JP2013195287A - Displacement detection device, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent detection of a displacement amount from being affected by errors.SOLUTION: A displacement detection device includes a light-emitting part 11 that irradiates the surface of a moving object with light, and an image sensor 12 that takes reflectance from the surface of the moving object into a light reception region as an image periodically, derives the displacement amount of the moving object from the movement amount of the taken-in image in the light reception region. The image sensor 12 adjusts the image taking-in period according to the movement speed of the moving object.

Description

  The present invention relates to a displacement amount detection device that detects a displacement amount of a moving object (hereinafter referred to as a moving object) and a time required for the displacement, and an electronic apparatus including the displacement amount detection device.

  In recent years, high-definition printing in printers and copiers has progressed, and fine patterns such as high-quality photographs can be printed.

  In the case of a printer, as the definition becomes higher, higher precision is required for the control of movement of papers to be printed along with the higher definition of the print head.

  In a general printer, paper to be printed is conveyed by rotation of a roller provided inside. That is, in order to increase the paper conveyance speed, the rotation speed of the roller is increased, and in order to decrease the paper conveyance speed, the rotation of the roller is decreased. As described above, the conveyance of the paper to be printed is controlled by the rotation control of the roller.

  By the way, the roller conveys the paper in the rotation direction of the roller by a frictional force with the paper. If this frictional force is maintained at a certain level, the paper can be transported at a stable speed. However, the friction of the roller due to wear of the roller due to long-term use or dust or dirt adhering to the roller surface. The force is reduced, and the paper being conveyed may slip on the roller.

  As described above, when the paper being transported slips on the roller, the paper movement amount assumed in advance by the rotation control of the roller is different from the actual paper movement amount, and is appropriately set to a desired position of the paper. This causes a problem that an image is not printed. That is, there is a problem that printing on paper cannot be performed with high accuracy and the quality of the printed image is lowered.

  Therefore, as a countermeasure against the occurrence of slipping of the paper being transported, the displacement amount of the paper being transported by the slip and the time (time amount) required for the displacement are detected, and the moving speed of the paper is determined from this detection result. Thus, there has been proposed a technique for controlling the rotation of the roller so as to correct the moving speed so as not to reduce the printing accuracy on the paper (Patent Documents 1, 2 and the like).

  For example, as shown in FIG. 9, a displacement amount detection device that detects the displacement amount of paper being transported and the time required for the displacement includes a displacement amount detection unit 1001 that detects the displacement amount of the paper being transported, The control signal generating unit 1002 generates a displacement amount detected by the unit 1001 and a time (time amount) required for the displacement as a control signal and outputs the control signal to the outside.

  The displacement detection unit 1001 irradiates light on the surface of the paper being conveyed by the light emitting unit 1011, and reads an image of the light reflected from the paper by the image sensor 1012. At this time, the image reading by the image sensor 1012 is periodically performed, and the obtained images are compared to calculate the displacement (dX, dY). Here, the amount of displacement is represented by a deviation (dX) in the x-axis direction and a deviation (dY) in the y-axis direction of the read image. That is, it is expressed as a displacement amount (dX, dY).

  The control signal generation unit 1002 receives the displacement amount (dX, dY) obtained by the displacement amount detection unit 1001, and obtains the time (time amount) required for the displacement in the displacement amount received internally, The amount and the time amount are output to the outside as control signals.

  From the displacement amount of the paper being conveyed and the time required for the displacement obtained in this way, the paper movement speed is obtained, and the rotation speed of the roller is controlled from the obtained movement speed to correct the paper movement speed. Thus, the printing accuracy on the paper is not lowered.

JP 2007-254094 A (released on October 4, 2007) JP 2007-278786 A (released on October 25, 2007)

  By the way, the image sensor 1012 includes a light receiving unit composed of light receiving pixels arranged in a matrix, and receives received reflected light as image data in the light receiving pixels at periodic timing.

  In the conventional displacement amount detection device, the period (image capturing period: frame rate) when capturing the received reflected light as image data in the light receiving pixels is fixed. For this reason, when the movement of the moving object is fast, the number of light receiving pixels indicating the amount of movement of the captured image in the light receiving region of the light receiving unit increases. When the movement of the moving object is slow, the number of light receiving pixels in the light receiving region of the light receiving unit is increased. The number of light receiving pixels indicating the amount of movement of the captured image is reduced.

  Normally, when the reflected light received by the light receiving pixels is captured as image data, an error of a maximum of one pixel occurs.

  Here, assuming that the amount of movement of the captured image in the light receiving area is N pixels, the error in capturing the image into the light receiving pixel is 1 / N at the maximum.

