JP2005077303A - Optical object identifying apparatus and printer using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply identify various types of objects using a reflection light from the detected object. <P>SOLUTION: A light emitting side optical system 23 and a light receiving side optical system 26 are accommodated in a housing 30 vertically movable to a detected object 27. An output from a light receiving element 25 is maximized when a focus location of the light emitting optical system 23 is located near the detected object 27. A plurality of types of the detected objects 27 can be identified in a high S/N ratio by vertically moving the housing 30 to the detected object 27 until the output from the light receiving element 25 is maximized, fixing the location and processing a plurality of signals using a signal processing part 29. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical object identification device that detects the type of an object in a non-contact manner and a printing apparatus using the same.

  Copiers and printers that perform recording processing while transporting recording media are becoming more functional, faster, and higher resolution, and the recording media used are plain paper, glossy paper, and OHP (overhead projector). There are various types of sheets. In this way, when printing on a variety of recording media by a printing machine that is an image recording device (particularly, a printing machine using an inkjet recording method) or the like, depending on the difference in ink permeation speed and drying time depending on the type of recording medium, In order to form a high-quality image, it is necessary to perform recording control according to the recording medium.

  Conventionally, there are a mechanical detection method, a thermal detection method, and an optical detection method as methods for detecting the type of paper such as printing paper and the type of recording medium such as a resin film or sheet. In the mechanical detection method, the type of the recording medium is detected by the amount of displacement of the contact or the like when the recording medium is inserted into the transport unit. In the thermal detection method, a heating element is applied to a recording medium, and the type of the recording medium is detected by a thermal change of the recording medium or a thermal change of the heating element itself.

  The optical detection method includes a light emitting element and a light receiving element, irradiates the recording medium with light from the light emitting element, and detects the type of the recording medium based on the amount of light reflected from the recording medium. For example, in “Paper Type Detection Device and Image Forming Apparatus Provided with this Device” disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 10-198174), as shown in FIG. The type of the paper 3 is detected by the change in the output from the light receiving element 2 due to two types of arrangement angles of 1a, 1b and the light receiving element 2. In the “recording medium identification device and identification method” disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2000-301805), as shown in FIG. Light passing through the grazing illuminator 13 irradiates the recording medium 12, and light from the vertical illuminator 14 illuminates the recording medium 12 vertically via the amplitude beam splitter 15. Then, a surface image of the recording medium 12 is obtained by a photodetector array 16 such as a CCD (Charge Coupled Device) or a C-MOS (Complementary Metal Oxide Semiconductor) device, and the recording medium 12 is subjected to two-dimensional image processing. The type of identification is performed.

  In addition, a detection liquid containing a predetermined dye or fluorescent substance is allowed to penetrate into the recording medium, and the reflected light intensity is measured by irradiating light at a wavelength region absorbed by the dye or fluorescent substance, or infrared light is irradiated. There is also a method of detecting the type of recording medium by measuring the infrared absorption spectrum of reflected light (see, for example, Patent Document 3 (Japanese Patent Laid-Open No. 2001-88275)).

  However, the conventional recording medium type detection method has the following problems. That is, in the case of the above-described mechanical detection method and thermal detection method, it is necessary to bring a contact or a heating element into contact with the recording medium, which may hinder the movement of the recording medium being conveyed. At the same time, there is a possibility of causing a change in the shape of the recording medium. In addition, there is a risk of erroneous detection due to deterioration due to wear of the contact portion.

  In the case of each of the optical detection methods described above, since the type is detected based on the difference in the amount of reflected light from the recording medium, the detection may not be possible if the difference in the amount of reflected light is small. The type is quite limited.

Furthermore, in the case of a method using an image sensor such as a CCD or a C-MOS device for the light receiving unit, the image processing becomes complicated, and the determination factor must be increased as the identification accuracy is increased. Not only is it complicated, but the light receiving element is also expensive. Furthermore, it is necessary to pay attention to adjusting the arrangement angle between the light emitting element and the light receiving element, and the assembly is troublesome. Further, in the case of a method in which the detection liquid is permeated into the recording medium and the reflected light from the portion is measured, there is a possibility that the recording medium is changed in color or stained. In addition, a means for penetrating the detection liquid is required, and the configuration of the light receiving unit and signal processing become complicated in order to increase the size of the apparatus and measure the infrared absorption spectrum.
Japanese Patent Laid-Open No. 10-198174 Japanese Patent Laid-Open No. 2000-301805 JP 2001-88275 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical object identification device that can easily identify many types of objects by reflected light from an object to be detected, and a printing apparatus using the same.

  In order to solve the above-described problems, an optical object identification device according to the present invention includes a light emitting element and an objective lens, and irradiates a moving object to be detected with light from the light emitting element to emit light on the object to be detected. A light output side optical system that forms a spot, a light receiving lens and a light receiving element, and the reflected light from the light spot is incident on the light receiving element to output a waveform corresponding to the surface irregularities of the detected object At least one light receiving side optical system for outputting a signal, a focus position moving unit for moving a focal position of the light emitting side optical system, and a focus position moving unit based on an output signal output from the light receiving side optical system. A drive control unit that controls the operation and sets the focal position of the light emitting side optical system so that the value of the output signal is maximized, and performs signal processing on the output signal output from the light receiving side optical system Trust And it includes a processing unit.

