JP2007062222A - Recording device and method of detecting recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording device which can accurately detect a variety of recording mediums while using an inexpensive and small-size sensor, and a recording medium detection method applied to the device. <P>SOLUTION: The recording device which records images by running a recording head in the direction nearly at right angles with the transfer direction of recording paper, comprises a reflection type sensor integrally with a plurality of light receiving elements and a plurality of light receiving elements on a carriage equipped with the recording head. The recording device casts light to the recording paper and detects the end position of the recording paper or the distance to the recording paper on the basis of the output signal level of specualrly reflected light or diffusedly reflected light obtained from the light receiving elements. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus and a recording medium detection method, and more particularly to a recording apparatus including a recording head that performs recording according to an inkjet method, and a recording medium that optically detects the position and thickness of the recording medium applied to the apparatus. It relates to a detection method.

  Conventional ink jet recording apparatuses (hereinafter referred to as recording apparatuses) have been equipped with sensors for various purposes in order to improve image quality, increase accuracy, and improve user convenience. Examples of the sensor include a sensor for detecting the width of the recording paper set in the apparatus, a sensor for measuring the density of a patch recorded on the recording paper, and a sensor for detecting the thickness of the recording paper.

  As a sensor for detecting the width of the recording paper, a reflection type sensor constituted by one light emitting element and one light receiving element is used, and a method of detecting the edge of the recording paper by a change in reflection intensity is generally used. is there.

  A sensor for detecting the thickness of the recording paper is composed of a light emitting element such as an LED or a semiconductor laser and a light receiving element such as a PSD (position detecting element) or a CCD. Light emitted from the light emitting element is reflected by the measurement object, and a part of the reflected light is received by the light receiving element. When the distance between the sensor and the measurement object changes, the position of the optical axis of the reflected light received by the light receiving element changes. When the light receiving element is a CCD, the amount of light can be measured for each pixel, so that the peak pixel can be detected and the distance between the sensor and the measurement object can be calculated from the position by triangulation. When the light receiving element is a PSD, the center position is detected by calculating two output values output by the change in the position of the optical axis of the reflected light received by the light receiving element, and the sensor is detected by triangulation from that position. The distance to the measurement object can be calculated. At this time, the reflected light includes irregular reflection and regular reflection, and the reflection state differs depending on the paper type.

  As an example of conventional paper detection, there is one in which the reflection state of a recording paper is detected using an optical sensor and the paper type is determined (for example, see Patent Document 1). In addition, there is one that detects the paper width using an optical sensor (see, for example, Patent Document 2).

In Patent Document 1, an optical sensor is provided to discriminate the type of recording medium and to correspond to image forming conditions. FIG. 13 shows a sheet provided with a light emitting unit 11 that emits the irradiation light L ₀ irradiated on the sheet P disclosed in Patent Document 1, and a light receiving unit 12 that detects the reflected scattered light _LDR reflected from the sheet. A detection sensor is shown. Then, the paper is discriminated by the judging means for discriminating the paper based on the output level from the paper detection sensor. In FIG. 13, L _RR is regular reflected light, L _DP is transmitted scattered light, and L _RP is regular transmitted light. Θ ₀ is the incident angle of the irradiation light with respect to the vertical direction of the paper P, and θ _ν is the scattering angle of the reflected scattered light with respect to the vertical direction of the paper P.

  According to Patent Document 2, as shown in FIG. 14, an infrared sensor 24 is disposed on the side surface of the carriage 12 of the recording apparatus. In particular, the sensor is provided on the downstream side B1 in the conveyance direction B of the recording paper 20 with respect to the recording area S1 of the recording head. Therefore, by simply transporting the recording paper 20 to the downstream side B1 in the transport direction B (without transporting it in the reverse direction), it is possible to detect the paper width before recording and to form a quick image.

In FIG. 14, 14BK, 14C, 14Y, and 14M are recording heads that discharge black ink, cyan ink, yellow ink, and magenta ink, respectively, and 15 is a nozzle row that includes a plurality of nozzles that discharge these inks. . Further, arrow A is the carriage scanning direction, C1 is the field circle of the infrared sensor 24, D1 is the diameter of the field circle, and L2 is the distance from the center of the field of view to the upstream end of the recording area S1. Further, L1 is the distance from the upstream end of the recording area S1 to the leading edge of the recording paper 20, and L5 is the distance between the visual field center of the infrared sensor 24 and the visual field center of the color density sensor 28.
Japanese Unexamined Patent Publication No. 4-77649 (page 8, FIG. 1) JP 2002-331648 A (page 11, FIG. 5)

  However, in the above-described conventional example, the sensors for detecting the characteristics of the recording paper, the paper edge, and the distance are greatly different from each other, and it is difficult to integrate these sensors. In addition, since each sensor uses complicated optical systems and expensive elements, there is a problem that an apparatus for mounting these sensors becomes large in size and expensive. It was.

  In order to solve such a problem, there is a method in which a light receiving sensor is arranged in accordance with the angle of regular reflection, and both regular reflected light / diffuse reflected light (diffuse reflected light) are received by the same light receiving sensor. However, in this configuration, when the carriage is moved up and down in accordance with the distance from the detected recording paper for optimal recording, the detection using the irregularly reflected light is performed at the same paper edge position depending on the height of the carriage. The detection position will be different. That is, the paper edge detection is not accurate.

  Since the characteristics of the surface of the recording paper differ depending on the type of recording paper, the reflection characteristics of regular reflection light / diffuse reflection light differ depending on the paper type. For this reason, some types of recording paper need to use diffusely reflected light, but there is a problem that the accuracy of detecting the paper edge is not uniform depending on the type of paper.