  Therefore, if the moving speed of the moving object is high, the number N of light receiving pixels indicating the amount of movement of the captured image in the light receiving area of the light receiving unit increases, the error (1 / N) decreases, and the moving speed of the moving object decreases. If this is the case, the number N of light-receiving pixels indicating the amount of movement of the captured image in the light-receiving region of the light-receiving unit is reduced, and the error (1 / N) increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to make the period when the reflected light received by the light receiving pixels is captured as image data variable according to the moving speed of the moving object. Thus, an object of the present invention is to provide a displacement amount detection device capable of reducing an error in detecting a displacement amount of a moving object and detecting an accurate displacement amount of the moving object.

The displacement detection device of the present invention is
A light emitting unit for irradiating light on the surface of the moving object;
The reflected light from the surface of the moving object is periodically captured as an image in a light receiving area, and an image sensor for obtaining a displacement amount of the moving object from the amount of movement of the captured image in the light receiving area,
The above image sensor
The image capturing period is adjusted according to the moving speed of the moving object.

  According to the above configuration, it is possible to adjust the amount of movement of the captured image in the light receiving region by adjusting the image capturing period according to the moving speed of the moving object.

  In general, when the image capturing period is fixed, the amount of movement of the captured image in the light receiving region increases as the moving speed of the moving object increases, and decreases as the moving speed of the moving object decreases.

  In addition, when the light receiving area is formed of a plurality of light receiving pixels, an error corresponding to a maximum of one pixel occurs when an image is taken into the light receiving pixels. Here, assuming that the amount of movement of the captured image in the light receiving area is N pixels, the error in capturing the image into the light receiving pixel is 1 / N at the maximum.

  Therefore, if the moving speed of the moving object is high, the number N of light receiving pixels indicating the amount of movement of the captured image in the light receiving area increases, the error (1 / N) decreases, and if the moving speed of the moving object decreases, There arises a problem that the number N of light receiving pixels indicating the amount of movement of the captured image in the light receiving region is reduced and the error (1 / N) is increased.

  However, in the above configuration, the image capturing cycle is not fixed, and the image capturing cycle is adjusted according to the moving speed of the moving object. Therefore, the movement amount (N pixels) of the captured image in the light receiving region is adjusted. Is possible.

  For example, if the moving speed of a moving object is slow, adjust the image capture cycle longer, and if the moving speed of the moving object is fast, adjust the image capture period to be shorter, so that the light is received regardless of the moving speed of the moving object. It is possible to increase the amount of movement of the image within the region as much as possible.

  In this way, regardless of the moving speed of the moving object, if the amount of movement of the image in the light receiving region can be increased as much as possible, the error during image capture can be reduced, and as a result, the amount of movement of the image in the light receiving region. Therefore, it becomes possible to detect the displacement amount of the moving object more accurately.

The above image sensor
It is preferable that a period adjustment unit is provided that adjusts the image capturing period according to the moving speed of the moving object within a range in which the moving amount of the moving object in the light receiving area does not exceed the light receiving area.

  According to the above configuration, since the moving amount of the moving object in the light receiving region is adjusted by the cycle adjusting unit in a range not exceeding the light receiving region, the image capturing cycle is adjusted according to the moving speed of the moving object. It is possible to increase the amount of movement of the image in the light receiving region as much as possible, and as a result, it is possible to reduce the error during image capture.

The period adjusting unit is
It is preferable to adjust the image capturing period so that the moving amount of the moving object in the light receiving region is maximized within a range not exceeding the light receiving region.

  According to the above configuration, the error at the time of image capture is made as small as possible by adjusting the image capture cycle so that the moving amount of the moving object in the light reception region is maximized in a range not exceeding the light reception region. be able to.

The period adjusting unit is
When the image capture cycle when the moving speed of the moving object is a preset speed is the reference cycle,
If the moving speed of the moving object is faster than the set speed, adjust the image capture period shorter than the reference period,
When the moving speed of the moving object is slower than the set speed, the image capturing period is adjusted to be longer than the reference period.

  According to the above configuration, when the moving speed of the moving object is faster than the set speed when the moving speed of the moving object is faster than the set speed when the moving speed of the moving object is faster than the set speed, When the moving speed of the moving object is adjusted to be shorter than the reference period and the moving speed of the moving object is slower than the set speed, the image capturing is performed in accordance with the moving speed of the moving object by adjusting the image capturing period longer than the reference period. The period can be adjusted appropriately.

  In this case, if the moving speed of the moving object is known, it is possible to appropriately adjust the above-described image capture cycle. Therefore, the calculation using a plurality of parameters such as the displacement amount of the moving object and the time required for the displacement is performed. Is no longer necessary.

The period adjusting unit is
While generating a timing signal for periodically capturing images, the period of the timing signal is adjusted according to the moving speed of the moving object,
The above image sensor
A timing signal whose period is adjusted and a displacement amount of the moving object obtained by the timing signal whose period is adjusted are output.

  According to the above configuration, the period adjusting unit generates a timing signal for periodically capturing an image, adjusts the period of the timing signal according to the moving speed of the moving object, and the image sensor has the period By outputting the adjusted timing signal and the displacement amount of the moving object obtained by the timing signal whose cycle is adjusted, the time required for the displacement can be obtained by this timing signal.

