JP4368192B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image of a document by being used alone as a scanner or mounted on a copying machine, a facsimile, or the like.

  In general, an image reading apparatus irradiates light from a light source onto an image surface of a document, and guides the reflected light to a reading device such as a CCD through a condenser lens while reflecting the reflected light by a plurality of mirror plates. An image of a document is acquired (read) as an electrical signal. The configuration of a conventional image reading apparatus that achieves such basic functions will be described below with reference to the drawings.

  As shown in FIGS. 3 to 5, the image reading apparatus 1 is configured by a main body housing 2 formed of a metal plate, and includes a left side plate 2 a, a right side plate 2 b, a front side plate 2 c, and a rear side plate 2 d. . A contact glass 3 on which an original is placed is provided on the upper surface of the main body housing 2. Further, in the main body housing 2, the reference position (left side plate 2 a side) and the reversing position (right side plate 2 b side) are linked in parallel with the contact glass 3 and along the front and rear side plates 2 c and 2 d. The first and second scanning optical system units 4 and 5 that are independent from each other are supported.

  First, the details of the configuration on the optical surface will be described. As shown in FIGS. 3 and 5, the first scanning optical system unit 4 has a first scanning frame body 40 formed of a metal plate for holding various components described later. One scanning frame 40 is a lamp 41 which is a light source for irradiating light on the image surface of the document placed on the contact glass 3, and a reflector for efficiently irradiating the document with the light from the lamp 41. 42 and a first mirror plate 43 that reflects the reflected light from the original (hereinafter sometimes referred to as “original reflected light”) toward the second optical system unit 5. On the other hand, the second scanning optical system unit 5 has a second scanning frame body 50 formed of a metal plate for holding various components to be described later. There are provided a second mirror plate 51 and a third mirror plate 52 that sequentially reflect the original reflected light from the first mirror plate 43 and guide it to the subsequent image reading unit 6. In FIG. 5, the optical path of the document reflected light is indicated by a one-dot chain line.

  Further, an image reading unit 6 having a condensing lens 60 and a CCD substrate 61 as a reading device in order from the upstream side of the optical path of the reflected light of the original is slightly closer to the right side plate 2b than the center in the main body housing 2. It is arranged. Specifically, the condensing lens 60 and the CCD substrate 61 are fixed on the bottom surface of the main body housing 2 in a state in which the adjustment in the optical axis direction (focus adjustment) and the adjustment in the height direction are made. 62 is mounted.

  Next, the detail of the structure which manages the scanning movement of the 1st, 2nd scanning optical system units 4 and 5 is demonstrated. The first and second scanning optical system units 4 and 5 are scanned and moved over the entire area of the document. At this time, the first scanning optical system unit 4 is changed to the second scanning optical system unit 5. On the other hand, the scanning movement is performed at a speed that is relatively twice as high, so that the focal length of the original reflected light with respect to the CCD substrate 61, that is, the optical path length of the original reflected light is always constant. Such scanning movement can be achieved by the following configuration.

  As shown in FIGS. 3 and 4, in the main body housing 2, in the vicinity of the inner side of the right side plate 2 b, the front and rear side plates 2 c and 2 d are penetrated along this and the rotation is supported rotatably via the bearing 7. A shaft 8 is provided. In the vicinity of the inner sides of the front and rear side plates 2c and 2d on the rotary shaft 8, a drum 80 around which a wire 9 (described later) is wound is coaxially arranged to control the scanning movement of the first and second scanning optical system units 4 and 5. It is fixed integrally in a shape.

  Further, a joint gear 81 to which a rotational force of forward / reverse rotation is transmitted from a stepping motor 10 to be described later is connected to one end portion of the rotating shaft 8 protruding from the rear plate 2d of the main body housing 2, and the rear plate 2d. A stepping motor 10 as a drive source is disposed outside (in FIG. 3, the back side of the paper surface). An output gear 11 is integrally provided on the output shaft of the stepping motor 10, and the output gear 11 meshes with a joint gear 81 of the rotary shaft 8 with an intermediate gear 82 interposed therebetween. Thereby, the rotation output of the stepping motor 10 is transmitted to the joint gear 81, and the rotating shaft 8 rotates forward and backward. Such a rotational drive transmission medium may be a combination of a pulley and a suspension belt.

  Further, in the vicinity of the inside of the front and rear side plates 2c and 2d in the main body housing 2, the first latch 12 protruding from the left side plate 2a and the front and rear side plates 2c and 2d are pivotally supported in order from the left. The first pulley 13, the second pulley 14 pivotally supported at the end of the second scanning frame 50, and the second latch 15 projecting from the base 62 are provided. Yes. Furthermore, a first guide rail 16 that guides the scanning movement of the first scanning optical system unit 4 and a second guide rail 17 that guides the scanning movement of the second scanning optical system unit 5 are respectively contact glass. 3 is provided so as to extend in parallel.

