JP2011056791A - Printer, position detector, and signal selection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer and a position detector capable of reducing an error of a detection signal. <P>SOLUTION: The printer 10 includes: a light emission part 61; a scale 51 wherein light transmitting parts 51a and light shielding parts 51b are formed alternately at least; a light receiving part 62 positioned on the opposite side to the light emission part 61 via the scale 51 and outputting at least two detection signals; a signal selection output means 100 selecting either one of the detection signals and outputting the selected signal; and a timing signal generation means 115 generating a timing signal instructing timing of ink jetting from a printing head 38 based on the detection signal outputted from the signal selection output means 100. The signal selection output means 100 compares the respective detection signals in such condition that an object 31 to be driven is driven at a fixed speed, and selects and outputs the detection signal closest to a reference detection signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printer, a position detection device, and a signal selection method.

  In an ink jet printer, a carriage and a print medium are moved by a motor. In this movement, an encoder is generally used to perform position control and speed control (see, for example, Patent Document 1). The encoder includes a photo sensor and a scale. Among these, the photosensor includes a light emitting element and a light receiving element. The scale also has a light-transmitting portion that transmits light emitted from the light-emitting element and a light-shielding portion that blocks light emitted from the light-emitting element, and the light-transmitting portion and the light-shielding portion are repeated at a constant pitch. ing.

  Patent Document 1 discloses a linear encoder including a linear linear scale and a photosensor arranged so as to sandwich the linear scale between a light emitting element and a light receiving element. In the linear encoder described in Patent Document 1, the photosensor includes a collimator lens that collimates the light emitted from the light emitting element, and the parallel light that has passed through the light transmitting portion of the linear scale is detected by the light receiving element. Has been. Further, in this linear encoder, the width of the light transmitting portion and the width of the light shielding portion of the linear scale are formed to be equal.

Japanese Unexamined Patent Application Publication No. 2004-202963 (see paragraph numbers 0004 to 0007, FIG. 21, etc.)

  By the way, in the encoder as described in Patent Document 1 described above, only the signal of either the A phase or the B phase is fixedly taken into the calculation circuit, and the rectangular encoder signal (detection) is detected. Signal) and the motor is controlled. In this configuration, in order to obtain two outputs of the A phase and the B phase, there are 2ch or more light receiving circuits. Here, since there are errors in the light receiving circuit and errors in an optical system such as an encoder, the two outputs of the A phase and the B phase are not uniform.

  Further, as the printer is used, the above-described optical system is deteriorated, so that an error (variation rate) with respect to a reference period increases in the two outputs of the A phase and the B phase.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a printer, a position detection device, and a signal selection method capable of reducing an error of a detection signal from a light receiving unit. .

  In order to solve the above problems, a first aspect of the printer of the present invention includes at least a light emitting unit that emits light, a light transmitting unit that transmits light from the light emitting unit, and a light shielding unit that blocks light from the light emitting unit. Based on alternating scales and light that is located on the opposite side of the light-emitting part across the scale and that has a periodic characteristic that is transmitted through a light-transmitting part that is generated in response to driving of the driven object A light receiving unit that outputs at least two detection signals having different phases; and a signal selection output unit that performs control to select and output one of the detection signals from among the two detection signals. And generating a timing signal for instructing the timing of ink ejection from the print head that ejects ink toward the print medium based on the detection signal output from the signal selection output means. And a signal selection output means that compares the detection signals in a state where the driven object is driven at a constant speed, and selects the detection signal closest to the reference signal. Output.

  In such a configuration, although at least two detection signals are input to the signal selection output means, the respective detection signals are compared, and the one closest to the reference detection signal is selected and output. is doing. For this reason, it is possible to reduce an error with respect to a reference detection signal as compared with the case of selecting / outputting a detection signal that has not been selected. Further, when the timing signal is generated by the timing signal generation unit based on the detection signal selected / output by the signal selection output unit, the ink is compared with the case where the timing signal is generated based on the detection signal not selected. This makes it possible to bring the injection timing closer to a more appropriate one. Therefore, it is possible to improve the image quality of the print image formed on the print medium by ejecting ink.

  According to another aspect of the present invention, in the above-described invention, the output level of the detection signal includes an H level that exceeds a predetermined threshold and an L level that does not exceed the predetermined threshold, and the signal selection output means includes: It is preferable to select and output the detection signal having the smallest error among the detection signal periods to the reference period serving as the reference of the detection signal.

