JPH08204901A - Image reader - Google Patents

Abstract

PURPOSE: To enable high-speed conveyance and high-speed reading while surely preventing an original from being floated on a reading plane at the image reader using a contact type line sensor. CONSTITUTION: This device is provided with a film 12, that is formed in white, arranged proximately to a position faced to a reading plane 11a over the full width of this reading plane 11a and a position regulating means 17 for regulating the position of the film 12 corresponding to the reading plane 11a so as to provide a fine original passing paper gap (d) between the reading plane 11a and this film 12. Then, the original can be conveyed at high speed through the gap of a small conveyance load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a contact type line sensor as a reading optical system, and an original is brought into close contact with the reading surface of the contact type line sensor and is conveyed by the contact type line sensor. The present invention relates to an image reading device such as a facsimile device that sequentially reads images.

[0002]

2. Description of the Related Art Generally, a contact type line sensor of this type includes a holding member such as a glass plate having a reading surface, a light source such as a light emitting diode, a short focus image forming lens, and a line type photoelectric conversion element such as a CCD line sensor. Are used in combination to reduce the size of a device such as a facsimile machine. Here, the contact type line sensor is characterized in that the depth of focus is shallow, and in order to perform good reading, the original to be read does not have to float on the reading surface and is conveyed in a close contact state. Needed. Further, in this type of contact-type line sensor, since white balance is taken before reading a document image, the white reference member is often read in the absence of a document, and normally,
A white reference member is required at a position facing the reading surface of the contact type line sensor.

In view of such a point, conventionally, a contact type line sensor is arranged facing downward on the lower side of the document conveying path, and a white roller whose outer peripheral surface is white on the reading surface of the contact type line sensor. There are many things that are installed by being pressed against and rotatably driven. As a result, prior to the reading of the original image, a white balance process is performed in which the white roller is exposed by the contact type line sensor and the reflected light is read to set the reference data. During the actual reading of the original image, the white roller is driven to rotate in the feeding direction by the original feeding system drive motor to feed the original while pressing it against the reading surface of the contact line sensor. Document image 1 by sensor
The operation of sequentially reading line by line is performed.

However, in the case of such a method (herein, referred to as "white roller pressure contact driving method" for convenience), there are the following drawbacks. First, since the white roller is rotated while being pressed against the reading surface to read the original while it is being conveyed, the load on the original conveying system drive motor is large, and the conveying speed is improved to increase the reading speed. It will be an obstacle in trying. This is because the white roller is pressed against the reading surface in a substantially line contact state, and the load is increased due to the high pressing force per unit area. In addition, since the white roller, which also functions as the white reference member, is pressed against the original, dirt, dust, etc. on the back of the original adheres to the surface of the white roller, and the whiteness of the white roller easily deteriorates, resulting in poor white balance. There is also. Furthermore, the white roller is a columnar body, and a space for arranging a drive transmission system such as a document transfer system drive motor and a gear between the drive system and the motor is indispensable, and the entire apparatus becomes large in the height direction. There is a drawback that.
This is contrary to the purpose of downsizing the device by using the contact type line sensor. However, by reducing the diameter of the white roller, it is possible to suppress the increase in size in the height direction to some extent, but if the curvature of the white roller is increased along with the reduction of the diameter, the white balance will not be high unless the white roller position accuracy is high. It becomes difficult to guide the reflected light from the white roller to the photoelectric conversion element in the contact type line sensor when setting the reference data for use, and it is necessary to mount the sensor with high positional accuracy. As a result, the cost is increased by simply using the white roller, and the manufacturing cost is increased because the mounting is performed with high positional accuracy.

The following two methods have been considered as countermeasures in consideration of the drawbacks of the white roller pressure contact driving method. First, as shown in FIG. 6, the white roller 2 is separated from the reading surface 1a of the contact-type line sensor 1 including a photoelectric conversion element or the like by a slight distance a corresponding to the interval of document passage. And rotatably support them with a gap 3 therebetween, and a roller pair of a feed roller 4 and a pinch roller 5 is provided on the upstream side and the downstream side of the contact type line sensor 1 and the white roller 2.
The original is passed through the gap 3 while the white roller 2 is rotationally driven in the transport direction together with the feed roller 4 and the like (in the present specification, it is referred to as "white roller separation drive system" for convenience). The white roller 2 is rotationally driven together with the feed roller 4 and the like by a document conveying system drive motor so that the existence of the white roller 2 does not become a load for document conveyance. in this case,
The load of the white roller 2 on the document conveying system drive motor is light.