  The present invention has been made in view of the above-described conventional example, and provides a recording apparatus capable of accurately detecting various types of recording media while using an inexpensive and small sensor, and a recording medium detection method applied to the apparatus. It is intended to provide.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a recording apparatus that records an image on a recording medium using a recording head, the conveying unit conveying the recording medium in a first direction, and the second direction perpendicular to the first direction. Scanning means for reciprocating a recording head, a first light emitting element mounted on the scanning means together with the recording head, for irradiating the recording medium with light at a first angle, and light for the recording medium Receiving a second light emitting element that emits light at a second angle, regular reflection light emitted from the first light emitting element and reflected by the recording medium, and irregular reflection light emitted from the second light emitting element and received by the recording medium First and second light receiving elements provided apart from each other with respect to the first direction and a third direction from the recording head to the recording medium perpendicular to the first and second directions. From the recording medium Measurement means for measuring incident light, output signals from the first and second light receiving elements when the specularly reflected light is received, and the first and second light receiving elements when the reflected light is received A comparison means for comparing the output signals of the recording medium and the type of the recording medium according to the comparison result by the comparison means, and according to the determination result, the thickness of the recording medium and the edge of the recording medium are detected. The selection means for selecting whether to use reflected light or the irregularly reflected light, and the recording medium and the measuring means are relatively moved by the conveying means or the scanning means, and the first and second light receiving light Detection means for detecting the end of the recording medium based on a change in the output signal obtained from the element, and detecting the thickness of the recording medium based on a function generated by the output signals from the first and second light receiving elements And Characterized in that it.

  Further, a platen provided on a plane including the first direction and the second direction, and calibration means for calibrating the absolute position of the edge detection position of the recording medium with the platen as a reference position. It is desirable to have.

  Further, the detecting means is a distance from the measuring means to the platen obtained by the measuring means emitting light to the platen and a distance from the measuring means to the recording medium obtained by emitting the measuring means to the recording medium. The thickness of the recording medium is obtained from the difference between the two.

  Further, when the selection means selects that the irregularly reflected light is used for detecting the thickness of the recording medium and the edge of the recording medium, the edge detection position is determined based on the distance from the measuring means to the recording medium. It is desirable to provide correction means for correcting the above.

  The first light emitting element is an infrared LED, the second light emitting element is a visible LED, and the first and second light receiving elements are first and second phototransistors, respectively. Is desirable.

  In this case, the output signals from the first and second phototransistors change according to the distance from the measuring means to the recording medium or the reflecting surface of the platen, respectively, and that distance of the output signals from the first and second phototransistors. The changes that follow are different from each other.

  Here, it is preferable that the function generated by the output signals from the first and second light receiving elements is a ratio of the difference and sum of the output signals from the first and second phototransistors.

  On the other hand, the output signals from the first and second phototransistors also change according to the relative positions of the measuring means with respect to the recording medium, and the changes in the output signals from the first and second phototransistors They are separated from each other in the transport direction.

  It is preferable that the first angle is 45 ° and the second angle is 90 °.

  According to another aspect of the present invention, the recording head includes a conveying unit that conveys the recording medium in a first direction and a scanning unit that reciprocally moves the recording head in a second direction perpendicular to the first direction. A recording medium detection method of a recording apparatus for recording an image on the recording medium using the recording medium, wherein the recording medium is conveyed by the conveying means, and is mounted on the scanning means together with the recording head. A first light emitting element that emits light at a first angle; a second light emitting element that emits light at a second angle to the recording medium; and the recording medium that is irradiated from the first light emitting element. The first head and the first and second directions perpendicular to the first direction and the first and second directions receive the specularly reflected light and the irregularly reflected light emitted from the second light emitting element, and are sent from the recording head to the recording medium. With respect to the third direction of A measurement step of measuring the reflected light from the recording medium by irradiating the recording medium with light using an optical sensor integrally provided with first and second light receiving elements provided separately from each other The output signals from the first and second light receiving elements when the regular reflected light is received are compared with the output signals from the first and second light receiving elements when the reflected light is received. According to the comparison step and the comparison result in the comparison step, the type of the recording medium is determined, and according to the determination result, the specular reflected light is used to detect the thickness of the recording medium and the edge of the recording medium, or A selection step for selecting whether to use the irregularly reflected light; and an end portion of the recording medium that is measured in the measurement step and that is obtained from the first and second light receiving elements, and that changes the end of the recording medium. Output from second light receiving element A recording medium detection method characterized by having a detection step of detecting the thickness of the recording medium based on the function generated by JP.

  Therefore, according to the present invention, the regular reflection light and the irregular reflection light of the recording medium are measured by the measuring means integrally including the plurality of light emitting elements and the plurality of light receiving elements, and the thickness and the edge of the recording medium are detected. There is an effect that can be.

  As a result, the thickness and edge of the recording medium can be detected while realizing cost reduction and downsizing of the apparatus. Further, it is possible to select regular reflection light or irregular reflection light according to the type of the recording medium, and to detect the thickness and the edge of the recording medium with appropriate reflected light.

  In addition, since detection is performed using output signals from two light receiving elements provided apart from each other in the conveyance direction of the recording medium and the distance direction to the recording medium, adverse effects on the detection accuracy that have entered the two output signals are offset. Thus, more accurate detection can be performed.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) does not represent only the case of forming significant information such as characters and graphics. In addition to this, an image, a pattern, a pattern, or the like is widely formed on a recording medium regardless of whether it is significant involuntary, or whether it is manifested so that a human can perceive it visually, or It also represents the case where the medium is processed.