  Thus, if the time required for the displacement is obtained by the timing signal for obtaining the displacement amount of the moving object, the displacement amount of the moving object and the time required for the displacement are managed by the same signal. Therefore, it is possible to accurately detect the time required for the displacement, and as a result, it is possible to appropriately adjust the moving speed of the moving object.

  If the moving speed of the moving object is appropriately adjusted, the image capturing period adjusted according to the moving speed of the moving object can also be adjusted appropriately, so that the moving amount of the moving object can be detected more accurately. it can.

  The amount of displacement of the moving object output from the image sensor and the timing signal used to determine the amount of displacement are input, and the time required for the displacement of the moving object is determined using the timing signal. A control unit that outputs the displacement amount and the time required for the displacement as a control signal is provided.

  As a result, since the control unit can manage the displacement amount of the moving object and the time required for the displacement, the displacement amount of the moving object and the time required for the displacement are not required for devices outside the displacement amount detection device. Can output control signals appropriately managed.

A moving speed information capturing unit that captures moving speed information indicating the moving speed of the moving object;
The above image sensor
The image capturing period is adjusted in accordance with the traveling speed information captured by the traveling speed information capturing unit.

  In this case, since the moving speed of the moving object, which is a parameter for adjusting the image capturing period, is captured from the outside as moving speed information, a process for obtaining the moving speed of the moving object in the displacement amount detection device is performed. There is no need to do it.

  In the electronic apparatus, the displacement detection device having the above-described configuration may be used.

  As a preferable electronic device, a printer whose moving object is paper can be cited. In this case, the paper moving speed can be determined appropriately by accurately detecting the amount of displacement of the paper being conveyed and the time required for the displacement. Accordingly, it is possible to appropriately adjust the paper conveyance speed (movement speed) according to the displacement of the paper being conveyed.

  The displacement amount detection apparatus of the present invention includes a light emitting unit that irradiates light on the surface of a moving object, and reflected light from the surface of the moving object that is periodically captured as an image in the light receiving region, and the captured image in the light receiving region. An image sensor for obtaining a displacement amount of the moving object from the movement amount of the moving object, and the image sensor is configured to adjust an image capturing period according to a moving speed of the moving object.

  Thus, if the amount of movement of the image in the light receiving area can be increased as much as possible regardless of the moving speed of the moving object, the error at the time of image capture can be reduced. As a result, the amount of movement of the image in the light receiving area can be reduced. There is an effect that the displacement amount of the moving object can be detected more accurately.

It is a block diagram which shows the detail of the displacement amount detection apparatus which concerns on one embodiment of this invention. It is the figure which showed the actual usage example of the displacement amount detection apparatus shown in FIG. It is a figure for demonstrating the principle of this invention, (a) shows the displacement of an actual moving object, (b) shows the displacement of the moving object when an error is the maximum, (c) When an error is the minimum The displacement of the moving object is shown. It is a figure which shows the displacement of a moving object when the moving speed of a moving object is small. It is a figure which shows the displacement of a moving object when the moving speed of a moving object is large. It is a flowchart which shows the flow of a frame rate process. FIG. 3 is a control block diagram illustrating an example in which the displacement amount detection device of the present invention is applied to a printer conveyance control mechanism. It is a block diagram which shows the detail of the displacement amount detection apparatus which concerns on other embodiment of this invention. It is a block diagram which shows schematic structure of the conventional displacement amount detection apparatus.

  Hereinafter, embodiments of the present invention will be described in detail.

<Embodiment 1>
An embodiment of the present invention will be described as follows.

(Outline of displacement detector) Fig. 2
As shown in FIG. 2, the displacement amount detection apparatus according to the present embodiment includes a displacement amount detection unit 1 that detects the displacement amount of a moving object, and the displacement amount and time amount detected by the displacement amount detection unit 1 ( This is a configuration including a control signal generation unit 2 that generates a time required for displacement) as a control signal.

  The displacement amount detection unit 1 includes a light emitting unit 11 having a light emitting element 111 (FIG. 1) that irradiates light to a moving object that irradiates light on the surface of the moving object, and reflected light from the surface of the moving object. And an image sensor 12 that periodically captures the image in the light receiving region and obtains the displacement of the moving object from the amount of movement of the captured image in the light receiving region.

  The image sensor 12 adjusts the image capturing period according to the moving speed of the moving object. Hereinafter, the image capturing period will be described as a frame rate.

  Details of the frame rate adjustment mechanism will be described later.

  Further, the image sensor 12 outputs a signal indicating the displacement amount of the moving object and a frame timing signal (timing signal) used for obtaining the signal indicating the displacement amount to the control signal generation unit (control unit) 2. It is supposed to be.

  In the displacement amount detection device, as shown in FIG. 2, the light emitting element 111 irradiates the surface of the moving object P that moves in the direction of the arrow with the irradiation light, and the image sensor 12 reflects the reflected light from the moving object P. Receive light.

