JP2001075193A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of always obtaining a high-quality read image while always keeping the balance of a scanning body. SOLUTION: A guide shaft 3 for guiding the movement of the dcanning body is disposed at a position where the total sum of the moment acting on the scanning body and caused by a holder 7 and a reading unit 1, a slider 2, a motor 5, a speed change means 8, a flat cable 9 and a synchronous mesh pulley disposed and supported on the holder 7 and the total of the moment caused by the acting force of a biasing member such as a spring or the like disposed between the unit 1 and the holder 7 becomes almost zero.

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 computer input, which reads an original such as a text or a photograph, converts the original into digital data, and outputs the digital data.

[0002]

2. Description of the Related Art A schematic configuration of a conventional color image reading apparatus as an image reading apparatus is shown in FIGS.

In FIG. 4, after a document P is placed on a document table glass 100 as a light transmitting member, a document cover 112 is placed.
Is closed and the original P is pressed onto the original platen glass 100. The reading unit (not shown) in the frame 111 is attached to the platen glass 10.
By scanning in parallel to 0, an image on the document P is read.

FIG. 5 is a perspective view showing an upper portion of a conventional image reading apparatus, that is, a state in which a document table glass 100 and the like are removed.

[0005] A frame 111 also serves as an exterior cover, and has the following components disposed therein. Reading unit 10
1 includes three colors (R, G, B) which are light sources for illuminating a document.
, A rod lens array that forms reflected light from a document illuminated by a light source on a light receiving element of the image sensor, and an image sensor. The light sources of the three colors are sequentially switched and turned on, and the image sensor reads the reflected light from the document for each color to perform color separation reading.

[0006] The reading unit 101 is arranged on a holder 107. The holder 107 includes a slider 10
2 are provided, and are slidably supported on a guide shaft 103 fixed to one end of the frame body 111.
The holder 107 is provided with a motor 105 as a drive source for moving the reading unit 101 along the guide shaft 103.

[0007] A transmission mechanism for transmitting the driving force from the motor 105 to the holder 107, that is, the reading unit 101, is housed in the frame 111. The synchromesh wire 104 has one end fixed to the frame 111,
The other end is supported by a biasing means (not shown) to maintain a predetermined tension.

The driving force of the motor 105 is
Is transmitted to a not-shown synchromesh pulley provided on the back surface of the holder 107. The synchromesh pulley is configured to maintain synchronous mesh with the synchromesh wire 104.

In this way, when the synchromesh pulley rotates forward and backward in response to the forward and reverse rotation of the motor 105, the reading unit 101 reciprocates in parallel along the platen glass (not shown).

A control board 106 is provided in the frame 111, and a flat cable 109, which is a control signal path for the reading unit 101 and the motor 105, is provided.
Is connected.

[0011]

However, in the case of the prior art as described above, the scanning member (reading unit 10
1, the motor 105, the holder 107, the transmission means 108, etc.), the guide shaft 103, which is a guide means, is disposed at one end of the scanning body, so that the scanning body smoothly moves when the scanning body moves. It may not move and behave unnaturally, which may affect the quality of the read image.

In particular, if the scanning member repeatedly stops and starts at the time of intermittent reading caused by waiting for processing by an external device such as a personal computer, the quality of the read image is further impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an image reading apparatus which always keeps the balance of a scanning body and always obtains a high quality read image. Is to do.

[0014]

According to the present invention, in order to achieve the above object, there is provided a scanning body which is scanned in parallel along a light transmitting member, and a guide means for guiding the scanning body. In the above image reading apparatus, the guide means is disposed at a position where the sum of moments applied to the scanning body becomes substantially zero.

The scanning body includes a reading unit that reads an original image via the light transmitting member, a driving source that applies a driving force, a biasing member that urges the reading unit to the light transmitting member, and the scanning body. And a control signal path connected to the control signal path.

It is preferable that the moment includes a moment caused by the reading unit, the driving source, the biasing member, and the control signal path.

Preferably, the power consumption required for scanning the scanning body is 2.5 W or less.

It is preferable to connect to an external device by a USB interface and to receive necessary power supply from the external device via the USB interface.

