JP6679994B2 - Information input device and subject distance measuring method - Google Patents

Description

  The present invention relates to an information input device and a subject distance measuring method.

An information input device such as an image reading device that inputs information such as an image or a shape of a subject (original) while the subject and the reading sensor move relatively is widely used.
In such an information input device, a read image is deteriorated when paper floats, such as when reading a spread book or reading a document having wrinkles or curls.

Causes of the deterioration include blurring, blackening due to insufficient illumination depth, distortion due to change in magnification, and brightness variation due to subject angle difference. Further, in the case of using a lens array such as a CIS (contact type image sensor), a false image is generated due to a sneak from an adjacent lens.
In order to avoid the deterioration of the read image due to these or to correct and restore it, it is already known that the distance to the subject and the floating are detected, and the correction processing such as focus improvement, density correction, and mask processing is performed according to the distance. ing.

However, in the conventional image reading apparatus, it is generally necessary to mount a distance measuring device separately, and in order to measure the distances at many positions of the original document which is the subject, many distance measuring devices must be mounted. . Therefore, there is a problem that the device becomes large and the cost becomes high.
As a distance measuring device, there is a distance meter using a pupil division method of an optical triangulation method. However, in order to divide an optical path from a subject through an imaging lens to a reading sensor, a plurality of secondary lenses or shielding plates and a moving mechanism therefor are used. Etc. were needed.

Therefore, for example, in Patent Document 1, the floating amount of the document from the platen is detected based on the image information read by the image reading apparatus having the CIS optical system, and the image information is corrected according to the floating amount. Proposed.
That is, the image information of an original is read by a line sensor, a characteristic part such as a high contrast area is extracted from the image information, the characteristic frequency is detected by performing frequency analysis on the image information, and the floating amount of the original is determined from the characteristic frequency. Identify.
According to this method, it is not necessary to mount a distance measuring device separately on the image reading apparatus, and the conventional CIS optical system can be used as it is to detect the floating amount of the document.

  However, in the method described in Patent Document 1, a characteristic portion such as a high-contrast area in the read image information is frequency-analyzed and the document floating amount is specified from the characteristic frequency. The floating amount can be specified only in a specific part such as a part. Further, except for the specific distance (only 2 mm and 4 mm are exemplified), the specific frequency is difficult to appear due to the frequency analysis of the image information, and thus it is not possible to measure an arbitrary distance. Further, there is a problem that the application target is limited to the image reading apparatus having the CIS optical system.

  The present invention has been made to solve these problems, and in an information input device, it is possible to accurately measure an arbitrary distance at an arbitrary position of an object from information of the object read by a reading sensor, It is an object of the present invention to be applicable to an information input device having an imaging optical system.

The present invention achieves the above-mentioned object in an information input device in which an image or shape information of a subject is read and input by a read sensor via an imaging optical system while the subject and the read sensor move relative to each other. Therefore, as the reading sensor, a first sensor and a second sensor having the same imaging optical system in common are provided, and the moving direction of the object is set on the imaging surface of the imaging optical system. It is arranged and provided at a position with a constant interval in a direction corresponding to the direction obtained by vertically projecting on the top.
The first sensor is a sensor that reads information about a first position of the subject on the front side in the moving direction, and the second sensor is the first position from the first position in the moving direction of the subject. It is a sensor that reads the information of the second position that has advanced by a distance corresponding to a fixed interval.
Further, after the information of the first position of the subject is read by the first sensor, the subject is moved by a distance corresponding to the certain interval, and the second sensor is used to move the second position of the subject. It has a distance measuring means for reading the position information and measuring the distance to the subject from the output difference between the first sensor and the second sensor.

  The information input device according to the present invention can accurately measure an arbitrary distance at an arbitrary position of the object based on the object information read by the reading sensor. Moreover, it can be applied to an information input device having various imaging optical systems.