  The image sensor 12 captures the received reflected light as an image at a predetermined timing by a frame timing signal, obtains a displacement amount of the moving object P, and outputs a signal indicating the obtained displacement amount and a frame timing signal as a control signal generation unit. Output to 2.

  According to the displacement amount detection device having the above-described configuration, the image sensor 12 outputs the frame timing signal used for obtaining the displacement amount in addition to the displacement amount. It is possible to obtain the time required for the displacement.

  Thus, if the time required for the displacement of the moving object P is obtained by the frame timing signal for obtaining the displacement amount of the moving object P, the displacement amount of the moving object P and the displacement of the moving object P are determined. Since the time required is managed by the same signal (frame timing signal), the time required for displacement of the moving object P can be detected accurately, and as a result, the moving speed of the moving object P can be adjusted appropriately. It becomes.

(Principle of the present invention)... FIG.
In general, when the image capturing period, that is, the frame rate is fixed, the movement amount of the captured image in the light receiving area of the light receiving unit 122 increases as the moving speed of the moving object increases, and the moving speed of the moving object decreases. Less.

  For example, as shown in FIG. 3A, when the actual moving amount of the moving object is five light receiving pixels constituting the light receiving unit 122, when an image is taken into the light receiving pixels, an error of one pixel at the maximum is generated. Assuming that this occurs, the maximum moving amount of the moving object is six light receiving pixels as shown in FIG. 3B, and the minimum moving amount of the moving object is as shown in FIG. 3C. This corresponds to four light receiving pixels.

  In this case, assuming that the amount of movement of the captured image (the number of light receiving pixels) in the light receiving region is N pixels, the error in capturing the image into the light receiving pixels is 1 / N at the maximum.

  Therefore, if the moving speed of the moving object is high, the number N of light receiving pixels increases and the error (1 / N) decreases, and if the moving speed of the moving object decreases, the number of light receiving pixels N decreases and the error (1 / N) increases.

  In this way, if the frame rate is fixed, if the moving speed of the moving object is high, the error at the time of capturing the image becomes small. Therefore, an accurate displacement amount of the moving object can be obtained. If the speed is slow, an error at the time of capturing an image becomes large, so that an accurate displacement amount of the moving object cannot be obtained.

  However, in the above configuration, the frame rate is not fixed and is adjusted according to the moving speed of the moving object, so that it is possible to adjust the movement amount (N pixels) of the captured image in the light receiving area.

  For example, if the moving speed of the moving object is slow, adjust the image capture cycle longer to slow the frame rate, and if the moving speed of the moving object is fast, adjust the image capture period to short to increase the frame rate. This makes it possible to increase the amount of movement of the image in the light receiving region as much as possible regardless of the moving speed of the moving object.

  Thus, regardless of the moving speed of the moving object, if the amount of movement of the image in the light receiving area can be increased as much as possible, the error at the time of capturing the image can be reduced. As a result, the amount of movement of the image in the light receiving area Therefore, it becomes possible to detect the displacement amount of the moving object more accurately.

  The configuration of the displacement detection device will be described in more detail.

(Details of displacement detector) Fig. 1
As shown in FIG. 1, the displacement amount detection device includes a displacement amount detection unit 1 including a light emitting unit 11 and an image sensor 12, and a control signal generation unit 2 including a counter 21 and a signal output unit 22. Become.

  As described above, the light emitting unit 11 includes the light emitting element 111 that irradiates the moving object P with light. As the light emitting element 111, an LED (Light Emitting Diode) is used. The light emitting element 111 is not limited to the LED as long as it can irradiate the moving object P with light. In particular, when the surface of the moving object P is glossy and it is difficult for the reflected light to be bright and dark, it is preferable to use a laser as the light emitting element 111 rather than an LED. In this case, even if the surface of the moving object P is glossy, an interference fringe is generated on the laser irradiation surface of the moving object P, and this interference fringe is received by the image sensor 12 as reflected light. become. If the amount of movement of the received interference fringes is detected, the amount of movement of the moving object P can be detected.

  The light emitting element 111 irradiates the moving object P with light at the timing when the image sensor 12 captures an image.

  The image sensor 12 includes a CMOS (Complementary Metal Oxide Semiconductor), a CCD (Charge Coupled Device), and the like, and is reflected by the light emitting unit 11 and reflected by the moving object P. Light is received, an image on the light irradiation surface of the moving object P is formed based on the received light, and converted into image data.

  Specifically, the image sensor 12 includes a timing control unit 121, a light receiving unit 122, and a displacement amount calculation unit 123.

  The timing control unit 121 generates a frame timing signal, and outputs the generated frame timing signal to the light receiving unit 122, the displacement amount calculation unit 123, and the control signal generation unit 2.

  The frame timing signal is a timing signal for capturing an image in the light receiving unit 122 in one frame cycle. This one frame period is adjusted according to the moving speed of the moving object P. The details of the point that is adjusted according to the moving speed of the moving object P, with one frame period as the frame rate, will be described later.

