions a, b, and c is fitted into the guide rail 30 in the direction of the arrow while being slightly crushed using its elasticity, so that the buffer member 31 after mounting is mounted on the guide rail 30. It is securely fixed without rattling. In the present embodiment, the level difference d of the buffer member 31 is set so that the level difference between the buffer member 31 and the sliding surface of the guide rail 30 is within 0.3 mm after mounting.

  FIG. 2 is a view showing the positional relationship between the sliders 28 and 29 of the first mirror base 20 and the buffer member 31 on the guide rail 30, wherein the upper stage is a side view and the lower stage is a plan view showing only one side configuration. .

  In the sliders 28 and 29 of the first mirror base 20, as shown in FIG. 2, the slider 28 on the FWD side is offset toward the inner side of the guide rail 30, and the slider 29 on the REV side is offset toward the outer side by e. ing.

  On the other hand, the buffer member 31 on the guide rail 30 passes the REV-side slider 29 through the passage line of the FWD-side slider 28 so that only the REV-side slider 29 of the first mirror base 20 passes and the FWD-side slider 28 does not pass. It is arranged on the outer side of the guide rail 30 that is out of position.

  The buffer member 31 is disposed in an area where the REV-side slider 28 of the first mirror base 20 passes after passing through the document reading area. Thus, neither the FWD-side slider 28 nor the REV-side slider 29 passes through the joint between the guide rail 30 and the buffer member 31 during image reading, and the read image does not blur due to the step of the joint.

  Thus, since the first mirror stage 20 has a moment M acting in the direction of the arrow due to a sudden stop after image reading, the REV-side slider 29 is lifted in the direction of travel as shown by the broken line in FIG. Since the buffer member 31 is arranged at the position where the floating slider 29 falls, there is no harsh impact sound generated when the slider 29 collides with the metal guide rail 30 as in the prior art.

  In the present embodiment, the buffer member 31 is disposed only at the stop position after the image reading apparatus reads the maximum-size document. This is because in the case of reading a document of a size other than the maximum size, the moment generated in the first mirror base 20 is suppressed by setting a long braking distance after the end of the reading, and the first mirror base 20 jumps off when stopped. This is because it can be prevented. However, if the level difference of the joint between the guide rail 30 and the buffer member 31 described in the present embodiment is set to almost zero, or if the image quality can be lowered due to the level difference, the same buffer is also applied to stop positions other than the maximum size. It is of course possible to arrange the members.

  Further, in the present embodiment, the FWD side slider 28 is disposed on the inner side and the REV side slider 29 is disposed on the outer side in consideration of ease of installation of the buffer member 31 on the guide rail 30. If installed at appropriate positions, the same effect can be expected even if the FWD side slider 28 is on the outside and the REV side slider 29 is on the inside.

  Further, according to the present embodiment, it is possible to independently set the friction coefficient of the support surface of the first mirror base 20 in the region where the normal reading operation is performed and the region where the speed is reduced and stopped. That is, if the friction coefficient of the buffer member 31 is set to be larger than that of the guide rail 20 surface, the first mirror base 20 slides smoothly on the guide rail 30 in the reading region, and the buffer member 31 in the stop region. The brake is applied due to the large friction coefficient, and the stop torque acting on the optical drive motor at the time of stop is reduced. As a result, even if an abrupt stop operation is performed, an effect is obtained that the optical drive motor is less likely to step out.

<Embodiment 2>
Next, a second embodiment of the present invention will be described.

  In the first embodiment, the case where the center of gravity G of the first mirror base 20 is above the guide rail 30 and the moment M is generated in the direction in which the REV-side slider 29 floats when stopped is described.