  In the case of such a configuration, an error with respect to a reference detection signal can be reduced as compared with the case of selecting / outputting a detection signal that has not been selected. Thereby, in various controls, it becomes possible to improve the accuracy of the control.

  According to another aspect of the present invention, in each of the above-described inventions, the driven object is a carriage to which a print head is attached, and the light emitting unit and the light receiving unit are attached to the carriage to drive the carriage. It is preferable to include a motor that applies driving force, and motor control means that controls driving of the motor based on the detection signal output from the signal selection output means.

  In such a configuration, the motor for driving the carriage is controlled based on the detection signal output from the signal selection output means. For this reason, it is possible to suppress speed fluctuations in the carriage speed control. In addition, the accuracy of position control such as carriage stop position control can be improved. In addition, it is possible to improve the image quality of a print image formed on a print medium by suppressing speed fluctuations and further improving the accuracy of position control.

  Further, according to another aspect of the present invention, in each of the above-described inventions, there is provided counting means for counting any index value of cumulative elapsed time, usage time, or number of print media printed by the print head. The signal selection output means selects and outputs one of the at least two detection signals by the signal selection output when the index value in the counting means reaches a predetermined determination threshold value. It is preferable to perform control.

  In such a configuration, the index value in the counting means reaches a predetermined determination threshold value in a situation where the printer is used only for a predetermined period and the outputs of the light emitting unit and the light receiving unit are considered to vary. Then, control for selecting and outputting one of the detection signals is performed by the signal selection output means. Therefore, even if the detection signal fluctuates due to some cause (for example, mist adhesion to the scale, encoder deterioration, etc.) due to long-term use of the printer, It is possible to select and output the detection signal closest to the detection signal to be. Thereby, it is possible to extend the life of the position detection device or encoder having the light emitting unit and the light receiving unit.

  In the position detection device according to another aspect of the present invention, a light emitting unit that emits light, a light transmitting unit that transmits light from the light emitting unit, and a light shielding unit that blocks light from the light emitting unit are alternately formed. The phase is different on the basis of the light having a periodic characteristic that is located on the opposite side of the light emitting unit across the scale and the light transmitting unit that is generated according to the driving of the driven object A light receiving unit that outputs at least two detection signals; and at least two detection signals are input, and a signal selection output unit that performs control to select and output one of these detection signals. The signal selection output means preferably compares the detection signals in a state where the driven object is driven at a constant speed, and selects and outputs the one closest to the reference detection signal.

  In such a configuration, although at least two detection signals are input to the signal selection output means, the respective detection signals are compared, and the one closest to the reference detection signal is selected and output. is doing. For this reason, it is possible to reduce an error with respect to a reference detection signal as compared with the case of selecting / outputting a detection signal that has not been selected.

  Further, in the signal selection method according to another aspect of the present invention, the light transmitting part that transmits light from the light emitting part and the light transmitting part of the scale in which the light shielding parts that block light are alternately formed are transmitted, And based on the light which has the periodic characteristic produced | generated according to the drive of the to-be-driven object, the at least 2 detection signal from which a phase differs is output from a light-receiving part, and any detection signal is output from those detection signals. In the signal selection method to be selected, in a state where the driven object is driven at a constant speed, it is preferable to compare the respective detection signals and select and output the one closest to the reference detection signal.

  When configured in this way, the respective detection signals are compared, and the one closest to the reference detection signal is selected and output. For this reason, it is possible to reduce an error with respect to a reference detection signal as compared with the case of selecting / outputting a detection signal that has not been selected.

1 is a perspective view illustrating a configuration of a printer according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a printer. FIG. 4 is a side sectional view of a portion related to paper feeding of the printer. It is a partial perspective view which shows the attachment aspect of a linear scale. It is a figure which shows the circuit structure of a linear encoder. It is a schematic diagram which shows the relationship between a linear scale and a photosensor. It is a figure which shows the analog signal and output pulse of an encoder. It is a schematic diagram which shows the modification of the relationship between a linear scale and a photosensor. It is a block diagram which shows schematic structure of a control part. It is a figure which shows the experimental result of the difference | error of the electric current made to conduct to a light emission part, and a detection signal. It is a block diagram which shows the modification of schematic structure of a control part.