  In the light receiving unit 122, light receiving pixels for receiving reflected light from the moving object P are arranged in a matrix, and image data is generated from signals from the respective light receiving pixels, and is synchronized with the frame timing signal. The generated image data is output to the displacement amount calculation unit 123.

  The displacement amount calculation unit 123 compares the image data received from the light receiving unit 122 before and after time series, and obtains a shift amount between the previous and next image data. This shift amount is obtained as a shift amount (dx) in the x-axis direction and a shift amount (dy) in the y-axis direction of the light receiving pixel in the light receiving unit 122, and a control signal is generated as the displacement amount (dx, dy) of the moving object P. Sent to part 2.

  The displacement amount calculation unit 123 obtains the displacement amount in synchronization with the frame timing signal input to the light receiving unit 122.

  Further, the displacement amounts (dx, dy) obtained by the displacement amount calculation unit 123 are also sent to the timing control unit 121. The timing control unit 121 obtains the number of light receiving pixels (the number of moving pixels) from which the moving object has moved per frame from the amount of displacement, and uses this to adjust the period of the frame timing signal to set the frame rate. It is supposed to change.

  As described above, the control signal generation unit 2 receives the frame timing signal from the timing control unit 121 and the displacement amount (dx, dy) of the moving object P.

  That is, the control signal generation unit 2 outputs the displacement amount (dx, dy) of the moving object P and the frame timing signal used for obtaining the displacement amount (dx, dy) output from the image sensor 12. The time required for the displacement of the moving object P is obtained using the frame timing signal, and the time required for the displacement and the displacement amount are output as control signals.

  The control signal generation unit 2 outputs a counter 21 that counts the number of times the frame timing signal from the image sensor 12 periodically changes, and a signal that outputs a displacement amount and a time (time amount) required for the displacement as control signals. And an output unit 22.

  That is, the control signal generation unit 2 obtains the time (time amount) required for the displacement of the moving object P from the count number of the counter 21, and the signal output unit 22 obtains the obtained time amount and the input displacement amount. Are output as control signals.

  As described above, the control signal generation unit 2 having the above-described configuration can easily measure an amount (count number) proportional to time by counting the number of frame timing signals that periodically change by the counter 21. Here, the counter 21 counts the number of the frame timing signals that become high level for each frame period.

  Thereby, the time (time amount) required for displacement of a moving object can be calculated | required easily and correctly.

  The control signal generator 2 may be configured to further add the period of the frame timing signal to the number of counts by the counter 21 and obtain the time required for displacement of the moving object P from the accumulated value.

  In this case, since the integrated value obtained by integrating the period of the frame timing signal with the count number obtained by the counter 21 represents time, the time required for the displacement of the moving object P can be easily obtained.

  Thereby, since the time (time amount) required for the displacement of the moving object can be obtained easily and accurately, for example, the user can easily calculate the moving speed of the moving object using the displacement amount and the time amount. It becomes like this.

  In the control signal generator 2, the counter 21 is not particularly essential, and the time required for the displacement of the moving object P may be obtained as follows.

  That is, the control signal generation unit 2 measures the period of the frame timing signal and obtains the time required for displacement of the moving object from the measured value.

  According to the above configuration, measuring the period of the frame timing signal in the control signal generation unit 2 measures the interval between image captures. Therefore, it is necessary for the displacement of the moving object P from the measured value of this period. Time can be detected more accurately.

  In this way, by measuring the actual image capture timing interval, a shift in the timing of image capture that occurs in the image sensor 12 (for example, a shift in the timing of image capture due to variations in ambient temperature, power supply voltage, etc. (A shift in the timing of image capture that occurs suddenly due to the above factors) can be corrected.

  The control signal generator 2 outputs a displacement amount at a timing at which the frame timing signal from the image sensor 12 periodically changes.

  As described above, the control signal generation unit 2 outputs the displacement amount at a timing at which the frame timing signal from the image sensor 12 periodically changes, so that the displacement of the moving object P obtained using the frame timing signal is obtained. It is possible to accurately output the time required for the movement and the displacement amount of the moving object P in association with each other.

  By using the time required for the displacement of the moving object P thus output and the displacement amount of the moving object P, the movement amount of the moving object P and the movement speed of the moving object P can be calculated more finely. It becomes possible and finer control becomes possible.

(Adjusting the frame rate)
Adjustment of the frame rate in the image sensor 12 is performed by the timing control unit 121.

  That is, the timing control unit 121 adjusts the frame rate according to the moving speed of the moving object P in a range where the moving amount of the moving object P in the light receiving region of the light receiving unit 122 does not exceed the light receiving region. It has become. That is, since the adjustment of the frame rate is equal to the adjustment of the image capture period, the timing control unit 121 functions as a period adjustment unit.

  It is preferable that the timing control unit 121 adjusts the frame rate so that the moving amount of the moving object P in the light receiving region of the light receiving unit 122 becomes maximum within a range not exceeding the light receiving region.

