JP2021141378A - Image reading device - Google Patents

Abstract

To prevent, at a relatively low cost, a reduction in image quality at a rear end of a document due to the release of a nip between rollers.SOLUTION: An image sensor 2 reads an image of a document that passes through a predetermined image reading position on a conveyance path of the document. Of upstream side conveying rollers arranged at positions on the upstream side of the predetermined image reading position on the conveyance path, a conveying roller 12a is closest to the predetermined image reading position. A plurality of step nip release rollers 15-1 to 15-N are arranged between the conveying roller 12a and the image reading position on the conveyance path, and whose widths become narrower in a direction perpendicular to a conveyance direction of the document as approaching the image reading position.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image reader.

When transporting a document by an automatic document feeder, one image reading device transports the document in a state where the direction of the document is tilted with respect to the transport direction, whereby the rear end of the document by the roller in front of the image scanning position. The fluctuation of the transport speed when the nip is released is suppressed to suppress the deterioration of the image quality (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-292279

However, in the above-mentioned image reading device, when the document passes through the image scanning position, the direction of the document is always tilted. Therefore, the tilt angle A of the document, the width W of the document, and the length L (lengths of the left and right sides). ) Is increased by dW (= W × cos (A) + L × sin (A) −W). It is necessary to use an image sensor, which increases the cost of the image reader.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain an image reader that suppresses image quality deterioration due to release of a roller nip at the rear end of a document at a relatively low cost.

The image reading device according to the present invention is arranged with an image sensor that reads an image of a document passing through a predetermined image reading position on the document transport path and a position upstream from the predetermined image reading position on the transport path. Among the upstream transport rollers, the first upstream transport roller closest to the predetermined image reading position and the image are arranged between the first upstream transport roller and the image reading position in the transport path. It is provided with a plurality of step nip release rollers whose width in a direction perpendicular to the transport direction of the document becomes narrower as it approaches the scanning position.

According to the present invention, it is possible to obtain an image reading device that suppresses image quality deterioration caused by releasing the nip of a roller at the rear end of a document at a relatively low cost.

The above or other objects, features and advantages of the present invention will be further clarified from the following detailed description along with the accompanying drawings.

FIG. 1 is a side view showing an internal configuration of an image reading device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of arrangement of a transport roller and a step nip release roller in the image reading device shown in FIG. FIG. 3 is a block diagram showing an electrical configuration of the image reader shown in FIGS. 1 and 2. FIG. 4 is a diagram illustrating the operation of the image reading device shown in FIGS. 1 to 3.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing an internal configuration of an image reading device according to an embodiment of the present invention. The image reading device shown in FIG. 1 is a device such as a scanner machine, a copier, a facsimile machine, or a multifunction device.

The image reading device shown in FIG. 1 includes a device main body 1, contact glasses 1a and 1b arranged on the upper surface of the device main body 1, an image sensor 2, and a document cover 3. The document cover 3 includes an automatic document feeder 4.

The contact glass 1a is a transparent member on which a document is placed when an image is read without using the automatic document feeder 4. Further, the contact glass 1b is a transparent member through which the original is passed when the automatic document feeder 4 automatically conveys the original and reads the image of the original image.

The image sensor 2 is a sensor that optically reads an image of a document that passes through a predetermined image reading position in the document transport path when the image of the document image is read while the document is automatically conveyed by the automatic document feeder 4. Is. The image sensor 2 reads the original image line by line.

The image sensor 2 includes a light source (light emitting diode or the like) and a light receiving element (line sensor or the like), emits light by the light source, and detects the reflected light reflected by the document or the like through the contact glasses 1a and 1b by the light receiving element. Then, an electric signal corresponding to the amount of reflected light is output. The controller 21, which will be described later, receives this electric signal and generates a manuscript image (that is, image data of the manuscript image) based on this electric signal.