It is a schematic block diagram which shows one Embodiment of the information input device by this invention. Similarly, it is an explanatory view showing the imaging target position of the subject on the first sensor and the second sensor by the optical lens when the subject has a focal length. Similarly, it is an explanatory view showing an imaging target position of the subject on the first sensor and the second sensor by the optical lens when the subject is far from the focal point. Similarly, it is an explanatory view showing the imaging target position of the subject on the first sensor and the second sensor by the optical lens when the subject is closer than the focal point. FIG. 6 is a diagram showing a change in brightness of a subject surface at an edge portion where an image changes from black to white. FIG. 7 is a diagram in which outputs obtained by reading the subject with a first sensor are superimposed for each distance ratio from a focus position to the subject. Similarly, it is a diagram in which the outputs of the subject read by the second sensor are superimposed for each distance ratio from the in-focus position to the subject. It is the diagram which overlapped the output difference of the 1st, 2nd sensor for every distance ratio from a focus position to a to-be-photographed object. FIG. 7 is a diagram showing a relationship between a distance ratio from a focused position to a subject and an integrated value of output differences of the first and second sensors shown in FIG. 6. FIG. 8 is a diagram showing the relationship between the distance ratio from the in-focus position to the subject and the time difference between the rising midpoints of the outputs of the first and second sensors shown in FIGS. 6 and 7. FIG. 7 is a diagram showing a change in brightness of the subject surface in the case where the image is a white line which is orthogonal to the moving direction of the subject on a black background. FIG. 7 is a diagram in which outputs obtained by reading the subject with a first sensor are superimposed for each distance ratio from a focus position to the subject. Similarly, it is a diagram in which the outputs of the subject read by the second sensor are superimposed for each distance ratio from the in-focus position to the subject. FIG. 13 is a diagram showing the relationship between the distance ratio from the in-focus position to the object and the time difference between the barycentric positions of the outputs of the first and second sensors shown in FIGS. 11 and 12. It is a schematic block diagram which shows an example of the conventional information input device. FIG. 11 is an explanatory diagram showing image formation target positions of the object by the upper half part and the lower half part of the optical lens when the object has a focal length in the case of distance measurement by the conventional pupil division method. Similarly, it is an explanatory view showing the imaging target position of the subject by the upper half and the lower half of the optical lens when the subject is far from the focal point. Similarly, it is an explanatory view showing the imaging target position of the subject by the upper half and the lower half of the optical lens when the subject is closer than the focal point.

Hereinafter, an embodiment for carrying out the present invention will be specifically described with reference to the drawings.
Prior to the description of the embodiments of the present invention, a conventional information input device to which the present invention is applicable and a conventional distance measuring method will be described.
FIG. 13 is a schematic configuration diagram showing an example of a conventional information input device. This information input device is an information input device such as an image reading device in which the reading sensor reads and inputs information about the image or shape of the subject through the imaging optical system while the subject and the reading sensor move relative to each other. .

  The subject 10 generally has information such as characters and figures recorded on one side or both sides of paper, and is often referred to as a "document". The subject 10 is moved along the upper surface of the document table 11 in a moving direction indicated by an arrow A at a predetermined speed. That is, the subject 10 is nipped and moved (conveyed) by the pair of conveying rollers 12 of the subject moving device that rotate in the arrow directions. The document table 11 is provided with a slit-shaped reading window 11a having a predetermined width and extending longer than the object width in the width direction orthogonal to the moving direction of the object 10.

Then, the surface of the subject 10 exposed to the reading window 11a is illuminated by an illumination device (not shown), and the image or shape information of the surface is transferred to the imaging surface of the imaging lens 13 that constitutes the imaging optical system. Form an image. The image is read by the reading sensor 15 such as a line sensor arranged on the sensor substrate 14. The output (analog signal) read by the reading sensor 15 is input to the image processing unit 16, and various kinds of processing are performed to obtain image data (information).
A series of image data output by the reading sensor 15 sequentially read line by line as the subject 10 moves is temporarily stored in an image memory and then sent to a printer to print on paper or as an image file to a personal computer or the like. Can be transferred to another host device.

In such an information input device, when the subject 10 rises or falls below the focusing surface of the imaging lens 13, image deterioration such as defocus occurs as described above. Therefore, it is necessary to measure the distance from the imaging lens 13 to the subject and correct the read image data according to the amount of deviation from the focusing surface.
There are various methods such as sound wave type and optical type for the distance measurement method for that purpose, but the pupil division method of the optical triangulation method is well known and is generally used in optical devices such as cameras. .

In the distance measurement by the pupil division method, conventionally, as shown in FIGS. 14A to 14C, two shield plates 17 and 18 divide the optical path from the subject to the reading sensor through the imaging lens to measure the distance. There is also a method of dividing the optical path by using two secondary lenses.
14A to 14C, the same reference numerals as those of the image forming lens 13 of FIG. 13 are given to the image forming lenses forming the image forming optical system for convenience.

