Image reading device

Abstract

To obtain an image reading device capable of appropriately arranging a moving optical system at a home position while avoiding collision of the moving optical system with a structure.SOLUTION: A controller 41 (a) refers to a pixel value of a first pixel position P1 corresponding to a terminal reference portion 31, a second pixel position P2 corresponding to a first surrounding region 32, and a third pixel position P3 corresponding to a second surrounding region 33 and different from the second pixel position P2 in a captured image of an image sensor unit 2, and (b) determines whether or not the image sensor unit 2 is disposed in the terminal reference portion 31 based on the pixel values.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image reading device. [Background technology]

[0002] Some image reading devices are provided with a mark indicating a home position, and when the carriage is moved, the carriage is positioned at the home position based on the position where the mark is read (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-5119 Summary of the Invention [Problem to be solved by the invention]

[0004] When a moving optical system such as a carriage is placed at a home position, the moving optical system is first moved in a forward direction and then moved in a reverse direction to reach the home position.

[0005] In order to position the home position for such a moving optical system, it is possible to provide another reference mark at the end of the movable optical system's range of motion opposite the home position, and when the movable optical system detects that reference mark, reverse the direction of movement of the moving optical system, thereby preventing the moving optical system from colliding with internal structures (such as a wall) at the end opposite the home position.

[0006] However, when the above-mentioned operation is performed with a document placed on the contact glass, if the document's color (print color or background color) is the same as or similar to the above-mentioned reference mark, the document may be erroneously detected as the edge opposite the home position, causing the movement direction of the moving optical system to be reversed at an incorrect position, and the moving optical system may collide with an internal structure (such as a wall) on the home position side, preventing it from being properly positioned at the home position. This problem is particularly likely to occur when the moving optical system is positioned below the contact glass for automatic document feeding.

[0007] The present invention has been made in consideration of the above problems, and aims to provide an image reading device that properly positions a moving optical system at a home position while avoiding collision of the moving optical system with a structure. [Means for solving the problem]

[0008] The image reading device according to the present invention includes a first contact glass for a document to be placed on the document, a second contact glass for a document transported from an automatic document feeder, a moving optical system that captures an image of a line along the main scanning direction of the document at a position below the first contact glass or the second contact glass, a drive device that moves the moving optical system in the sub-scanning direction, a controller that controls the drive device to position the moving optical system at a home position, a terminal reference section provided at an end of the movable range of the moving optical system opposite the home position, a first peripheral area provided at a specific position on a frame of the first contact glass, and a second peripheral area provided at a specific position on a frame of the second contact glass. The controller (a) references pixel values at a first pixel position corresponding to the terminal reference section, a second pixel position corresponding to the first peripheral area, and a third pixel position corresponding to the second peripheral area and different from the second pixel position in an image obtained by the imaging of the moving optical system, and (b) determines whether the moving optical system is positioned at the terminal reference section based on the pixel values. [Effects of the Invention]

[0009] According to the present invention, an image reading device can be obtained that appropriately positions a moving optical system at a home position while avoiding collision of the moving optical system with a structure.

[0010] 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. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a side view showing the internal configuration of an image reading device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating the arrangement position of the image sensor unit 2 in FIG. [Figure 3] FIG. 3 is a block diagram showing the electrical configuration of the image reading apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] 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 illustrating the arrangement position of an image sensor unit 2 in Fig. 1. The image reading device shown in Fig. 1 is a device such as a scanner, copier, facsimile machine, or multifunction device.

[0014] 1 includes a device body 1, contact glasses 1a and 1b arranged on the top surface of the device body 1, an image sensor unit 2, and a document cover 3. The document cover 3 includes an automatic document feeder 4.

[0015] 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 image reading of the document image is performed while the automatic document feeder 4 is automatically transporting the document.

[0016] The image sensor unit 2 is a moving optical system that optically reads an original document and generates an image output signal corresponding to the image on the original document. The image sensor unit 2 captures an image of a line along the main scanning direction of the original document at a position below the contact glass 1a or contact glass 1b. The drive device 21 moves the image sensor unit 2 in the sub-scanning direction.

[0017] 2, when reading an image of a document placed on a contact glass 1a (flat head), the image sensor unit 2 optically reads the image of the document while being moved below the contact glass 1a by a drive device 21. The drive device 21 moves the image sensor unit 2 in the sub-scanning direction.

[0018] 2, when image reading of an original document is performed while the original document is automatically transported by the automatic document feeder 4, the image sensor unit 2 is placed under the contact glass 1b and, in a stationary state, optically reads the image of the original document passing through a predetermined image reading position in the original document transport path. The image sensor unit 2 reads the original document image line by line.

[0019] A reference plate (not shown) for shading correction is provided between the contact glasses 1a and 1b, and the position below the reference plate is set as the home position, for example.