  Hereinafter, a printer 10 according to an embodiment of the present invention, a position detection device provided in the printer 10 and a signal selection method will be described with reference to FIGS. The printer 10 according to the present embodiment is an ink jet printer. However, the ink jet printer may be an apparatus that employs any ejection method as long as the apparatus can eject ink and print on a print medium. good.

  In the following description, the lower side refers to the side where the printer 10 is installed, and the upper side refers to the side away from the installed side. In addition, a direction in which a carriage 31 to be described later moves is a main scanning direction, a direction orthogonal to the main scanning direction, and a direction in which the print medium P is conveyed is a sub-scanning direction. Further, the side on which the print medium P is supplied is described as a paper feed side (rear end side), and the side on which the print medium P is discharged is described as a paper discharge side (front side).

  As shown in FIG. 1, the printer 10 includes a housing unit 20, a carriage drive mechanism 30, a paper transport mechanism 40, a linear encoder 50, a rotary encoder 80, and a control unit 100 as main components. Yes.

  Among these, the housing | casing part 20 is equipped with the chassis 21 installed in the installation surface, and the support frame 22 standing upright from this chassis 21. As shown in FIG. The carriage drive mechanism 30 includes a carriage 31, a carriage motor (CR motor 32), a belt 33, a gear pulley 34, a driven pulley 35, and a carriage shaft 36. Among these, each color ink cartridge 37 can be mounted on the carriage 31. Further, as shown in FIG. 2, a print head 38 capable of ejecting ink droplets is provided on the lower surface of the carriage 31. The belt 33 is an endless belt, and a part of the belt 33 is fixed to the back surface of the carriage 31. The belt 33 is stretched by a gear pulley 34 and a driven pulley 35.

  The above-described print head 38 is provided with a nozzle row (not shown) corresponding to each ink, and a piezo element (not shown) is arranged in the nozzle constituting the nozzle row. By the operation of this piezo element, it is possible to eject ink droplets from the nozzle at the end of the ink passage. The print head 38 is not limited to a piezo drive system using a piezo element. For example, a heater system that heats ink with a heater and uses the generated foam force, a magnetostriction system that uses a magnetostrictive element, and a mist that is controlled by an electric field. A mist method or the like may be employed. The ink filled in the cartridge 37 may be mounted with any type of ink such as dye-based ink / pigment-based ink.

  As shown in FIG. 3, the paper transport mechanism 40 includes a PF motor 41 (see FIG. 2 and others) for transporting the print medium P and the like, and a paper feed roller 42 corresponding to the feeding of plain paper or the like. Yes. Further, a PF roller pair 43 for conveying / clamping the print medium P is provided on the paper discharge side with respect to the paper feed roller 42. On the paper discharge side of the PF roller pair 43, the platen 44 and the above-described print head 38 are disposed so as to face each other vertically. The platen 44 supports the print medium P conveyed below the print head 38 by the PF roller pair 43 from below. Further, on the paper discharge side with respect to the platen 44, a paper discharge roller pair 45 similar to the above-described PF roller pair 43 is provided. Of the pair of paper discharge rollers 45, the drive force from the PF motor 41 is transmitted to the paper discharge drive roller 45a together with the PF drive roller 43a.

  Further, as shown in FIG. 2, the linear encoder 50 can function as a part of components of the position detection device, and includes a linear scale 51 and a photosensor 60.

  The linear scale 51 is formed in a long shape (elongated linear shape) from a thin plate of transparent resin or the like. The linear scale 51 is attached to the support frame 22 in parallel with the main scanning direction. That is, in the printer 10, the linear scale 51 is attached to the support frame 22 in a state where the short direction of the linear scale 51 is the height direction. Elongated locking holes 53 as shown in FIG. 4 are provided at both ends of the linear scale 51. A locking claw 22a fixed to the support frame 22 is inserted into the locking hole 53, and the linear scale 51 is supported in a stretched state by the locking claw 22a.

  The photo sensor 60 is a light projecting / receiving sensor, and includes a light emitting portion 61 and a light receiving portion 62 as shown in FIG. 5 and the like, and as shown in FIG. It is fixed via 63. The fixing member 63 has two mounting portions 63a and 63b facing each other, and the linear scale 51 is located in a space between the two mounting portions 63a and 63b.