The other one is, as shown in FIG. 7, a reading surface 6 of a contact type line sensor 6 having a built-in photoelectric conversion element and the like.
A transparent flexible sheet 7 such as a polyester film, which is inclined along the transport direction so that the upstream side of the document does not contact the downstream side and the downstream side elastically contacts with respect to a, is provided. A white portion 8 is provided on the upper surface of 7 at a position corresponding to the reading line. This is disclosed in Japanese Patent Laid-Open No. 5-
It is disclosed in Japanese Patent No. 63924 and is referred to as "flexible sheet contact system" in the present specification for convenience. According to this flexible sheet contact method, since the flexible sheet 7 is brought into surface contact with the reading surface 6a, the contact pressure is reduced and the positional accuracy with respect to the contact type line sensor 6 is required too much. Not done. Furthermore, the flexible sheet 7 side does not require a document conveying function, and thus does not require a drive system, the overall height of the apparatus can be reduced.

[0007]

According to the white roller separation driving method, a gap 3 is formed between the reading surface 1a of the contact type line sensor 1 and the white roller 2, and the white roller 2 is arranged in the conveying direction. Since it is driven to rotate, the load on the document conveyed on the reading surface 1a is small, and high-speed reading is possible. However, if the spacing a of the gap 3 is larger than a predetermined size, the adherence of the conveyed document to the reading surface 1a is poor, and the contact type line sensor 1 is out of focus due to floating or the like, which causes a reading failure. Becomes Further, if the spacing a is not uniform over the entire width in the transport direction, it causes skew. Therefore, the distance a is adjusted by using a jig or a gauge, and the mechanism at both ends of the shaft of the white roller 2 is used to maintain the distance a at a predetermined distance. In addition to that, it is difficult to provide the white roller 2 that is rotationally driven with minute intervals a evenly on the left and right.
Further, not only in the height direction, when the white roller 2 is obliquely arranged in the horizontal plane, the portion forming the gap 3 is linear due to only the lowest point of the white roller 2, and therefore the skew is generated. In addition, it becomes difficult to guide the reflected light from the white roller 2 to the photoelectric conversion element in the contact type line sensor 1 when the reference data for white balance is set. Furthermore, since the white roller 1 is used and the white roller 1 is driven to rotate, the total height of the apparatus is the same as in the case of the white roller pressure drive method.

On the other hand, according to the flexible sheet contact system, a drive system is not required on the side of the flexible sheet 7 and the flexible sheet 7 can be constituted only by the sheet material, which is effective in keeping the overall height of the apparatus low. . However, since the flexible sheet 7 is in contact with the reading surface 6a of the contact type line sensor 6 under its own weight and the weight of the weight, the document is conveyed through this portion, and therefore at least the document thickness is required. Since it is necessary to float the flexible sheet 7 only, the load on the document is increased and the high-speed conveyance property is impaired. Further, the flexible sheet 7 is supported in the front and rear in the transport direction so that the downstream side portion thereof elastically contacts the reading surface 6a, but the left and right (width direction) balance is made uniform. It is difficult to perform, and there is an inconvenience that the skew is likely to occur.

[0009]

SUMMARY OF THE INVENTION According to the present invention, an image is read in such a manner that an original is brought into close contact with the reading surface of a contact type line sensor and the images of the original are sequentially read by the contact type line sensor while the original is being conveyed. In the apparatus, a white-formed film that is disposed close to a position facing the reading surface over the entire width of the reading surface, and the reading surface and this film by regulating the position of the film with respect to the reading surface. The position regulating means is provided with a minute document passage interval between them.