[0020] 1, the document cover 3 is a rotatable member that can come into surface contact with the contact glass 1a, and it keeps the document tightly attached to the contact glass 1a and prevents ambient light from entering the device through the contact glasses 1a and 1b during image reading. The automatic document feeder 4 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.

[0021] Fig. 3 is a block diagram showing the electrical configuration of the image reading device shown in Fig. 1. The image reading device shown in Fig. 1 includes an image sensor unit 2, an automatic document feeder 4, a drive device 21, and a controller 41, as shown in Fig. 3, for example.

[0022] 3, the image sensor unit 2 is, for example, a CIS, and includes a light source 2a such as a light emitting diode, a line sensor 2b, and a control IC (Integrated Circuit) 2c. The control IC 2c controls the light source 2a to emit light, detects the light reflected off an original or the like via the contact glasses 1a and 1b with the line sensor 2b, and outputs an image output signal (captured image) corresponding to the amount of reflected light.

[0023] The controller 41 also includes a processor that executes a program, an ASIC (Application Specific Integrated Circuit), and the like, and controls the driving device 21 to move the image sensor unit 2. For example, the controller 41 controls the driving device 21 to position the image sensor unit 2 at the home position.

[0024] Specifically, the image sensor unit 2 can change its image reading position within a predetermined movable range by the drive device 21, and when image reading is performed using the automatic document feeder 4, the image reading position of the image sensor unit 2 is set to the position where the document passes on the contact glass 1b, and the image sensor unit 2 optically reads the image of the document conveyed by the automatic document feeder 4 as it passes over the contact glass 1b. The image sensor unit 2 may be a color image sensor.

[0025] Furthermore, the interior top surface of the housing of the image reading device is provided with a terminal reference portion 31, a first surrounding area 32, and a second surrounding area 33. The terminal reference portion 31 is a portion provided at the end opposite the home position in the movable range of the image sensor unit 2, and may be a single member or a part of a certain member. The terminal reference portion 31 has a specific color (here, red).

[0026] The first peripheral region 32 is a region provided at a specific position on the frame of the contact glass 1a. The second peripheral region 33 is a region provided at a specific position on the frame of the contact glass 1b. The first peripheral region 32 and the second peripheral region 33 each have a specific color (here, black).

[0027] In addition, the controller 41 (a) refers to the pixel values of a first pixel position P1 corresponding to the terminal reference portion 31, a second pixel position P2 corresponding to the first surrounding region 32, and a third pixel position P3 corresponding to the second surrounding region 33 and different from the second pixel position P2 in the image obtained by imaging the image sensor unit 2, and (b) determines whether the image sensor unit 2 is positioned at the terminal reference portion 31 based on these pixel values.

[0028] Specifically, the controller 41 determines that the image sensor unit 2 is positioned in the terminal reference portion 31 if the pixel value at the first pixel position P1 matches the color (known) of the terminal reference portion 31, the pixel value at the second pixel position P2 matches the color (known) of the first surrounding region 32, and the pixel value at the third pixel position P3 does not match the color of the second surrounding region 33.

[0029] On the other hand, if the pixel value at the third pixel position P3 matches the color of the second surrounding region 33, the controller 41 determines that the image sensor unit 2 is not positioned in the terminal reference portion 31 even if the pixel value at the first pixel position P1 matches the color of the terminal reference portion 31.

[0030] At the sub-scanning direction position of the terminal reference portion 31 and the main scanning direction position of the second peripheral region 33, the color of the frame of the contact glass 1a is different from the color of the second peripheral region 33. For example, the color of the frame of the contact glass 1a has a different density from the color of the second peripheral region 33.

[0031] Here, the controller 41 determines that the pixel value of the first pixel position P1 matches the color of the end reference portion 31 if the average value of the pixel values in a predetermined first position range including the first pixel position P1 (for example, the range from the first pixel (the first pixel) to the 16th pixel) is within a predetermined color range. Furthermore, the controller 41 determines that the pixel value of the second pixel position P2 matches the color of the first surrounding region 32 if the average value of the pixel values in a predetermined second position range including the second pixel position P2 (for example, the range from the 32nd pixel to the 48th pixel) is within a predetermined color range. Furthermore, the controller 41 determines that the pixel value of the third pixel position P3 matches the color of the second surrounding region 33 if the average value of the pixel values in a predetermined third position range including the third pixel position P3 (for example, the range from the 5182nd pixel to the 5198th pixel) is within a predetermined color range.

[0032] Next, the operation of the image reading device will be described.

[0033] Before reading an image of a document, the controller 41 places the image sensor unit 2 in the home position.