  In this way, by adjusting the frame rate and maximizing the amount of movement of the moving object P within a range that does not exceed the light receiving area, it becomes possible to minimize the error when capturing the image into the light receiving pixels. .

  For example, when the moving speed of the moving object P is faster than the set speed when the moving speed of the moving object P is faster than the set speed when the image capturing period when the moving speed of the moving object P is a preset set speed is a reference period, If the image capture cycle is adjusted to be shorter than the reference cycle and the moving speed of the moving object is slower than the set speed, the frame rate can be adjusted by adjusting the image capture cycle to be longer than the reference cycle. By maximizing the amount of movement of the moving object P within a range that does not exceed the light receiving area, it is possible to minimize the error when capturing the image into the light receiving pixels.

(Specific description of frame rate adjustment)... FIG. 4, FIG. 5, FIG.
Here, in the light receiving region of the light receiving unit 122, for example, as shown in FIG. 4, it is assumed that the light receiving pixels 122a are arranged in a matrix of 16 pixels in the vertical direction and 16 pixels in the horizontal direction, and an image captured from the reflected light of the moving object. When the number of pixels in the moving direction is 4, the maximum moving amount of the image is 12 pixels.

  However, when the moving speed of the moving object P is slow, the moving amount of the moving object when the image is captured at a certain frame rate in the light receiving area of the light receiving unit 122 is smaller than the maximum 12 pixels. In FIG. 4, the moving amount is 6 pixels.

  As described above, when the moving amount of the moving object is small, an error at the time of capturing the image into the light receiving pixel 122a increases, and it is difficult to obtain an accurate moving amount. For this reason, it is necessary to increase the moving amount of the moving object as much as possible.

  Therefore, in the present embodiment, when the moving speed of the moving object is slow, the moving amount of the moving object is increased by lowering the frame rate and increasing the image capturing period. For example, when the moving speed of the moving object is the same as that shown in FIG. 4, if the image capturing period is doubled by halving the frame rate and the image capturing is performed, FIG. As shown, the amount of movement of the moving object increases to 12 pixels.

  As described above, if the amount of movement of the moving object is increased, an error when the image is captured into the light receiving pixel 122a is reduced, and an accurate amount of movement can be obtained.

  Accordingly, when M is the number of light receiving pixels arranged in the moving direction of the light receiving region in the light receiving region, and N is the number of light receiving pixels arranged in the moving direction of the moving object image in the light receiving region, the maximum number of moving objects. The amount of movement is equal to the number of light receiving pixels (MN). Here, M is larger than N and is an integer of 2 or more, and N is an integer of 1 or more.

  In this case, since the image sensor 12 obtains the amount of movement of the moving object, that is, the amount of displacement by image comparison, the captured image does not protrude from the light receiving area. This is the maximum amount of movement. Therefore, by setting the moving object to the maximum movement amount (MN), it is possible to reduce the error at the time of moving object image capture.

  In the present embodiment, since the amount of movement of the moving object, that is, the amount of displacement is obtained by image comparison, it is assumed that the captured image does not protrude from the light receiving area. However, if the image of the portion that protrudes from the light receiving area can be predicted by using the image interpolation technique, the captured image may protrude from the light receiving area.

  Here, the adjustment of the frame rate will be described with reference to the flowchart shown in FIG. The timing control unit 121 adjusts the frame rate.

  First, the number of moving pixels per frame is acquired (step S101). Here, the timing control unit 121 obtains the number of light receiving pixels (the number of moving pixels) to which the moving object has moved per frame from the displacement amounts (dx, dy) from the displacement amount calculation unit 123.

  Next, it is determined whether or not the obtained number of moving pixels is the maximum (step S102). Here, the maximum number of moving pixels is the maximum number of light receiving pixels 122 a arranged in the moving direction of the moving object in the light receiving region of the light receiving unit 122.

  If it is determined in step S102 that the number of moving pixels is the maximum, no adjustment of the frame rate is necessary. Therefore, the process proceeds to step S101 again to acquire the number of moving pixels per frame.

  On the other hand, if it is determined in step S102 that the number of moving pixels is not the maximum, the process proceeds to step S103 to lower the frame rate. Here, the frame rate is lowered by a predetermined amount. This reduction amount can be set arbitrarily.

  Then, after lowering the frame rate, the process proceeds to step S101 again to acquire the number of moving pixels per frame. Thereafter, the above process is repeated.

  According to the displacement amount detection apparatus having the above-described configuration, the error in detecting the movement amount of the moving object P can be reduced by adjusting the frame rate at the time of capturing the image according to the moving speed of the moving object P. The displacement amount of the moving object P can be obtained appropriately. Thereby, it becomes possible to correct | amend the displacement of the said movement P appropriately from the displacement amount of the moving body P. FIG.

  As described above, it is effective to use the displacement detection device of the present invention for an electronic device that needs to appropriately correct the displacement of the moving object P, for example, a printer.