[0010]

In the image reading apparatus of the present invention, the film formed in white opposes the reading surface in a state where the white formed film has a minute sheet passing interval over the entire width of the reading surface by the position regulating means. Since the document is conveyed so as to pass through a gap due to a minute document passage distance, the document is prevented from floating on the reading surface and the document conveyance load is small. High-speed reading can be supported. In this case, it is possible to maintain the minute document passage interval between the film and the reading surface over the entire width simply by regulating the position of the film by the position regulation means.
No skew will occur.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The image reading apparatus according to the present embodiment is applied to, for example, a transmitting apparatus such as a facsimile apparatus. First,
A contact type line sensor 11 is provided on the lower side of the document conveyance path with the reading surface 11a facing upward. The contact type line sensor 11 has a well-known configuration in which a short focus lens, a line type photoelectric conversion element, and the like are built in. The film 12 forms a gap 13 at a position facing the reading surface 11a of the contact type line sensor 11. They are arranged close to each other. Also,
The contact type line sensor 1 is located at the lower side of the document feeding path.
1, the upstream side and the downstream side of the feed roller 14a,
14b is provided, and pinch rollers 15a, 15b are provided on the upper side of these feed rollers 14a, 14b.
15b are arranged opposite to each other in a contact state. These feed rollers 14a and 14b are rotated in the transport direction by a document transport system drive motor (not shown) and its transmission system.
Further, the film 12 has pinch rollers 15a and 15b.
At the same time, it is attached to an upper frame 16 made of plastics that can be opened and closed with respect to the apparatus main body, and by opening the upper frame 16, the document conveying path can be opened.

Here, the film 12 is a white sheet made of polyester or the like having a thickness of about 0.1 mm and having good flatness and flexibility, and has a strip shape having a length of at least the contact type line sensor 11 or more. As shown in FIG. 4, a flat portion 12a which forms a gap 13 and faces the reading surface 11a, and a flat portion 12a which is formed on both sides (upstream / downstream side) of the flat portion 12a and which is obliquely bent and formed. Paper guide 12
b and the mounting portion 12c extending from both ends of the flat portion 12a
It is formed by and. Corresponding to such a film 12, on the lower surface side of the upper frame 16 and at both end positions of the contact type line sensor 11, the mounting portions 12c are provided.
Is formed with a hook portion 16a for locking.
Further, on the lower surface side of the upper frame 16, there is formed a protrusion 16b which is located inside (closer to the center) of the hook portion 16a and applies tension to the flat portion 12a of the film 12 which is locked between the hook portions 16a. There is. Since the notch 16c as shown in FIG. 5A is formed around the protrusion 16b, the protrusion 16b is made movable as shown in FIG. 5B, and the tension caused by the elastic force of the plastics is applied. Can be applied to the film 12.

On the other hand, on the reading surface 11a of the contact type line sensor 11, the film 12 facing the reading surface 11a is provided at both ends (left and right ends in the transport direction) outside the sheet passing range.
A spacer 17 formed to have a thickness for restricting the gap 13 to a predetermined document passage interval d is attached. This spacer 17 functions as a position regulating means,
Although the thickness of the document is usually about 0.1 to 0.16 mm, depending on the depth of focus of the contact type line sensor 11, the document passage interval d is formed to a thickness of d = 0.2 mm, for example. Has been done. More specifically, for example, the spacer 17 is formed by stacking two tape materials each having a thickness of 0.1 mm and adhering the tape materials on the end portion of the reading surface 11a. further,
The lower end of the protrusion 16b of the upper frame 16 is the spacer 17 when the upper frame 16 is closed.
The height is set so that it can be located lower than the upper surface, and when the upper frame 16 is closed, tension is further applied to the film 12 stretched between the protrusions 16b.

Therefore, the film 12 is attached to the upper frame 16
2, the flat portion 12a of the film 12 is in a flat state between the protrusions 16b because tension is applied by the protrusions 16b as shown in FIG. Furthermore, the film 12
When the upper frame 16 to which is attached is closed with respect to the apparatus main body, the lower end of the protrusion 16b is lower than the position of the spacer 17 as shown in FIG. The film 12 is pushed up while coming into contact with the, and the elastic force due to the greater deformation of the protrusion 16b is received as tension. Therefore, the flat portion 12a of the film 12 is set and maintained in a state where the flat portion 12a is regulated by the thickness of the spacer 17, that is, in a state where the document passing interval d is maintained, without causing slack over the entire width in the transport direction. .

