JP4443254B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that is used in a digital copying machine, an image scanner, or the like to scan and read a document.

  2. Description of the Related Art Conventionally, in a mirror scanning type copying machine, an original is placed on a contact glass of an original reading unit, and a scanning unit such as a light source or a traveling mirror provided below the contact glass is scanned with a predetermined driving device. A mechanism for reading a manuscript image by moving it in parallel is widely used.

  FIG. 4 is a schematic diagram of a conventional image reading apparatus. Reference numeral 100 denotes a document. The document 100 is placed on a document holding member (not shown), that is, a contact glass attached to the upper portion of the apparatus main body 102 with the document surface facing downward. In addition, guide rails 103 as a pair of guide members are fixed in parallel to each other inside the apparatus main body 102 below the contact glass. Further, the guide rail 103 is parallel to the contact glass.

  Reference numeral 104 denotes an illumination unit (first scanning unit) including a light source and a mirror (both not shown), and 105 denotes a mirror unit (second scanning unit) including a mirror 105a and the like. It is held by a power transmission means (not shown) so as to be able to reciprocate on the guide rail 103 in the directions of arrows A and B. A plate-like support member (hereinafter referred to as ISU base) 106 is attached between frames in the front-rear direction of the apparatus main body 102, and a condenser lens 107 and a photoelectric conversion element (reading means) (reading means) are provided on the upper surface of the ISU base 106. (Hereinafter referred to as CCD) 108 is mounted.

  In this manner, the positions of the contact glass, the illumination unit 104, the mirror unit 105, the condenser lens 107, and the CCD 108 are determined. In the above configuration, the original 100 is illuminated by the light source of the illumination unit 104, the illumination unit 104 moves in the direction of arrow A at a predetermined speed, and the mirror unit 105 is in the same direction at half the speed of the illumination unit 104. Moving. As a result, the image light D formed by illumination of the illumination unit 104 is guided to the condensing lens 107 by the mirror unit 105, and after being condensed, forms an image on the CCD 108. The formed image light D is subjected to pixel decomposition in the CCD 108, converted into an electric signal corresponding to the density of each pixel, and an image is read.

  FIG. 5 is a perspective view showing a driving mechanism of a conventional image reading apparatus. Portions common to those in FIG. 4 are denoted by the same reference numerals and description thereof is omitted. In the figure, the image reading apparatus is provided with scanning means comprising an illumination unit 104 and a mirror unit 105, and each unit 104, 105 has a guide rail 103 disposed in the scanning direction (arrow A direction) at both ends thereof. It is slidably held by.

  The illumination unit 104 is equipped with an exposure lamp 104a and a first mirror 104b that reflects light reflected from the original by irradiation of the exposure lamp 104a in a direction parallel to a contact glass (not shown). The mirror unit 105 is equipped with a second mirror 105a and a third mirror 105b, and the reflected light from the first mirror 104b passes through the second mirror 105a and the third mirror 105b, and the condenser lens 107 (see FIG. 4). The original image is formed on the photoelectric conversion element 108 (see FIG. 4).

  Next, a drive mechanism for reciprocating the illumination unit 104 and the mirror unit 105 will be described. Reference numeral 40 denotes a pulse motor that drives the illumination unit 104 and the mirror unit 105. Here, a stepping motor that is easy in speed control and advantageous in terms of cost is used. The pulse motor 40 rotationally drives the shaft 43 via a spur gear 41 and timing belts 42a and 42b. Wire drums 44 a and 44 b are fixed to both ends of the shaft 43. Here, the wire drum 44b is not shown.

  Driving wires 46a and 46b are stretched between the wire drum 44a and pulleys 45a, 45c and 45e, and between the wire drum 44b and pulleys 45b, 45d and 45f, respectively. One ends of the driving wires 46 a and 46 b are locked to wire locking portions 47 a and 47 b provided in the apparatus main body 102. The other ends of the drive wires 46a and 46b are fixed to a side surface (not shown) of the apparatus main body 102 via a wire tension spring 48, and an appropriate tension is applied to the drive wires 46a and 46b.

  FIG. 6 is a schematic view of the drive mechanism of the image reading apparatus as viewed from the side (in the direction of arrow B in FIG. 5). For convenience of explanation, the guide rail 103, the pulse motor 40, the spur gear 41, the timing belts 42a and 42b, etc. are not shown. Although only the driving wire 46b side is shown here, the driving wire 46a side will be described in exactly the same manner.

