JPH08197U - Image reading device - Google Patents

Abstract

(57) [Summary] [Structure] A linear image sensor 2 having an image reading direction b in a direction orthogonal to the feeding direction a of the document table is arranged above the document table 1. A pair of detection lines L1 and L2 are formed on both outer sides of the original reading width by the sensor 2, and a detection line L3 is formed at the original reading start position at right angles to the main scanning direction a. The mounting state and tilting state of the document table are detected and adjusted by the output voltage waveforms obtained by reading the detection lines L1, L2, and L3. [Effect] Prior to image reading, it is possible to automatically and accurately adjust the mounting state of the platen, the tilted state, and the like in the vertical direction and the horizontal direction. It is possible to read various images.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a plane scanning type image reading apparatus using a linear image sensor.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, there is known an apparatus that scans a document platen in which a document is sandwiched between parallel flat plate glasses, and transmits or reflects light to the document, and reads the image using a linear image sensor.

[0003]

[Problems to be solved by the device]

 In such an image reading apparatus, the mounting state of the platen and the tilted state thereof have a great influence on the quality of the image to be read. Especially when using a self-contact type SELFOC lens with a shallow depth of focus, the focal length varies due to variations in the surface shape of the document, etc., and this effect is greatly affected, causing local blurring in the input image. Will occur. Since the work of mounting the platen is visually performed by the operator, the misalignment during the mounting work cannot be detected until the image is actually input into the document, so a high-definition image is obtained. Therefore, a great deal of labor was required to correct this deviation.

Therefore, an object of the present invention is to make it possible to adjust the mounting state of the platen, the tilted state, and the like prior to image reading, and it is possible to read a high-definition image with a simple configuration and a small amount of labor. Especially.

[0005]

[Means for Solving the Problems]

 A feature of the present invention is that a pair of detection lines are provided parallel to the feeding direction of the platen at positions on both sides of the document reading width by the linear image sensor of the platen and within the effective reading width. Of the output waveforms obtained by reading the pair of detection lines by the image sensor, the outputs at the positions corresponding to the pair of detection lines are used to determine the focal distance in the vicinity of both ends in the image reading direction of the linear image sensor. And a first adjusting means for adjusting the error so that all the outputs at the positions corresponding to the pair of detection lines are within an allowable range based on the detection result. Further, a detection line is provided at the original reading start position on the platen, orthogonal to the feeding direction of the platen. Detecting an error of Gyodo with certain second adjusting means for adjusting the error at digits set.

[0006]

【Example】

 FIG. 1 shows an embodiment of the image reading apparatus of the present invention. A linear image sensor 2 having an image reading direction (sub scanning direction) b in a direction orthogonal to the feeding direction (main scanning direction) a of the document table 1 is arranged above the document table 1. A lens system 3 such as a SELFOC lens array is arranged between the document table 1 and the linear image sensor 2.

As shown in FIG. 2, the document table 1 has a width along the sub-scanning direction b that is larger than the effective reading width e of the linear image sensor 2, and is adjusted to a position outside this width e. A screw hole 4 for use is provided. An adjusting screw 5 (see FIG. 1) is screwed into the screw hole 4, and by rotating the adjusting screw, the end portion of the document table 1 can be moved up and down by Δd, and the inclination angle Δθ can be finely adjusted. It can be adjusted.

A document reading width f by the linear image sensor 2 is set on the document table 1 with a width smaller than the effective reading width e, and the document 6 is set in an area within this width f. A pair of detection lines L1 and L2 are provided in parallel to the main scanning direction a at positions on both outsides of the document reading width f and inside the effective reading width e by vapor deposition or printing. Further, on the document table 1, a detection line L3 is formed at the document reading start position orthogonal to the main scanning direction a by vapor deposition or printing.

As shown in FIG. 7, the document table 1 is attached to a carrier 20 for feeding the document table in the main scanning direction a. The document table 1 is supported in a three-point support state so that the mounting state between the document table 1 and the carrier 20 can be finely adjusted in plan. That is, a fulcrum 21 is projected on one side of the carrier 20, and two pieces 22 and 23 are provided on the opposite side of the carrier 20 at a predetermined interval centered on the position facing the fulcrum 21. One piece 22 is elastically contacted with the original table 1 by a spring 24, and the other piece 23 is fixed to the tip of an adjusting screw 25 and can move forward and backward toward the original table 1. The adjusting screw 25 is screwed into the screw hole 20a of the carrier 20, and by rotating the adjusting screw 25, the piece 23 can be advanced and retracted, and the document table 1 can be swung about the fulcrum 21.

When reading an image, the document 6 is set on the document table 1 in parallel with the detection lines L1 and L2 and aligned with the detection line L3. When the user inputs an error adjustment instruction to the main control circuit 7 shown in the block diagram of FIG. 3, the main control circuit 7 controls the motor M1 for driving the document table 1 by the main scanning drive circuit 8. The original table 1 is driven and sent in the main scanning direction a to a position where an error in the focal length should be detected. First, a pair of detection lines L1 and L2 are read by the linear image sensor 2 at a position where they do not overlap the detection line L3 and are stored in the storage circuit 12 via the amplifier 9 and the A / D converter 11, and this data is stored. It is supplied to the main control circuit 7. As a result, an output voltage waveform having two peaks at the positions corresponding to the detection lines L1 and L2 is obtained. For example, if the output voltage waveform g shown in FIG. 4 is obtained, the peak waveform on the left side indicates that the voltage is below the reference value on the detection line L1 and thus is in focus, and the peak waveform on the right side is Since the detection line L2 does not reach the reference value, it indicates that it is out of focus.