When the subject is at the focal length of the imaging lens 13, as shown in FIG. 14A, the incident light on the lower half portion or the upper half portion of the image of the imaging lens 13 is not focused on the subject. The image target position does not change.
The positions of the imaging lens 13 and the reading sensor 15 shown in FIG. 13 are immovable, and the sensor position is always at the imaging plane position of the imaging lens 13. In the case shown in FIG. 14A, the subject position is at the focus position (on the focus plane).

When the subject position is farther than the focal point of the imaging lens 13, as shown in FIG. 14B, the incident light to the lower half and the incident light to the upper half of the image of the imaging lens 13 are The image formation target positions of are different.
When the subject position is closer than the focal point of the imaging lens 13, as shown in FIG. 14C, when the incident light to the lower half part and the incident light to the upper half part in the diagram of the imaging lens 13 are The imaging target position of is different from the case of FIG. 14B in the opposite direction.

In this way, by switching the shield plates 17 and 18, the output of the reading sensor due to the difference in the imaging target position of the subject due to the light incident on one half of the imaging lens 13 and the light incident on the other half of the imaging lens 13 causes The distance to can be measured.
However, in order to divide the optical path from the subject to the reading sensor through the imaging lens, a plurality of shielding plates and their moving mechanisms or a plurality of secondary lenses are required, which not only increases cost but also requires extra space. Was needed. There is also a problem that the optical system in an information input device such as an ordinary image reading device cannot be used as it is.

  The present invention has been made in order to solve the problem in such a distance measuring device using the conventional pupil division method. That is, according to the present invention, an image forming optical system for inputting information is provided in an information input device such as an ordinary image reading device as shown in FIG. 13 without using a shielding flat plate or a secondary lens. Use it as it is so that you can measure the distance to the subject.

Embodiments of an information input device and a subject distance measuring method according to the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic configuration diagram showing an embodiment of an information input device according to the present invention, which includes a subject distance measuring device for carrying out a subject distance measuring method according to the present invention. In FIG. 1, parts that are the same as the parts of FIG. 13 described above are given the same reference numerals, and a description thereof will be simplified.

The information input device shown in FIG. 1 also includes an imaging lens 13 that forms an imaging optical system for the information of the image or shape of the object 10 while the object 10 generally called a document and the reading sensor move relatively. It is read by the reading sensor unit 5 and input. The subject 10 is moved along the upper surface of the document table 11 by the transport roller 12 at a predetermined speed. However, when the subject 10 is curled as shown in the drawing, the conveyance direction thereof is not always parallel to the upper surface of the document table 11, and may be oblique as shown by the arrow A direction.
The document table 11 is provided with a reading window 11b which is wider in the object moving direction than the reading window 11a shown in FIG.

The reading sensor unit 5 mounted on the sensor substrate 4 is provided on the opposite side of the reading window 11b with the imaging lens 13 interposed therebetween.
The reading sensor unit 5 is provided with a first sensor 5A and a second sensor 5B, which have a common imaging optical system by the imaging lens 13, as reading sensors. The first sensor 5A and the second sensor 5B are arranged on the imaging surface of the imaging lens 13. Further, the first sensor 5A and the second sensor 5B are obtained by vertically projecting the moving direction of the subject 10 (direction of arrow A) onto the image forming plane of the imaging lens 13 (direction of arrow B). Direction) is arranged at a position with a constant distance d.

Although the image forming optical system using the image forming lens 13 shown in this example is an equal-magnification inverted image forming optical system, it can be configured by combining a plurality of lenses and optical elements such as mirrors as necessary.
Therefore, the moving direction of the subject 10 is set as the “corresponding direction” to the direction (direction of arrow B) obtained by vertically projecting on the image forming surface of the image forming lens 13. This is because in the example shown in FIG. 1, the direction obtained by vertically projecting the moving direction of the subject 10 on the image forming plane is the horizontal direction, but it is not limited to this depending on the configuration of the image forming optical system.
For example, when a mirror is provided in the imaging optical system and the optical axis L is bent in the horizontal direction in FIG. 1 to form an image, the imaging surface of the imaging lens is vertical. This is because, in that case, the “direction in which the moving direction of the subject 10 corresponds to the direction obtained by vertically projecting on the image plane” is also the vertical direction in FIG.

Note that it is usually assumed that the subject 10 is conveyed along the upper surface of the document table 11. In that case, the moving direction of the subject 10 (arrow A direction) and the “direction obtained by vertically projecting the moving direction of the subject 10 on the image forming surface of the imaging lens 13 (arrow B direction)” Parallel directions, that is, the same direction. The direction is a direction parallel to the image forming surface of the image forming lens 10 (horizontal direction in FIG. 1).
Therefore, even if "the first sensor 5A and the second sensor 5B are arranged at positions with a constant distance d in the direction corresponding to the moving direction of the subject 10," there is almost no practical problem. .

