JP7510600B2 - Image reader - Google Patents

Description

The present invention relates to an image reading device.

In one image reading device, when an original is transported by an automatic document feeder, the original is transported with its orientation tilted relative to the transport direction, thereby suppressing fluctuations in the transport speed when the nip of the trailing edge of the original by the roller in front of the image reading position is released, thereby suppressing degradation of image quality (see, for example, Patent Document 1).

JP 2004-29279 A

However, in the above-mentioned image reading device, the document is always tilted as it passes through the image reading position, so it is necessary to use an image sensor that can read a document with a width Wd (= W + dW) that is greater than the document width W (width of the top and bottom sides) by an increase dW (= W x cos(A) + L x sin(A) - W) depending on the document tilt angle A, the document width W, and the document length L (length of the left and right sides), which increases the cost of the image reading device.

The present invention was made in consideration of the above problems, and aims to provide an image reading device that is relatively low cost and suppresses degradation of image quality caused by release of the roller nip at the trailing edge of the document.

The image reading device of the present invention comprises an image sensor that reads an image of a document passing through a predetermined image reading position on a document transport path, a first upstream transport roller among a plurality of upstream transport rollers arranged at a position upstream from the predetermined image reading position on the transport path, which is closest to the predetermined image reading position, and a plurality of stage nip release rollers arranged on the transport path between the first upstream transport roller and the image reading position, and which become narrower in width in a direction perpendicular to the document transport direction the closer they are to the image reading position.

The present invention provides an image reading device that is relatively low cost and reduces degradation of image quality caused by release of the roller nip at the trailing edge of the document.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

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

The following describes an embodiment of the present invention with reference to the drawings.

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

The image reading device shown in FIG. 1 includes a device body 1, contact glasses 1a and 1b arranged on the top surface of the device 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 image reading is performed without using the automatic document feeder 4. The contact glass 1b is a transparent member over which a document passes when the document is automatically transported by the automatic document feeder 4 and the document image is read.

When the automatic document feeder 4 is used to read the image of a document while the document is automatically transported, the image sensor 2 optically reads the image of the document as it passes through a predetermined image reading position in the document transport path. The image sensor 2 reads the document image one line at a time.

The image sensor 2 includes a light source (such as a light-emitting diode) and a light-receiving element (such as a line sensor). The light source emits light, and the light-receiving element detects the light reflected off an original document or the like via the contact glasses 1a and 1b, and outputs an electrical signal corresponding to the amount of reflected light. The controller 21, which will be described later, receives this electrical signal and generates an original document image (i.e., image data of the original document image) based on this electrical signal.

The document cover 3 is a member that is installed so as to be able to make surface contact with the contact glass 1a and to be freely rotatable, and it presses the document against the contact glass 1a and prevents ambient light from entering the inside of the device through the contact glasses 1a and 1b during image reading. The automatic document feeder 4 also transports documents placed on the document tray 11 one by one using transport rollers 12 and 13, passes them over the contact glass 1b, and discharges them onto the discharge tray 14.

The image sensor 2 can change its image reading position by a drive device (not shown). When image reading is performed using the automatic document feeder 4, the image reading position of the image sensor 2 is set to the position where the document passes on the contact glass 1b, and the image sensor 2 optically reads the image of the document transported by the automatic document feeder 4 as it passes over the contact glass 1b. Here, the image sensor 2 is a color image sensor, and reads document images of multiple 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 positioned directly below the contact glass 1b.

Furthermore, the image reading device is equipped with multiple stage nip release rollers 15-1 to 15-N (N>1) in the automatic document feeder 4.

Figure 2 shows an example of the arrangement of the transport rollers and step nip release rollers in the image reading device shown in Figure 1.

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

The transport roller 12 is an upstream transport roller that is located upstream from a predetermined image reading position on 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 that is located downstream from a predetermined image reading position on the transport path.

The multiple stage 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 original 101, and the closer they are to the image reading position, the narrower their widths become in the direction perpendicular to the transport direction of the original 101. For example, in the case of FIG. 2, N=3.

In this embodiment, one end of the stage nip release rollers 15-1 to 15-N (for example, the left end in the case of FIG. 2) is aligned, and the stage nip release rollers 15-1 to 15-N nip the side edge of the document 101 (for example, the left edge in the case of FIG. 2).

The width of the step nip release rollers 15-1 to 15-N (contact area when nipping) is narrower than the width of the conveying rollers 12 and 13 (contact area when nipping).

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

Figure 3 is a block diagram showing the electrical configuration of the image reading device shown in Figures 1 and 2.

