JP2020121357A - Mark detector, cutting device and automatic adjustment program for light emission intensity of light source - Google Patents

Abstract

To accurately and automatically correct the consistency of sensitivity on a light-receiving side and a light emission side.SOLUTION: A mark detector for detecting a mark formed on a medium has light emission units (71, 72), light sensor units (72, 76) and a control unit 50. The control unit 50 has: a binary search unit 82 for coarse search that is capable of calibrating a light source, and compares a detection value detected by the light sensor unit with a target value, determines whether the detection value is within a range of ±α centered at the target value (α is a positive real number) (an allowable range), and performs a binary search when the detection value is outside the allowable range; and a minute increase/decrease search unit 92 for detailed search that varies the light emission intensity of the light source at minimum resolution to determine the maximum value and the minimum value within the allowable range, and stores an intermediate value between the maximum value and the minimum value as a light emission intensity of the light source corresponding to the target value.SELECTED DRAWING: Figure 2

Description

The present invention relates to a mark detection device, a cutting device, and a program for automatically adjusting the amount of light emitted from a light source (particularly, a mark detection light source).

For example, Patent Document 1 discloses a mark detection device (a sensor having a light emitting unit and a light receiving unit) that detects a mark on a printing paper.

In paragraph [0003] of Patent Document 1, "Generally, a test paper or a printing paper to be used is read before printing to correct the current amount of a light emitting unit or a light receiving unit, or a process on a sensor output side. There is a method of correcting the detection level in the circuit."

Note that in Patent Document 1, the output voltage is level-shifted at any time in order to eliminate the need for such prior correction.

Further, in the cutting device, a technique for positioning the cutting head using a mark printed on a medium (medium) called a crop mark is described in Patent Document 2, for example.

Japanese Patent Laid-Open No. 10-76717 JP, 2008-8366, A

On the light receiving side of the sensor, the presence or absence of a mark is determined by comparing an electric signal (voltage signal) obtained by photoelectric conversion with a threshold value. As an example, the threshold value is the power supply voltage (Vcc) of the light receiving circuit. Half the voltage (Vcc/2) is used. For accurate reading, it is necessary to match the sensitivity of each sensor on the light emitting side and the light receiving side.

In other words, it is important that the threshold value (Vcc/2) on the light receiving side and the emission intensity (reference emission intensity) corresponding to the threshold value on the light emitting side are matched. If the threshold voltage is not obtained on the light receiving side and an error occurs when light is emitted at the reference emission intensity, the noise margin at the time of the determination will be reduced by the amount of the error, and erroneous determination may occur. Will increase.

For example, when a cutting device (the same applies to a multifunction device having a printing function) is distributed in the market, the sensitivity of each sensor on the light emitting side and the light receiving side described above is used in a manufacturer's factory using a predetermined standard medium. The alignment is well done.

However, the media (media) used in the field where the product is actually used may be different from the standard media described above, and in this case, the reflectance and the characteristics of the ink used are also different, and There may be some deviation in the consistency between the sensors.

Further, when the product is installed, for example, near a window, there is a possibility that the adverse effect of ambient light cannot be ignored due to the effect of external light entering through the window. These can be dealt with in the field by appropriately correcting the specifications (initial specifications) regarding the consistency.

However, conventionally, in the field, adjustment of the sensitivity of the sensor on the light emitting side (adjusting the reference emission intensity so as to correspond to the above threshold value) has been manually performed by an operator, for example. Since it is manual adjustment, its accuracy is limited. For example, in order to cope with a severe condition such as an error of 0.02 V in the voltage level on the light receiving side, it takes a long time to adjust, and the burden on the worker increases.

Further, in recent years, the voltage of the light receiving circuit has been lowered, and the margin in the determination tends to be reduced. Further, in recent years, for example, customers are required to be able to perform accurate reading even under a condition of outside light.

Further, in order to reduce the cost, it is preferable to enable accurate adjustment without using an expensive and expensive sensor.

In order to meet these requirements, it is preferable to automate the above-mentioned correction so that the high-accuracy correction can be automatically performed. However, there is no disclosure of an automation method for highly accurate adjustment in the past.

An object of the present invention is to enable correction of the matching of the sensitivities of the light-receiving side and the light-emitting side with high accuracy and automatically. Other objects of the present invention will become apparent to those skilled in the art by referring to the aspects and the best embodiments illustrated below, and the attached drawings.

Hereinafter, for easy understanding of the outline of the present invention, embodiments according to the present invention will be exemplified.