The first sensor 5A is a sensor that reads information at a first position a on the front side (left side in FIG. 1) in the moving direction of the subject 10 (direction of arrow A).
The second sensor 5B is a sensor that reads information at a second position b, which is ahead of the first position a in the moving direction of the subject 10 by a distance corresponding to a constant interval d.

Then, after the information of the first position a of the subject 10 is read by the first sensor 5A, the subject 10 is moved by the conveying roller 12 by a distance corresponding to the constant interval d, and the second sensor 5B is used to move the subject. The information at the second position b of 10 is read. At this time, the second sensor 5B reads substantially the same part as the part read by the first sensor 5A of the subject 10.
The outputs of the first sensor 5A and the second sensor 5B are input to the distance measuring unit 6 having a comparison circuit and compared, and the distance to the subject 10 is measured based on the difference. Details of the measurement process will be described later.

The output of the first sensor 5A is electrically delayed by the delay circuit 7 serving as a delay unit for a time required for the subject 10 to move by a distance corresponding to the constant interval d, and then input to the distance measuring unit 6. Let
In this embodiment, the distance measuring unit 6 measures the distance to the subject 10 from the difference between the output of the first sensor 5A delayed by the delay circuit 7 and the output of the second sensor 5B.
Therefore, the reading control circuit for the reading sensor unit 5, the drive control circuit for driving and controlling the conveying roller 12 of the subject moving mechanism, the distance measuring unit 6 and the delay circuit 7 constitute a distance measuring means. When the delay circuit 7 is not provided, the distance measuring unit 6 may be provided with a storage unit that temporarily stores the output of the first sensor 5A. For example, when the storage means is a RAM (memory), it also includes a later-described measurement process by associating the memory address with the delay time.

When the imaging optical system forms an erect image, the direction in which the subject 10 is moved by the “distance corresponding to the constant distance d” is the direction of the second sensor 5B (arrow) viewed from the first sensor 5A. This corresponds to the same direction as the reading movement direction shown in C). However, in the example shown in FIG. 1, since the imaging optical system by the imaging lens 13 forms an inverted image, the direction of moving the subject 10 is the second sensor 5B viewed from the first sensor 5A. Corresponds to the direction opposite to the direction (the direction of arrow C).
The term “corresponding to” is used here. In the case where a mirror is provided in the imaging optical system and the optical axis L is bent to form an image, the direction in which the subject 10 is moved is actually the first direction. This is because the direction of the second sensor 5B viewed from the sensor 5A will not be "same direction" or "reverse direction".

The “distance corresponding to the constant distance d” is the distance between the first position a and the second position b of the subject 10, and is substantially the same position as the position read by the first sensor 5A of the subject 10. Is the moving distance of the subject 10 for causing the second sensor 5B to read the information of.
The moving distance is equal to the distance d between the first sensor 5A and the second sensor 5B when the imaging optical system by the imaging lens 13 forms an equal-magnification image as in the example shown in FIG. Is. However, when the imaging optical system performs 1 / N reduction imaging, the moving distance is N times the distance between the first sensor and the second sensor.

In the embodiment of the information input device shown in FIG. 1, an image data generation unit 8 and an image data correction processing unit 9 are also provided.
The image data generation unit 8 is an image data generation unit that generates image data from the output of the second sensor 5B. Alternatively, an image data generating means for generating image data from the output of the first sensor 5A may be provided.
The image data correction processing unit 9 is an image data correction processing unit that corrects the image data generated by the image data generation unit 8 according to the distance measured by the distance measuring unit 6 of the distance measuring unit. The correction is a known correction such as brightness correction, contrast correction, averaging correction, smoothing correction according to the measured distance to the subject. By this correction, the deterioration of the read image due to the deviation of the subject position from the in-focus position is corrected and the image quality is improved.

Each of the first sensor 5A and the second sensor 5B arranged in the reading sensor unit 5 may be a line sensor that reads the image of the subject 10 for every one line or a plurality of lines in the main scanning direction. In that case, it is desirable that the interval between the first sensor 5A and the second sensor 5B be an integral multiple of the line interval.
The main scanning direction is a direction orthogonal to the sub-scanning direction, which is the B direction shown by the arrow, within a plane parallel to the image forming surface of the imaging lens 13 in FIG. Therefore, in this case, the first sensor 5A and the second sensor 5B are arranged in parallel in the main scanning direction, and in each case, a plurality of sensor elements are linearly arranged in the main scanning direction.