  According to the above configuration, since the focus position of the light emitting side optical system is set by the drive control unit so that the value of the output signal output from the light receiving side optical system is maximized, The focal position is located in the vicinity of the surface of the detected object, and the diameter of the light spot formed on the detected object is optimally set, and the variation of the diameter is reduced.

  Therefore, the SN ratio of the output signal having a waveform corresponding to the surface irregularity of the detected object output from the light receiving element constituting the light receiving side optical system is improved. That is, based on the signal processing result for the output signal by the signal processing unit, the type of the ratio detection object is accurately identified.

  The optical object identification device of the present invention includes a light emitting element and an objective lens, and at least forms a light spot on the detected object by irradiating the moving detected object with the light from the light emitting element. A light-emitting side optical system, a light-receiving lens and a light-receiving element; and at least a reflected light from the light spot is incident on the light-receiving element and outputs an output signal having a waveform corresponding to the surface irregularities of the detected object Based on one light-receiving side optical system, a focus position moving unit that moves the focus position of the light-emitting side optical system, and the output signal output from the light-receiving side optical system, the center of the objective lens and the center of the light-receiving lens A distance measuring unit that measures the distance between the reference line passing through the object to be detected, and the operation of the focal position moving unit based on the measurement result by the distance measuring unit, Focal position A drive control unit that sets the focal position of the light-emitting side optical system so that the surface of the object to be detected is positioned at a position, and a signal processing unit that performs signal processing on the output signal output from the light-receiving side optical system I have.

  According to the above configuration, the focus position of the light emission side optical system is set by the drive control unit so that the surface of the object to be detected is positioned at the focus position of the light emission side optical system. As a result, the diameter of the light spot formed on the object to be detected is set optimally, and the variation in diameter is reduced.

  Therefore, the SN ratio of the output signal having a waveform corresponding to the surface irregularity of the detected object output from the light receiving element constituting the light receiving side optical system is improved. That is, based on the signal processing result for the output signal by the signal processing unit, the type of the ratio detection object is accurately identified.

  In the optical object identification device of one embodiment, the light emitting element is a semiconductor laser.

  According to this embodiment, since the light emitting element is a semiconductor laser, the light focusing by the objective lens is efficiently performed. Therefore, it is possible to obtain reflected light having a light quantity necessary for obtaining an output signal that can more accurately identify the type of the object to be detected.

  Further, in the optical object identification device of one embodiment, the focal position moving unit includes a light emitting side optical system moving unit that moves at least the entire light emitting side optical system in a direction perpendicular to the object to be detected. Has been.

  According to this embodiment, the focal position of the light emitting side optical system is easily moved by moving the whole light emitting side optical system. Further, the light emitting side optical system can be integrally formed, and the optical axis can be easily adjusted.

  In the optical object identification device of one embodiment, the focal position moving unit includes a movable objective lens in which the position of the objective lens is movable in the optical axis direction, and the movable objective lens as the light beam. It consists of an objective lens drive unit that moves in the axial direction.

  According to this embodiment, the focal position is moved only by moving the movable objective lens in the optical axis direction by the objective lens driving unit. Therefore, the focal position is moved with a small driving force, and the change in the amount of reflected light in that case is very small. As a result, the focal position of the light emitting side optical system is accurately set.

  In the optical object identification device of one embodiment, the focal position moving unit passes the entire light emitting side optical system through the position of the light emitting point of the light emitting element, and the optical axis of the light emitting side optical system and the light receiving side. The light-emitting side optical system rotation drive unit is configured to rotate about a rotation axis extending in a direction perpendicular to a plane including the optical axis of the optical system.

  According to this embodiment, the light-emitting side optical system can be integrally formed, and the optical axis can be easily adjusted.

  In the optical object identification device of one embodiment, the driving force of the objective lens driving unit or the light emitting side optical system rotation driving unit is an electromagnetic force.

  According to this embodiment, since the driving force of the objective lens driving unit or the light emitting side optical system rotation driving unit is an electromagnetic force, the objective lens driving unit and the light emitting side optical system rotation driving unit are configured to be small and light. .

  In the optical object identification device having the distance measuring unit according to one embodiment, the light receiving element is a position detecting element.

  According to this embodiment, the position of incident light with respect to the light receiving element can be detected. Therefore, the distance measuring unit measures the distance between the reference line and the detected object by triangulation using light emitted from the light emitting side optical system and incident on the light receiving side optical system. It becomes possible.

Further, in the optical object identification device having the distance measurement unit of one embodiment,
The distance measurement unit measures the distance between the reference line and the object to be detected based on a ratio of a plurality of outputs from the position detection element.

  According to this embodiment, the distance measurement unit detects the position of the incident light with respect to the position detection element based on the ratio of the plurality of outputs from the position detection element, and triangulation using the incident position is performed. The distance between the reference line and the object to be detected is measured.

  In the optical object identification device having the distance measurement unit according to one embodiment, the signal processing unit performs signal processing on the sum of a plurality of output signals from the position detection element.

  According to this embodiment, based on a plurality of output signals from the position detection element, processing is performed on an output signal having a waveform corresponding to the surface irregularities of the detected object.