  As shown in the figure, the driving wire 46b is wound around the wire drum 44b by a predetermined amount, and one end extending from the wire drum 44b in the scanning direction (the direction of arrow A in FIG. 5) is stretched over the pulley 45b to change the direction. In other words, after it is wound around the pulley 45d and changes its direction again, it is locked to the wire locking portion 47b. On the other hand, the other end extending in the opposite direction is stretched over the pulley 45f to change the direction, and then spanned over the pulley 45d to change the direction again, and then fixed to the apparatus main body 102 (not shown) via the wire tension spring 48. . The illumination unit 104 is fixed to the drive wire 46b between the pulley 45b and the pulley 45d, and the mirror unit 105 is fixed to the pulley 45d. Here, the pulleys 45 b and 45 f are fixed to the apparatus main body, but the pulley 45 d can reciprocate together with the mirror unit 105.

  In this configuration, when the wire drum 44b is rotationally driven in the direction of arrow C by the pulse motor 40, the spur gear 41, and the timing belts 42a and 42b (see FIG. 5) during document reading, the drive wire 46b moves in the direction of arrow D. Then, the illumination unit 104 and the mirror unit 105 also follow this and move in the same direction. At this time, since the pulley 45d serves as a moving pulley, the mirror unit 105 moves in the same direction with respect to the illumination unit 104 at a half speed. Further, after the reading is completed, the wire drum 44b is reversely rotated to return the illumination unit 104 and the mirror unit 105 to their original positions.

  In the image reading apparatus described above, in recent years, the mainstream of a motor is changing from a conventional DC servo motor to a pulse motor such as a stepping motor from the viewpoint of miniaturization and cost reduction of a wire driving motor. Along with this, vibration (gogging vibration) generated by the movement of each phase of the stepping motor, which was not a problem in the analog image reading apparatus, is transmitted via drive transmission means such as a gear train and a timing belt. It is transmitted to the wire drive pulley and further propagated to the scanning means comprising the illumination unit and the mirror unit via the drive wire. For this reason, there is a problem that regular shading (jitter) appears in the scanned image due to the occurrence of slight vibrations in the entire scanning means or in the mirror, and a normal scanned image cannot be obtained and the image quality deteriorates.

  Therefore, various methods for preventing micro-vibration of the scanning means have been proposed, and Patent Document 1 discloses that an elastic member is interposed between the carriage of the illumination unit and the light source support that supports the light source. A method for reducing vibration transmitted to a light source on a carriage is disclosed. Patent Document 2 discloses a method of preventing resonance by changing the natural frequency by attaching a vibration isolating member such as iron or glass to the rear surface of the mirror of the mirror unit to increase the rigidity of the mirror. ing.

However, in each of the methods of Patent Documents 1 and 2, since the weight of the carriage increases, the load on the drive motor that drives the scanning unit increases, which may reduce the life of the drive motor. Cost increase due to an increase in the process is also a problem. In addition, since the carriage and the drive wire are directly connected, the slight vibration generated from the motor is transmitted to the carriage via the drive wire.
Japanese Utility Model Publication No. 2-13257 Japanese Patent Laid-Open No. 2001-22009

  In view of the above problems, the present invention reduces vibrations propagated from the motor to the scanning means via the drive transmission means without increasing the weight of the mirror or the carriage of the scanning means or increasing the rigidity. An object of the present invention is to provide an image reading apparatus that reliably prevents deterioration of a read image.

In order to achieve the above object, the present invention includes a first scanning unit including a light source that illuminates an original and a mirror that guides reflected light from the original as image light, and a mirror that changes an optical path of the image light. Second scanning means, and driving means for driving the first and second scanning means via a driving wire, and the first scanning means is fixed to the driving wire by a wire fixing member. The second scanning unit is connected to the driving wire by a pulley and moved at a constant scanning speed to read the original image. The driving wire is connected to the first scanning unit. , the longitudinal ends are sandwiched between the wire fixing member slidably mounted on said first scanning means and the wire fixing member and the drive wire of the first scanning means An elastic member is interposed between, is characterized by fixing the said driving wire without contact with the first scanning means and the wire fixing member.

  According to the present invention, in the image reading apparatus having the above configuration, the first scanning unit and the wire fixing member are connected by a fixing screw, and the driving wire and the elastic member are fastened by the fixing screw. It is characterized by being clamped by predetermined pressure.

According to the present invention, in the image reading apparatus having the above-described configuration, the elastic member is disposed between the sliding portion of the wire fixing member and the fixing screw , surrounds the driving wire, and fixes the fixing member. It is characterized by being arranged in a U-shaped cross-section that opens in the direction of the machine screw.

  According to the first configuration of the present invention, the rigidity of parts such as a carriage and a mirror can be increased by elastically fixing the drive wire to the first scanning means and the wire fixing member through the elastic member. Without increasing the load on the motor, vibration transmitted from the motor to the first scanning means via the drive wire can be suppressed, and high-quality images can be read.