  “Recording media” (sometimes referred to as “recording paper” or “media”) includes not only paper used in general recording apparatuses but also a wide range of fabrics, plastic films, metal plates, glass, ceramics. , Wood, leather, etc., which can accept ink.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. That is, by being applied on the recording medium, it is used for forming an image, pattern, pattern, etc., processing the recording medium, or processing the ink (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

<Description of Inkjet Recording Apparatus (FIG. 1)>
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus which is a typical embodiment of the present invention.

  As shown in FIG. 1, a multi-purpose sensor 102 and a recording head 103 are mounted on the carriage 101, and reciprocatingly scans on the shaft 105 by the conveyance belt 104. Here, the scanning direction of the carriage 101 is the X direction. On the other hand, for example, a recording medium such as the recording paper 106 is conveyed on the platen 107 by a conveying roller (not shown). The conveyance direction of the recording paper 106 at this time is defined as the Y direction. A direction perpendicular to the XY plane formed by the X direction and the Y direction is taken as a Z direction. Here, in the illustrated XYZ arrows, the respective directions are defined as upstream, and the opposite side is defined as downstream.

  During the recording operation, ink droplets are ejected from the recording head 103 while the carriage 101 scans in the X direction on the recording paper 106 conveyed on the platen 107 by the conveying rollers. When the carriage 101 scans to the end of the recording paper 106, the transport roller transports a certain amount of recording paper 106 and positions the area for the next recording scanning on the platen 107. By repeating this operation, an image is formed on the recording paper 106. The measurement area of the multi-purpose sensor 102 is positioned downstream of the recording position of the recording head 103 in the Y direction, and the lower surface of the sensor 102 is disposed at the same position as or higher than the lower surface of the recording head 103. By providing the multipurpose sensor 102 at such a position, the width of the recording medium can be detected before recording, and a recording operation can be performed without transporting the recording medium in the reverse direction.

  FIG. 2 is a configuration diagram of the multipurpose sensor 102.

  2A is a plan view, and FIG. 2B is a side view.

  The multipurpose sensor 102 is integrally provided with two phototransistors, three visible LEDs, and one infrared LED as optical elements, and each element is driven from an external circuit (not shown). These elements are all bullet-type elements (general production type of φ3.0 to 3.1 size) having a maximum diameter of about 4 mm.

  The infrared LED 201 has an irradiation angle of 45 degrees with respect to the surface (hereinafter referred to as measurement surface) of the recording paper 106 parallel to the XY plane, and the irradiation light center (irradiation axis) is the normal line (Z axis) of the measurement surface. It is arranged so as to intersect the parallel sensor central axis 202 at a predetermined position. The position from the sensor up to this intersection is called the reference position. The width of the irradiation light of the infrared LED 201 is adjusted by the opening and is optimized so as to form an irradiation surface having a diameter of about 4 to 5 mm on the measurement surface at the reference position.

  The phototransistors 203 and 204 are sensitive to light having wavelengths from visible light to infrared light. When the measurement surface is at the reference position, the light receiving axis of the phototransistors 203 and 204 is parallel to the reflection axis of the infrared LED 201, and the light receiving axis of the phototransistor 203 is moved by +2 mm in the X direction and +2 mm in the Z direction. It arrange | positions so that it may become. Similarly, the light receiving axis of the phototransistor 204 is arranged so as to be moved to -2 mm in the X direction and -2 mm in the Z direction.

  When the measurement surface is at the reference position, the intersection between the measurement surface and the irradiation axes of the infrared LED 201 and the visible LED 205 coincides, but the light receiving regions of the phototransistors 203 and 204 at this position are formed so as to sandwich the intersection. A spacer having a thickness of about 1 mm is sandwiched between the two elements, and the light received from each other is prevented from entering. An opening is also provided on the phototransistor side in order to limit the light incident range, and the size is optimal so that only reflected light in the range of 3 to 4 mm in diameter on the measurement surface at the reference position can be received. It becomes.

  In FIG. 2, reference numeral 205 denotes a monochromatic visible LED having a green emission wavelength (about 510 to 530 nm), and is installed so as to coincide with the sensor central axis 202.

  Reference numeral 206 denotes a monochromatic visible LED having a blue emission wavelength (about 460 to 480 nm), which is located at a position moved +2 mm in the X direction and −2 mm in the Y direction with respect to the visible LED 205 as shown in FIG. The LED 206 is disposed so as to intersect the light receiving axis of the phototransistor 203 at the intersection between the irradiation axis and the measurement surface when the measurement surface is at the reference position.

  Reference numeral 207 denotes a single-color visible LED having a red emission wavelength (about 620 to 640 nm), and is located at a position shifted by −2 mm in the X direction and +2 mm in the Y direction with respect to the visible LED 205 as shown in FIG. When the measurement surface is at the reference position, the LED 207 is disposed so as to intersect the light receiving axis of the phototransistor 204 at the intersection of the irradiation axis and the measurement surface.

  FIG. 3 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 3, the controller 600 includes an MPU 601, a ROM 602, a special purpose integrated circuit (ASIC) 603, a RAM 604, a system bus 605, an A / D converter 606, and the like. Here, the ROM 602 stores a program corresponding to a control sequence to be described later, a required table, and other fixed data. The ASIC 603 generates control signals for controlling the carriage motor M1, the transport motor M2, and the recording head 103. The RAM 604 is used as a development area for image data, a work area for program execution, and the like. A system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data. The A / D converter 606 inputs analog signals from the sensor group described below, performs A / D conversion, and supplies a digital signal to the MPU 601.