  Further, in the optical object identification device according to one embodiment, the signal processing unit includes an average value calculation method for calculating an average value of output values with respect to a section having a predetermined time length in the output signal, each output value, and the above-described values. Find the difference from the average value, average amplitude value calculation method to double the average value of the absolute value of this difference, average amplitude value / average value calculation method to calculate the average value, the maximum value as 1, each output Frequency distribution calculation method to find the frequency distribution of values, spectrum distribution by Fourier transform to obtain the spectrum distribution, power spectrum area ratio calculation method to obtain the area ratio between different distribution ranges in this spectrum distribution, the average value after passing through the filter circuit Signal processing is performed by at least one signal processing method of a filter pass method for calculating at least one of average amplitude value and average amplitude / average value.

  According to this embodiment, more types can be accurately identified as compared with the case where the types of the detected objects are simply identified based on the amount of reflected light from the detected objects.

  In one embodiment of the optical object identification device, the signal processing unit includes the average value calculation method, the average amplitude value calculation method, the average amplitude / average value calculation method, the frequency distribution calculation method, and the power spectrum area ratio calculation method. Therefore, signal processing is performed by a plurality of signal processing methods in the filter passing method.

  According to this embodiment, it becomes possible to identify more types of the detected objects more accurately than in the case of only the processing result by one signal processing method.

  In the optical object identification device of one embodiment, the signal processing unit may calculate the average value calculation method and the average amplitude value for a plurality of different sections associated with the movement of the detected object in the output signal. Signal processing is performed by at least one of the method, the average amplitude / average value calculation method, the frequency distribution calculation method, the power spectrum area ratio calculation method, and the filter pass method, and the average value of the processing results for the plurality of sections is calculated. It is supposed to be.

  According to this embodiment, the signal processing unit obtains an average value of processing results regarding a plurality of sections in one output signal. Therefore, it is possible to identify the type of the detected object more accurately than in the case of only the processing result relating to one section.

  The printing apparatus of the present invention is equipped with the optical object identification apparatus of the present invention.

  According to the above configuration, there is provided an optical object identification device capable of performing signal processing on an output signal having a waveform corresponding to the surface unevenness of the detected object and obtaining a processing result capable of identifying the type of the detected object. It is installed. Therefore, the type of paper or film to be printed is correctly identified.

  As is clear from the above, in the optical object identification device of the present invention, the drive control unit controls the operation of the focal position moving unit that moves the focal position of the light-emitting side optical system, and the value of the output signal is maximized. Since the focal position of the light emitting side optical system is set so as to be, the focal position of the light receiving side optical system can be positioned near the surface of the object to be detected. Therefore, the diameter of the light spot formed on the detected object can be optimally set and the variation in the diameter can be reduced, and the output of the waveform corresponding to the surface unevenness of the detected object output from the light receiving element The signal-to-noise ratio of the signal can be improved.

  That is, according to the present invention, the type of the ratio detection object can be accurately identified based on the signal processing result for the output signal by the signal processing unit. That is, it is possible to identify many types of objects.

  Further, in the optical object identification device according to the present invention, the operation of the focal position moving unit is controlled by the drive control unit, and the light emitting side optical unit is positioned so that the surface of the object to be detected is positioned at the focal position of the light emitting side optical system. Since the focal position of the system is set, the diameter of the light spot formed on the object to be detected can be set optimally and fluctuations in the diameter can be reduced. Therefore, the S / N ratio of the output signal having a waveform corresponding to the surface unevenness of the detected object output from the light receiving element can be improved.

  That is, according to the present invention, the type of the ratio detection object can be accurately identified based on the signal processing result for the output signal by the signal processing unit. That is, it is possible to identify many types of objects.

  Further, the printing apparatus of the present invention is capable of obtaining a processing result capable of identifying the type of the detected object by performing signal processing on the output signal having a waveform corresponding to the surface unevenness of the detected object. Since the optical object identification device is mounted, it is possible to correctly identify the type of paper or film to be printed. Therefore, the printing conditions can be further optimized, and the printing quality can be further improved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

First Embodiment FIG. 1 is a schematic configuration diagram of an optical system in an optical object identification device according to the present embodiment. The optical object identification device includes a light emitting side optical system 23 including a light emitting element (preferably a semiconductor laser) 21 and an objective lens 22, and a light receiving side optical system 26 including a light receiving lens 24 and a light receiving element 25. . Then, a light spot 28 having a predetermined spot diameter (50 μm or less) is formed on the detected object 27 by irradiating the detected object 27 with light emitted from the light emitting side optical system 23, and this light spot 28 The reflected light from the light enters the light receiving side optical system 26. Various processes are performed by the signal processing unit 29 on the signal corresponding to the amount of received light output from the light receiving element 25.

  Each optical component constituting the light emitting side optical system 23 and the light receiving side optical system 26 is arranged in the housing 30 so that the output of the light receiving element 25 is maximized at a predetermined position (reference position). Then, if the housing 30 is moved in the direction perpendicular to the object 27 (in the direction of the arrow) and the light spot 28 is positioned in the vicinity of the focal position of the light-emitting side optical system 23 having the predetermined spot diameter, the light is received. The output from the element 25 is maximized. Then, by fixing the housing 30 at that position, fluctuations in the spot diameter of the light spot 28 can be reduced, and the S / N ratio of the output signal having a waveform corresponding to the surface irregularities of the detected object 27 output from the light receiving element 25 can be reduced. Can be improved. Therefore, the type of the ratio detection object 27 can be accurately identified based on the signal processing result for the output signal by the signal processing unit 29.