One aspect of the mark detecting device of the present invention is a mark detecting device for detecting a mark formed on a medium, which comprises: a light emitting unit having a light source for irradiating the medium with light; and an intensity of light reflected from the medium. An optical sensor unit for detecting, and a control unit having a function of controlling the emission intensity of the light source, the control unit, as a result of irradiating the medium on which the mark is not formed with light, It is possible to perform a calibration for controlling the emission intensity of the light source so that the detection value detected by the sensor unit matches a desired target value, and the detection is performed by the optical sensor unit. The detected value is compared with the target value, and it is determined whether the detected value is within a range of ±α (α is a positive real number) (hereinafter referred to as an allowable range) centered on the target value. When it is outside and the detected value is smaller than the target value, the next light emission of the light source is made to be an intermediate point between the current light emission intensity of the light source and the previous or past maximum light emission intensity of the light source. When the first control for increasing the intensity is performed, and the detected value is out of the allowable range and is larger than the target value, the present light emission intensity of the light source and the previous or past lowest light emission of the light source are performed. The second control for reducing the next emission intensity of the light source is performed so as to become an intermediate point with the intensity, and the first or second control is repeated until the detected value falls within the allowable range. , A rough binary search unit for making a detection value when the value is within the allowable range a first detection value, and a light emission intensity of the light source, a light emission when the first detection value is obtained. The intensity is increased from the intensity with the minimum resolution, the maximum value of the detected values that does not exceed the upper limit value obtained by adding the α to the first detected value is detected, and the maximum value is detected as the second detected value. And the emission intensity of the light source is reduced from the emission intensity when the first detection value is obtained with minimum resolution, and the lower limit of subtracting the α from the first detection value is set. A minimum value of the detection values that does not become less than a value is detected, the minimum value is set as a third detection value, and the middle of emission intensity of each of the light sources corresponding to the obtained second and third detection values. A minute increase/decrease search unit for detailed search, the value of which is the light emission intensity of the light source corresponding to the target value.

In this aspect, the emission intensity of the light source that can obtain the detection value in the allowable range (range of the target value ±α) can be detected (searched) at high speed by the binary search as the rough search. In other words, the light amount of the light source can be narrowed down at high speed.

In addition, a small increase/decrease search as a detailed search does not exceed the upper limit value (target value+α), does not exceed the maximum detection value (second detection value) and the lower limit value (target value−α), The minimum value (third detection value) is detected.

The second and third detection values correspond to “target value+α” and “target value−α” when measured with the minimum resolution. This is considered to mean that the intermediate value between the second and third detection values is exactly the target value. Therefore, the light emission intensity of the light source corresponding to the intermediate value between the second and third detection values is the desired light emission intensity. In other words, the intermediate value of the light emission intensities of the light source corresponding to the second and third detection values is the light emission intensity of the light source corresponding to the target value. Therefore, the light emission intensity of the light source such that the detected value becomes the desired target value can be obtained extremely accurately (highly accurately). Further, since the binary search is made to converge to a value near the target value and the detailed search is started from that point, it is possible to efficiently reach both the second and third detected values. .. That is, when the drive current of the light source is increased or decreased stepwise, the number of steps can be minimized. Therefore, high-speed and efficient processing is realized.

Therefore, according to this aspect, it is possible to automatically and accurately perform the correction of the matching of the sensitivity between the light receiving side and the light emitting side (correction from the specifications at the time of factory shipment to the specifications suitable for the site). become able to. As a result, the noise margin at the time of mark detection is properly secured, and, for example, even if the noise component due to external light or the like increases, the possibility of proper mark detection is increased. Further, even if a relatively inexpensive sensor is used, highly accurate adjustment can be performed, which is advantageous in terms of cost.

Those skilled in the art will readily appreciate that the illustrated embodiments according to the invention may be further modified without departing from the spirit of the invention.