The document cover 3 is a member that can be surface-contacted with the contact glass 1a and is rotatably installed. The document is brought into close contact with the contact glass 1a, and ambient light is emitted from the contact glasses 1a and 1b to the inside of the device during image reading. Prevents incident on the glass. Further, the automatic document feeder 4 conveys the documents placed on the document tray 11 one by one by the transfer rollers 12 and 13, passes over the contact glass 1b, and discharges the documents to the discharge tray 14.

Further, the image reading position of the image sensor 2 can be changed by a drive device (not shown), and when the image reading is executed by using the automatic document feeder 4, the image reading position of the image sensor 2 is changed. The image sensor 2 is set to the passing position of the document on the contact glass 1b, and the image sensor 2 optically reads the image of the document conveyed by the automatic document feeder 4 when passing over the contact glass 1b. Here, the image sensor 2 is a color image sensor that reads original images of a plurality of colors such as RGB at different image reading positions in the transport direction.

In this embodiment, a CIS (Contact Image Sensor) is used as the image sensor 2, and when image reading is performed using the automatic document feeder 4, the image sensor 2 is arranged directly under the contact glass 1b. ..

Further, the image reading device includes a plurality of step nip release rollers 15-1 to 15-N (N> 1) in the automatic document feeder 4.

FIG. 2 is a diagram showing an example of arrangement of a transport roller and a step nip release roller in the image reading device shown in FIG.

The transport rollers 12 and 13 are driven by a predetermined driving force source (roller drive unit 22 described later), and transport the document 101 along the transport path.

The transport roller 12 is an upstream transport roller arranged at a position upstream from a predetermined image reading position in the transport path. The transport roller 12a is the first upstream transport roller of the transport rollers 12 that is closest to the predetermined image reading position.

The transport roller 13 is a downstream transport roller arranged at a position downstream from a predetermined image reading position in the transport path.

The plurality of step nip release rollers 15-1 to 15-N are arranged between the transport roller 12a and the image reading position in the transport path of the document 101, and the closer to the image scanning position, the more the document 101 is transported in the transport direction. A roller that narrows in the vertical direction. For example, in the case of FIG. 2, N = 3.

In this embodiment, one ends of the stepped nip release rollers 15-1 to 15-N (for example, the left end in the case of FIG. 2) are aligned, and the step nip release rollers 15-1 to 15-N are the document 101. Nip the side part (for example, the left side in the case of FIG. 2).

The width of the stepped nip release rollers 15-1 to 15-N (contact range at the time of nip) is narrower than the width of the transport rollers 12 and 13 (contact range at the time of nip).

Further, the step nip release rollers 15-1 to 15-N may be driven rollers.

FIG. 3 is a block diagram showing an electrical configuration of the image reader shown in FIGS. 1 and 2.

The image reading device shown in FIG. 3 further includes a controller 21 and a roller driving unit 22. The controller 21 includes a processor for executing a program, an ASIC (Application Specific Integrated Circuit), etc., and (a) electrically controls the roller drive unit 22 and the like to control the operations of the transfer rollers 12, 13 and the like. b) An electric signal indicating a document image is received from the image sensor 2, image data corresponding to the electric signal is generated, and a predetermined image process is executed on the image data.

The roller drive unit 22 is a drive unit (motor or the like) that drives the above-mentioned transport rollers 12, 13 and the like.

Next, the operation of the image reader will be described. FIG. 4 is a diagram illustrating the operation of the image reading device shown in FIGS. 1 to 3. FIG. 4A is a diagram showing a transport state when the nip of the rear end of the document 101 is released by the transport roller 12a. FIG. 4B is a diagram showing a transport state when the rear end of the document 101 is released from the nip by the stepped nip release roller 15-1. FIG. 4C is a diagram showing a transport state when the rear end of the document 101 is released from the nip by the final stage nip release roller 15-3.

The controller 21 executes the document image reading using the automatic document feeder 4 as follows according to a user operation on an operation panel (not shown).