  Moreover, the light emitting part 61 is attached to one attachment part 63a, and the light receiving part 62 is attached to the other attachment part 63b. The light emitting unit 61 and the light receiving unit 62 are arranged in a state of facing each other with the linear scale 51 interposed therebetween. Further, the light emitting unit 61 is provided with a collimator lens 64 through which light passes, as shown in FIG. 5, and is arranged so that the light traveling toward the linear scale 51 becomes parallel light.

  The light emitting unit 61 includes a light emitting element 610 such as a light emitting diode, and light generated by the light emitting element 610 is emitted toward the linear scale 51. A current is supplied to the light emitting element 610 through a variable resistor 611. Therefore, the amount of light emitted from the light emitting element 610 can be increased or decreased by the variable resistor 611.

  Further, as shown in FIGS. 5 and 6, the light receiving unit 62 includes a substrate 65 and a first light receiving element array 66 and a second light receiving element array 67 provided on the substrate 65. In one light receiving element row 66, a plurality of light receiving elements 66a, 66b are arranged in a row, and also in the second light receiving element row 67, a plurality of light receiving elements 67a, 67b are arranged. The light receiving elements 66a to 67b include light receiving elements such as phototransistors, photodiodes, and photo ICs that can convert received light into electric signals corresponding to the light quantity. Two of these light receiving elements 66a to 67b are arranged for one pitch composed of the light transmitting part 51a and the light shielding part 51b. Further, in the present embodiment, the first light receiving element row 66 and the second light receiving element row 67 are arranged so as to be shifted by a quarter pitch. That is, the phase difference between the first light receiving element array 66 and the second light receiving element array 67 is 90 degrees.

  Here, in the present embodiment, the width dimensions of the light transmitting portion 51a and the light shielding portion 51b are equal, but in this case, one light receiving element 66a is provided for each of the light transmitting portion 51a and the light shielding portion 51b. ˜67b is a corresponding arrangement relationship. In this embodiment, when the light receiving elements 66a, 66b, 67a, 67b are one set, about four sets are provided on the substrate 65. However, the light receiving elements 66a to 67b may have a configuration in which four sets or more or four sets or less are provided on the substrate 65.

  As shown in FIG. 5, the plurality of light receiving elements 66 a to 67 b are connected to a signal amplification circuit 68, and an analog waveform corresponding to the amount of light output from the light reception elements 66 a to 67 b by the signal amplification circuit 68. Are amplified and output to the first comparator 69a and the second comparator 69b. The first comparator 69a and the second comparator 69b output a digital signal (detection signal) having a pulse waveform based on the analog signals output from the respective light receiving element arrays 66 and 67 via the signal amplifier circuit 68. To do.

  Here, the light receiving element 66a of the first light receiving element row 66 is connected to the + side terminal of the first comparator 69a, and the light receiving element 66b of the same first light receiving element row 66 is connected to the − side terminal. Is done. In the second comparator 69b, the light receiving elements 67a and 67b of the second light receiving element array 67 are similarly connected. For example, when the level of the analog signal input to the + side terminal is higher than the level of the analog signal input to the − side terminal, a high level (H level) signal is output, and vice versa. Outputs a low level (L level) signal. Thereby, it is possible to output pulse signals (ENC-A, ENC-B; detection signals) as shown in FIG. 7 corresponding to the detection of the light transmitting part 51a / the light shielding part 51b.

  As shown in FIG. 7, the analog signal output from the light receiving element 66a and the analog signal output from the light receiving element 66b are shifted by a half cycle, but the first signal corresponding to the first light receiving element array 66 is shown. Through the 1 comparator 69a, the A-phase signal ENC-A, which is a rectangular wave, is output. Similarly, a B-phase signal ENC-B, which is a rectangular wave whose phase is shifted by 90 degrees, is output from the second comparator 69b corresponding to the second light receiving element row 67 arranged by being shifted by ¼ pitch. . In the following description, both the A-phase signal ENC-A and the B-phase signal ENC-B are referred to as “detection signals” when it is not necessary to distinguish both.

  Further, the configuration shown in FIG. 8 in which one light receiving element array 660 exists may be adopted without adopting the configuration as described above. In this case, the light receiving element 660a is connected to either the + side or the − side terminal of the first comparator 69a, and the light receiving element 660b is connected to either the + side or the − side terminal of the second comparator 69b. Connected.