In the information input device according to the present invention, the reading sensor is moved in accordance with the movement of the subject 10 (in the example shown in FIG. 1, the measurement position is moved) to measure the distance. Therefore, the first sensor 5A and the second sensor 5B are arranged in parallel at a certain distance d in the direction corresponding to the moving direction of the subject 10.
Then, in accordance with the movement of the subject 10, the first sensor 5A when the image of the measurement target comes on the first sensor 5A, and the second sensor 5B when it comes on the second sensor 5B. Read with.

  The delay circuit 7 outputs the output of the first sensor 5A for the moving time until the subject 10 reaches the second position b read by the second sensor from the first position a read by the first sensor 5A. By delaying, the measurement position is moved. The distance measuring unit 6 can calculate the distance to the subject 10 by comparing the outputs of the first and second sensors 5A and 5B.

This information input device does not require a shielding plate or a secondary lens which has been conventionally required. As the image forming optical system and the moving means for moving the subject, those having the same structure as the conventional general information input device as shown in FIG. 13 can be used as they are.
The image reading unit (scanner unit) of the information input device can be provided with a distance measuring function instead of separately installing the distance measuring device.

Further, this information input device does not simply extract the distance from the image input data by image processing, but measures the distance by a method similar to the triangulation or pupil division method. Therefore, like the pupil-division type camera with a distance meter, it is possible to accurately and directly measure the distance at an arbitrary position where an image is present, such as the center of a subject (original).
Incidentally, in the past, the distance was measured by a small number of distance meters, and the distance of a necessary place was obtained by an indirect method. For example, by measuring the shape of the edge of the original and determining whether it is a double-page spread, if it is a double-page spread, the distance is estimated according to the profile input in advance, or the whole is estimated from the distance from the pressure plate that holds the original. . However, in the information input device and the subject distance measuring method according to the present invention, it is not necessary to prepare such a profile and the like, and the distance of an arbitrary portion of the subject (original) can be accurately measured.

In the subject distance measuring method according to the present invention, as shown in FIGS. 2A to 2C, the subject 10 in FIG. 1 is moved in the arrow A direction. Correspondingly, by moving the sensor position which is the measurement position in the opposite arrow C direction (actually, switching from the first sensor 15A to the second sensor 15B), the incident angle from the subject 10 to the reading sensor Change the to measure the distance. In this case, it is assumed that the arrow A direction, which is the moving direction of the subject 10, is parallel to the image plane (the same direction as the arrow B direction in FIG. 1).
The positions of the imaging lens 13 and the reading sensor unit 5 shown in FIG. 1 are immovable, and the sensor position is always at the imaging plane position of the imaging lens 13.

When the subject 10 is at the focal length of the imaging lens 13, even the downward incident light from the first position a of the subject 10 to the imaging lens 13 is connected from the second position b as shown in FIG. 2A. Even with the upward incident light on the image lens 13, the imaging target position of the subject 10 does not change.
When the subject 10 is farther than the focal point of the imaging lens 13, as shown in FIG. 2B, downward incident light from the first position a of the subject 10 to the imaging lens 13 and the second position b. From the upward incident light on the imaging lens 13, the imaging target position of the subject 10 is different.

  Even when the subject 10 is closer than the focal point of the imaging lens 13, as shown in FIG. 2C, downward incident light from the first position a of the subject 10 to the imaging lens 13 and the second position b. From the upward incident light on the imaging lens 13, the imaging target position of the subject 10 is different. However, in the case shown in FIG. 2C, the direction different from that in the case shown in FIG. 2B is opposite.

The first sensor 5A is disposed at the image forming position e of the subject 10 from the first position a by the downward incident light on the image forming lens 13. Further, the second sensor 5B is arranged at the image forming position f by the downward incident light from the second position b of the subject 10 to the image forming lens 13.
As a result, as shown in FIG. 2A, when the subject 10 is at the focal length of the imaging lens 13, the output of the first sensor 5A and the output of the second sensor 5B are the same and there is no difference. .