[0019]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) An embodiment will be described with reference to FIGS. FIG. 1 is a perspective view showing an upper portion of an image reading apparatus according to the present invention, that is, a state in which a platen glass or the like which is a light transmitting member is removed.

Reference numeral 11 denotes a frame which also serves as an exterior cover, and has the following components disposed therein. The reading unit 1 includes three color (R, G, B) LEs, which are light sources for irradiating a document.
D, a rod lens array for forming an image of the reflected light from the document on a light receiving element of the image sensor and an image sensor are incorporated. The light sources of the three colors are sequentially switched and turned on, and the image sensor reads the reflected light from the document for each color to perform color separation reading.

The reading unit 1 is arranged on a holder 7. The slider 2 is provided on the holder 7 and is slidably supported on the guide shaft 3 fixed to the frame 11. The reading unit 1 is provided in the holder 7.
A motor 5 is provided as a drive source for moving along the guide shaft 3.

In the frame 11, a transmission mechanism for transmitting the driving force from the motor 5 to the holder 7, that is, the reading unit 1, is accommodated. The synchromesh wire 4 has one end fixed to the frame 11 and the other end supported by a biasing means (not shown), and maintains a predetermined tension.

The driving force of the motor 5 is transmitted through the speed change means 8
The power is transmitted to the synchromesh pulley 14 (see FIG. 2) disposed on the back surface of the holder 7. The synchromesh pulley 14 is configured to maintain synchronous mesh with the synchromesh wire 4. The reading unit 1 can reciprocate in parallel along the platen glass (not shown) by the normal / reverse rotation of the synchromesh pulley 14 in response to the normal / reverse rotation of the motor 5.

A control board 6 is provided in the frame 11, and a flat cable 9 which is a control signal path for the reading unit 1 and the motor 5 is connected thereto.

FIG. 2 is a three-dimensional exploded view for explaining the reading unit 1 and the holder 7 part.

The holder 7 is provided with the motor 5, the speed change means 8, the synchromesh pulley 14, and the slider 2 described above.

The reading unit 1 includes a biasing member 13 such as a spring.
And is disposed on the holder 7 via. Further, spacers 12 made of a material having a low friction coefficient are provided at both ends in the longitudinal direction of the reading unit 1.

The flat cable 9 as a control signal path is provided between the holder 7 and the reading unit 1.

The flat cable 9 has one end C connected to the control board 6, the other end branched off the holder 7 from the middle, and one end S connected to the reading unit 1 including the sensor. The other end M side is connected to the motor 5.

The arrangement of the flat cable 9 on the C side connected to the control board 6 is similar to that of the guide shaft 3.
In order to avoid the influence of moment on the guide shaft 3, it is desirable to dispose it as close as possible to the guide shaft 3 (in the longitudinal direction of the reading unit 1).

Thus, the reading unit 1 is
The scanner scans in parallel along the platen glass and reads an image on the document while maintaining a light contact with the platen glass via the.

FIG. 3 is a functional block diagram of the image reading apparatus. In the figure, a portion 15 surrounded by a dashed line is a portion corresponding to the above-described scanning body, and a portion surrounded by a dotted line is the above-described portion. This is a part corresponding to the control board 6.

The operation of the image reading apparatus by the basic functional blocks is as follows. The control unit 26 drives the motor driving unit 27 and the image sensor driving unit 17. Then, the image sensor driving means 17 is connected to a 3
While the color LEDs are switched and turned on, the reflected light from the document is photoelectrically converted and accumulated.

Here, the image sensor and the image sensor driving means 17 and the three-color LED constitute a part of the reading unit 1.

The motor 5 moves the reading unit 1 in the sub-scanning direction. The output signal from the image sensor 16 is amplified by the amplifier 21 and then converted into a digital image signal by the A / D converter 22.

The image signal digitized by the A / D converter 22 is subjected to image processing such as shading correction using the shading data stored in the RAM 25, digital gain adjustment, digital black correction, and the like in the image processing means 23. Will be applied.

Thereafter, the digital image signal is stored in the line buffer 24 and transferred to an external device such as a personal computer (PC) via an interface.