  Further, as shown in FIG. 2, the rotary encoder 80 includes a disk-shaped rotary scale 81 and a photo sensor 82 similar to the linear encoder 50 described above. Since the rotary encoder 80 has the same configuration as that of the linear encoder 50, the detailed description thereof is omitted.

<Regarding the configuration of the control unit>
As shown in FIG. 2, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, an EEPROM 104, an ASIC 105, a motor driver 106, and the like, and these are connected via a transmission path 107 such as a bus. The control unit 100 is connected to the computer 120. The configuration shown in the block diagram of FIG. 9 is achieved by the cooperation of these hardware and the software and / or data stored in the ROM 102 or the EEPROM 104, or the addition of circuits or components for performing specific processing. Functionally realized.

  As shown in FIG. 9, the control unit 100 includes an ENC signal extraction unit 110, an error calculation unit 111, an ENC signal determination unit 112, a memory 113, an ENC signal selection unit 114, a timing signal generation unit 115, A motor control unit 116. Of the control unit 100, the ENC signal extraction unit 110, the error calculation unit 111, the ENC signal determination unit 112, the memory 113, and the ENC signal selection unit 114 are a signal selection output unit and a position detection device. This corresponds to the component of the part.

  Among these, the ENC signal extraction unit 110 receives the A-phase signal ENC-A and the B-phase signal ENC-B, respectively. The ENC signal extraction unit 110 extracts (samples) the A phase signal ENC-A and the B phase signal ENC-B for a predetermined period. That is, the ENC signal extraction unit 110 measures the time length of each cycle by a predetermined number of cycles for each of the A-phase signal ENC-A and the B-phase signal ENC-B, and the A-phase signal ENC-A And the average value of the period of B phase signal ENC-B is calculated. In this extraction (sampling), the period of the A-phase signal ENC-A and the B-phase signal ENC-B is simultaneously (or predetermined) in a region where the CR motor 32 is driven at a constant speed (constant speed portion). To the extent that the phase shift is allowed).

  It should be noted that a specific one period of the A phase signal ENC-A and the B phase signal ENC-B is taken out without calculating the average value of the periods of the A phase signal ENC-A and the B phase signal ENC-B. Also good. In the following description, the cycle of the A-phase signal ENC-A calculated by the ENC signal extraction unit 110 is set as a cycle TA, and the cycle of the B-phase signal ENC-B calculated by the ENC signal extraction unit 110 is set as the cycle TA. A period TB is assumed.

The error calculation unit 111 calculates how much error the cycle TA and the cycle TB have with respect to the cycle T serving as a reference with no error. Specifically, based on the following (Expression 1) and (Expression 2), periodic errors TAe and TBe expressed in% are calculated.
TAe = (1-TA / T) × 100 (Formula 1)
TBe = (1−TB / T) × 100 (Formula 2)

  The ENC signal determination unit 112 determines whether to output one of the detection signals of the A phase signal ENC-A and the B phase signal ENC-B from the results of the cyclic errors TAe and TBe calculated by the error calculation unit 111. decide. Here, it is determined that a detection signal with a small value of the cyclic error TAe and the cyclic error TBe should be output.

  The memory 113 stores information indicating which of the A-phase signal ENC-A and the B-phase signal ENC-B is to be output by the ENC signal determination unit 112 as ENC signal determination unit 112. This is a part to be stored based on the instruction. The memory 113 may correspond to the above-described EEPROM 104, but other storage media that can hold information even when the printer 10 is powered off may be used as the memory 113.

  The ENC signal selection unit 114 accesses the memory 113 and obtains information regarding the detection signal determined to be output. Further, both the A-phase signal ENC-A and the B-phase signal ENC-B are input to the ENC signal selection unit 114. Then, the ENC signal selection unit 114 outputs the detection signal determined to be output, of the A-phase signal ENC-A and the B-phase signal ENC-B.

  The detection signal output from the ENC signal selection unit 114 is input to the timing signal generation unit 115 (corresponding to the timing signal generation unit). Then, the timing signal generation unit 115 generates a timing signal PTS (Print Timing Signal) from the input detection signal. At this time, a predetermined multiplication process may be performed on the input detection signal to generate the timing signal PTS.

  The timing signal PTS generated by the timing signal generator 115 is supplied to the print head 38. Based on this timing signal PTS, timing control of a drive signal separately supplied to the print head 38 is performed.