However, as shown in FIG. 2B or FIG. 2C, when the subject 10 is at a far distance or a short distance from the focal point of the imaging lens 13, the output of the first sensor 5A and the output of the second sensor 5B are different, There is a difference. Also, the output of the first sensor 5A and the output of the second sensor 5B are different depending on whether the subject 10 is farther or closer than the focal point of the imaging lens 13. , The difference is also reversed. The magnitude of the difference corresponds to the amount of deviation of the subject 10 from the focus position of the imaging lens 13.
Therefore, the distance from the imaging lens 13 to the subject 10 can be calculated from the difference between the output of the first sensor 5A and the output of the second sensor 5B.

A specific example of subject position measurement will be described with reference to FIGS.
3 to 6 and 9 to 11, the horizontal axis indicates the reading position on the subject (relative position before and after the reference position is 0) or the passage of time. The vertical axis represents the relative level of the brightness of the image of the object plane in FIGS. 3 and 9, the output of the first sensor in FIGS. 4 and 10, and the output of the second sensor in FIGS. 5 and 11. 6 shows the relative levels of the output differences of the first and second sensors, respectively.

7, FIG. 8, and FIG. 12, the horizontal axis represents the distance ratio to the subject, the vertical axis represents the integrated value or integrated value (area) of the output differences of the first and second sensors, the time difference of the output rising midpoints, And the time difference of the barycentric position of the output is shown.
FIG. 3 is a diagram showing a change in the brightness of the object surface at the edge portion where the image changes from black to white.

  FIG. 4 is a diagram in which the outputs obtained by reading the subject with the first sensor are superimposed for each distance ratio from the in-focus position to the subject. The distance ratio from the in-focus position to the subject is a parameter, and the distance ratio of the in-focus position is set to 1, and the distance ratios of eight different line types from 0.8 to 2.2 at intervals of 2.2. The sensor output in the case of is shown. The same applies to the distance ratio, which is a parameter in each of the following diagrams.

FIG. 5 is a diagram in which outputs obtained by reading the subject with the second sensor are overlapped for each distance ratio from the focus position to the subject, which is a parameter.
FIG. 6 is a diagram in which the output differences of the first and second sensors are overlapped for each distance ratio from the focus position to the document, which is a parameter.
FIG. 7 is a line showing the relationship between the distance ratio from the in-focus position to the subject and the integrated value or integrated value (area of peaks or valleys) of the output difference of the first and second sensors shown in FIG. It is a figure.
FIG. 8 is a diagram showing the relationship between the distance ratio from the in-focus position to the subject and the time difference between the rising midpoints of the outputs of the first and second sensors shown in FIGS. 4 and 5.

As shown in FIG. 7, the integrated value or integrated value (area of peaks or valleys) of the output difference of the first and second sensors corresponding to the difference in brightness of the subject is measured from the focus position to the subject. There is a correlation with the distance ratio.
Further, the time difference between the rising midpoints (timings of the midpoints of the rising periods) of the outputs of the first and second sensors shown in FIGS. 4 and 5 is also the distance from the in-focus position to the object as shown in FIG. Correlates with ratio. When the edge portion where the image of the object surface changes from white to black is read by the first and second sensors, the falling midpoint of each output of the first and second sensors (the midpoint of the falling period) time difference between the timing), so that there is a correlation between the distance ratio to the subject from the focused position.

Even if the time difference between the rising midpoint and the falling midpoint of each output of the first and second sensors is not the time difference between the rising position and the falling position, the distance ratio from the in-focus position to the object is calculated. There is a correlation. The “position” of the rising position or the falling position is a temporal position, that is, a timing.
The distance from the position of the imaging lens 13 to the focused position thereof is known. Therefore, based on the integrated value or integrated value of the output difference of the first and second sensors, or the time difference between the rising timing and the falling timing of the outputs of the first and second sensors, the distance to the subject (focus point) The amount of deviation from the position may be calculated).

FIG. 9 is a diagram showing a change in brightness of the subject surface when the image is a white line which is orthogonal to the moving direction of the subject on a black background.
FIG. 10 is a diagram in which the output obtained by reading the subject with the first sensor is superimposed for each distance ratio from the focused position to the subject, which is a parameter.
FIG. 11 is a diagram in which outputs obtained by reading the subject with the second sensor are also superimposed for each distance ratio from the focus position to the subject, which is a parameter.
FIG. 12 is a diagram showing the relationship between the distance ratio from the in-focus position to the document and the time difference between the barycentric positions (mountain center positions) of the outputs of the first and second sensors shown in FIGS. 11 and 12. Is.