[0034] At this time, the controller 41 controls the drive device 21 to move the image sensor unit 2 toward the end on the terminal reference portion 31 side while causing the image sensor unit 2 to capture an image, and repeatedly determines whether the image sensor unit 2 is positioned at the terminal reference portion 31 based on the pixel values of the first pixel position P1, the second pixel position P2, and the third pixel position P3 in the captured image of the image sensor unit 2, as described above.

[0035] When it is determined that the image sensor unit 2 is placed at the distal reference portion 31, the controller 41 controls the drive device 21 to reverse the direction of movement of the image sensor unit 2 and move the image sensor unit 2 to the home position.

[0036] The controller 41 places the image sensor unit 2 at the home position by moving the image sensor unit 2 by a predetermined distance from the position where the edge of the reference plate is detected in the image captured by the image sensor unit 2.

[0037] The controller 41 acquires an image captured by the image sensor unit 2 at the home position and derives the amount of shading correction.

[0038] Thereafter, the controller 41 moves the image sensor unit 2 to a position below the contact glass 1a or the contact glass 1b, and executes image reading of the document.

[0039] As described above, according to the above embodiment, the image sensor unit 2 captures an image of a line along the main scanning direction of a document at a position below the contact glass 1a for a document to be placed or the contact glass 1b for automatic document feeding. The image sensor unit 2 has a terminal reference portion 31 at an end of its movable range opposite the home position, a first peripheral region 32 at a specific position on the frame of the contact glass 1a, and a second peripheral region 33 at a specific position on the frame of the contact glass 1b. The controller 41 then (a) references pixel values at a first pixel position P1 corresponding to the terminal reference portion 31, a second pixel position P2 corresponding to the first peripheral region 32, and a third pixel position P3 corresponding to the second peripheral region 33 and different from the second pixel position P2, in the captured image of the image sensor unit 2, and (b) determines whether the image sensor unit 2 is located at the terminal reference portion 31 based on these pixel values.

[0040] As a result, when the image sensor unit 2 is positioned below the contact glass 1b, even if a document of a similar color to the terminal reference part 31 is placed on the contact glass 1b, erroneous detection of the terminal reference part 31 is suppressed, and the image sensor unit 2 is appropriately positioned in the home position while avoiding collision of the image sensor unit 2 with the structure.

[0041] 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, it is intended that such changes and modifications be included within the scope of the claims. [Industrial Applicability]

[0042] The present invention is applicable to, for example, an image reading device. [Explanation of symbols]

[0043] 1a Contact glass (an example of the first contact glass) 1b Contact glass (an example of the second contact glass) 2 Image sensor unit (an example of a moving optical system) 4 Automatic document feeder 21 Drive unit 31 Terminal reference section 32 First Surrounding Area 33 Second Surrounding Area 41 Controller

Claims

1. a first contact glass for placing an original thereon; a second contact glass for the document conveyed from the automatic document feeder; a moving optical system that captures an image of a line along a main scanning direction of the document at a position below the first contact glass or the second contact glass; a drive device that moves the moving optical system in a sub-scanning direction; a controller that controls the drive device to place the moving optical system at a home position; a terminal reference unit provided at an end of the movable range of the moving optical system opposite to the home position; a first peripheral region provided at a specific position on a frame of the first contact glass; a second peripheral region provided at a specific position on the frame of the second contact glass; The controller (a) refers to pixel values of a first pixel position corresponding to the terminal reference portion, a second pixel position corresponding to the first surrounding region, and a third pixel position corresponding to the second surrounding region and different from the second pixel position in the image obtained by the imaging of the moving optical system, and (b) determines whether the moving optical system is disposed in the terminal reference portion based on the pixel values. An image reading device characterized by:

2. The image reading device described in claim 1, characterized in that the controller determines that the moving optical system is located in the terminal reference section (a) if the pixel value of the first pixel position matches the color of the terminal reference section, the pixel value of the second pixel position matches the color of the first surrounding area, and the pixel value of the third pixel position does not match the color of the second surrounding area, and (b) if the pixel value of the third pixel position matches the color of the second surrounding area, it determines that the moving optical system is not located in the terminal reference section even if the pixel value of the first pixel position matches the color of the terminal reference section.

3. 3. The image reading device according to claim 2, wherein the color of the frame of the first contact glass at the sub-scanning direction position of the terminal reference portion and the main-scanning direction position of the second peripheral region is different from the color of the second peripheral region.

4. 4. The image reading device of claim 1, wherein the controller determines that the pixel value of the first pixel position matches the color of the terminal reference portion if the average value of pixel values in a predetermined first position range including the first pixel position is within a predetermined color range, determines that the pixel value of the second pixel position matches the color of the first surrounding area if the average value of pixel values in a predetermined second position range including the second pixel position is within the predetermined color range, and determines that the pixel value of the third pixel position matches the color of the second surrounding area if the average value of pixel values in a predetermined third position range including the third pixel position is within the predetermined color range.

Images