FIG. 1A is a diagram showing an overall configuration of an example of a printing apparatus having a cutting head (in other words, a cutting apparatus with a printing function), in which the mark detection apparatus of the present invention is mounted, and FIG. It is a figure which expands and shows the structure of the mark detection apparatus vicinity in the apparatus of FIG. 1(A). FIG. 2A is a diagram showing a usage example of the crop mark used for positioning the cutting head, and FIG. 2B is a diagram showing a configuration example of a main part of the mark detection device. FIG. 3A is a diagram showing the relationship between the detection threshold and each level of black and white when the mark detection method in which the black level is on the power supply voltage (Vcc) side is adopted, and FIG. It is a figure which shows the relationship between a detection threshold value and each level of black and white when the mark detection method whose white level is the power supply voltage (Vcc) side is adopted. FIGS. 4A to 4D are diagrams showing an outline of the first detection and the second detection (and the adjustment of the light source) by the binary search unit for rough search. FIGS. 5A to 5D are diagrams showing an outline of the third detection (and adjustment of the light source) by the binary search unit for rough search. 6(A) to 6(H) are diagrams showing an outline of the process of obtaining the maximum value of the detected values within the allowable range by the minute increase/decrease search unit for detailed search. FIG. 7A to FIG. 7H are diagrams showing an outline of the process of obtaining the minimum value of the detected values within the allowable range by the minute increase/decrease search unit for detailed search. FIG. 8 is a flowchart showing an example of the procedure of the detection processing (calibration processing) of the emission intensity of the light source corresponding to the target value by the mark detection device.

The best embodiments described below are used for easy understanding of the present invention. Therefore, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

FIG. 1A is a diagram showing an overall configuration of an example of a printing apparatus having a cutting head (in other words, a cutting apparatus with a printing function), in which the mark detection apparatus of the present invention is mounted, and FIG. It is a figure which expands and shows the structure of the mark detection apparatus vicinity in the apparatus of FIG. 1(A). In the following description, an inkjet printer (having a cutting head) will be described as an example, but the present invention is also applicable to a dedicated cutting device.

As shown in FIGS. 1A and 1B, the inkjet printer 10 includes a base member 14 supported by a base member 12 and extended in the main scanning direction, and left and right sides of the base member 14. Side members 16L and 16R arranged orthogonally to the base member 14 at both ends, a center wall 18 connecting the left and right side members 16L and 16R, and a wall surface of the center wall 18 extending in the main scanning direction. And a second guide rail 22 arranged in parallel with the guide rail 20, and a second guide rail 22 arranged parallel to the guide rail 20, and movably arranged in the main scanning direction along the wall surface of the central wall 18. A drive belt 24 (see FIG. 1B), a cutting head 26 that is slidable along the guide rail 20 by being fixed to the drive belt 24, and a medium (recording paper) on the base member 14. Ink head 28 slidably disposed on first and second guide rails 20 and 22 so as to face 200.

The cutting head 26 is a head device that cuts the medium 200 into a predetermined shape by the cutter 32. As shown in FIG. 1B, the cutter 32 is disposed on the left side via a holder 34. A cutter blade 36 is attached to the lower end of the cutter 32.

Further, below the cutting head 26, there is provided a light emitting/light receiving unit 42 for reading a positioning mark (reference numeral M in FIG. 3A) of the cutting head 26 called a crop mark. The light emitting/receiving unit 42 is a component of the mark detecting device. The specific configuration of the mark detection device will be described later.

Further, the ink head 28 has a plurality of inkjet nozzles (not shown), and a desired image can be printed on the medium 200 by ejecting ink. However, “printing” is an example of a mark forming method, and is not limited to this. A light emitting/receiving unit 38 is also provided near the ink head 28.

The cutting head 26 and the ink head 28 are connected by a connecting member 40. However, the connection state between the cutting head 26 and the ink head 28 can be released by using a mechanism (not shown).

Next, refer to FIG. FIG. 2A is a diagram showing a usage example of the crop mark used for positioning the cutting head, and FIG. 2B is a diagram showing a configuration example of a main part of the mark detection device. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. Note that this point is the same in the following drawings.

In the example of FIG. 2A, cropping marks M for positioning the cutting head are formed (printed) on the medium 200 in correspondence with the four corners of the cutting area CU.

The light emitting/receiving unit 42 detects the crop mark M, the cutting position setting unit 77 (see FIG. 2B) sets the cutting position based on the position, and the cutting control unit 79 (see FIG. 2B). ) Controls the cutting position of the medium 200 by the cutting head 28 based on the setting by the cutting position setting unit 77.

Next, the mark detection device will be described. As shown in FIG. 2B, the mark detecting device includes a light emitting/receiving unit 42 and a control unit 50.

The light emitting/light receiving unit 42 includes a case 77, a light emitting portion PE having a light emitting element (LED or the like) 71 housed and fixed in the case 77, and a light receiving element similarly housed and fixed in the case 77 ( An optical sensor unit DE having a photo diode, a light source driving unit 72 (having a driving current (output light intensity) switching unit 74), and an output signal of the optical sensor unit DE (current signal or voltage signal photoelectrically converted). An amplifying circuit 76 for amplifying the signal (however, it may further have a circuit having a level shift function or an impedance conversion function). Reference numeral 75 indicates a circuit board on which the IC is mounted.