  According to the second configuration of the present invention, in the image reading apparatus having the first configuration, the elastic member and the driving wire are clamped at a predetermined pressure by fastening the fixing screw. Thus, the elastic member is deformed by the inertial force, and then the elastic member is restored, so that there is no possibility that the first scanning means vibrates.

According to the third configuration of the present invention, in the image reading apparatus having the second configuration , the driving wire is enclosed between the sliding portion of the wire fixing member and the fixing screw, and the fixing screw is used. By disposing the elastic member having a U-shaped cross section that opens in the direction, the driving wire and the elastic member can be effectively crimped by fastening the fixing screw.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view of the illumination unit (first scanning unit) of the image reading apparatus of the present invention as viewed from the side of the apparatus (in the direction of arrow C in FIG. 5). Portions common to FIG. 5 of the conventional example are denoted by the same reference numerals and description thereof is omitted. In FIG. 1, reference numeral 1 denotes a carriage of the illumination unit 104. The carriage 1 is provided with a light source 104a and a first mirror 104b for illuminating the document. The light source 104 a is supported at both ends by the contact member 3 on support portions provided on the carriage 1, and the first mirror 104 b is supported at both ends by the lower portion of the carriage 1.

  A contact 4 is provided at the lower end portion of the carriage 1 in contact with the upper surface of the guide rail 103, and the contact surface of each contact 4 with the guide rail 103 is a spherical surface. Further, driving wires 46a and 46b for driving the illumination unit 104 along the guide rail 103 slide up and down above the flanges 1a and 1b protruding from the left and right of the carriage 1 and the flanges 1a and 1b. It is clamped between the wire fixing metal fittings 5 (wire fixing members) that can be attached. The wire fixture 5 can be provided separately from the carriage 1.

  The flanges 1a and 1b and the wire fixing bracket 5 are connected by a fixing screw 6. By fastening the fixing screw 6, the driving wires 46a and 46b are fixed to the carriage 1, and the illumination unit 104 is attached to the guide rail 103. A reciprocating motion is made along the scanning direction (the paper surface direction in the figure). An elastic member 7 is disposed between the flanges 1a and 1b and the wire fixing bracket 5 and the driving wires 46a and 46b.

  FIG. 2 is an enlarged view of a wire fixing portion (inside circle A in FIG. 1) in FIG. Here, only one side of the illumination unit 104 (right side in FIG. 1) will be described, but the opposite side (left side in FIG. 1) will be described in exactly the same manner. In the figure, the elastic member 7 is disposed in a U-shaped cross section so as to surround the drive wire 45 b, and the U-shaped opening is directed toward the fixing screw 6. With this configuration, the driving wire 46b is not in direct contact with the carriage 1 and the wire fixing bracket 5, and the slight vibration generated from the pulse motor 40 (see FIG. 4) is directly transmitted to the carriage 1 through the driving wire 46b. To prevent it.

  Further, since the elastic member 7 is crimped between the flange 1b of the carriage 1 and the wire fixing bracket 5 by fastening the fixing screw 6, even when the illumination unit 104 is moved at a high speed, the elastic member 7 can be accelerated at the initial acceleration. There is no possibility that the elastic member 7 is deformed by the inertial force and the illumination unit 104 is vibrated by the restoring force of the elastic member 7 thereafter. Therefore, by adopting the configuration of the present embodiment, it is possible to effectively prevent the illumination unit 104 from vibrating when the document is read.

  Here, the driving wire 46b is sandwiched in the vertical direction by the flange 1b of the carriage 1 and the wire fixing bracket 5, but may be configured to be sandwiched in the horizontal direction. Alternatively, the carriage 1 and the wire fixing bracket 5 may be integrally formed so as to be elastically deformable, and the driving wire 46b and the elastic member 7 may be crimped and sandwiched by fastening the fixing screw 6.

  The fixing method of the collars 1a and 1b of the carriage 1 and the wire fixing bracket 5 is not limited to screw fixing, and various fixing methods such as fixing using rivets and eyelets, caulking, and fixing by welding can be used. However, by using a fixing screw as in this embodiment, the pressure for sandwiching the drive wire 46b and the elastic member 7 can be adjusted, and if the elastic member 7 is deteriorated with time, it can be easily replaced. Therefore, it is more preferable.