  In FIG. 3, reference numeral 610 denotes a computer (or an image reading reader, digital camera, or the like) serving as an image data supply source, and is collectively referred to as a host device. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 610 and the recording apparatus 1 via an interface (I / F) 611.

  Reference numeral 620 denotes a switch group, which includes a power switch 621, a print switch 622, a recovery switch 623, and the like. The print switch 622 is used for instructing the start of printing. The recovery switch 623 is used to instruct the start of processing (recovery processing) for maintaining the ink ejection performance of the recording head 3 in a good state. These switches are used to receive command inputs from the operator.

  Reference numeral 630 denotes a sensor group for detecting the apparatus state, and includes the multi-purpose sensor 102, the position sensor 631, the temperature sensor 632, and the like. The position sensor 631 is a sensor for detecting a home position h such as a photocoupler, and the temperature sensor 632 is a sensor provided at an appropriate position of the recording apparatus and used for detecting an environmental temperature.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, and 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the recording medium P. Further, reference numeral 644 denotes a carriage substrate mounted on the carriage 2, which electrically connects the recording head 3 to supply power from the recording apparatus and transfer an image signal and a control signal.

  FIG. 4 is a block diagram showing a detailed configuration of a control circuit related to the input / output signal processing of the multipurpose sensor. In FIG. 4, the same components as those already described are denoted by the same reference numerals.

  The MPU 601 outputs an on / off control signal for the infrared LED 201 and the visible LEDs 205 to 207 and calculates an output signal obtained according to the amount of light received from the phototransistors 203 and 204. The drive circuit 302 receives an ON signal sent from the MPU 601 and supplies a constant current to each LED to emit light. On the other hand, the I / V conversion circuit 303 converts the current value of the output signal from the phototransistors 203 and 204 into a voltage value. Then, the amplifier circuit 304 amplifies the minute output signal converted into the voltage value to an optimum level in the A / D conversion. The A / D conversion circuit 606 converts the output signal amplified by the amplification circuit 304 into a 10-bit digital value and inputs the converted signal to the MPU 601. This digital signal is temporarily stored in the RAM 604.

  Note that a ROM 602 stores a reference table necessary for a recording medium detection process, which will be described later, and the MPU 601 reads the information to the RAM 604 as necessary.

  Next, a procedure for detecting the distance to the recording sheet 106 using the multipurpose sensor 102 provided in the recording apparatus having the above configuration will be described.

  When the recording sheet 106 is conveyed onto the platen by the conveying roller, the multipurpose sensor 102 is conveyed to the recording sheet 106 and the infrared LED 201 is turned on. The light emitted from the infrared LED 201 is reflected by the measurement surface, and the phototransistors 203 and 204 receive a part of the reflected light. The outputs of the phototransistors 203 and 204 change in relation to the area where the irradiation region of the infrared LED 201 and the light receiving region of the phototransistors 203 and 204 change depending on the distance to the measurement surface.

  FIG. 5 shows changes in the positions of the irradiation region and the light receiving region that change depending on the distance from the sensor 102 to the measurement surface. In FIG. 5, reference numeral 501 denotes an irradiation region of the infrared LED 201, 502 denotes a light receiving region of the phototransistor 203, and 503 denotes a light receiving region of the phototransistor 204.

  FIG. 6 is a diagram showing two phototransistor output fluctuations depending on the distance (SGD) from the sensor to the measurement surface. In FIG. 6, “a” represents the output of the phototransistor 203, and “b” represents the output of the phototransistor 204.

  As can be seen from FIG. 5, the centers of the light receiving areas 502 and 503 are off the center of the irradiation area 501. For this reason, compared with the sensor arrangement that measures the position where the light receiving area passes through the center of the irradiation area, the sensor arrangement of this embodiment has a large overlap between the light receiving areas 502 and 503 due to slight fluctuations in the distance from the sensor to the measurement surface. Change.

  FIG. 5A shows how the irradiation region 501 overlaps with the light receiving regions 502 and 503 when the distance from the sensor 102 to the measurement surface is approximately 1 mm from the reference position (SGD = A). In this case, most of the light receiving area 502 coincides with the irradiation area 501. Accordingly, as shown in FIG. 6, the output (curve b) from the phototransistor 203 at this time has a peak. On the other hand, since the light receiving region 503 is out of the irradiation region 501, the output (curve a) from the phototransistor 204 is at the minimum level at this time as shown in FIG.

  FIG. 5B shows how the irradiation area 501 and the light receiving areas 502 and 503 overlap when the distance from the sensor 102 to the measurement surface is at the reference position (SGD = B). In this case, the area where the light receiving region 502 and the irradiation region 501 coincide is substantially the same as the area where the light receiving region 503 and the irradiation region 501 coincide. Accordingly, the outputs from the phototransistors 203 and 204 at that time are substantially the same as shown in FIG.

  FIG. 5C shows how the irradiation region 501 and the light receiving regions 502 and 503 overlap when the distance from the sensor 102 to the measurement surface is about 1 mm from the reference position (SGD = C). In this case, most of the light receiving region 503 coincides with the irradiation region 501. Accordingly, as shown in FIG. 6, at this time, the output from the phototransistor 204 (curve a) has a peak. On the other hand, since the light receiving region 502 is out of the irradiation region 501, the output (curve b) from the phototransistor 203 is at the minimum level.