Further, since the case 77 moves in the main scanning direction, it is arranged in a non-contact manner with the surface of the medium 200 with a distance d. In the figure, “L1” indicates light (emitted light or output light) emitted from the light emitting unit PE (light source 71). Further, “R1” indicates the reflected light reflected on the medium 200. Since there is the distance d, it is not possible to ignore the possibility that the reflected light due to the external light (disturbed light) is superimposed on the regular reflected light R1 via this gap. This is unavoidable.

The case 77 is movable in the x direction (main scanning direction). The y direction is the sub-scanning direction, and the z direction is the height direction.

The control unit 50 also includes a coarse search unit 80 (having a binary search unit 82), a detailed search unit 90 (having a minute increase/decrease search unit 92), a comparison circuit 51, and a storage unit 93. By providing the above-mentioned search unit (80, 90), the correction of the matching of the sensitivity between the light receiving side and the light emitting side (calibration: here, the light emitting intensity of the light emitting side is corrected) can be performed with high accuracy. And it can be done automatically.

The calibration will be specifically described below. Please refer to FIG. FIG. 3A is a diagram showing the relationship between the detection threshold and each level of black and white when the mark detection method in which the black level is on the power supply voltage (Vcc) side is adopted, and FIG. It is a figure which shows the relationship between a detection threshold value and each level of black and white when the mark detection method whose white level is the power supply voltage (Vcc) side is adopted. In addition, in the following description, the color of the ink will be described as black for convenience (but not limited to this).

For example, when the power supply voltage (Vcc) of the comparison circuit 91 (in a broad sense, the IC that constitutes this circuit) is set to 5V, the black and white determination threshold Vth is ideally set to 2.5V (Vcc/2). It is common to In FIG. 3A, the black level, which is the detection level of the marked area, is associated with the power supply voltage (Vcc).

Black ideally does not reflect light, and in this case it is 5V, but in reality, even with black ink, light is reflected on the surface, and the amount of reflected light depends on the type of ink and It varies depending on the density. Therefore, an error VQ corresponding to the amount of reflected light is generated, and the black level is reduced from the power supply voltage (Vcc) 5V by VQ.

Also, the reflected light from the surface of the medium 200 around the black ink may be detected as if it were the reflected light from the surface of the black ink. The amount of the reflected light depends on the type of the medium and the surface of the case 77 and the medium 200. Fluctuates according to the distance d between Therefore, an error VP corresponding to the reflected light amount is generated, and the black level is further lowered. In the example of FIG. 3A, the black level is 4V, and the power supply voltage (Vcc=5V) cannot be effectively used.

In particular, when the inkjet printer shown in FIG. 1 is installed near the window of an office, the intensity of ambient light due to sunlight is increased, and in this case, the black level tends to be further reduced. Therefore, it cannot be denied that the noise margin is lowered in the voltage range above Vth (2.5 V). If the influence of the ambient light is large, erroneous detection may easily occur.

Further, conventionally, since the threshold voltage Vth is manually adjusted, the adjustment accuracy is limited, and even if there is some variation, this is unavoidable.

In consideration of this point, it is preferable to adopt the example of FIG. 3B in the present invention. In the example of FIG. 3B, the detection level (white level) due to the reflected light from the surface of the medium on which ink is not formed is on the power supply voltage (Vcc) side. In the example of FIG. 3B, the white level is set to 4.84 V (an example) in consideration of a minute loss of the power supply voltage in the IC including the comparison circuit. Strictly speaking, Vth is preferably set to 2.42V. In the example of FIG. 3B, the white level only rises to the power supply voltage (Vcc=5V) even under the influence of external light, and Vth (2.5V) as shown in FIG. ) There is no problem of noise margin reduction in the voltage range above. The black level rises by the above-mentioned error VP and error VQ, but as the noise margin, it is possible to secure the almost same level as in the case of FIG. 3A, and there is no particular problem. Can be said.

Therefore, it can be said that the method shown in FIG. 3B is preferably adopted in actual detection of the mark (however, the method is not limited to this). However, in the example of FIG. 3B, the processing is performed on the assumption that the threshold voltage Vth is strictly set to 2.42V. In the conventional manual adjustment, it is quite difficult to perform the adjustment in the unit of "0.01V", and the adjustment takes time. Therefore, in the present invention, the automatic adjustment is performed.