First, the controller 21 starts the operation of the image sensor 2 and controls the automatic document feeder 4 to start the transfer of the documents 101 one by one from the document tray 11.

In the automatic document feeder 4, the transfer roller 12 conveys the document 101 fed from the document tray 11 along the transfer path. Then, when the document 101 reaches the image reading position, the image sensor 2 reads the image of the document 101 line by line. After that, the transport roller 13 transports the document 101 and discharges it to the discharge tray 14.

Then, for example, as shown in FIG. 4 (A), when the nip of the rear end of the document 101 is released by the transfer roller 12a, the document 101 is in a state of being nipated by the stepped nip release rollers 15-1 to 15-N, so that the document 101 is conveyed. Vibration of the document 101 caused by releasing the nip of the roller 12a is suppressed.

After that, as shown in FIG. 4B, for example, when the document 101 is released from the rear end of the document 101 by the step nip release roller 15-1, the document 101 is nipped by the step nip release rollers 15-2 to 15-N. Therefore, the vibration of the document 101 caused by the nip release of the stepped nip release roller 15-1 is suppressed. After that, the nip of the step nip release roller 15-i (1 <i <N) is sequentially released one by one, and finally, as shown in FIG. 4C, for example, the nip of the step nip release roller 15-N. Is released. At that time, since the width of the stepped nip release roller 15-N is narrow, vibration of the document 101 caused by the nip release is suppressed.

In this way, the nip of the stepped nip release rollers 15-1 to 15-N is sequentially released. Since the width of the stepped nip release rollers 15-1 to 15-N gradually narrows, the nipped range gradually narrows when the nip of the step nip release rollers 15-1 to 15-N is sequentially released. To go. Therefore, the nip is gradually released while suppressing the vibration of the document 101 caused by the release of the nip.

The original image thus obtained is stored as an image data file in a storage device (not shown), transmitted as an image data file to an external device (not shown), or printed by a printing device (not shown).

As described above, according to the above embodiment, the image sensor 2 reads the image of the document passing through the predetermined image reading position in the document transport path. The transport roller 12a is the one closest to the predetermined image reading position among the upstream transport rollers arranged at the position upstream from the predetermined image reading position in the transport path. The plurality of step nip release rollers 15-1 to 15-N are arranged between the transfer roller 12a and the image reading position in the transfer path, and the closer to the image reading position, the more perpendicular to the original transfer direction. The width becomes narrower.

As a result, since the document 101 is not tilted and conveyed, the readable document width Wd required for the image sensor 2 can be small, the cost of the image sensor 2 is low, and the cost is relatively low, and the rear end of the document is relatively low. Suppresses the deterioration of image quality due to the release of the roller nip (fluctuation of transport speed and vibration of the document when the nip is released).

It should be noted that various changes and modifications to the above-described embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the intent and scope of the subject and without diminishing the intended benefits. That is, such changes and amendments are intended to be included in the claims.

The present invention can be applied to, for example, a scanner machine, a multifunction device, and the like.

2 Image sensor 12a Conveyor roller (example of first upstream transfer roller)
15-1 to 15-N step nip release roller

Claims (4)

An image sensor that reads an image of a document that passes through a predetermined image reading position in the document transport path,
Among the upstream transport rollers arranged at positions upstream from the predetermined image reading position in the transport path, the first upstream transport roller closest to the predetermined image reading position and
A plurality of steps arranged between the first upstream transport roller and the image reading position in the transport path, and the width in a direction perpendicular to the transport direction of the document becomes narrower as the image is read closer to the image reading position. Nip release roller and
An image reading device comprising. The image reading device according to claim 1, wherein one ends of the plurality of step nip release rollers are aligned, and the plurality of step nip release rollers nip side sides of the original. The image reading device according to claim 1 or 2, wherein the width of the plurality of step nip release rollers is narrower than the width of the conveying roller. The image reading device according to any one of claims 1 to 3, wherein the plurality of step nip release rollers are driven rollers.

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