(Printer) .... Fig. 7
FIG. 7 shows an example in which the displacement detection device having the above-described configuration is used in a paper transport mechanism of a printer.

  As shown in FIG. 7, the paper transport mechanism includes a displacement detection device 101, a transport device 102, and a transport control unit 103.

  The displacement amount detection device 101 is the same as the displacement amount detection device shown in FIG.

  The displacement amount detection device 101 is disposed to face the transport device 102 via the transport path of the moving object P (paper).

  The transport device 102 includes a transport roller for transporting the moving object P in the direction of the arrow, and a rotation control unit (not shown) that controls the rotation (arrow direction) speed of the roller. By adjusting the rotation speed of the roller by this rotation control unit, the conveyance speed (movement speed) of the paper that is the moving object P is adjusted.

  The conveyance control unit 103 transmits a control signal (conveyance control signal) to the rotation control unit.

  The conveyance control unit 103 obtains the conveyance speed (movement speed) of the moving object P based on the control signal (displacement amount, time amount) output from the displacement amount detection apparatus 101, and A conveyance control signal for controlling the rotation of the roller is output.

  Thus, in the printer having the above-described configuration, the paper that is the moving object P is conveyed by the rotation of the roller of the conveying device 102 provided therein. In other words, the roller conveys the paper in the rotation direction of the roller by the frictional force with the paper. If this frictional force is maintained at a certain level, the paper can be transported at a stable speed. However, the friction of the roller due to wear of the roller due to long-term use or dust or dirt adhering to the roller surface. There is a risk that the paper being conveyed slips due to a decrease in force.

  In this way, when the paper being conveyed slips, the amount of movement of the paper assumed in advance by the rotation control of the roller differs from the actual amount of movement of the paper, and an image is appropriately displayed at a desired position on the paper. The problem of not being printed occurs. That is, there is a problem that printing on paper cannot be performed with high accuracy and the quality of the printed image is lowered.

  Therefore, in the transport control mechanism of the printer having the above-described configuration, as a countermeasure when a slip of the paper being transported occurs, the displacement amount detection apparatus 101 and the time (time amount) required for the displacement of the paper being transported due to the slip. ) And the conveyance control unit 103 controls the rotation of the rollers in the conveyance device 102 by transmitting a conveyance control signal for performing the rotation control of the rollers according to the detection result to the conveyance device 102. The paper moving speed is adjusted so that the printing accuracy on the paper is not lowered.

  Here, if the paper moving speed is not accurately determined, the printing accuracy on the paper is lowered. In other words, how accurately the paper moving speed is obtained is important.

  In order to accurately determine the moving speed of the paper, it depends on how accurately the displacement amount detecting device 101 detects the displacement amount of the paper as the moving object P and the time (time amount) required for the displacement. Is done.

  In the displacement amount detection apparatus 101 having the above configuration, as described above, the displacement amount output from the image sensor 12 is synchronized with the time for taking out the displacement amount, so that the displacement amount error is eliminated and accurate. Since the moving amount of the moving object can be detected, the moving speed of the moving object can be accurately grasped.

  Therefore, if the displacement amount detection device according to the present embodiment is applied to a printer, even if the paper that is the moving object P is not properly conveyed due to the slip of a roller, the displacement amount of the paper, Since the time required for the displacement can be accurately detected and the moving speed of the paper can be obtained accurately, even if the paper is displaced, the print quality on the paper is not deteriorated.

  That is, even if the paper slips by the roller, the paper moving speed can always be detected with high accuracy, so that the print quality on the paper is not deteriorated.

  So far, the example in which the displacement amount detected by the image sensor 12 is used as the moving speed of the moving object P for use in adjusting the frame rate has been described. That is, the example using the displacement obtained by the displacement detection device has been described.

  However, the present invention is not limited to this, and information related to the moving speed of the moving object P may be acquired from outside the displacement detection device and used to adjust the frame rate. For example, as shown in FIG. 7, when the displacement amount detection device 101 is mounted on a printer, the rotation amount of the roller of the transport device 102 is used as information on the moving speed of the paper (moving object P). 101 may obtain and adjust the frame rate.

  In the following second embodiment, an example will be described in which information regarding the moving speed of the moving object P is acquired from a device external to the displacement detection device and the frame rate is adjusted.

<Embodiment 2>
Another embodiment of the present invention will be described as follows. Note that members having the same functions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the displacement amount detection apparatus according to the present embodiment, as shown in FIG. 8, the configuration of the displacement amount detection unit 1 is the same as the displacement amount detection unit 1 shown in FIG. 1, and the configuration of the control signal generation unit 2 is as shown in FIG. A timing control unit 23 is added to the control signal generation unit 2 shown in FIG. 1, and control information regarding the moving speed of the moving object is input to the timing control unit 23.

  That is, the displacement amount detection device according to the present embodiment has a control signal generation unit 2 as a moving speed information capturing unit that captures control information related to the moving speed of a moving object (roller rotational speed information and the like) as moving speed information. A timing control unit 23 is provided.