  Further, as described above, the housing 30 is moved in the vertical direction (arrow direction) with respect to the detected object 27 to detect the position where the output from the light receiving element 25 is maximized, whereby the housing 30 is The amount of displacement from the reference position, that is, the thickness of the detected object 27 can be measured. Therefore, by using this thickness information as well, it becomes possible to identify the type of the ratio detection object 27 with higher accuracy.

  The housing 30 is moved by controlling the operation of the drive device 31 such as a stepping motor by the drive control unit 32 in accordance with the processing result from the signal processing unit 29. That is, in the present embodiment, the driving device 31 constitutes the focal position moving unit and the light emission side optical system moving unit.

  FIG. 2 shows another configuration example of the light emitting side optical system 23 and the light receiving side optical system 26. However, the same number is attached to the same thing as FIG. 1 for easy understanding.

  In FIG. 2A, the light emitting side optical system 23 includes a light emitting element (preferably a semiconductor laser) 21, a collimator lens 33, a beam splitter 34, and an objective lens 22. Further, the light receiving side optical system 26 includes an objective lens 22, a beam splitter 34, a light receiving lens 24, a pinhole 35, and a light receiving element 25. The light emitted from the light emitting element 21 is converted into parallel light by the collimator lens 33, passes through the beam splitter 34, is condensed by the objective lens 22, and irradiates the detected object 27 substantially vertically and also detects the detected object. A light spot 28 is formed on 27. Reflected light from the light spot 28 is reflected by the beam splitter 34 in the direction perpendicular to the optical axis of the light-emitting side optical system 23, condensed by the light receiving lens 24, passes through the pinhole 35, and receives the light receiving element 25. Is incident on. Also in this case, as in the case of FIG. 1, the light emitting side optical system 23 and the light receiving side optical system 26 are accommodated in a housing (not shown), and the housing is perpendicular to the object 27 to be detected (arrow direction). ).

  In FIG. 2B, the light-emitting side optical system 23 includes a light-emitting element (preferably a semiconductor laser) 21, a beam splitter 34, and a combination lens 36. The light receiving side optical system 26 includes a combination lens 36, a beam splitter 34, a pinhole 35, and a light receiving element 25. The light emitted from the light emitting element 21 passes through the beam splitter 34, is collected by the combination lens 36, and irradiates the detected object 27 substantially vertically to form a light spot 28 on the detected object 27. . Reflected light from the light spot 28 is reflected and condensed by the beam splitter 34 in the direction perpendicular to the optical axis of the light-emitting side optical system 23, passes through the pinhole 35, and enters the light receiving element 25. The Also in this case, a housing (not shown) housing the light emitting side optical system 23 and the light receiving side optical system 26 is moved in the vertical direction (arrow direction) with respect to the detected object 27.

  In the light-emitting side optical system 23 shown in FIG. 2, the housing that is housed is moved in the vertical direction with respect to the detected object 27, but as described in detail in the second embodiment. Only the objective lens 22 or the combination lens 36 can be moved in the optical axis direction. In that case, control at the time of movement becomes easier as compared with the case of moving the housing.

  Incidentally, in the light receiving side optical system 26 shown in FIG. 2, a pinhole (desirably, a hole diameter of 100 μm or less) 35 is provided immediately before the light receiving element 25. Therefore, as shown in FIG. 3A, when the detected object 27 is in the vicinity of the in-focus position of the light-emitting side optical system 23, the reflected light is collected in the hole of the pinhole 35 and received. The amount of light incident on the element 25 (that is, the amount of light reflected from the light spot 28 on the detected object 27) increases. On the other hand, when the detected object 27 is not near the focus position of the light-emitting side optical system 23, the reflected light is condensed in a region wider than the hole diameter of the pinhole 35 as shown in FIG. Therefore, the amount of incident light is greatly reduced. Therefore, the focal position of the light-emitting side optical system 23 can be easily positioned near the surface of the detection object 27 based on the output of the light receiving element 25, and the S / N ratio of distance measurement by the output from the light receiving element 25 is improved. To do.

  Next, processing performed on the received light signal by the signal processing unit 29 in the optical object identification device including the light emitting side optical system 23 and the light receiving side optical system 26 having the above configuration will be described. As described above, the housing 30 is moved so that the detected object 27 is positioned near the position where the output from the light receiving element 25 is maximized, that is, near the focal position of the light emitting side optical system 23. After that, the detection object 27 is moved in the extending direction while the housing 30 is fixed at the position.

  At that time, as shown in FIG. 4A, the output signal from the light receiving element 25 is an output waveform corresponding to the surface state (surface irregularity) of the detected object 27 as the detected object 27 moves. Presents. Therefore, by performing signal processing on the output signal of the predetermined length section by the signal processing unit 29, compared to the case of identifying the type based on the amount of reflected light from the detected object as in the past, more correctly, The type of the detected object 27 can be identified.