That is, in consideration of the situation at the site, the process of detecting the light emission intensity of the light emitting unit PE (light source 71) corresponding to 2.42 V (in other words, the drive current amount of the light source) with extremely high accuracy is automatically performed. To do. As a result, the emission intensity and the received light voltage level (detection voltage level) can be matched, in other words, the sensitivities on the light emitting side and the light receiving side can be matched, and therefore extremely accurate calibration can be automatically performed. Therefore, the burden on the worker is reduced. Further, according to the present embodiment, it is possible to shorten the calibration time (speed up).

Hereinafter, a specific description will be given with reference to FIGS. The calibration is performed in two steps. First, a coarse search using a binary search is performed. Reference is now made to FIG. FIGS. 4A to 4D are diagrams showing an outline of the first detection and the second detection (and the adjustment of the light source) by the binary search unit for rough search.

As shown in FIG. 4A, the upper limit and the lower limit of the drive current of the light source 71 are 15.00 mA and 5.00 mA, respectively. In the example of FIG. 4A, first, the light amount (emission intensity, drive current) is set to 10.00 mA (drive current value at the midpoint) and detection (search) is started (first drive current). Adjustment). It should be noted that it is possible to start from another value instead of the midpoint.

As shown in FIG. 4B, the upper limit voltage on the light receiving side (detection side) is Vcc (=5V), and the lower limit is ground (0V). A detection value Vs of 2.00 V is obtained corresponding to the driving of the light source 71 at 10.00 mA in FIG. 4A (first detection). The target voltage (target value) Vt is 2.42V with a difference of 0.42V.

Here, the allowable error is 0.02V. In other words, the target value of 2.42V±0.02V is the allowable range. In FIG. 4B, the detected value Vs is outside the allowable range. Since the detection value Vs is lower than the target value Vt, it is necessary to increase the drive current on the light source side in order to increase it.

Therefore, as shown in FIG. 4C, it is an intermediate value (midpoint divided into two) between the maximum light amount (maximum drive current 15.00 mA) and the current light amount (drive current value 10.00 mA). The amount of light (drive current) is increased to 0.5 mA (second adjustment of drive current).

Then, as shown in FIG. 4D, a detection value Vs of 2.50 V is obtained in response to the driving of the light source 71 at 12.25 mA in FIG. 4C (second detection). The difference from the target value Vt is 0.08V, which is not within the allowable range. Further, this time, the detected value Vs is a value exceeding the target value Vt. Therefore, next, the drive current of the light source 71 is decreased so that the detection value (detection voltage) Vt falls within the allowable range.

If the detected value Vs falls below the target value Vt, this time, again, the intermediate value (divided midpoint) between the maximum light amount (maximum drive current) and the current light amount (drive current value) The measurement is performed by increasing the drive current of the light source 71.

Please refer to FIG. FIGS. 5A to 5D are diagrams showing an outline of the third detection (and adjustment of the light source) by the binary search unit for rough search. Note that FIGS. 5A and 5B are reprints of FIGS. 4C and 4D for easy understanding.

Since the detection value Vs (2.50 V) as the second detection result exceeds the target value 2.42 V, the drive current of the light source 71 is reduced this time, as shown in FIG. 5(C). Here, it is an intermediate value (midpoint divided into two) between the current light amount (driving current 12.50 mA) and the previous lowest light amount (previous lowest emission intensity: 10.00 mA in FIG. 4A). The amount of light is reduced to 11.25 mA (third adjustment of drive current).

As a result, as shown in FIG. 5D, the detected value Vs becomes 2.44V, which is within the range (allowable range) of error 0.02V centered on the target value of 2.42V. Therefore, the rough search (binary search) ends.

If the detected value Vs exceeds the target value Vt, this time again, an intermediate value between the present light amount (emission intensity) and the lowest past light amount (emission intensity) (midpoint divided into two). Then, the drive current of the light source 71 is reduced and another measurement is performed.

In this way, the coarse search unit 80 (the binary search unit 82) shown in FIG. 2B reduces the adjustment room (range) by dividing it into two until the detected voltage becomes a value within the allowable range. And guide to the vicinity of the target value. As a result, the process of setting the detection voltage Vs within the allowable range of the target value (in other words, within the vicinity range) is realized at high speed. Note that 2.44 V in FIG. 5D is the first detection value, and the emission intensity (driving current value) corresponding to this is 11.25 mA, and these values are associated and stored in the storage unit. 93 (see FIG. 2).