  The detection signal output from the ENC signal selection unit 114 is input to the motor control unit 116. The motor control unit 116 performs drive control of the CR motor 32 based on the input detection signal. Note that the drive control of the CR motor 32 may be controlled to follow a predetermined target speed table or a predetermined target position table by feedback control such as PID control. In addition, when the drive control of the CR motor 32 is performed, a predetermined open control may be performed. In addition, a predetermined multiplication process may be performed on the input detection signal to control the driving of the CR motor 32.

<Operations resulting from the configuration of the control unit>
As described above, when the A-phase signal ENC-A and the B-phase signal ENC-B are input to the control unit 100, the operation related to the signal selection method is executed. That is, it is determined to output one of the detection signals of the A phase signal ENC-A and the B phase signal ENC-B, and the information is stored in the memory 113. Then, the ENC signal selection unit 114 accesses the memory 113 to acquire information regarding the detection signal determined to be output. Then, in the ENC signal selection unit 114, the timing signal generation unit 115 and / or the motor control unit 116 selects the detection signal determined to be output from the A phase signal ENC-A and the B phase signal ENC-B. Output to.

  As a result, the timing signal generator 115 generates the timing signal PTS from the selected detection signal. In the print head 38, timing control of a separately supplied drive signal is performed based on the timing signal PTS. Further, the motor control unit 116 performs drive control such as speed control or position control of the CR motor 32 based on the selected detection signal.

<Effect>
According to the printer 10, the position detection apparatus, and the signal selection method configured as described above, two detection signals are input to the ENC signal extraction unit 110 of the control unit 100, and the cyclic error TAe and TBe are calculated by the error calculation unit 111. Then, the ENC signal determination unit 112 determines which detection signal to output, and stores it in the memory 113. Then, the ENC signal selection unit 114 outputs a detection signal determined to be output.

  By doing so, it is possible to reduce an error with respect to a reference detection signal as compared with the case of selecting / outputting a detection signal that has not been selected. This state will be described with reference to FIG. FIG. 10 shows how much error the A-phase signal ENC-A and the B-phase signal ENC-B have with respect to the reference period T when the current conducted to the light emitting unit 61 is changed. It is an experimental result which shows whether it is.

  In the experimental result (A), the error in the A-phase signal ENC-A is smaller by about 4% than the error in the B-phase signal ENC-B. Under this situation, if the detection signal to be output from the ENC signal selection unit 114 is determined to be the A-phase signal ENC-A, the period of the detection signal to be output is compared with the case of selecting another detection signal. Thus, it is possible to reduce the error by the error in the latter half of the 4% range. In the experimental result (B), the error in the B-phase signal ENC-B is smaller than the error in the A-phase signal ENC-A by about 3%. Under this situation, if the detection signal to be output from the ENC signal selection unit 114 is determined to be the B-phase signal ENC-B, the period of the detection signal to be applied is compared with the case of selecting another detection signal. Thus, it is possible to reduce the error by an error of about 3%.

  In the present embodiment, when the timing signal PTS is generated by the timing signal generation unit 115 based on the detection signal output from the ENC signal selection unit 114, the timing signal PTS is generated based on the detection signal not selected. Compared with the case where it does, it becomes possible to make the timing of the ejection of ink closer to a more appropriate one. Therefore, it is possible to improve the image quality of a print image formed on the print medium P by ink ejection.

  Furthermore, in the present embodiment, the control unit 100 (ENC signal extraction unit 110 to ENC signal selection unit 114) has the smallest error in the period of each detection signal with respect to the reference period that is the reference of the detection signal. A thing is selected and output to the outside. For this reason, it is possible to reduce an error with respect to a reference detection signal as compared with the case of selecting / outputting a detection signal that has not been selected. Thereby, in various controls, it becomes possible to improve the accuracy of the control.

  Further, in the present embodiment, the motor control unit 116 controls the CR motor 32 that drives the carriage 31 based on the detection signal output from the control unit 100 (ENC signal extraction unit 110 to ENC signal selection unit 114). It has been done. For this reason, it is possible to suppress speed fluctuations in the speed control of the carriage 31. Further, the accuracy of position control such as stop position control of the carriage 31 can be improved. Further, it is possible to improve the image quality of the print image formed on the print medium P by suppressing the speed fluctuation and further improving the accuracy of the position control.