  In this case, the processing method of the output signal includes an average value, an average amplitude value, an average amplitude value / average value, a frequency distribution, an area ratio of the power spectrum, a filter circuit passing through the output signal from the light receiving element 25. Any one of the signal processing methods for calculating the average value, the average amplitude value, and the average amplitude / average value of the subsequent waveform is used. Here, the average amplitude value is defined as a value obtained by calculating a difference between an individual output value and an average value in the output signal and doubling an average of absolute values of the calculated difference. Further, as shown in FIG. 4B, the area ratio of the power spectrum is obtained by performing a Fourier transform on the output signal to obtain a spectrum distribution, and the predetermined distribution range in the obtained spectrum distribution and another predetermined distribution range. Defined as area ratio. The frequency distribution is defined as a frequency distribution of each output value when the maximum output value is “1” as shown in FIG. In the following, each of the above signal processing methods is referred to as “average value calculation method”, “average amplitude value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method”, “power spectrum area”, respectively. The ratio calculation method and the filter pass method will be referred to.

  By the way, although it is possible to identify the type of the detected object 27 even if each of the signal processing methods is independently performed on the output signal from the one light receiving element 25, the type of the detected object 27 is determined. It may be difficult to identify all of them reliably. For example, as shown in FIG. 5, taking the case of using the “average value calculation method” as an example, the value varies depending on the type of the detected object 27, so that there are some that can be identified. However, it is difficult to identify with certainty in the case where the difference between the average values is small, such as type A and type C or type D and type E. Similarly, in the case of the above “average amplitude value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method”, “power spectrum area ratio calculation method”, “filter pass method” Whether or not the object 27 can be identified depends on its type.

  However, the above-mentioned “average value calculation method”, “average amplitude value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method”, “power spectrum area ratio calculation method”, and “filter pass method” If a plurality of calculated values are used, the identification accuracy of the type of the detected object 27 is improved. Therefore, the signal processing unit 29 in the present embodiment performs a plurality of these signal processing methods. The type of the detected object 27 is identified by combining these signal processing methods. By doing so, even if there are more types of detected objects 27, it becomes possible to identify the types with high accuracy.

  Further, instead of performing a plurality of the signal processing methods, the signal processing unit 29 performs the “average value calculation method”, “average amplitude” for a plurality of different sections accompanying the movement of the detected object 27 in the output signal. Signal processing is performed by at least one of “value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method”, “power spectrum area ratio calculation method”, and “filter pass method”, You may calculate the average value of the process result regarding this several area. Also in this case, the type of the detected object can be identified more accurately than in the case of only the processing result relating to one section.

  As described above, in the present embodiment, the light emitting side optical system 23 and the light receiving side optical system 26 are accommodated in a housing 30 that is movable in the vertical direction (arrow direction) with respect to the detected object 27. . Therefore, when the housing 30 is moved and the detected object 27 is positioned near the focus position of the light-emitting side optical system 23, the output of the light receiving element 25 is maximized. That is, according to the optical object identification device of the present embodiment, the housing 30 is moved in the vertical direction with respect to the detected object 27 until the output of the light receiving element 25 is maximized, and then fixed at that position. By the processing unit 29, the “average value calculation method”, “average amplitude value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method”, “ A combination of a plurality of signal processing of “power spectrum area ratio calculation method” and “filter pass method”, or any one signal for a plurality of different sections associated with movement of the detected object 27 in the output signal. By averaging the signals processed by the processing method, a plurality of types in the detected object 27 can be accurately identified with a high S / N ratio.

  Further, by providing the pinhole 35 immediately before the light receiving element 25 in the light receiving side optical system 26, it is possible to detect the time when the output of the light receiving element 25 becomes maximum more accurately.

  Further, the amount of displacement of the housing 30 from the reference position is detected by moving the housing 30 in the direction perpendicular to the object 27 (in the direction of the arrow) and detecting the position where the output from the light receiving element 25 is maximized. That is, the thickness of the detected object 27 can be measured. Therefore, by using this thickness information, the type of the ratio detection object 27 can be identified with higher accuracy.

  Although not shown, a plurality of different output patterns from the signal processing unit 29 can be obtained by providing a plurality of the light emitting side optical system 23 or the light receiving side optical system 26 so as to have different incident angles or reflection angles. Can do. Therefore, by using the output pattern information, it is possible to identify the type of the ratio detection object 27 with higher accuracy.

Second Embodiment FIG. 6 is a schematic configuration diagram of an optical system in the optical object identification device of the present embodiment. The optical object identification apparatus includes a light emitting side optical system 45 including a light emitting element (preferably a semiconductor laser) 41, a collimating lens 42, a movable objective lens 43 and an objective lens driving unit 44, a light receiving lens 47 and a light receiving element 48. Including a light receiving side optical system 49. Then, a light spot 51 having a predetermined spot diameter (50 μm or less) is formed on the detected object 50 by irradiating the detected object 50 with light emitted from the light emitting side optical system 45, and this light spot 51 The reflected light from the light enters the light receiving side optical system 49. Further, the incident light to the light receiving side optical system 49 is condensed by the light receiving lens 47 and is incident on the light receiving element 48. The signal processing unit 52 performs various processes on the signal corresponding to the amount of received light output from the light receiving element 48 as in the case of the first embodiment.

  The movable objective lens 43 is moved in the optical axis direction (arrow direction) by the objective lens driving unit 44. Here, the objective lens driving unit 44 is an actuator using electromagnetic force as a driving force, and moves the movable objective lens 43 in the optical axis direction in accordance with a control signal from the drive control unit 46. The light receiving element 48 is a position detection element (preferably PSD (position sensor)), and in the present embodiment, the distance to the detected object 50 is measured by triangulation. The light emitting side optical system 45, the light receiving side optical system 49, the drive control unit 46, and the signal processing unit 52 are housed in a housing 53.