As a result, the state shown in FIG. 3 is established, and the upstream feed roller 14a and pinch roller 15 are provided.
The original fed by the pair a is conveyed through the gap 13 between the film 12 and the reading surface 11a while being guided by the sheet passing guide portion 12b, and is conveyed to the downstream side while receiving the reading operation during this period. Therefore, the original is read on the reading surface 11a.
Since the sheet passes through the gap 13 at the top, the load on the original document is small, and the original document can be conveyed at high speed. Therefore, high-speed reading can be coped with. In addition, the gap 13
Since, for example, the spacer 17 is formed to have a thickness of about 0.2 mm, the document passing through the gap 13 does not have a floating that causes a reading failure. Also, the reading surface 11
Since the spacers 17 provided at both ends of the sheet a in the conveyance direction can keep the original sheet passing distance d evenly over the entire width of the film 12, there is no difference in the conveying performance between the left and right sides, and the original sheet skew occurs. There is no such thing. In particular, since the document sheet spacing d to be secured with respect to the reading surface 11a is regulated by the spacer 17 attached to the reading surface 11a itself, the dimension can be maintained accurately. Further, since the flatness 12a is maintained flat by applying tension to the film 12 outwardly of the spacers 17, a mounting structure capable of applying a certain amount of tension or more is provided. It is also possible to easily balance the left and right by simply doing so, and no special precision is required other than the spacer 17.

Prior to reading the original image, a white balance process for setting reference data is performed by exposing the flat portion 12a of the film 12 formed in white by the contact line sensor 11 and reading the reflected light. However, since the flat portion 12a is maintained in a favorable flat state and faces the reading line as a surface having a width, the light reflected from the flat portion 12a of the film 12 can be reliably contacted with the line sensor. It can be led to the photoelectric conversion element in 11. Although the film 12 formed in white is used in this embodiment, an arbitrary film may be used in which the flat portion is white-treated. Further, in the case of the present embodiment, the film 12 side does not need the document conveying function, so that the space for arranging the drive transmission system etc.
Moreover, since the film 12 is used, the total height of the device can be kept low as in the case of the flexible sheet contact method. Further, it can be constructed at a lower cost than that using a white roller.

Further, in the case of the present embodiment, the height of the film 12 with respect to the reading surface 11a is determined by the spacer 17, but the film 12 itself is attached to the upper frame 16 side so that the upper frame 16 can be opened. For example, since the film 12 follows and the reading surface 11a is opened,
This is convenient for maintenance such as cleaning the reading surface 11a. However, if the release of the film 12 from the reading surface 11a is not considered, the film 12 may be attached by directly affixing it to the spacer 17 with some tension. Further, the means for applying the tension so that the film 12 does not sag is not limited to the one using the plastic elastic force of the protrusion 16b, but a spring or the like may be used.

[0018]

According to the image reading apparatus of the present invention, while the original is brought into close contact with the reading surface of the contact type line sensor and the original is conveyed, the images of the original are sequentially read by the contact type line sensor. In the image reading device,
Between the reading surface and the film, the film formed in white is disposed close to the reading surface over the entire width of the reading surface, and the position of the film with respect to the reading surface is regulated. Since the position regulating means for providing a minute document passing interval is provided, the document is fed in a state in which no floating occurs on the reading surface and the conveyance load is small so as to pass the minute document passing interval. Can be transported,
Therefore, the document can be conveyed at high speed, and high-speed reading can be supported, and the minute document-passing interval between the film and the reading surface can be reduced to the full width simply by regulating the position of the film by the position regulating means. Since it can be maintained across, it is possible to prevent the occurrence of skew or the like.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a reading unit according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional front view showing a state in which the upper frame is separated.

FIG. 3 is a schematic side view of the overall configuration.

FIG. 4 is a perspective view showing a film shape.

FIG. 5 is a perspective view showing a protruding portion, and FIG. 5 (b) is a front view.

FIG. 6 is a schematic side view showing a conventional example of a white roller separation drive system.

FIG. 7 is a schematic side view showing a conventional example of a flexible sheet contact system.

[Explanation of symbols]

 11 Contact Line Sensor 11a Reading Surface 12 Film 17 Position Control Means

Claims (1)

[Claims] 1. An image reading apparatus in which an image of an original is sequentially read by the contact type line sensor while the original is brought into close contact with the reading surface of the contact type line sensor and the original is conveyed. A film formed in white close to a position facing the reading surface and a position of the film with respect to the reading surface to regulate the position of the film and a minute original sheet passing between the reading surface and the film. An image reading apparatus, which is provided with position regulating means for providing a space.