JPH11215320A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately make a read unit travel by supporting a tension pulley and a motor unit by means of a metallic rail member with less thermal expansion/contraction and hanging a transmission belt between them. SOLUTION: For a guide rail 3, a metallic axis member is used, a screw hole 3 is provided for a piece end part and a driving pulley 8 is fixed to the driving axis of a motor 5. One end of a belt 4 hangs on the pulley 8, and a read unit 2 fixed to the other end of the belt 4 is made to travel through the belt 4. A tension pulley 6 is freely turnably supported by a tension pulley stand 6a, and a long hole 9 exists in the guide rail 3 so that it can be adjusted/fixed in a direction where the tension of the belt 4 is given. The tension pulley 6 gives a prescribed tension to the belt 4, and the tension pulley 6 and the guide rail 3 are fastened by a screw 7. One end of the guide rail 3 is engaged/ positioned to a hole 11c, and the other end to a U-groove 11d with respect to a lower frame body 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing system including an image reading device (image scanner), an image processing device such as a computer, and an output device such as a display and a printer.

[0002]

2. Description of the Related Art FIG. 3 is a schematic three-view diagram showing an example of a conventional color image reading apparatus.
(B) shows a cross-sectional front view, and (c) shows a left side view.

In FIG. 1, P denotes an original to be read placed on an original platen glass 100. An image on the original is read by scanning a reading unit 101 in parallel with the original platen glass 100.

As shown schematically in FIG. 4, a reading unit 101 includes three color LEDs (light emitting diodes) 101R, 101G, and 101 as light sources for illuminating a document.
B, a rod lens array 101L for forming an image of light reflected from a document on a light receiving element of the image sensor, and an image sensor 101S are incorporated.

The light sources 101R / G / B for the three colors are sequentially switched on and turned on, and the image sensor reads the reflected light from the document for each color, thereby enabling color separation reading.

In FIG. 3, the reading unit 101 is fixedly supported on a slider 102 that slides on a guide shaft 103 fixed to a lower frame 113 of the apparatus. One end of a belt 104 for transmitting power from a motor serving as a scanning drive source is fixed to the slider 102.

The material of the lower frame 113 of the apparatus is resin (AB).
S) is generally used.

[0008] A plurality of driving components described below are fixed to the lower frame 113. 1) A motor unit 105 having a motor 105a, a driving gear and a pulley 105b as a unit. A tension pulley 504a for applying tension to the belt 104 is fixed to the lower (bottom) frame 113 of the tension pulley unit 504 rotatably supported by a pulley shaft 504b. And the tension pulley unit 504 are connected by the belt 104.

By the forward / reverse rotation of the motor 105a, the reading unit 101 can perform reciprocating scanning in the range of the original table glass 100.

As described above, the configuration in which the belt tension of the belt 104 is maintained by the rigidity of the lower frame 113 is generally used.

The components of the image reading apparatus include an electrical unit 106 including a control board and a power supply in addition to the above components. These components are arranged in a housing composed of a combination of an upper cover 112 for fixedly supporting the document table glass 100 and a lower frame 113.

A document cover 111 for pressing a document onto the glass is mounted on the document table glass 100 so as to be openable and closable.

FIG. 5 is a block diagram showing the configuration of a read image data processing circuit of the image reading apparatus of FIG. The image data read by the image sensor 101S in synchronization with each of the LEDs 101R / G / B blinking sequentially is output to the amplifier 1
After being sent to 21 and amplified, the A / D converter 122
Is converted into a digital image signal.

The A / D converter 122 divides the dynamic range of the image sensor 101S (the difference between the read output between the pure white part and the pure black part on the original) by the number of bits, and according to the brightness of the image on the original. Assign the number of gradations.

For example, when the A / D converter 122 having a resolution of 8 bits is used, the interval from white to black is 2
In the case of the 10-bit A / D converter 122, it can be identified as 56 tone levels, and in the case of the 10-bit A / D converter 122, as 1024 tone levels.

Therefore, the 8-bit A / D converter 12
In the image reading apparatus using the light source 2, the light sources 1 of R, G, and B colors are used.
24 bits = about 1670 in reading by 01R / G / B
All colors, 30 bits in the case of 10 bits = about 1 billion 740
10,000 colors can be identified.

There are several types of output modes of the image signal of the image reading apparatus, and an output mode suitable for each purpose can be selected according to the use of the read image.

When reading a text and applying the content to an OCR (optical character reader) or when reading a monochrome line drawing, a monochrome binary image is suitable. Image data obtained by binarizing an image signal obtained by turning on only the G light source 101G among the three light sources 101R / G / B at a certain threshold value by an image processing circuit incorporated in the gate array 123, for example. Is used.