  The wire 9 that actually controls the scanning movement of the first and second scanning optical system units 4 and 5 is, as shown in FIG. 3, one end with a tension coil spring 18 interposed in the first latch 12. Is fixed on the second pulley 14, and is then wound around the first pulley 13, wound around the drum 80 of the rotating shaft 8 a plurality of times, and then returned to the end of the first scanning frame 40. After the portion is fixed and hung on the second pulley 14 again, the other end is fixed and stretched to the second hooking stop 15.

  Under such a configuration, when the output shaft of the stepping motor 10 is rotated forward or backward, the drum 80 is rotated forward or backward together with the rotational shaft 8, and accordingly, the wire 9 is moved, The first and second scanning optical system units 4 and 5 are scanned and moved between the reference position and the reverse position while maintaining a predetermined speed ratio. As a result, the entire document is scanned, and the image of the document is read.

  The above-described image reading apparatus 1 includes the image reading unit 6 such as the condenser lens 60 and the CCD substrate 61 separately from the first and second scanning optical system units 4 and 5 that are actually scanned and moved. There is a so-called separate type fixed to the housing 2, but there is also a so-called one-type type in which the image reading unit 6 is fixed to one scanning optical system unit and scanned and moved integrally therewith.

  By the way, in recent image reading apparatuses, the reading speed is remarkably increased in response to market needs, and accordingly, the scanning movement speed of the first and second optical system moving units 4 and 5 is strongly increased. Required. For this reason, the rotational speed of the rotary shaft 8 reflected in the scanning movement speed inevitably becomes high.

  In response to such recent demands, in the conventional image reading apparatus 1 described above, excessive vibration may occur in the rotating shaft 8. Since the vibration of the rotating shaft 8 propagates to the first and second scanning optical system units 4 and 5 via the drum 80 and the wire 9, the first mirror plate 43 and the second and third mirrors included therein are provided. The mirror plates 51 and 52 oscillate and reach resonance, thereby inducing a problem such as blurring in the acquired image.

  Therefore, conventionally, from the viewpoint of preventing such a problem, as shown in FIGS. 5 to 7, as shown in FIGS. 5 to 7, it is opposite to the back surface of the first mirror plate 43, that is, the reflecting surface used for reflecting the reflected light of the document. A first reinforcing member 45 whose longitudinal direction is perpendicular to the direction in which the first and second scanning optical system units 4 and 5 are scanned is interposed on the surface with an adhesive such as a double-sided adhesive tape or adhesive. Pasted. Similarly, a second reinforcing member 55 is attached to the back surface of the second mirror plate 51, and a third reinforcing member 56 is attached to the back surface of the third mirror plate 52 (for example, Patent Document 1). reference).

These first, second, and third reinforcing members 45, 55, and 56 are plate-shaped members formed of a metal such as aluminum, glass, rubber, or the like, and these are the first, second, and second members. By integrating with the three mirror plates 43, 51, 52, the natural frequency, that is, the resonance frequency of the first, second, third mirror plates 43, 51, 52 becomes the first and second scanning optics. It is substantially shifted from the frequency of the vibration propagated to the system units 4 and 5. Therefore, resonance is suppressed together with the vibration of the first, second, and third mirror plates 43, 51, and 52. In particular, when the first, second, and third reinforcing members 45, 55, and 56 are made of metal, the rigidity of the first, second, and third mirror plates 43, 51, and 52 integrated therewith is substantially increased. Therefore, the natural frequency is substantially increased accordingly, which is advantageous for effective reduction of vibration.
JP-A-8-106129

  However, in the conventional image reading apparatus 1 described above, one surface of the first, second, and third reinforcing members 45, 55, and 56 has the first, second, and third surfaces with an adhesive interposed therebetween. Are attached to the mirror plates 43, 51, and 52, and the flatness of one surface of the first, second, and third reinforcing members 45, 55, and 56, and the first, second, and third reinforcing members Due to the cautiousness at the time of attaching 45, 55, and 56, the thickness and adhesive force of the adhesive layer may be uneven. In this case, a biased force is applied between the first, second, and third mirror plates 43, 51, and 52 and the first, second, and third reinforcing members 45, 55, and 56. As a result, the first, second, and third mirror plates 43, 51, and 52 themselves are distorted. This eventually results in an inconvenient problem of distortion in the image acquired by the image reading apparatus 1.

  In addition, higher stability is strongly desired for the suppression of vibrations with respect to the first, second, and third mirror plates 43, 51, and 52.

  Accordingly, the present invention has been made in view of the above problems, and provides an image reading apparatus capable of maintaining the quality of an acquired image while more stably suppressing the vibration of a mirror plate for reflecting the reflected light of a document. It is intended to do.