Then, in response to a command from the main control circuit 7, the first adjusting means 13 automatically adjusts the error of the focal length. That is, the focal length correction driving circuit 14 is controlled by the main control circuit 7 to drive the motor M2 for driving the adjusting screw 5, and the rotation of the adjusting screw 5 causes one end portion of the document table 1 to move up and down by Δd, and its inclination angle. Fine adjustment of Δθ is performed.

Then, the detection lines L1 and L2 are read by the linear image sensor 2 again, and when the output voltage waveform h shown in FIG. 5 is obtained this time, in this waveform, the two peak waveforms are The voltage below the reference value is obtained from the detection line, indicating that both lines are in focus. Since the detection lines L1 and L2 are located near both ends of the linear image sensor 2, when the waveform h is obtained, the entire original reading width f by the linear image sensor 2 is in focus. It will be.

If the detection lines L1 and L2 are read again after the tilt angle Δθ of the document table 1 is finely adjusted by the adjusting means 13 and the output voltage waveform i shown in FIG. 6 is obtained, Since both peak waveforms do not reach the reference value, such a waveform indicates that both detection lines are out of focus. In such a case, another means is used to adjust the distance between the document table 1 and the linear image sensor 2 to match the focal length.

Further, it is detected whether or not the detection line L3 is parallel to the sub-scanning direction b, and the error of the parallelism is finely adjusted. When a user inputs an instruction to adjust the parallelism error into the main control circuit 7 shown in the block diagram of FIG. 3, the main control circuit 7 controls the main scanning drive circuit 8 to drive the motor M1 and the document table. 1 is sent to the reading start position (the position of the detection line L3) in the main scanning direction a. Here, the detection line L3 is read by the linear image sensor 2 and stored in the memory circuit 12 via the amplifier 9 and the A / D converter 11, and this data is supplied to the main control circuit 7. At this time, if the output voltage waveform j as shown in FIG. 8 is obtained, both the high level and the low level exist in the output voltage waveform j of the detection line L3, which are biased. The output at a uniform level of is not obtained. This means that the linear image sensor 2 and the detection line L3 are deviated from each other, and the detection line L3 is not parallel to the image reading direction b.

Then, in response to a command from the main control circuit 7, the adjusting means 15 automatically adjusts the parallelism error. That is, as shown in FIG. 7, under the control of the main control circuit 7, the parallelism correction drive circuit 16 drives the motor M3 that drives the adjusting screw 25, and the adjusting screw 25 rotates to move the piece 23 forward and backward. To be done. As the frame 23 advances and retracts, the spring 24 elastically reciprocating the frame 22 expands and contracts, and the document table 1 swings on the horizontal plane about the fulcrum 21 to finely adjust the mounting state. Then, the detection line L3 is read again by the linear image sensor 2, and when the output voltage waveform k shown in FIG. 9 is obtained this time, the output is obtained at a constant and uniform level for this waveform k. , The image reading direction b of the linear image sensor 2 and the detection line L3 are parallel.

Then, the reading of the original 6 is started for the first time, and as the original table 1 is sent in the main scanning direction a by the carrier 20, the image of the original 6 is read by the linear image sensor 2 and stored in the storage circuit 12. It Then, under the control of the main control circuit 7, the storage circuit 12 outputs the input image.

[0017]

[Effect of device]

 The image reading apparatus of the present invention configured as described above can automatically and accurately adjust the mounting state and the tilted state of the platen, both vertically and horizontally, prior to image reading. Therefore, it is possible to read a high-definition image without requiring much labor for correction. Further, since it has a simple structure, it can be attached at a low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an embodiment of the present invention.

FIG. 2 is a plan view of a document table.

FIG. 3 is a block diagram showing driving means.

FIG. 4 is an output waveform diagram of detection lines L1 and L2.

FIG. 5 is an output waveform diagram of detection lines L1 and L2.

FIG. 6 is an output waveform diagram of detection lines L1 and L2.

FIG. 7 is a plan view showing an attached state of a document table.

FIG. 8 is an output waveform diagram of a detection line L3.

FIG. 9 is an output waveform diagram of a detection line L3.

[Explanation of symbols]

 1 Original Plate 2 Linear Image Sensor 6 Original 5 First Adjusting Means (Adjusting Screw) 13 First Adjusting Means 15 Second Adjusting Means 25 Second Adjusting Means (Adjusting Screws) a Original Feeding Direction b Image Reading Direction f Original reading width e Effective reading width L1, L2 detection line L3 detection line g, h, i Output waveform j, k Output waveform

Claims (1)

[Scope of utility model registration request] 1. An image reading device for reading an image of a document set on a document table by a linear image sensor, wherein the image reading device is located on both sides of a document reading width of the document table by the linear image sensor and within a valid reading width. A pair of detection lines are provided in parallel with the feeding direction of the document table, and a position corresponding to the pair of detection lines in the output waveform obtained by reading the pair of detection lines by the linear image sensor. The output of the linear image sensor detects an error in the focal length in the vicinity of both ends in the image reading direction, and based on this detection result, all the outputs at the positions corresponding to the pair of detection lines are within the allowable range. First adjusting means is provided to adjust the error so that A detection line is provided orthogonally to the direction, an error in parallelism between the image reading direction of the linear image sensor and the detection line is detected, and second adjusting means is provided for adjusting the error based on the detection result. An image reading device characterized in that