FIG. 7 shows the principle of the triangulation. In FIG. 7, angles α, β formed by two sides AC, BC and side AB connecting two points A, B, which are end points of one side of the triangle, and point C on the object, and two points A, B, If the distance D between B is known, the distance L between the side AB and the object C is given by
L = D {(sin α · sin β) / sin (α + β)}
Can be calculated by: Here, the point A in FIG. 7 is assumed to be the center of the movable objective lens 43, the point B is assumed to be the center of the light receiving lens 47, and the point C is assumed to be a point on the surface of the detected object 50. Then, the values corresponding to α and D are known from the irradiation angle of the light-emitting side optical system 45 and the arrangement of the components constituting the light-emitting side optical system 45 and the light-receiving side optical system 49. Therefore, if the value of β is calculated from the incident position of the reflected light to the light receiving element 48, the distance L between the detected object 50 and the housing 53 can be calculated by the above formula.

  Here, assuming that the light receiving element 48 is a PSD, the signal processing unit 52 can measure the incident position on the PSD based on the ratio of outputs from, for example, two places on the PSD. Therefore, by obtaining a line segment connecting the incident position on the PSD and the center B of the light receiving lens 47, the value of β can be calculated, and the center of the movable objective lens 43 and the center of the light receiving lens 47 can be calculated. A distance L (hereinafter referred to as a distance between the housing 53 and the detected object 50) L between the passing reference line and the detected object 50 can be calculated.

  That is, in the present embodiment, the objective lens driving unit 44 constitutes the focal position moving unit, and the signal processing unit 52 constitutes the distance measuring unit.

When the distance L between the housing 53 and the detected object 50 is obtained by the signal processing unit 52 as described above, the drive control unit 46 positions the surface of the detected object 50 at the focal position of the light-emitting side optical system 45. In this case, a difference ΔL between the distance L ₀ between the detected object 50 and the housing 53 and the distance L is calculated. The distance L ₀ can be calculated because the focal length and the angle α of the light-emitting side optical system 45 are known.

  Further, the drive control unit 46 outputs a control signal that makes the value of the difference ΔL zero to the objective lens drive unit 44. Then, the movable objective lens 43 is moved in the direction according to the control signal by the objective lens driving unit 44. When the value of the difference ΔL becomes zero and the surface of the detection object 50 is positioned at the focal position of the light-emitting side optical system 45, the objective lens driving unit 44 is stopped. In this way, by setting the position of the movable objective lens 43 so that the focal position of the light-emitting side optical system 45 is positioned on the surface of the detection object 50, the size variation of the light spot 51 can be suppressed, As the detected object 50 moves, the S / N ratio of the waveform corresponding to the surface state (surface irregularity) of the detected object 50 appearing in the output signal of the light receiving element 48 is improved. As a result, the detection accuracy of the type of the detection object 50 is improved. When the light receiving element 48 is configured by PSD, the signal processing unit 52 may perform signal processing using the sum of outputs from, for example, two places on the PSD as an output waveform of the received light signal.

  Next, a specific configuration example of the housing 53 will be described with reference to FIG. 8A is a side view of the housing 53, and FIG. 8B is a front view taken along the line AA 'in FIG. 8A. In the upper part of the housing 53, a guide groove 54 of the detected object 50 opened toward one side is provided. Further, on the one side of the housing 53, a light emitting side optical system housing groove 56 for housing the light emitting side optical system 45 and a light receiving side optical system housing groove 57 for housing the light receiving side optical system 49 are provided. Then, the light emitting side optical system 45 housed in the light emitting side optical system housing groove 56 irradiates light to the detected object 50 sent out by the transport roller 55 and moving in the guide groove 54. On the other hand, the reflected light from the object to be detected 50 enters the light receiving side optical system 49 housed in the light receiving side optical system housing groove 57.

  In addition, a rectangular recess 58 communicating with the guide groove 54 is formed at the formation position of the light spot 51 on the opposite side of the light emitting side optical system storage groove 56 and the light receiving side optical system storage groove 57 with respect to the guide groove 54. An antireflection film 59 or an antireflection sheet is formed on the upper surface of the recess 58 in the drawing. In this way, part of the light emitted from the light-emitting side optical system 45 is reflected by the upper surface of the concave portion 58 and is prevented from entering the light-receiving side optical system 49 as pseudo-reflected light. As a result, the SN ratio of the output waveform of the light receiving element 48 is further improved.

  In the above description, the type of the detected object 50 is determined. However, it is also possible to measure the thickness of the detected object 50 by applying the above-described distance measuring technique to the detected object 50. . Further, by using the thickness information of the object 50 to be detected, it is possible to perform type identification with higher accuracy.