As described above, the time difference between the barycentric positions (mountain center positions) of the outputs of the first and second sensors has a correlation with the distance ratio from the in-focus position to the subject. The “position” of the position of the center of gravity or the center position of the mountain is also a temporal position or timing.
Therefore, the distance to the subject (or the amount of deviation from the in-focus position) may be calculated based on the time difference between the rising timing and the falling timing of the outputs of the first and second sensors at the midpoint. You can

Therefore, first, the time difference between the rising timing or the falling timing of the output of the second sensor, or based on the time difference between the timing of the midpoint between the rising timing and falling timing of the respective output, distance to the subject ( The amount of deviation from the in-focus position may be calculated).
Also, the distance to the subject can be calculated based on the integrated value or integrated value of the output differences of the first and second sensors.

In this way, focusing on the difference in the output change timings of the first and second sensors, for example, from the time difference between the center of the image, the center of the rising edge, the center of the falling edge, and the like by the output signal of each sensor, The distance to the subject can be calculated. Alternatively, focusing on the difference in brightness of the image of the subject read by the first and second sensors, the distance of the subject can be obtained from the difference in output level of the first and second sensors.
You may make it calculate the difference of the output of the 1st sensor 5A and the output of the 2nd sensor 5B by accumulating the difference of the output of the front-back or left-right neighboring pixel.

Actually, image reading is continuously performed at a constant interval (line interval) and at a constant cycle (line cycle).
For example, when the first sensor 5A and the second sensor 5B are line sensors and the interval d is set to be the same as the line interval, both the first sensor 5A and the second sensor 5B are simultaneously used for each cycle. You may read in. In that case, the distance output can be obtained for each line by delaying the read output by the first sensor 5A by one line cycle and comparing the read output by the second sensor 5B with the read output.

  As a result, it is possible to more accurately and highly improve the blurring due to the deviation of the subject (original) from the in-focus position, the blackening due to insufficient illumination depth, the distortion due to the magnification change, and the variation in brightness due to the difference in subject angle. It will be possible. When a plurality of lenses such as CIS are arranged in the image forming optical system, it is possible to more accurately and highly improve the false image due to the sneak from the adjacent lens.

Of course, the interval between the first sensor 5A and the second sensor 5B may be a two-line interval or a three-line interval. In this case, a large output difference can be obtained with a small distance, and the sensitivity is increased, but the reading range is widened, so that the processing amount in the distance measuring unit 6 is increased.
The distance measuring unit 6, the image data generating unit 8, the image data correction processing unit 9 and the like shown in FIG. 1 can be easily implemented by analog signal processing and software processing using a microcomputer.

  The information input device, the subject distance measuring device, and the subject distance measuring method according to the present invention can be used for an image reading device such as an image scanner, an image forming device such as a copying machine, a facsimile device, a digital multi-function peripheral, or the like.

Although the embodiment of the present invention has been described above, the specific configuration of each part of the embodiment, the content of processing, and the like are not limited to those described therein.
Further, it goes without saying that the present invention is not limited to the above-described embodiments, and is not limited at all except for having the technical features described in each claim of the claims.
Furthermore, the configuration examples, operation examples, and modification examples of the embodiments described above may be appropriately changed or added, or some of them may be deleted, and may be implemented in any combination as long as they do not contradict each other. is there.

4: Sensor board 5: Reading sensor unit 5A: First sensor
5B: Second sensor 6: Distance measuring unit 7: Delay circuit 8: Image data generating unit 9: Image data correction processing unit 10: Subject (original) 11: Document table
11a, 11b: Reading window 12: Conveying roller
13: Imaging lens (constituting imaging optical system) 14: Sensor substrate
15: Reading sensor 16: Image processing unit 17, 18: Shielding plate

JP, 2013-135246, A

Claims (12)