  Further, in the present embodiment, even if an inexpensive linear encoder is used by providing the control unit 100 in the present embodiment without using an expensive linear encoder with a small detection signal error, the detection signal Since the error can be reduced, the cost can be reduced.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be variously modified. This will be described below.

  In the above-described embodiment, the detection signal with a smaller error is output from the ENC signal selection unit 114 out of the two detection signals of the A-phase signal ENC-A and the B-phase signal ENC-B. . However, the number of detection signals is not limited to two, and it is of course possible to apply the present invention to a signal having three or more detection signals.

  Furthermore, in the above-described embodiment, the point that output fluctuation of the detection signal occurs when the printer 10 is used for a long time is not mentioned. However, the printer 10 may be configured to cope with a case where the detection signal output fluctuates due to long-term use of the printer 10. Hereinafter, this case will be described.

  The control unit 100A illustrated in FIG. 11 includes a counting unit 117 corresponding to the counting unit. The count unit 117 receives a signal related to an index value of either the cumulative elapsed time from the start of use of the printer 10, the usage time, or the number of print media P printed by the print head 38. In 117, the index value is counted. In addition, the count unit 117 determines whether or not the above-described index value has reached a determination threshold value stored in the storage part of the count unit 117 or a separate memory (whether the index value is greater than the determination threshold value, or greater than or equal to the determination threshold value). Or not). As a result of this determination, if it is determined that the index value has reached the determination threshold value, the ENC signal extraction unit 110 starts differential operation in response to a command from the counting unit 117, and two (or a plurality) detection signals are detected. The detection signal to be output is determined from the above.

  In the case of such a configuration, any detection signal is caused by any cause (for example, mist adhesion to the linear scale 51, deterioration of the linear encoder 50, etc.) due to the long-term use of the printer 10. Even when fluctuations occur, it is possible to select and output the detection signal closest to the reference detection signal. As a result, the life of the linear encoder 50 having the light emitting unit 61 and the light receiving unit 62 can be extended.

  In the above-described embodiment, the control unit 100 (ENC signal extraction unit 110 to ENC signal selection unit 114) selects the one with the smallest error among the periods of the respective detection signals with respect to the linear encoder 50. Output to the outside. However, the application of the present invention is not limited to the linear encoder, and it is of course possible to apply the present invention to the rotary encoder 80, for example. It is of course possible to apply the present invention to encoders that output other detection signals of A phase and B phase, or a plurality of detection signals higher than that.

  In the above-described embodiment, the control unit 100 is described as existing in the printer 10. However, some components of the control unit 100 may be used by being mounted on a separate measuring device. For example, the ENC signal extraction unit 110, the error calculation unit 111, and the ENC signal determination unit 112 may be mounted on a separate measuring device and used. Here, even when some components of the control unit 100 are mounted on a separate measuring device, (excluding some components of the printer 10) and (some components are By using a separate measuring device), it is possible to configure the same printer (printer system) as the printer 10 in the present embodiment.

  In the above-described embodiment, each configuration in the control unit 100 may be realized by software or may be realized by a circuit.

  In each of the above-described embodiments, the printer 10 is the ink jet printer 10. However, the printer 10 is not limited to being applied to the ink jet printer 10, and may be various types of printers such as a gel jet printer, a toner printer, and a dot impact printer. In addition, a multifunction machine including a scanner device other than a printer, a fax device, a copy device, and the like may be used as the printer of the present invention.

  Further, the concept of the printer 10 in the above-described embodiment includes fluids such as liquids other than ink (liquids themselves, liquids obtained by dispersing or mixing functional material particles in liquids, and gels). It is also possible to include a fluid ejecting apparatus that ejects or discharges (including material). As such, a liquid containing a material such as an electrode material or a color material (pixel material) used for manufacturing a liquid crystal display, an EL (electroluminescence) display, and a surface emitting display is dispersed or dissolved. There are a liquid ejecting apparatus, a fluid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, a fluid ejecting apparatus that ejects a liquid that is used as a precision pipette and serves as a sample.

  Further, the concept of the printer 10 of the present invention includes a micro hemispherical lens (optical lens) used in a fluid ejecting apparatus, an optical communication element, and the like that ejects lubricating oil pinpoint to a precision machine such as a watch or a camera. A fluid ejecting apparatus that ejects a transparent resin liquid such as an ultraviolet curable resin onto a substrate to form a substrate, a fluid ejecting apparatus that ejects an etchant such as an acid or an alkali to etch the substrate, etc., a gel (for example, a physical gel ) And the like.