When reading an image such as a photograph and outputting the image to a monochrome printer, the image signal is similarly binary-coded using a halftone process such as a dither method or an error diffusion method using an image signal from the G light source 101G. The converted image data is used. When performing color image processing, multi-valued (24-bit etc.) image data is suitable.

The image signal that has passed through the image processing circuit is output to a computer device 200 such as a personal computer via an interface circuit 124.

[0021]

However, the conventional image reading apparatus as described above has the following disadvantages.

(1) As shown in FIG. 3, the above-mentioned image reading apparatus has a housing (lower) frame 113 on which components are placed, and a tension pulley 504 as shown in FIG.
a and the motor 105a are generally supported.

The lower (bottom) frame 113 made of resin easily expands and contracts due to a change in environmental temperature.
In particular, when the position of the tension pulley 504a for applying tension to the belt 104 is shifted, the belt 10 is disturbed.
4 changes, and the drive cannot be transmitted accurately.

(2) After the guide rails, the driving parts, the belt 104, etc. are attached to the lower frame 113, the position of the tension pulley 504a must be adjusted, and an assembling method for applying tension to the belt 104 must be adopted. , Causing a reduction in assemblability.

The present invention has been made in view of the above situation, and has as its object to provide means for solving each of the above problems.

[0026]

SUMMARY OF THE INVENTION The present invention aims to achieve the above object by providing an image reading apparatus having the following configuration.

(1) Photoelectric conversion means for reading an image and converting it into an electric signal to read image information, a driving member for scanning the photoelectric conversion means in parallel, and transmitting this drive to the photoelectric conversion means. A belt member, a pulley member for applying tension to the belt member, and a traveling guide member for scanning the photoelectric conversion unit in parallel, supported by the driving member, the pulley member, and the traveling guide member, and The image reading device according to claim 1, wherein the driving member and the pulley member are connected by the belt member.

[0028]

According to the structure of the present invention as described above, (1) By adopting a structure in which the traveling guide member supports the tension pulley and the motor unit, a box-shaped resin bottom frame can be formed even when a temperature change occurs. The image sensor can be run with high precision without causing the belt tension to change due to expansion and contraction.

(2) According to the above configuration, it is possible to incorporate the tension pulley into the bottom cover after adjusting the position of the tension pulley. Therefore, it is possible to provide an image reading apparatus (image scanner) having good assemblability and high productivity. Can be.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail based on a plurality of examples with reference to the drawings.

[0031]

(Embodiment 1) FIG. 1 is a schematic diagram showing four views of an image reading apparatus according to a first embodiment of the present invention. (A) is a top view, (b) is a sectional front view, and (c) and (d) are left and right side views, respectively.

In the figure, P is a read original placed on the original platen glass 1, and an image on the original is read by scanning the reading unit 2 in parallel with the original platen glass 1.

The reading unit 2 includes a light source 101R / G / B for irradiating a document as shown in FIG. 4, a lens 101L for forming reflected light from the document on a light receiving element of an image sensor 101S, and an image. The sensor 101S is incorporated.

Reference numeral 11 denotes a lower (lower) frame which also serves as an exterior cover, in which, in addition to the platen glass 1 and the reading unit 2, a guide rail 3 of a metal shaft for guiding the movement of the reading unit 2; A transmission timing belt 4 for transmitting a driving force to the unit 2, a tension pulley 6 for applying a tension to the belt 4, a motor 5 as a driving source, a control board, a power supply, and the like are housed.

The lower frame 11 has a box shape, is constituted by side walls 11a and 11b, and has a hole 11c and a U-groove 11d into which both ends of the guide rail 3 are fitted. Has spiral holes 3b and 3c (not shown).

In this embodiment, the guide rail 3 uses a shaft member having a metal diameter of 8 mm and a length of 350 mm.
One end has a spiral hole 3a.

A drive pulley 8 is fixed to a drive shaft of the motor 5. One end of the belt 4 is hung on the pulley 8, and the reading unit 2 fixed to the other end of the belt 4 can travel via the belt 4.

The motor base 5a supports the motor 5, and is fixed to the rail 3 and a plurality of screws 12.

The tension pulley 6 is rotatably supported by a tension pulley table 6a, and has an elongated hole 9 so that the tension can be adjusted and fixed in a direction in which the tension of the belt 4 is applied to the guide rail 3. doing.

After a predetermined tension is applied to the belt 4 by the tension pulley 6, the tension pulley 6 is
And the guide rail 3 are fastened. Thus, a predetermined tension can be applied to the belt 4.