  Thus, the outputs of the phototransistors 203 and 204 change according to the distance from the sensor to the measurement surface. The interval between the positions where the outputs of the phototransistors 203 and 204 reach a peak is determined by the relative shift amount of the phototransistors 203 and 204 in the Z direction, the inclination with respect to the measurement surface, and the inclination of the infrared LED 201 with respect to the measurement surface. In any case, this arrangement is optimized based on the width of the desired measurement range.

  When the outputs of the phototransistors 203 and 204 that change depending on the distance to the recording sheet 106 are obtained, the MPU 601 obtains the distance coefficient L based on these two outputs. The distance coefficient L is obtained by the following equation, where Va is the output of the phototransistor 203 and Vb is the output of the phototransistor 204.

L = (Va−Vb) / (Va + Vb)
Therefore, the value of the distance coefficient L changes according to the distance from the sensor 102 to the measurement surface. When the output of the phototransistor 203 (curve b in FIG. 6) has a peak (SGD = A), the value of the distance coefficient L is minimum. On the other hand, when the output of the phototransistor 204 (curve a in FIG. 6) has a peak (SGD = C), the value of the distance coefficient L is maximum. Due to the nature of the distance coefficient L, the measurement range is preferably within the peaks of the two phototransistors 203 and 204, and the measurement range of the sensor 102 described in the present embodiment is the reference position ± 1 mm.

  When the distance coefficient L is obtained by the arithmetic processing in the MPU 601, the distance reference table stored in the ROM 602 is read.

  FIG. 7 is a diagram illustrating an example of a change curve of a distance coefficient represented by a distance reference table.

  The distance coefficient L obtained by the above formula increases slightly in a curve with respect to the distance due to the output characteristics of the phototransistors 203 and 204, but has a substantially linear characteristic. The distance reference table is used to more accurately obtain the distance to the measurement object from the distance coefficient L obtained by the calculation.

  The MPU 601 obtains the distance to the measurement object from the distance coefficient L obtained by the calculation and the distance reference table, and outputs the value. When the distance (SGD) to the measurement surface is obtained, the thickness of the recording paper 106 can be calculated from the relative distance from the platen 107. That is, the thickness of the recording paper can be obtained by obtaining the difference between the distance when the platen is used as the measurement surface and the distance when the recording paper is used as the measurement surface.

  As described above, the distance to the measurement surface can be detected using the multipurpose sensor 102.

  In a general distance measuring sensor, two light receiving elements are arranged on the same plane as the light emitting element. Therefore, the diffused light has a variation in the intensity of light irradiated on the measurement object, and the irradiation area and the light receiving area are blurred due to distance fluctuations. There is an influence by. For this reason, the slope until the output reaches the peak in the output curve from each light receiving element and the slope after the peak become asymmetrical. As a result, the accuracy as a distance measuring sensor is affected by the position of low sensitivity. There is a problem that it falls.

  On the other hand, when the multipurpose sensor of this embodiment is used, the symmetry of the rising and falling of the output curve is improved. Specifically, the characteristic of the distance coefficient obtained from the ratio of the difference between the output signals obtained from the two phototransistors and the sum ratio becomes more linear with respect to the distance to the measurement surface, enabling accurate distance detection. Become.

  Generally, there are differences in reflection characteristics depending on the type of recording paper. For example, regular reflection is dominant in a sheet having a high smoothness on the surface of a recording sheet such as glossy sheet. On the other hand, the diffuse reflection is dominant in the paper having a low smoothness on the surface of the recording paper such as plain paper. Therefore, the change in the distance coefficient L depending on the distance is slightly different depending on the characteristics of the recording paper. In order to obtain the distance between the sensor and the surface of the recording paper with high accuracy, it is desirable to select the distance according to the type of the recording paper instead of providing only one distance reference table.

  In this embodiment, the infrared LED 201 and the phototransistors 203 and 204 are arranged so that the angle is a regular reflection angle so that the distance can be detected even for a recording sheet such as a clear film. However, since the multi-purpose sensor 102 also has a visible LED 205, for the recording paper for which it is difficult to detect the distance by regular reflection, the diffuse reflected light is emitted using the visible LED 205 that irradiates the recording paper perpendicularly. Can be measured.

  Next, a processing procedure for detecting the edge of the recording paper 106 using the sensor 102 will be described.

  Edge detection of the recording paper 106 is performed by calculating the difference between the outputs of the phototransistors 203 and 204. First, the sensor 102 is moved onto the recording paper 106, and the infrared LED 201 is turned on. Adjustment is performed by the amplifier circuit 304 so that the outputs of the phototransistors 203 and 204 are approximately the same, and the gain at that time is fixed. Subsequently, the sensor 102 is moved to the end of the recording paper 106 while sampling the output values of the phototransistors 203 and 204 at a constant cycle. Specifically, when detecting the leading end of the recording sheet 106 in the conveyance direction, the recording sheet 106 reaches the detection range of the sensor 102 by conveying the recording sheet 106. When detecting the paper width of the recording paper 106 in the scanning direction, the sensor 102 is moved to the end of the recording paper 106 by scanning the carriage.

  When the sensor 102 is on the recording paper 106, the output values of the phototransistors 203 and 204 are at the same level as at the time of the first gain adjustment, so that there is little difference between the values. However, when the sensor 102 reaches the vicinity of the end of the recording paper 106, a part of the light receiving region of one phototransistor deviates from the measurement surface. For this reason, the reflected light of the infrared LED 201 is not received by one of the phototransistors, and as a result, the output of the phototransistor that does not receive the reflected light is lowered.

  FIG. 8 is a diagram showing changes in the output values of the two phototransistors until the detection range of the sensor moves from the recording paper to a position outside the recording paper.