  DESCRIPTION OF SYMBOLS 10 ... Printer, 20 ... Housing | casing part, 21 ... Chassis, 22 ... Support frame, 30 ... Carriage drive mechanism, 31 ... Carriage, 32 ... CR motor, 38 ... Print head, 40 ... Paper conveyance mechanism, 41 ... PF motor, DESCRIPTION OF SYMBOLS 50 ... Linear encoder, 51 ... Linear scale (corresponding to a scale), 51a ... Translucent part, 51b ... Light-shielding part, 60 ... Photo sensor, 61 ... Light-emitting part, 62 ... Light-receiving part, 66a-67b, 660a, 660b ... Light reception Element, 66, 67, 660... Light receiving element array, 80... Rotary encoder, 81... Rotary scale, 82... Photo sensor, 100, 100A .. Control unit (corresponding to signal selection output means) 110. ... error calculation unit, 112 ... ENC signal determination unit, 113 ... memory, 114 ... ENC signal selection unit, 15 ... timing signal generation unit (corresponding to the timing signal generating means), 116 ... motor control unit, 117 ... counter unit (corresponding to the count means), 120 ... Computer, 610 ... light emitting element, P ... print medium, PTS ... timing signal

Claims (6)

A light emitting unit that emits light;
A scale in which at least alternating light-transmitting parts that transmit light from the light-emitting part and light-shielding parts that block light from the light-emitting part are formed;
Based on light having a periodic characteristic that is located on the opposite side of the light emitting unit with the scale interposed and transmitted through the light transmitting unit generated in response to driving of the driven object, the phase is different from at least 2 A light receiving unit that outputs two detection signals;
At least two detection signals are input, and a signal selection output unit that performs control to select and output one of these detection signals,
Timing signal generation means for generating a timing signal for instructing the timing of ejection of the ink from the print head that ejects ink toward the print medium based on the detection signal output from the signal selection output means; ,
Comprising
The signal selection output means compares the detection signals in a state where the driven object is driven at a constant speed, and selects and outputs the one closest to the reference detection signal.
A printer characterized by that. The printer according to claim 1,
The detection signal output level includes an H level exceeding a predetermined threshold and an L level not exceeding the predetermined threshold,
The signal selection output means selects the one having the smallest error among the periods of the detection signals with respect to a reference period serving as a reference of the detection signal, and outputs the selected one to the outside.
A printer characterized by that. The printer according to claim 1 or 2,
The driven object is a carriage to which the print head is attached,
The light emitting unit and the light receiving unit are attached to the carriage,
A motor for providing a driving force for driving the carriage;
Motor control means for controlling the drive of the motor based on the detection signal output from the signal selection output means;
A printer comprising: The printer according to any one of claims 1 to 3,
A counting means for counting an index value of any one of cumulative elapsed time, usage time or the number of print media printed by the print head;
The signal selection output means selects and outputs one of at least two detection signals by the signal selection output when the index value in the counting means reaches a predetermined determination threshold. Do control,
A printer characterized by that. A light emitting unit that emits light;
A scale in which at least alternating light-transmitting parts that transmit light from the light-emitting part and light-shielding parts that block light from the light-emitting part are formed;
Based on light having a periodic characteristic that is located on the opposite side of the light emitting unit with the scale interposed and transmitted through the light transmitting unit generated in response to driving of the driven object, the phase is different from at least 2 A light receiving unit that outputs two detection signals;
At least two detection signals are input, and a signal selection output unit that performs control to select and output one of these detection signals,
Comprising
The signal selection output means compares the detection signals in a state where the driven object is driven at a constant speed, and selects and outputs the one closest to the reference detection signal.
A position detecting device characterized by that. Periodic light transmitted through a light transmitting part of a scale in which light transmitting parts that transmit light from the light emitting part and light shielding parts that block light are alternately formed and generated according to driving of the driven object A signal selection method for outputting at least two detection signals having different phases based on light having characteristics from a light receiving unit and selecting one of the detection signals from the detection signals,
In the state where the driven object is driven at a constant speed, the detection signals are compared, and the one closest to the reference detection signal is selected and output.
And a signal selection method.

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