  In order to achieve the above object, the present invention comprises a scanning optical system unit that is scanned and moved with respect to an original, and a mirror plate provided on the scanning optical system unit for reflecting light that is irradiated onto the original. In the image reading apparatus that reflects and reads an image of the original, reinforcing members having a longitudinal direction in a direction perpendicular to the scanning movement direction of the scanning optical system unit are provided at both ends in the short direction on the back surface of the mirror plate. The reinforcing member has a shape that is raised so that the central portion in the short direction is separated from the mirror plate.

  As a result, one surface of the reinforcing member is not attached to the mirror plate over the entire area with an adhesive interposed therebetween, and is attached along the longitudinal direction in a part of the region, that is, both ends in the short direction. Therefore, even if the thickness and adhesive strength of the adhesive layer are not uniform, the influence is unlikely to occur because the adhesive area is small. Therefore, an equal force is applied between the mirror plate and the reinforcing member, and the mirror plate is hardly distorted. In addition, with respect to the shape of the reinforcing member, since the central portion in the short direction is raised so as to be separated from the mirror plate, the rigidity of the reinforcing member itself is further increased, and the rigidity of the mirror plate integrated therewith is also increased. More real increase. For this reason, the natural frequency of the mirror plate is substantially increased.

  According to the image reading apparatus of the present invention, since the mirror plate integrated with the reinforcing member is hardly distorted, it is possible to maintain the quality of the acquired image, and also due to the shape of the reinforcing member. As a result, the natural vibration of the mirror plate increases but the vibration of the mirror plate can be more stably suppressed.

  Hereinafter, an image reading apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a mirror plate in a short direction in an image reading apparatus according to an embodiment of the present invention. In the figure, parts having the same names and performing the same functions as those in FIGS. 3 to 7 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the first, second, and third mirror plates 43, 51, and 52 are provided on the back surface, that is, on the surface opposite to the reflection surface used for reflecting the reflected light of the original, The first, second and third reinforcing members 45, 55 and 56 made of metal having a direction perpendicular to the scanning and moving direction of the scanning optical system units 4 and 5 are double-sided adhesive tape or adhesive. It is pasted with an adhesive. However, the first, second, and third reinforcing members 45, 55, and 56 have a central portion a in the short direction of the first, second, and third mirror plates 43, 51, It has a shape in which the cross-section is raised in a mountain shape so as to be separated from the back surface of 52, and is attached along the longitudinal direction only at both ends b1 and b2.

  As a result, one surface of the first, second, and third reinforcing members 45, 55, and 56 is attached to the first, second, and third mirror plates 43, 51, and 52 over the entire area with the adhesive interposed therebetween. It is not affixed, and since it is affixed along the longitudinal direction at a part of the region, that is, both ends b1 and b2 in the short direction, the thickness and adhesive force of the adhesive layer are not uniform. However, since the adhesion area is small, it is difficult for the influence to occur. Therefore, an equal force is applied between the first, second, and third mirror plates 43, 51, and 52 and the first, second, and third reinforcing members 45, 55, and 56. The second and third mirror plates 43, 51 and 52 are less likely to be distorted. Therefore, in the image reading apparatus 1 including the first, second, and third mirror plates 43, 51, and 52, it is possible to maintain the quality of the acquired image.

  In addition, with respect to the shapes of the first, second, and third reinforcing members 45, 55, and 56, the central portion a in the short direction is separated from the first, second, and third mirror plates 43, 51, and 52. Therefore, the first, second, and third reinforcing members 45, 55, and 56 themselves have increased rigidity, and the first, second, and third mirror plates 43 integrated with the first, second, and third mirror plates 43 are integrated. , 51 and 52 are also substantially increased in rigidity. Therefore, the natural frequencies of the first, second, and third mirror plates 43, 51, and 52 are substantially increased. Accordingly, it is possible to more stably suppress the vibrations of the first, second, and third mirror plates 43, 51, and 52.

  The first, second, and third reinforcing members 45, 55, and 56 are made of metal materials such as aluminum, stainless steel, galvanized steel plate (SECC), titanium, inorganic materials such as glass and ceramics, plastic, rubber, and the like. A metal plate formed of the above resin material is applied, and a metal plate having a high strength of the reinforcing member itself is particularly preferable.