  In FIG. 8, “a” indicates the output from the phototransistor 203, and “b” indicates the output from the phototransistor 204. As shown in FIG. 8, the output (a) of the phototransistor 203 near the edge of the sheet starts to decrease first and then the output (b) of the phototransistor 204 according to the relative position change of the sensor position with respect to the recording sheet. Decreases. The shift amount of the output decrease of the phototransistors 203 and 204 is related to the shift amount in the X direction.

  In this embodiment, the outputs from the phototransistors 203 and 204 are monitored, and the position of the sensor 102 when the output is 50% of the output at the first adjustment is recorded. When the position of the sensor 102 is determined, an intermediate position of the position is calculated by the MPU 601 and obtained. The intermediate position obtained in this way is the position when the intermediate position between the phototransistor 203 and the phototransistor 204 has just passed the end of the recording paper 106. Therefore, the absolute position of the recording paper 106, the width of the recording paper 106, and the like can be obtained from the positional relationship of the sensors.

  As described above, the edge of the recording sheet 106 can be detected using the sensor.

  In general, a sensor used for detecting the edge of a recording sheet has a configuration in which one light-receiving element is provided for one light-emitting element, and when the reflection intensity falls below a predetermined threshold value, the position is set to the end of the recording sheet. It was detected as. However, with this method, when the recording paper is wavy and the measurement surface near the edge is at a position higher or lower than the reference height, the timing below the threshold is different from that for normal recording paper. Therefore, there was a risk of erroneous detection.

  On the other hand, the multi-purpose sensor of this embodiment has two light receiving elements, receives light reflected from the light source at the same time with the light receiving regions adjacent to each other, and detects the edge of the recording paper from the two outputs. Yes. As a result, it is possible to cancel the change in output due to the undulation of the recording paper, and it is possible to perform accurate edge detection independent of the distance to the measurement object.

  In the multipurpose sensor of this embodiment, the infrared LED 201 is turned on and its reflected light is received, so that end detection is performed using the specularly reflected light to be measured. In addition to this, since the sensor also includes a visible LED 205, edge detection can be performed using diffused reflected light to be measured by turning on visible light and receiving the reflected light. The selection from these two detection methods is preferably determined from the reflection characteristics of the recording paper 106.

  In the end detection described above, the MPU 601 determines the position when each phototransistor output is 50% of the peak output. However, the present invention is not limited to this method. For example, the outputs of the phototransistors 203 and 204 can be compared using a comparator, and a position where the outputs are equal can be obtained as an intermediate position. As a result, the processing load on the MPU is reduced, and end detection can be performed at higher speed.

  The end position detected as described above has no correlation with the absolute position without calibration.

  Therefore, the end of the reference surface where the absolute position is determined is detected, the position information at that time is stored, and the relative relationship between the detected position and the absolute position is obtained.

  FIG. 9 is a diagram illustrating a state in which the sensor detects a reference plane provided on the platen 107.

In FIG. 9, reference numeral 701 denotes a reference plane, and Z ₀ denotes an interval from the sensor 102 to the reference plane 701, which is a reference height. FIG. 9 shows a state in which infrared light is irradiated from the infrared LED 201 and reflected by the reference surface 701, and the reflected light is received by the phototransistor 203.

  FIG. 10 shows changes in output values obtained from two phototransistors until the sensor 102 moves from a position on the reference plane to a position off the reference plane, and the CR encoder pulse and pulse count value at that time. FIG. The CR encoder (not shown) is an encoder mounted on the carriage 101.

In this embodiment, first, as shown in FIG. 10, the outputs of the phototransistors 203 and 204 are adjusted to V ₀ on the reference plane 701 of the platen 107.

The output respective photo-transistors 203 and 204 positions of the sensor 102 to the respective recording when it becomes half (V _0/2) output V _0. The position is determined using the count value of the output pulse from the CR encoder.

10, since the count value of the CR encoder sensor output is in the V _0/2 is "X ₀ -1" and "X ₀ +2", the end of the reference position when obtained by calculation process the intermediate position The part is “X ₀ +0.5”. Therefore, in the end detection of the recording paper according to this embodiment, the count value of the output pulse from the CR encoder and the end count value “X ₀ +0.5” of the reference value when the end of the recording paper is detected by the sensor. The absolute position of the end is calculated from the difference from “”.

  FIG. 11 is a flowchart showing processing for selectively switching the detection method according to the type of the recording medium in detecting the edge of the recording sheet and detecting the distance to the recording sheet.

  Hereinafter, these processes will be described with reference to this flowchart.

  First, in step S11, the sensor is moved onto the recording medium to be measured. Actually, the sensor is relatively moved by conveying the recording medium.

  In steps S12 and S13, the infrared LED 201 and the visible LED 205 are turned on, respectively, and the outputs from the phototransistors 203 and 204 are measured. The regular reflection light is measured by the infrared light irradiation from the infrared LED 201, and the irregular reflection light is measured by the visible light irradiation from the visible LED 205.

  In step S14, the output (RR) from the phototransistor by regular reflection light and the output (DR) from the phototransistor by diffuse reflection light are compared. If RR >> DR, the process proceeds to step S15, and it is determined that the recording medium is a “transparent film” such as OHP, for example. Further, in step S17, it is determined that the edge / distance detection of the recording medium uses regular reflection. This is because the transparent film has a large transmittance at the time of irregular reflection, and is selected to perform detection processing using regular reflection light.