Next, a detailed search will be described. First, refer to FIG. 6(A) to 6(H) are diagrams showing an outline of the process of obtaining the maximum value of the detected values within the allowable range by the minute increase/decrease search unit for detailed search. 6(A) to 6(D) correspond to FIGS. 6(E) to 6(H), respectively.

As described above, when the detected value 2.44V (first detected value) within the allowable range in FIG. 5D is obtained, the drive current value (light emission intensity) on the light source side is 11. It is 25 mA (this is the state of FIG. 6(A)). This drive current value is increased stepwise in the unit of minimum resolution (here, 0.01 mA) of increase and decrease of the drive current (emission intensity). In FIG. 6(B), it is increased to 11.26 mA, and then gradually increased, and in FIG. 6(C), it is increased to 11.30 mA.

Here, as can be seen from FIGS. 6(E) to 6(G), the detection value (detection voltage) corresponding to the change in the drive current in FIGS. 6(A) to 6(C) is 2.44V. no change. The difference from the target value 2.42V is 0.02V, which is within the allowable range.

Then, in FIG. 6D, the drive current increases to 11.31 mA. Then, in FIG. 6H, the detected value (detected voltage) rises to 2.45V, the difference from the target value 2.42V becomes 0.03V, and the difference exceeds the allowable range (error 0.02V). .. Therefore, the maximum value of the effective drive current value that stays within the allowable range (2.42 V+0.02 V range) is “11.30 mA”. Therefore, the voltage (here, 2.44 V) in FIG. 6G corresponding to this 11.30 mA becomes the second detection value. The second detection value and 11.30 mA are associated with each other and stored in the storage unit 93.

Next, refer to FIG. FIG. 7A to FIG. 7D are diagrams showing an outline of the processing for obtaining the minimum value of the detected values within the allowable range by the minute increase/decrease search unit for detailed search. 7A to 7D correspond to FIGS. 7E to 7H, respectively.

As described above, the drive current value (light emission intensity) on the light source side is 11.25 mA when the detected value 2.44 V within the allowable range in FIG. 5D is obtained (this is shown in FIG. (It is in the state of (A)). This drive current value is gradually reduced in units of the minimum resolution (0.01 mA) of increase/decrease in drive current (light emission intensity). In FIG. 7(B), it is reduced to 11.24 mA. After that, it further decreases gradually, and in FIG. 7(C), it decreases to 10.90 mA.

Here, as can be seen from FIGS. 7(E) to 7(G), the detection value (detection voltage) corresponding to the change in the drive current in FIGS. 7(A) to 7(C) is “2.44V. , “2,44V”, and “2.40V”, but the difference (absolute value here) from the target value 2.42V is 0.02V, which is within the allowable range. ..

Then, in FIG. 7D, the drive current is reduced (decreased) to 10.89 mA. Then, in FIG. 7H, the detection value (detection voltage) is reduced to 2.39V, the difference from the target value 2.42V is 0.03V, and the difference exceeds the allowable range. Therefore, the minimum value of the effective drive current value that stays within the allowable range (2.42V-0.02V range) is "10.90mA". The voltage (2.40 V) in FIG. 7G corresponding to this 10.90 mA becomes the third detection value. The third detection value and 10.90 mA are associated with each other and stored in the storage unit 93.

Here, the maximum value of the effective drive current value corresponding to the maximum allowable value "2.42V+0.02V" is "11.30" mA, and the maximum allowable value is "2.42V-0.02V". "10.90" mA is the minimum value of the effective drive current value corresponding to "."

The target value 2.42V is the midpoint between the allowable maximum value and the allowable minimum value. Therefore, the drive current value (emission intensity) corresponding to the target value 2.42V is calculated by (11.30mA + 10.90mA)/2. It is called "11.1mA". Such calculation is performed by, for example, a calculation unit (not shown) included in the detailed search unit 90. In this way, the drive current value (emission intensity, emission amount) corresponding to the target value 2.42 V is detected (measured) with high accuracy.

In rough detection (binary search as rough detection), the initial value of the detailed search is within the allowable range centered on the target value, so the current value is increased or decreased based on this value. As a result, the drive current values (light emission intensity, light emission amount) corresponding to the above allowable maximum value and allowable minimum value can be efficiently obtained. In other words, the binary search is made to converge to a value near the target value, and the detailed search is started from that point, so that it is possible to efficiently reach both the second and third detected values. it can. That is, when the drive current of the light source is increased or decreased stepwise, the number of steps can be minimized. Therefore, high-speed and efficient processing is realized.