The image reading device shown in FIG. 3 further includes a controller 21 and a roller drive unit 22. The controller 21 includes a processor that executes a program, an ASIC (Application Specific Integrated Circuit), and the like, and (a) electrically controls the roller drive unit 22 and the like to control the operation of the transport rollers 12, 13, and the like, and (b) receives an electrical signal indicating an original image from the image sensor 2, generates image data corresponding to the electrical signal, and performs predetermined image processing on the image data.

The roller drive unit 22 is a drive unit (such as a motor) that drives the above-mentioned transport rollers 12, 13, etc.

Next, the operation of the image reading device will be described. FIG. 4 is a diagram for explaining the operation of the image reading device shown in FIGS. 1 to 3. FIG. 4(A) is a diagram showing the transport state when the transport roller 12a releases the nip at the rear end of the document 101. FIG. 4(B) is a diagram showing the transport state when the stage nip release roller 15-1 releases the nip at the rear end of the document 101. FIG. 4(C) is a diagram showing the transport state when the final stage nip release roller 15-3 releases the nip at the rear end of the document 101.

The controller 21 performs document image reading using the automatic document feeder 4 in the following manner, in accordance with user operations 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 transporting the documents 101 one by one from the document tray 11.

In the automatic document feeder 4, the transport rollers 12 transport the document 101 fed from the document tray 11 along the transport path. Then, when the document 101 reaches the image reading position, the image of the document 101 is read line by line by the image sensor 2. Then, the transport rollers 13 transport the document 101 and discharge it onto the discharge tray 14.

For example, as shown in FIG. 4A, when the transport roller 12a releases the nip at the rear end of the document 101, the document 101 is in a state of being nipped by the step-wise nip release rollers 15-1 to 15-N, so vibrations of the document 101 caused by the release of the nip by the transport roller 12a are suppressed.

After that, as shown in FIG. 4B, for example, when the stage nip release roller 15-1 releases the nip at the rear end of the document 101, the document 101 is nipped by the stage nip release rollers 15-2 to 15-N, so vibration of the document 101 caused by the release of the nip by the stage nip release roller 15-1 is suppressed. After that, the nips of the stage nip release rollers 15-i (1<i<N) are released one by one in sequence, and finally, as shown in FIG. 4C, for example, the nip of the stage nip release roller 15-N is released. At that time, because the stage nip release roller 15-N has a narrow width, vibration of the document 101 caused by the release of the nip is suppressed.

In this way, the nips of the stage nip release rollers 15-1 to 15-N are released sequentially. Because the stage nip release rollers 15-1 to 15-N are gradually narrower in width, the nipped area gradually narrows as the nips of the stage nip release rollers 15-1 to 15-N are sequentially released. Therefore, the nip is gradually released while suppressing vibrations of the document 101 caused by the release of the nip.

The document image obtained in this manner 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 a predetermined image reading position on the document transport path. The transport roller 12a is the closest to the predetermined image reading position among the upstream transport rollers arranged upstream from the predetermined image reading position on the transport path. The multiple stage nip release rollers 15-1 to 15-N are arranged between the transport roller 12a and the image reading position on the transport path, and the closer they are to the image reading position, the narrower their width in the direction perpendicular to the document transport direction becomes.

As a result, the original 101 is not transported at an angle, so the readable original width Wd required for the image sensor 2 is small, the cost of the image sensor 2 is reduced, and the degradation of image quality caused by the release of the roller nip at the rear end of the original (fluctuations in the transport speed when the nip is released and vibration of the original) is suppressed at a relatively low cost.

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 spirit and scope of the subject matter and without diminishing its intended advantages. In other words, such changes and modifications are intended to be included within the scope of the claims.

The present invention can be applied to, for example, scanners, multifunction devices, etc.

2 Image sensor 12a Transport roller (an example of a first upstream transport roller)
15-1 to 15-N Step Nip Release Roller

Claims (4)

an image sensor that reads an image of a document passing a predetermined image reading position in a document transport path;
a first upstream transport roller that is closest to the predetermined image reading position among a plurality of upstream transport rollers that are disposed on the transport path at a position upstream of the predetermined image reading position;
a plurality of staged nip release rollers disposed in the transport path between the first upstream transport roller and the image reading position, the staged nip release rollers each having a width that is narrower in a direction perpendicular to the transport direction of the document as the staged nip release rollers approach the image reading position;
An image reading device comprising: The image reading device according to claim 1, characterized in that one end of the multiple stage nip release rollers is aligned, and the multiple stage nip release rollers nip the side edge portion of the document. 3. The image reading apparatus according to claim 1, wherein the widths of the plurality of stepwise nip release rollers are all narrower than the widths of the plurality of upstream transport rollers. The image reading device according to any one of claims 1 to 3, characterized in that the multiple stage nip release rollers are driven rollers.

Images