  On the other hand, if RR >> DR is not satisfied, the process proceeds to step S16, and the detection process is selected to be performed using diffusely reflected light that is relatively less affected by the floating or tilting of the recording medium.

  Finally, a correction processing procedure for detecting the edge of the recording paper 106 using the sensor 102 will be described.

  In this embodiment, in order to perform optimum recording, control is performed so as to keep the sheet interval (distance between the carriage 101 and the recording sheet) constant. In this embodiment, the carriage 101 is moved up and down by a lift motor (not shown) for adjusting the paper gap. When the carriage 101 is moved up and down, the paper irradiation detection using regular reflection changes both the LED irradiation position and the sensor aiming position, but the detection position does not change. On the other hand, when using irregular reflection, only the aiming position of the sensor changes, so that the paper edge detection position also changes according to the height of the carriage 101. This greatly affects the accuracy of paper edge detection.

  For this reason, in this embodiment, the paper edge detection position is corrected when irregularly reflected light is selected for the detection process. The correspondence when the sheet interval changes in each of irregular reflection and regular reflection is shown below.

  FIG. 12 is a diagram showing the relationship between the multipurpose sensor and the recording paper when the carriage moves up and down. In FIG. 12, it is assumed that the angle of the phototransistor 203 from the Z direction is θ, and the sensor array is parallel to the X direction (perpendicular to the paper surface).

  This correction is calculated based on the height of the reference surface.

FIG. 12A shows a state of “calibration of end detection” which is a reference when using irregularly reflected light. In FIG. 12A, “A” is the distance (on the XY plane) from the tip of the phototransistor 203 to the sensor aiming position (intersection of the optical axis received by the phototransistor 203 and the reference plane) at the time of detecting the reference plane. Yes, A = Z ₀ · tan θ.

  FIG. 12B shows a state in which the distance to the recording sheet due to irregularly reflected light is detected.

In FIG. 12B, “Z1” is the difference between the height when the calibration reference surface 701 is present and the height when the recording paper 106 is present, and “A1” is the distance from the tip of the phototransistor 203 to the sensor aiming position. Distance (on the XY plane). As can be seen from FIG. 12B, A1 = (Z ₀ + Z ₁ ) · tan θ. At this time, the difference between A and A1 is the difference in the paper edge detection position.

In other words, when the height difference is “Z1”, correction of A1−A = Z ₁ · tan θ is necessary. In this embodiment, “Z ₁ · tan θ” is reflected as a correction value in the count value of the output pulse from the CR encoder at the time of paper edge detection, so that the paper edge is accurately detected even if the height changes. I am doing so.

  FIG. 12C shows a state of “calibration of end detection” which is a reference when using specularly reflected light. FIG. 12D shows a state in which the distance to the recording sheet by specular reflection light is detected. In FIG. 12D, “Z2” is the difference between the height when the calibration reference surface 701 is present and the height when the recording paper 106 is present. “A2” is the distance from the tip of the phototransistor 203 to the sensor aiming position. As shown in FIG. 12D, since the irradiation position of the infrared LED 201 and the sensor aiming position change equally, the detection position does not change.

  Therefore, no correction is performed when regular reflection light is used. Considering the fact that specularly reflected light was used for a recording medium such as a transparent film as described above, the correction value is calculated according to the type of the recording medium and reflected in the paper edge detection position. Even when the distance to the medium changes, the edge can be accurately detected.

  Therefore, according to the embodiment described above, the output signals from the two phototransistors arranged at the respective positions in the Z direction that is the thickness direction of the recording medium and the Y direction that is the conveyance direction of the recording medium are output. It can be used to detect the thickness and edge of the recording medium.

  Since the output signals of the two phototransistors have characteristics that depend on the direction of conveyance of the recording medium, even if the recording paper undulates, the change in the two outputs is canceled and accurate edge detection is performed. It becomes possible.

  The distance coefficient generated from the ratio of the sum and difference of the output signals of the two phototransistors has a substantially linear characteristic with respect to the distance between the recording medium (measurement surface) and the recording head (sensor). By using this, it becomes possible to perform accurate distance detection.

  In the above embodiments, the liquid droplets ejected from the recording head are described as ink, and the liquid stored in the ink tank is described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The above embodiments are provided with means (for example, an electrothermal converter, a laser beam, etc.) for generating thermal energy as energy used for performing ink ejection, particularly in the ink jet recording system. The thermal energy causes a change in the state of the ink, thereby achieving high recording density and high definition.

  The multi-purpose sensor shown in the above embodiments reads the density of the recorded check pattern, adjusts the recording position in the scanning direction / conveyance direction of the recording head (registration adjustment), and receives light from the phototransistor when each LED is irradiated. The type of the recording medium can also be determined from the amount.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. It is a block diagram of a multipurpose sensor. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. It is a block diagram which shows the detailed structure of the control circuit relevant to the process of the input-output signal of a multipurpose sensor. The figure shows changes in the positions of the irradiation region and the light receiving region that change depending on the distance from the sensor to the measurement surface. It is a figure which shows two phototransistor output fluctuation | variation by the distance (SGD) from a sensor to a measurement surface. It is a figure which shows the example of the change curve of the distance coefficient represented by the distance reference table. It is a figure which shows the change of the output value of two phototransistors until a sensor moves to the position which removed the recording paper from the recording paper. It is a figure which shows a mode that a sensor detects the reference plane provided on the platen. It is the figure which showed the change of the output value obtained from two phototransistors until a sensor moves to the position which deviated from the reference plane from the position on a reference plane, and the pulse and pulse count value of the CR encoder at that time. 6 is a flowchart showing processing for selectively switching the detection method according to the type of recording medium when detecting the edge of the recording sheet and detecting the distance to the recording sheet. FIG. 4 is a diagram illustrating a relationship between a multipurpose sensor and a recording sheet when a carriage moves up and down. It is a figure which shows the paper detection sensor provided with the light emission part which inject | emits the irradiation light irradiated to a paper, and the light-receiving part which detects the reflected scattered light reflected from a paper. FIG. 3 is a diagram illustrating a relationship between an infrared sensor disposed on a side surface of a carriage of a recording apparatus and a recording area of a recording head.