An information input device in which the reading sensor reads and inputs information of an image or a shape of the object through an imaging optical system while the object and the reading sensor relatively move,
As the reading sensor, a first sensor and a second sensor that share the image forming optical system are provided on the image forming surface of the image forming optical system, and the moving direction of the subject is on the image forming surface. It is arranged at a position with a certain interval in the direction corresponding to the direction obtained by vertically projecting,
The first sensor is a sensor that reads information of a first position on the near side of the moving direction of the subject,
The second sensor is a sensor for reading information at a second position which is advanced from the first position in the moving direction of the subject by a distance corresponding to the constant interval,
After the information of the first position of the subject is read by the first sensor, the subject is moved by a distance corresponding to the constant interval, and the second position of the subject is moved by the second sensor. An information input device comprising: a distance measuring unit that reads the information of 1. and measures the distance to the subject from the output difference between the first sensor and the second sensor.   2. The information input according to claim 1, wherein the distance measuring unit measures the distance to the subject based on an integrated value or an integrated value of output differences between the first sensor and the second sensor. apparatus. An information input device in which the reading sensor reads and inputs image or shape information of the subject in the previous period through an imaging optical system while the subject and the reading sensor relatively move,
As the reading sensor, a first sensor and a second sensor that share the image forming optical system are provided on the image forming surface of the image forming optical system, and the moving direction of the subject is on the image forming surface. It is arranged at a position with a certain interval in the direction corresponding to the direction obtained by vertically projecting,
The first sensor is a sensor that reads information of a first position on the near side of the moving direction of the subject,
The second sensor is a sensor for reading information at a second position which is advanced from the first position in the moving direction of the subject by a distance corresponding to the constant interval,
After the information of the first position of the subject is read by the first sensor, the subject is moved by a distance corresponding to the constant interval, and the second position of the subject is moved by the second sensor. Information input by reading the information of (1) and measuring the distance to the subject based on the time difference between the rising timing or the falling timing of each output of the first sensor and the second sensor. apparatus. An information input device in which the reading sensor reads and inputs image or shape information of the subject in the previous period through an imaging optical system while the subject and the reading sensor relatively move,
As the reading sensor, a first sensor and a second sensor that share the image forming optical system are provided on the image forming surface of the image forming optical system, and the moving direction of the subject is on the image forming surface. It is arranged at a position with a certain interval in the direction corresponding to the direction obtained by vertically projecting,
The first sensor is a sensor that reads information of a first position on the near side of the moving direction of the subject,
The second sensor is a sensor for reading information at a second position which is advanced from the first position in the moving direction of the subject by a distance corresponding to the constant interval,
After the information of the first position of the subject is read by the first sensor, the subject is moved by a distance corresponding to the constant interval, and the second position of the subject is moved by the second sensor. Of the first sensor and the second sensor to measure the distance to the subject based on the time difference between the rising timing and the falling timing of the outputs of the first sensor and the second sensor. Information input device characterized by.   5. The direction obtained by vertically projecting the moving direction of the subject onto the image forming plane is a direction parallel to the moving direction of the subject, according to claim 1. Information input device.   When the imaging optical system forms an erect image, the direction in which the subject is moved by a distance corresponding to the certain interval is the same as the direction of the second sensor viewed from the first sensor. Correspondingly, when the imaging optical system forms an inverted image, it corresponds to a direction opposite to the direction of the second sensor viewed from the first sensor, and the information input according to claim 5. apparatus.   The distance corresponding to the constant interval for moving the subject is equal to the interval between the first sensor and the second sensor when the imaging optical system forms an image of the same size. The information input device according to claim 6, wherein when the optical system forms a 1 / N reduced image, the distance is N times the distance between the first sensor and the second sensor. The information input device according to any one of claims 1 to 7,
The information input device, wherein the distance measuring means has a delay means for electrically delaying the output of the first sensor by a time required for the subject to move by a distance corresponding to the constant interval. .   The information input device according to any one of claims 1 to 8, wherein an image data generating unit that generates image data from an output of one of the first sensor and the second sensor, and the image data generating unit. An information input device, comprising: image data correction processing means for correcting the generated image data according to the distance measured by the distance measuring means.   Each of the first sensor and the second sensor is a line sensor that reads the image of the subject for each line or a plurality of lines in the main scanning direction, and the interval between the first sensor and the second sensor is a line interval. The information input device according to claim 9, wherein the information input device is an integral multiple of. A method for measuring a subject distance in an information input device, wherein the reading sensor reads and inputs image or shape information of the subject while the subject and the reading sensor move relatively to each other,
As the reading sensor, an imaging optical system is used in common, and in the direction corresponding to the direction obtained by vertically projecting the moving direction of the subject on the imaging surface of the imaging optical system. Using a first sensor and a second sensor, which are arranged at regular intervals,
After the information of the first position of the subject is read by the first sensor, the subject is moved by a distance corresponding to the constant interval, and the second sensor moves the subject in the moving direction of the subject. A method for measuring a subject distance, which comprises reading information on a second position which is advanced from the first position by the distance and measuring the distance to the subject from the output difference between the first sensor and the second sensor.   The output of the first sensor is electrically delayed by a time required for the subject to move by a distance corresponding to the fixed interval, and the difference between the delayed output and the output of the second sensor. The object distance measuring method according to claim 11, wherein the distance from the object to the object is measured.