The content of the processing described above can be paraphrased as follows. That is, the control unit 50 of FIG. 2B emits light from the light source 71 so that the detection value detected by the optical sensor unit DE as a result of irradiating the medium 200 with light matches a desired target value. It is possible to execute the calibration for controlling the intensity (light emission amount), and the rough search binary search unit 82 compares the detection value Vs detected by the optical sensor unit DE with the target value Vt, and detects it. It is determined whether the value Vs is within a range of ±α (α is a positive real number) (hereinafter referred to as an allowable range) around the target value Vt, and the value Vs is outside the allowable range, and the detected value Vs is the target value Vt. When it is smaller, it is an intermediate point between the present light emission intensity (light amount, specifically, drive current) of the light source 71 and the previous or past maximum light emission intensity (maximum light amount, specifically, maximum drive current) of the light source 71. As described above, the first control (which can be referred to as an upper binary search) for increasing the next emission intensity of the light source 71 is performed, and the value is outside the allowable range and the detection value Vs is larger than the target value Vt. In this case, the current emission intensity (light amount, specifically, driving current) of the light source 71 is set to an intermediate point between the previous or past minimum emission intensity (minimum light amount, specifically, minimum driving current) of the light source 71. Secondly, a second control (which can be referred to as a lower binary search) for reducing the next emission intensity of the light source 71 is performed, and the first or second control is performed until the detected value Vs falls within the above-mentioned allowable range. The control is repeated and the detected value Vs when it is within the allowable range is set to the first detected value (corresponding to “2.44V” in FIG. 5D).

In addition, the minute increase/decrease search unit 92 for detailed search determines the light emission intensity (light amount, specifically, drive current value) of the light source 71 from the light emission intensity when the above first detection value is obtained. The maximum detected value Vs that does not exceed the upper limit value (allowable upper limit value) obtained by adding α to the first detected value is detected, and the detected maximum value is set to the first detected value. 2 (corresponding to “2.44 V” in FIG. 6(G)) and the light emission intensity (light quantity, specifically, drive current value) of the light source 71 is set to the above first detection value. The minimum value of the detection value Vs, which is not less than the lower limit value (allowable lower limit value) obtained by subtracting the above α from the first detection value, is decreased from the emission intensity obtained at the minimum resolution. Each detected light emission of the light source 71 corresponds to the obtained second and third detection values by using this minimum value as the third detection value (corresponding to “2.40V” in FIG. 7G). The intermediate value ((11.30 mA+10.90 mA)/2=11.1 mA of the intensity (here, “11.30 mA” in FIG. 6(C) and “10.90 mA” in FIG. 7(C)) corresponds to this. Is set as the emission intensity of the light source 71 corresponding to the target value Vt.

Next, refer to FIG. FIG. 8 is a flowchart showing an example of the procedure of the detection processing (calibration processing) of the emission intensity of the light source corresponding to the target value by the mark detection device.

First, the initial value of the drive current of the light source (“10.00 mA” in the example of FIG. 4A) is set, and each processing of light emission/light reception/light reception level (hereinafter, light reception level detection processing) is performed. Yes (step S100).

If the detected value is a desired level within the allowable range (Y in step S101), the drive current value Ia at that time is stored (step S105), and the binary search is ended.

If the detected value is out of the allowable range (N in step S101), then it is determined whether the light receiving level (detected value) is smaller than the target value (step S102).

If Y in step S102, the current is switched to a current that is intermediate (median value) between the current light emission intensity and the maximum light emission intensity of the light source, and light reception level detection processing (upper dichotomy search) is performed (step S103).

When the result is N in step S102, the current is switched to a current (median value) intermediate between the present light emission intensity and the previous or past lowest light emission intensity, and light reception level detection processing (lower binary search) is performed (step S104). ). After that, the same processing is repeated until it becomes Y in step S101. When the result in step S101 is Y, the binary search ends.

After that, the detailed search is started. First, the drive current is incremented (increased) in the minimum unit (minimum resolution) (step S106). Then, it is determined whether the detected value exceeds the allowable upper limit (step S107).

If the answer is N in step S107, the process returns to step S106. If Y in step S107, an effective current value (upper limit drive current value) Imax that does not exceed the allowable upper limit is stored (step S108).

Then, the drive current is decremented (decreased) by the minimum unit (minimum resolution) (step S109). Next, it is determined whether the detected value is less than the allowable lower limit (step S110).

If the answer is N in step S110, the process returns to step S109. If Y in step S110, an effective current value (lower limit drive current value) Imin that does not fall below the allowable lower limit is stored (step S111).