Thus, in the present embodiment, the movable objective lens 43 that is moved in the optical axis direction by the objective lens driving unit 44 according to the control signal from the drive control unit 46 is provided as the light emitting side optical system 45. ing. Further, the signal processing unit 52 calculates the distance L from the reference line to the detected object 50 using the principle of triangulation, and outputs it to the drive control unit 46. Therefore, the difference between the distance L ₀ from the reference line to the detected object 50 and the distance L when the surface of the detected object 50 is located at the focal position of the light emission side optical system 45 by the control by the drive control unit 46. Based on ΔL, the movable objective lens 43 is moved until the detected object 50 is located in the vicinity of the in-focus position of the light-emitting side optical system 45 and then fixed at that position. Then, the signal processing unit 52 performs the above “average value calculation method”, “average amplitude value calculation method”, “average amplitude / average value calculation method”, “frequency distribution calculation method” for the output signal from the light receiving element 48. ”,“ Power spectrum area ratio calculation method ”and“ filter pass method ”, or a combination of a plurality of signal processes, or for a plurality of different sections accompanying the movement of the detected object 50 in the output signal. By averaging the signals processed by one signal processing method, a plurality of types in the detected object 50 can be accurately identified with a high S / N ratio.

  The position of the objective lens can be adjusted by the method shown in FIG. 9 in addition to the method using the movable objective lens 43 and the objective lens driving unit 44. That is, the light-emitting side optical system including the light-emitting element 61 and the objective lens 62 is integrally stored in the light-emitting side optical system storage unit 63. Then, the light-emitting side optical system housing part 63 extends in a direction perpendicular to a plane that passes through the position of the light-emitting point 64 of the light-emitting element 61 and includes the optical axis of the light-emitting side optical system and the optical axis of the light-receiving side optical system 67. It is attached to the housing 70 so as to be rotatable about an existing rotation axis. By doing so, the focal position 69 of the light emitting side optical system approaches or moves away from the housing 70 as the light emitting side optical system housing 63 is rotated by the light emitting side optical system rotation drive unit (not shown). can do. Therefore, in this case, the focus position of the light emitting side optical system can be positioned near the surface of the detected object 68 by control based on the value of the difference ΔL by a drive control unit (not shown).

  At that time, the light-emitting side optical system including the light-emitting element 61 and the objective lens 62 is integrally stored in the light-emitting side optical system storage unit 63. Therefore, the optical axis of the light emitting side optical system can be easily adjusted. Incidentally, 65 is a light receiving lens, and 66 is a light receiving element.

Third Embodiment The present embodiment relates to a printing apparatus such as a printer or a copier equipped with the optical object identification device in each of the above embodiments.

  FIG. 10 shows a concept relating to detection object type identification and control in the printing apparatus. The optical object identification device 91 has any configuration of the optical object identification device in the first and second embodiments. Then, under the control of the control unit 92, as described above, signal processing is performed on the output signal from the light receiving element based on the reflected light from the moving object 93 to be detected, and a signal indicating the processing result Is transmitted to the control unit 92.

  Then, the control unit 92 identifies the type of the detected object 93 based on the signal from the optical object identification device 91, and sends a control signal for performing processing according to the identification result to the processing unit 94. To do. And the process according to the said control signal is performed by the process part 94. FIG. For example, when the printing apparatus is an inkjet printer, the control unit 92 identifies the type of paper that is the object to be detected 93, and the processing unit 94 prints the ink amount suitable for the identified type of paper. The conditions are optimized. Thus, the print quality can be improved.

  At that time, as described in the first and second embodiments, the optical object identification device 91 sets the focal position of the light-emitting side optical system so as to be on the surface of the detected object 93. It is possible. The signal processing unit performs signal processing using a plurality of different signal processing methods. Therefore, the signal-to-noise ratio of the waveform corresponding to the surface state (surface irregularity) of the detected object 93 appearing in the output signal of the light receiving element with the movement of the detected object 93 can be improved, and the detected object 93 is more accurately detected. The type can be identified.

  That is, according to the printing apparatus equipped with the optical object identification device 91, the printing conditions can be further optimized, and the printing quality can be further improved.

  The optical object identification device of the present invention is useful when detecting the type of an object in a non-contact manner, and can be used for a printing device or an object type classification device.

It is a schematic block diagram of the optical system in the optical object identification device of this invention. It is a figure which shows the structural example different from FIG. 1 of the light emission side optical system and light reception side optical system in FIG. It is a figure for demonstrating the function of the pinhole in FIG. It is explanatory drawing of the signal processing by the output signal waveform from the light receiving element in FIG. 1, and a signal processing part. It is a figure which shows the average value of the output signal in multiple types of to-be-detected object. It is a schematic block diagram of the optical system in the optical object identification device different from FIG. It is a figure which shows the principle of triangulation. It is a figure which shows the specific structural example of the housing in FIG. It is explanatory drawing of the position adjustment method of the objective lens different from FIG. It is a figure which shows the concept in the printing apparatus of this invention. It is explanatory drawing of the paper type detection apparatus as an example of the conventional object identification apparatus. It is explanatory drawing of the identification device of the recording medium as an example of the conventional object identification device.

Explanation of symbols

21, 41, 61 ... light emitting element,
22, 62 ... objective lens,
23, 45 ... Light-emitting side optical system,
24, 47, 65 ... light receiving lens,
25, 48, 66 ... light receiving element,
26, 49, 67 ... optical system on the light receiving side,
27, 50, 68 ... detected object,
28,51 ... light spot,
29, 52 ... signal processing unit,
30, 53, 70 ... housing,
31 ... Drive device,
32, 46 ... drive control unit,
33,42 ... collimating lens,
34 ... Beam splitter,
35 ... pinhole,
36 ... Combination lens,
43. Movable objective lens,
44 ... Objective lens drive unit,
54 ... Guide groove,
59 ... Antireflection film,
63... Light emitting side optical system housing,
64 ... luminous point,
69 ... the focal position of the light-emitting side optical system,
91 ... Optical object identification device,
92 ... control unit,
94: Processing unit.