In the configuration of the embodiment of the present invention, when the ambient temperature is 1
Assuming that the temperature changes from 0 ° C. to 50 ° C., the linear expansion coefficient of the guide rail 3 is 10 × 10 ⁻⁶ (° C. ⁻¹ ), and the linear expansion coefficient of the lower frame 11 is 5 × 10 ⁻⁵ (° C. ⁻¹ ). Therefore, the length of 350 mm of the guide rail 3 is 350.14 mm = 350
(1 + 10 × 10 ^-6 (50-40)), and the lower frame 1
1, the length of 350 mm is 350.7 mm = 350 (1
+ 5 × 10 ^-5 (50-40)).

Therefore, a dimensional difference of 350.7 mm-350.14 mm = 0.56 mm occurs between the guide rail and the lower frame.

In order to prevent the scanner main body from being deformed even if this dimensional difference occurs, the guide rail 3
Is fitted and positioned in the hole 11c and the other end is fitted in the U groove 11d.

Therefore, the lower frame 11 is changed by the environmental temperature change.
And rail 3 have a fitting hole 11c even if a dimensional difference occurs due to thermal expansion.
Can be absorbed by the gaps Δx and Δy in the longitudinal direction of the shaft.

With the above-described configuration, it is possible to prevent the image from being reduced due to the internal stress and to prevent the scanner main body 2 from being deformed.

The motor base 5a and the lower frame 11 are fastened and fixed by screws 5b1 and 5b2, but both ends of the guide rail 3 are supported on the lower frame 11 so as to be able to extend and contract in the length direction. Therefore, even if a difference in expansion and contraction occurs between the lower frame 11 and the guide rail 3, the positional relationship between the tension pulley 6 fixed to the guide rail 3 and the drive pulley 8 is maintained.

Even if an environmental temperature change occurs at 40 ° C.,
Since the change in the length of the guide rail 3 is only about 0.14 mm, the change in the tension of the belt 4 hanging between the tension pulley 6 at one end supported by the guide rail 3 and the driving pulley 8 at the other end is as follows. , The reading unit 2 can be driven stably and accurately.

(Embodiment 2) FIG. 2 is a schematic four side view of an image reading apparatus according to a second embodiment of the present invention (corresponding to FIG. 1).
In FIG. 1, each of the constituent elements and the corresponding elements is represented by a three-digit number bearing the same two-digit number.

In the first embodiment, the guide rail 3 is formed of a metal shaft member, but a guide rail of a sheet metal member may be used.

As in the first embodiment, the tension pulley 2
Reference numeral 06 denotes an elongated hole 209 that is rotatably supported by the tension pulley table 206a and can be adjusted and fixed in a direction in which belt tension is applied to the guide rail 203.
Exists.

The belt 204 has a tension pulley 206
After applying a predetermined tension, the tension pulley 206 and the guide rail 203 are fastened with the screw 207.

The reading unit includes guides 202a and 203
The guide 202a is in contact with the surface of the guide rail 203a and guides in the height direction. The guide 202a guides the reading unit guide 203b and the guide rail 202b in a direction perpendicular to the moving direction. Moving.

[0053]

As described above, according to the present invention,
The following effects can be obtained by employing a configuration in which the tension pulley and the motor unit are supported on the metal rail member having little thermal expansion and contraction, and the transmission belt is hung between them.

(1) Even if the use environment temperature changes, the tension of the running belt does not change. The reading unit can be run with high accuracy.

(2) After adjusting the position of the tension pulley,
Since the image scanner can be incorporated in the lower (bottom) frame, it is possible to provide an image scanner with good assemblability and high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating four sides of an image reading apparatus according to a first embodiment.

FIG. 2 is a schematic diagram illustrating four sides of an image reading apparatus according to a second embodiment.

FIG. 3 is a schematic three-view diagram of an example of a conventional image reading apparatus.

FIG. 4 is a schematic diagram of a conventional image reading unit.

FIG. 5 is a configuration block diagram of a conventional read image data processing circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen glass 2 reading unit 3 guide rail 4 timing belt 5 motor 6 tension pulley 7 set screw 8 pulley 9 elongated hole 11 lower (bottom) frame 12 upper cover 202 reading unit 202 a, 203 b guide 204 belt 206 tension pulley 206 a tension Pulley stand 209 Slot 212 Upper cover 213 Lower (bottom) frame

Claims (1)

[Claims] 1. A photoelectric conversion means for reading an image and converting the information into an electric signal to read image information; a driving member for scanning the photoelectric conversion means in parallel; and a belt for transmitting the drive to the photoelectric conversion means. A member, a pulley member for applying tension to the belt member, and a traveling guide member for causing the photoelectric conversion unit to scan in parallel, wherein the driving member and the pulley member are supported by the traveling guide member, and The image reading device according to claim 1, wherein the driving member and the pulley member are connected by the belt member.