  A specific example of the above embodiment will be described. As the first, second, and third mirror plates 43, 51, and 52, a glass plate having a thickness of 4.8 mm, a longitudinal length of 300 mm, and a lateral length of 15 mm is applied, On the front surface of the glass plate, a metal film forming a reflective surface is deposited. On the other hand, the first, second, and third reinforcing members 45, 55, and 56 have a thickness of 1 mm, a length in the longitudinal direction of 280 mm, and a total length in the lateral direction of 13 mm. A metal plate made of aluminum having a length of b2 of 4 mm and a length of the central portion a of 5 mm is applied, and the central portion a protrudes up to 2.5 mm from both end portions b1 and b2. The first, second, and third reinforcing members 45, 55, and 56 having the above-described configuration are provided at both ends b1 and b2 with a double-sided adhesive tape having a thickness of about 0.1 mm as an adhesive. The first, second, and third mirror plates 43, 51, and 52 are attached.

  The first, second, and third mirror plates 43, 51, and 52 in which the first, second, and third reinforcing members 45, 55, and 56 are integrated in this way are used as test pieces of this embodiment. Using the image reading apparatus 1 actually provided with these, an acceleration pickup (manufactured by Lion Co., Ltd.) is attached to the first reinforcing member 45 attached to the back surface of the first mirror plate 43, and the first and first The scanning level of the first mirror plate 43 and the natural frequency were measured by scanning the scanning optical units 4 and 5 of No. 2 at a speed of 415 mm / sec. The acceleration pickup measures the vibration level with a voltage value (unit: V), amplifies the voltage value signal of the acceleration pickup with a charge amplifier (manufactured by Sanei Co., Ltd.), and FFT analyzer (manufactured by Ono Sokki Co., Ltd.). ) To read the voltage value. Furthermore, the voltage value of the vibration level was read as the natural frequency (unit: Hz) by Fourier transform using an FFT analyzer. The measurement results are shown in FIG. In addition, as a conventional test piece for comparison, first, second, and third metal plates made of aluminum having a thickness of 1 mm, a length in the longitudinal direction of 280 mm, and a length in the short direction of 10 mm are used. The reinforcing members 45, 55, and 56 are attached to the same first, second, and third mirror plates 43, 51, and 52 as described above, with the same adhesive material interposed over the entire surface. The vibration level and natural frequency of the mirror plate 43 were measured by the same method as described above.

  As is clear from FIG. 2, the output value of the natural frequency from the FFT analyzer is 130 [Hz] in the test piece for comparison, but is increased to 133 [Hz] in the test piece of the present embodiment. The rigidity of the test piece of this embodiment is substantially increased. On the other hand, the output value of the magnitude of the vibration level from the accelerometer (a value corresponding to the amplitude of vibration) is 0.74 [V] for the comparative test piece, whereas the test piece of the present embodiment. Then, it is reduced to 0.58 [V], and the vibration in the test piece of this embodiment is suppressed. Thus, the suppression of the vibration in this embodiment was demonstrated.

  In addition, this invention is not limited to said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the cross-sectional shape of the central portion a in the short direction of the first, second, and third reinforcing members 45, 55, and 56 is not limited to the mountain shape, and may be deformed as long as the rigidity increases. Absent.

  The present invention is useful for an image reading apparatus provided with a mirror plate that reflects reflected light of a document while being scanned and moved with respect to the document.

It is sectional drawing of the transversal direction of the mirror board in the image reading device which is one Embodiment of this invention. It is a figure which shows an example of the vibration measurement result of the mirror plate in the image reading apparatus which is one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the drive mechanism of the conventional general image reading apparatus applied also to this invention. It is a top view which shows the principal part of the drive mechanism in the conventional general image reading apparatus applied also to this invention. It is a longitudinal cross-sectional view which shows the structure in the optical surface of the conventional general image reading apparatus applied also to this invention. It is a perspective view which shows the external appearance of the 2nd scanning optical system unit in the conventional image reading apparatus. It is sectional drawing of the transversal direction of the mirror board in the conventional image reading apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reader 2 Main body housing | casing 4 1st optical system moving unit 5 2nd optical system moving unit 8 Rotating shaft 9 Wire 10 Stepping motor 40 1st scanning frame body 43 1st mirror board 45 1st reinforcement | strengthening Member 50 Second scanning frame 51 Second mirror plate 52 Third mirror plate 55 Second reinforcing member 56 Third reinforcing member 80 Drum 81 Joint gear 82 Intermediate gear a Middle portion of mirror plate in short direction b1, b2 Ends of the mirror plate in the short direction

Claims (1)

An image reading unit that includes a scanning optical system unit that scans and moves with respect to the original, and reflects the light irradiated and reflected on the original by a mirror plate provided in the scanning optical unit, thereby reading the image of the original In the device
On the back surface of the mirror plate, a reinforcing member having a longitudinal direction perpendicular to the scanning movement direction of the scanning optical system unit is attached along the longitudinal direction at both ends in the lateral direction. An image reading apparatus according to claim 1, wherein the reinforcing member has a shape in which a central portion in a short direction is raised so as to be separated from the mirror plate.

Images