All of these operations are performed by the control unit 26 controlling each functional block based on instructions from the driver means of the external device.

In the above image reading apparatus, the reading unit 1, the slider 2, the motor 5, the holder 7, the speed change means 8, the flat cable 9, the synchromesh pulley 14
There are a number of moments with respect to the guide shaft 3 which is a guiding means for guiding the movement of the scanning body constituted by the above.

That is, the holder 7, the reading unit 1, the slider 2, the motor 5, the speed change means 8, the flat cable 9, the synchromesh pulley 1,
4 and the moment due to the acting force of the biasing member 13 such as a spring disposed between the reading unit 1 and the holder 7.

In the image reading apparatus according to the present invention, the guide shaft 3 is a guiding means for guiding the movement of the scanning body.
Are arranged at positions where the sum of the moments acting on the scanning body becomes substantially zero.

More specifically, the guide shaft 3 minimizes the difference between the urging forces of the scanning body with respect to the platen glass at both ends in the longitudinal direction of the scanning body, and maintains the balance of the scanning body supported by the guide shaft 3 at all times. Are located in

Therefore, the biasing force of the scanning body at both ends in the longitudinal direction of the scanning body with respect to the platen glass is extremely different in the related art, so that the scanning movement cannot be performed smoothly. Is extremely small, and the scanning movement becomes smooth.

In the configuration described above, since unnecessary force relating to the scanning movement does not act, the balance of the scanning body is always maintained, a high-quality read image can always be obtained, and the driving force of the scanning body is minimized. Can be suppressed. Further, since the driving force of the scanning body can be suppressed as much as possible, the power consumption of the apparatus can be reduced.

In combination with the reading unit 1 described in this embodiment, the power consumption during the reading operation can be suppressed to 2.5 W or less.

The power consumption of 2.5 W or less is the amount of power that can be supplied to peripheral devices connected to a USB, which is an interface of a personal computer (PC), which has been rapidly spreading in recent years. The adopted image reading device of the USB interface does not require a power supply unit unlike a conventional product, and can operate only by connecting to a personal computer (PC).

[0048]

As described above, according to the present invention, when the scanning body is scanned and moved, unnecessary force does not act and the balance of the scanning body is always maintained, so that a high-quality read image is always obtained. Obtainable.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an image reading apparatus according to an embodiment.

FIG. 2 is an exploded perspective view showing a reading unit and a holder of the image reading apparatus according to the embodiment;

FIG. 3 is a functional block diagram illustrating the image reading device according to the embodiment;

FIG. 4 is an overall perspective view showing a conventional image reading apparatus.

FIG. 5 is a perspective view showing a conventional image reading apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reading unit 2 Slider 3 Guide shaft 4 Synchromesh wire 5 Motor 6 Control board 7 Holder 8 Transmission means 9 Flat cable 11 Frame 12 Spacer 13 Biasing member 14 Synchromesh pulley 17 Image sensor drive means 21 Amplifier (AMP) 22 A / D converter 23 Image processing means 24 Line buffer 25 RAM 26 Control unit 27 Motor driving means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigeru Kawasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term (reference) 2H108 AA01 CB01 FB21 FB66 FB75 FB91 JA10 5B047 BA02 BC16 5C072 AA01 BA13 LA02 MA05

Claims (5)

[Claims] 1. An image reading apparatus comprising: a scanning body that is scanned in parallel along a light transmitting member; and a guide unit that guides the scanning body. An image reading device, wherein the image reading device is disposed at a position where the sum is substantially zero. A scanning unit that reads a document image via the light transmitting member; a driving source that applies a driving force; a biasing member that urges the reading unit to the light transmitting member; The image reading apparatus according to claim 1, further comprising a control signal path connected to the scanning body. 3. The image reading apparatus according to claim 2, wherein the moment includes a moment caused by the reading unit, the driving source, the bias member, and the control signal path. 4. The image reading apparatus according to claim 1, wherein power consumption required for scanning the scanning body is 2.5 W or less. 5. The image reading apparatus according to claim 4, wherein the image reading apparatus is connected to an external device via a USB interface, and receives necessary power supply from the external device via the USB interface.