Explanation of symbols

101 Carriage 102 Multipurpose sensor 103 Recording head 104 Conveying belt 105 Shaft 106 Recording paper 107 Platen 201 Infrared LED
202 Sensor central axis 203, 204 Phototransistor 205, 206, 207 Visible LED
302 Driving circuit 303 I / V conversion circuit 304 Amplifying circuit 501 Irradiation area 502, 503 of infrared LED Photosensitive area 601 of phototransistor MPU
602 ROM
603 ASIC
604 RAM
606 A / D converter 610 Host device 701 Reference plane

Claims (10)

A recording apparatus for recording an image on a recording medium using a recording head,
Conveying means for conveying the recording medium in a first direction;
Scanning means for reciprocating the recording head in a second direction perpendicular to the first direction;
A first light emitting element that is mounted on the scanning unit together with the recording head and irradiates the recording medium with light at a first angle, and a second light that irradiates the recording medium with light at a second angle. The first direction and the first direction receiving light from the first light emitting element, regular reflected light from the recording medium and irregularly reflected light from the second light emitting element. A first light receiving element and a second light receiving element which are provided apart from each other with respect to a third direction from the recording head to the recording medium perpendicular to the first and second directions; Measuring means for measuring the reflected light of
Comparison comparing output signals from the first and second light receiving elements when receiving the regular reflection light and output signals from the first and second light receiving elements when receiving the reflected light Means,
According to the comparison result by the comparison means, the type of the recording medium is determined, and according to the determination result, the regular reflection light is used for detecting the thickness of the recording medium and the end of the recording medium, or the irregular reflection light is used. A selection means for selecting whether to use;
The recording medium and the measuring means are moved relative to each other by the conveying means or the scanning means, and the end of the recording medium is moved based on the change in the output signal obtained from the first and second light receiving elements. And a detecting unit configured to detect a thickness of the recording medium based on a function generated by output signals from the first and second light receiving elements. A platen provided on a plane including the first direction and the second direction;
The recording apparatus according to claim 1, further comprising a calibration unit configured to calibrate an absolute position of an end detection position of the recording medium with the platen as a reference position.   The detection means includes a distance from the measurement means to the platen obtained by the measurement means emitting light with respect to the platen, and a measurement means obtained by the measurement means emitting light with respect to the recording medium. The recording apparatus according to claim 2, wherein the thickness of the recording medium is obtained from a difference from the distance to the recording medium.   When the selection means selects the irregularly reflected light to be used for detecting the thickness of the recording medium and the edge of the recording medium, the edge is determined based on the distance from the measuring means to the recording medium. The recording apparatus according to claim 3, further comprising a correction unit that corrects the part detection position. The first light emitting element is an infrared LED;
The second light emitting element is a visible LED;
The recording apparatus according to claim 1, wherein the first and second light receiving elements are first and second phototransistors, respectively. The output signals from the first and second phototransistors change according to the distance from the measuring means to the recording medium or the reflecting surface of the platen, respectively.
6. The recording apparatus according to claim 5, wherein changes according to the distance of output signals from the first and second phototransistors are different from each other.   The function generated by output signals from the first and second light receiving elements is a ratio of a difference and a sum of output signals from the first and second phototransistors. Recording device. The output signals from the first and second phototransistors respectively change according to the relative position of the measuring means with respect to the recording medium,
The recording apparatus according to claim 5, wherein the change in the output signal from the first and second phototransistors is based on the conveyance direction of the recording medium. The first angle is 45 °;
The recording apparatus according to claim 1, wherein the second angle is 90 °. A conveying unit configured to convey the recording medium in a first direction; and a scanning unit configured to reciprocate the recording head in a second direction perpendicular to the first direction. The image is recorded on the recording medium using the recording head. A recording medium detection method for a recording apparatus for recording
A first light emitting element that transports the recording medium by the transporting means, is mounted on the scanning means together with the recording head, and irradiates the recording medium with light at a first angle; and the recording medium A second light-emitting element that emits light at a second angle; specularly reflected light emitted from the first light-emitting element and reflected by the recording medium; and irregularly reflected light emitted from the second light-emitting element and reflected by the recording medium. First and second light receiving elements that receive light and are spaced apart from each other with respect to the first direction and the third direction from the recording head to the recording medium perpendicular to the first and second directions. And measuring the reflected light on the recording medium by irradiating the recording medium with light using an optical sensor integrally provided with
Comparison comparing output signals from the first and second light receiving elements when receiving the regular reflection light and output signals from the first and second light receiving elements when receiving the reflected light Process,
According to the comparison result in the comparison step, the type of the recording medium is determined, and according to the determination result, the regular reflection light is used for detecting the thickness of the recording medium and the end of the recording medium, or the irregular reflection light is used. A selection step for selecting whether to use;
A function that is measured in the measurement step and that generates an end portion of the recording medium based on the output signals from the first and second light receiving elements based on changes in the output signals obtained from the first and second light receiving elements. And a detecting step of detecting the thickness of the recording medium based on the recording medium.

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