Claims (14)

At least one light-emitting side optical system that includes a light-emitting element and an objective lens, and irradiates a moving object to be detected with light from the light-emitting element to form a light spot on the object to be detected;
A light-receiving lens and a light-receiving element, and at least one light-receiving-side optical system that outputs reflected light from the light spot to the light-receiving element and outputs an output signal having a waveform corresponding to the surface unevenness of the object to be detected; ,
A focal position moving unit that moves the focal position of the light emitting side optical system;
Drive control for controlling the operation of the focal position moving unit based on the output signal output from the light receiving side optical system and setting the focal position of the light emitting side optical system so that the value of the output signal is maximized And
An optical object identification device comprising a signal processing unit for performing signal processing on an output signal output from the light receiving side optical system. At least one light-emitting side optical system that includes a light-emitting element and an objective lens, and irradiates a moving object to be detected with light from the light-emitting element to form a light spot on the object to be detected;
A light-receiving lens and a light-receiving element, and at least one light-receiving-side optical system that outputs reflected light from the light spot to the light-receiving element and outputs an output signal having a waveform corresponding to the surface unevenness of the object to be detected; ,
A focal position moving unit that moves the focal position of the light emitting side optical system;
Based on an output signal output from the light receiving side optical system, a distance measuring unit that measures a distance between a reference line passing through the center of the objective lens and the center of the light receiving lens and the object to be detected;
Based on the measurement result by the distance measuring unit, the operation of the focal position moving unit is controlled, and the focal position of the light emitting side optical system is set so that the surface of the object to be detected is positioned at the focal position of the light emitting side optical system. A drive control unit to be set;
An optical object identification device comprising a signal processing unit for performing signal processing on an output signal output from the light receiving side optical system. In the optical object identification device according to claim 1 or 2,
An optical object identification device, wherein the light emitting element is a semiconductor laser. In the optical object identification device according to claim 1 or 2,
The focus position moving unit is composed of a light emitting side optical system moving unit that moves at least the entire light emitting side optical system in a direction perpendicular to the object to be detected. apparatus. In the optical object identification device according to claim 1 or 2,
The focal position moving unit is
A movable objective lens in which the position of the objective lens is movable in the optical axis direction;
An optical object identification device comprising an objective lens driving unit that moves the movable objective lens in the optical axis direction. In the optical object identification device according to claim 1 or 2,
The focal position moving unit passes the entire light emitting side optical system through a position of a light emitting point of the light emitting element and is perpendicular to a plane including the optical axis of the light emitting side optical system and the optical axis of the light receiving side optical system. An optical object identification device comprising a light-emitting side optical system rotation drive unit that rotates about a rotation axis extending in a direction. The optical object identification device according to claim 5 or 6,
An optical object identification device characterized in that the driving force of the objective lens driving unit or the light emitting side optical system rotation driving unit is an electromagnetic force. In the optical object identification device according to claim 2,
The light receiving element is a position detecting element. The optical object identification device according to claim 8,
Optical object identification, wherein the distance measurement unit measures the distance between the reference line and the object to be detected based on a ratio of a plurality of outputs from the position detection element. apparatus. The optical object identification device according to claim 8,
The optical object identification device, wherein the signal processing unit is configured to perform signal processing on the sum of a plurality of output signals from the position detection element. In the optical object identification device according to claim 1 or 2,
The signal processing unit, for a section of a predetermined time length in the output signal,
Average value calculation method for calculating the average value of each output value,
The difference between each output value and the above average value is calculated, and the average amplitude value calculation method for doubling the average value of the absolute value of this difference,
Average amplitude value / average value calculation method for calculating average amplitude value / average value,
A frequency distribution calculation method for obtaining a frequency distribution of each output value with the maximum value being 1,
A power spectrum area ratio calculation method for obtaining a spectrum distribution by performing Fourier transform and obtaining an area ratio between different distribution ranges in the spectrum distribution,
A filter passing method for calculating at least one of the average value, the average amplitude value, and the average amplitude / average value after passing through the filter circuit;
An optical object identification device that performs signal processing by at least one signal processing method. The optical object identification device according to claim 11,
The signal processing unit includes a plurality of signal processing methods among the average value calculation method, the average amplitude value calculation method, the average amplitude / average value calculation method, the frequency distribution calculation method, the power spectrum area ratio calculation method, and the filter pass method. An optical object identification device characterized by performing signal processing. The optical object identification device according to claim 11,
The signal processing unit is configured to calculate the average value calculation method, average amplitude value calculation method, average amplitude / average value calculation method, frequency distribution calculation for a plurality of different sections associated with movement of the detection object in the output signal. An optical system characterized in that signal processing is performed by at least one of a method, a power spectrum area ratio calculation method, and a filter pass method, and an average value of processing results for the plurality of sections is calculated. Object identification device.   A printing apparatus comprising the optical object identification device according to any one of claims 1 to 13.

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