  Then, the image sensor 12 in the displacement amount detection device adjusts the frame rate by adjusting the image capturing period in accordance with the moving speed information captured by the timing control unit 23.

  Here, a different part from the said Embodiment 1 is demonstrated.

  When the control information regarding the moving speed of the moving object is input from an external device, the timing control unit 23 outputs the control information to the timing control unit 121 of the image sensor 12 at a predetermined timing.

  The timing control unit 121 uses the received control information as information related to the moving speed of the moving object P, and sets one frame period of a frame rate signal, which is a timing signal for capturing an image in the light receiving unit 122 in one frame period. adjust. That is, the timing control unit 121 adjusts the frame rate according to the control information.

  Since the processing after the frame rate adjustment is the same as that in the first embodiment, description thereof is omitted.

  In the displacement amount detection apparatus according to the present embodiment, control information related to the moving speed of the moving object is acquired from an external device, and the frame rate is adjusted using this control information. As in FIG. 1 of the first embodiment, it is not necessary to input the displacement amount that is the calculation result of the displacement amount calculation unit 123 to the timing control unit 121.

  As described above, also in the displacement amount detection apparatus according to the present embodiment, the time (time amount) required for the displacement can be obtained with high accuracy as in the first embodiment. The speed can be determined accurately.

(Substitution possibility of invention)
As described above, the displacement detection device of the present invention can be suitably used for a printer. However, in addition to the printer, the displacement amount detection device is suitably used for any electronic device that needs to accurately measure the speed of the moving object P. be able to. For example, if it is an electronic device other than a printer, a copier can be considered. Even in the case of a copying machine, since the paper that is the printing object moves, it is important to accurately grasp the moving speed of the paper in order to increase the printing accuracy.

  Another application example is a mouse. For example, when the displacement amount detection device of the present invention is applied to a mouse, the mouse itself corresponds to the moving object P, and the movement of the mouse can be detected with high accuracy, so that high-speed operation by the mouse becomes possible.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is effective for accurate detection of the amount of displacement of a moving object and the time required for the displacement. The present invention can be suitably used in the field of detecting the amount of displacement of a moving object and the time required for displacement, such as detection of the moving speed of printing paper or detection of the moving speed of a material in a product production process.

1 Displacement detection unit 2 Control signal generation unit (control unit)
DESCRIPTION OF SYMBOLS 11 Light emission part 12 Image sensor 21 Counter 22 Signal output part 23 Timing control part (movement speed information acquisition part)
101 Displacement Detection Device 102 Transport Device 103 Transport Control Unit 111 Light Emitting Element 121 Timing Control Unit (Cycle Adjustment Unit)
122 light receiving part 122a light receiving pixel 123 displacement amount calculating part P moving object

Claims (8)

A light emitting unit for irradiating light on the surface of the moving object;
The reflected light from the surface of the moving object is periodically captured as an image in a light receiving area, and an image sensor for obtaining a displacement amount of the moving object from the amount of movement of the captured image in the light receiving area,
The above image sensor
A displacement amount detection apparatus, wherein an image capturing period is adjusted according to a moving speed of the moving object. The above image sensor
2. A period adjusting unit that adjusts the image capturing period in accordance with a moving speed of the moving object within a range in which a moving amount of the moving object in the light receiving area does not exceed the light receiving area. The displacement amount detection device described in 1. The period adjusting unit is
3. The displacement amount detection apparatus according to claim 2, wherein the image capturing period is adjusted so that the moving amount of the moving object in the light receiving region is maximized within a range not exceeding the light receiving region. The period adjusting unit is
When the image capture cycle when the moving speed of the moving object is a preset speed is the reference cycle,
If the moving speed of the moving object is faster than the set speed, adjust the image capture period shorter than the reference period,
The displacement amount detection device according to claim 2, wherein when the moving speed of the moving object is slower than the set speed, the image capturing period is adjusted to be longer than the reference period. The period adjusting unit is
While generating a timing signal for periodically capturing images, the period of the timing signal is adjusted according to the moving speed of the moving object,
The above image sensor
The displacement according to any one of claims 2 to 4, wherein a timing signal whose period is adjusted and a displacement amount of the moving object obtained by the timing signal whose period is adjusted are output. Quantity detection device.   The amount of displacement of the moving object output from the image sensor and the timing signal used to determine the amount of displacement are input, and the time required for the displacement of the moving object is determined using the timing signal. The displacement amount detection apparatus according to claim 5, further comprising a control unit that outputs the displacement amount and a time required for the displacement as a control signal. A moving speed information capturing unit that captures moving speed information indicating the moving speed of the moving object;
The above image sensor
The displacement amount detection apparatus according to claim 1, wherein an image capturing period is adjusted in accordance with the moving speed information captured by the moving speed information capturing unit.   An electronic apparatus using the displacement detection device according to claim 1.

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