  As a material of the elastic member 7, for example, a low-resilience damping rubber such as butyl rubber, neoprene rubber, urethane rubber or the like is effective in dampening vibration, but is not limited thereto. Here, the elastic member 7 is disposed around the drive wire 46b in a U-shaped cross section. However, the configuration is not limited thereto as long as the drive wire 46b is not in direct contact with the carriage 1 and the wire fixing bracket 5. For example, it may be arranged only above and below the drive wire 46b as shown in FIG. 3 (a), and surrounds the entire circumference of the drive wire 46b as shown in FIGS. 3 (b) and 3 (c). It may be arranged.

  However, the fastening of the fixing screw 6 is achieved by adopting the configuration of the present embodiment in which the elastic member 7 is disposed in a U-shaped cross section around the driving wire 46 b with the opening portion directed toward the fixing screw 6. Is efficiently transmitted to the driving wire 46b through the elastic member 7, and the elastic member 7 and the driving wire 46b can be effectively crimped and clamped, and the driving wire 46b is in direct contact with the side surface of the carriage 1. It is more preferable because it does not occur.

The present invention includes a first scanning unit that includes a light source that illuminates a document and a mirror that guides reflected light from the document as image light, a second scanning unit that includes a mirror that changes the optical path of the image light, Driving means for driving the first and second scanning means via a driving wire, the first scanning means is fixed to the driving wire by a wire fixing member, and the second scanning means is driven by a pulley. In an image reading apparatus that is connected to a wire for scanning and moves at a constant scanning speed and reads a document image, the driving wire is slidable on both ends of the first scanning means and the first scanning means in the longitudinal direction. The drive wire is sandwiched between the attached wire fixing member and an elastic member is interposed between the first scanning means and the wire fixing member and the driving wire, and the driving wire is connected to the first scanning means and the wire. Fixed part And it is fixed without contact with.

  As a result, vibrations propagated from the motor to the first scanning means via the drive wire without increasing the rigidity of the parts such as the carriage and the mirror or increasing the weight to increase the load on the motor. An image reading apparatus capable of suppressing and reading high-quality images is provided at low cost.

  Further, by holding the elastic member and the driving wire at a predetermined pressure by fastening the fixing screw, the elastic member is deformed by an inertial force at the initial acceleration at the start of reading, and then the elastic member is restored to restore the first. Since there is no possibility that the scanning means vibrates, the vibration of the first scanning means can be more effectively prevented.

Between the fixing screw and sliding portion of the wire fixing member surrounds the drive wire, and by a U-shaped section of the elastic member to open the fixing screw direction is disposed, the fixing screw The driving wire and the elastic member by fastening are more effectively crimped, and there is no possibility that the driving wire contacts the carriage.

These are side views showing the illumination unit (first scanning means) of the image reading apparatus of the present invention. These are the enlarged views of the wire fixing part of a lighting unit. These are sectional drawings which show the other arrangement | positioning method of an elastic member. FIG. 1 is a schematic view of a conventional image reading apparatus. These are perspective views which show the drive mechanism of the conventional image reading apparatus. These are the schematic views which looked at the drive mechanism of the conventional image reading apparatus from the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carriage 1a, 1b collar part 3 Contact member 4 Contactor 5 Wire fixing metal fitting 6 Fixing screw 7 Elastic member 40 Pulse motor 41 Flat gear 42a, 42b Timing belt 43 Shaft 44a, 44b Wire drum 45a, 45b, 45c, 45d, 45e, 45f Pulley 46a, 46b Driving wire 47a, 47b Wire locking part 100 Document 102 Apparatus body 103 Guide rail 104 Illumination unit (first scanning means)
104a Light source 104b First mirror 105 Mirror unit (second scanning means)
105a Second mirror 105b Third mirror

Claims (3)

A first scanning unit including a light source for illuminating the document and a mirror for guiding reflected light from the document as image light; a second scanning unit including a mirror for changing an optical path of the image light; And a driving means for driving the second scanning means via a driving wire, the first scanning means is fixed to the driving wire by a wire fixing member, and the second scanning means is fixed by a pulley. In an image reading apparatus that is connected to the driving wire and moves at a constant scanning speed to read a document image,
The driving wire is sandwiched between the first scanning unit and the wire fixing member slidably attached to both longitudinal ends of the first scanning unit, and the first scanning unit And an elastic member interposed between the wire fixing member and the driving wire, and the driving wire is fixed without contacting the first scanning means and the wire fixing member. Image reading device.   The first scanning means and the wire fixing member are connected by a fixing screw, and the driving wire and the elastic member are clamped at a predetermined pressure by fastening the fixing screw. The image reading apparatus according to claim 1. The elastic member is disposed between the sliding portion of the wire fixing member and the fixing screw , and surrounds the driving wire and is arranged in a U-shaped cross section that opens in the fixing screw direction. The image reading apparatus according to claim 2, wherein:

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