  However, considering the configuration of various mirror stands, the position of the mirror 26 is low as shown in FIG. 4, the mirror 26 is very thick, and the weight of the mirror 26 is affixed to the back. In such a case, contrary to the first embodiment, it is conceivable that a moment M in the direction of the arrow is generated such that the FWD side slider 28 floats as shown by a broken line in FIG. In such a case, as shown in FIG. 4, contrary to the first embodiment, the FWD slider 28 is offset toward the outside of the guide rail 30 and the REV slider 29 is offset toward the inside by e. In addition, the buffer member 31 may be disposed at a position after the FWD side slider 28 is out of the reading region and in a region through which only the FWD side slider 28 passes.

  By adopting such a configuration, in the image reading apparatus according to the present embodiment including the first mirror base 20 in which a moment M is generated such that the FWD-side slider 28 jumps when stopping after the reading is finished. The same effect as in the first embodiment can be obtained.

<Embodiment 3>
Next, a third embodiment of the present invention will be described.

  In the first and second embodiments, the description has been made on the assumption that noise is generated when the mirror table is stopped after finishing image reading.

  However, in an actual product, after the mirror table finishes reading and stops, an operation of returning to a standby position called a home position occurs to perform the next reading operation. In this case, since the return operation does not involve image reading, it is possible to start deceleration more quickly and set the braking distance longer than that during the reading operation, or to reduce the operation speed, and the mirror base will bounce. It is possible to stop so that there is no.

  However, in order to perform the next reading operation sooner, if it is necessary to return at a high speed and stop suddenly, the mirror base will bounce during stoppage in the return operation as well as the image reading operation. If you want to. Even in such a case, as shown in FIG. 5, the same noise reduction effect as that in the reading operation can be obtained by arranging the second buffer member 32 at the return operation stop position.

  In this case, originally, the buffer member 32 may be disposed only at the dropping point of the FWD-side slider 28, but the step between the buffer member 32 and the guide rail 30 is not a problem during the return operation. A buffer member 32 having a size straddling the passing lines of the sliders 28 and 29 is disposed. Of course, the second buffer member 32 is disposed before the reading start position.

  The present invention can be applied to an image reading apparatus such as a copying machine, a facsimile machine, or a scanner that reads a document by moving a scanning optical system that reads the document placed on the placement unit along the support unit.

1 is a perspective view of an image reading apparatus according to Embodiment 1 of the present invention. It is a figure which shows the positional relationship of the slider of a 1st mirror stand, and the buffer member on a guide rail in the image reading apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the attachment structure to the guide rail of the buffer member of the image reading apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the positional relationship of the slider of a 1st mirror stand, and the buffer member on a guide rail in the image reading apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the positional relationship of the slider of a 1st mirror stand, and the buffer member on a guide rail in the image reading apparatus which concerns on Embodiment 3 of this invention. It is sectional drawing of the conventional image forming apparatus. It is sectional drawing of the 1st mirror stand of the conventional image forming apparatus. It is a figure explaining the proposal of patent document 1. FIG.

Explanation of symbols

20 First mirror stand (scanning optical system)
21 Second mirror stand (scanning optical system)
28 FWD slider (sliding member)
29 REV side slider (sliding member)
30 Guide rail (support means)
31 Buffer member 32 Second buffer member

Claims (6)

In an image reading apparatus comprising: a placement unit that places a document; a scanning optical system that reads a document placed on the placement unit; and a support unit that slidably supports the scanning optical system.
An image reading apparatus characterized in that a buffer member is provided on a surface of the support means that supports the scanning optical system.   When the scanning optical system is provided with a plurality of sliding members that come into contact with the support means, the sliding members are arranged offset in a direction perpendicular to the scanning direction, and the scanning optical system moves in one direction. The image reading apparatus according to claim 1, wherein the buffer member is arranged at a position where at least one of the sliding members passes.   The image reading apparatus according to claim 1, wherein the buffer member is provided at at least one or more preset stop positions of the scanning optical system.   The image reading apparatus according to claim 3, wherein the stop position is a position after the scanning optical system reads a document of a maximum size.   The image reading apparatus according to claim 1, wherein the buffer member is provided at a position outside the image reading area.   6. The image reading apparatus according to claim 1, wherein a coefficient of friction of the buffer member is set larger than that of the support means.

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