Next, the median value of the upper limit current and the lower limit current is calculated. In other words, the calculation process of Icenter=(Imax+Imin)/2 is performed (step S112). Then, the obtained median value (Icenter) is stored (step S113).

As described above, according to the present invention, the matching of the sensitivities of the light receiving side and the light emitting side can be automatically corrected with high accuracy. Therefore, the burden on the worker is reduced. In addition, high-speed calibration is possible. Also, on the premise of a reading method in which the white level is associated with the power supply voltage side, the reflected light from the medium on which no mark is formed is detected and used as the detection value (detection voltage), so a wide noise margin can be secured. Therefore, it is possible to realize a mark detection device in which erroneous detection is unlikely to occur even in an environment in which external light (external light) is adversely affected. Further, the automatic calibration of the present invention enables highly accurate detection even when an inexpensive sensor is used. Therefore, high performance of the cutting device can be achieved at low cost. The present invention can be applied to various devices other than the cutting device.

The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily change the above-described exemplary embodiments within the scope of the claims. ..

10... Printing device having cutting head (cutting device with printing function), 26... Cutting head, 28... Printing head, 42... Light emitting/receiving unit, 71... Light source (LED etc.) ), 72... Light receiving element (light receiving sensor, photodiode, etc.), 50... Control section, 72... Light source driving section, 74... Driving current (output light intensity) switching section, 76... Amplifying circuit, etc. 77... Cutting position setting unit, 79... Cutting control unit, 80... Coarse searching unit, 82... Binary searching unit, 90... Detailed searching unit, 92... Minute Increase/decrease search unit, 91... Comparison circuit, 93... Storage unit, PE... Light emitting unit,
DE... Optical sensor section (light receiving section), 200... Media (recording paper etc.), M... Crop mark, CU... Cutting area

Claims (4)

A mark detecting device for detecting a mark formed on a medium,
A light emitting unit having a light source for irradiating the medium with light,
An optical sensor unit that detects the intensity of reflected light from the medium,
A control unit having a function of controlling the emission intensity of the light source,
Have
The control unit performs a calibration for controlling the light emission intensity of the light source so that the detection value detected by the optical sensor unit as a result of irradiating the medium with light matches a desired target value. Is possible, and
The detection value detected by the optical sensor unit is compared with the target value, and the detection value is within a range of ±α (α is a positive real number) (hereinafter referred to as an allowable range) with the target value as a center. If it is outside the permissible range and the detected value is smaller than the target value, it is set as an intermediate point between the current emission intensity of the light source and the previous or past maximum emission intensity of the light source. First, the first control for increasing the next light emission intensity of the light source is performed, and when the detected value is outside the allowable range and is larger than the target value, the current light emission intensity of the light source and the The second control is performed to reduce the next emission intensity of the light source so as to be at an intermediate point between the previous emission intensity of the light source and the lowest emission intensity in the past, and the first control is performed until the detected value falls within the allowable range. , Or the second control is repeated, and the detected value when it is within the allowable range is set as the first detected value, and a coarse search binary search unit,
The light emission intensity of the light source is increased from the light emission intensity when the first detection value is obtained with the minimum resolution, and does not exceed the upper limit value obtained by adding the α to the first detection value. Detecting the maximum value of the detection values, using the maximum value as the second detection value, and determining the emission intensity of the light source from the emission intensity when the first detection value is obtained to the minimum resolution. And the minimum value of the detection values that is not less than the lower limit value obtained by subtracting α from the first detection value is detected, and the minimum value is set as the third detection value, and the obtained value is obtained. A minute increase/decrease search unit for detailed search, wherein an intermediate value of the light emission intensities of the light source corresponding to the second and third detection values is set as the light emission intensity of the light source corresponding to the target value,
A mark detection device having. The mark detection device according to claim 1, wherein the detection value is a detection value detected by the optical sensor unit as a result of irradiating the medium on which the mark is not formed with light. A mark detection device according to claim 1 or 2,
A cutting position setting unit that sets the cutting position of the medium based on the position of the mark detected by the mark detecting unit;
A cutting head that performs a cutting process on the medium at the cutting position set by the cutting position setting unit,
A cutting control unit that controls the cutting position of the medium by the cutting head based on the setting by the cutting position setting unit;
A cutting device having. A program for automatically adjusting the light emission intensity of a light source, which causes a computer to function as a control unit having the binary search unit for rough search and the minute increase/decrease search unit for detailed search according to claim 1.

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