JP2008281372A - Position detection device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection device capable of detecting inexpensively a proper mark detection signal without requiring another constitution even when a period of the mark detection signal is shortened by high-speed movement of an object. <P>SOLUTION: An encoder device 1 has an encoder scale 2 with a plurality of marks necessary for position detection of the object formed thereon; and an encoder sensor 4 equipped with a light emitting part 4a and a light receiving part 4b, detecting optically a mark by a light intensity reaching the light receiving part 4b through the encoder scale 2 in the light from the light emitting part 4a. The device 1 is used for detecting a variation of an object position from the detected mark. The plurality of marks includes a black mark part 3a and a gray mark 3b having each different light intensity reaching the light receiving part 4b, when the light intensity from the light emitting part 4a is fixed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a position detection device used for controlling the position or speed of a DC motor or the like.

  Conventionally, an encoder device has been widely used as a position detection device for controlling a motor for moving a carriage (ink ejection unit) in an inkjet printer or the like. An example of a conventional inkjet printer provided with an encoder device is shown in FIG.

  FIG. 6A is a diagram illustrating a schematic configuration of a conventional inkjet printer 100. FIG. 6B is a diagram illustrating a schematic configuration of the peripheral portion of the encoder device 101 of the inkjet printer 100.

  As shown in FIG. 6A, the inkjet printer 100 includes an encoder device 101, a carriage 105, a DC motor 106, a motor driver 107, and a CPU 108. The encoder device 101 includes an encoder scale 102 and an encoder sensor 104.

  The encoder scale 102 is composed of a transparent belt-like scale, and black tape is continuously provided on the scale at regular intervals. By providing the black tape, the encoder scale 102 is formed with a slit 103 from a black mark portion 103a which is a black tape portion and a transparent portion 103b which is a transparent portion where no black tape is provided.

  As shown in FIG. 6B, the encoder sensor 104 includes a light emitting unit 104a that emits light toward the encoder scale 102, a light receiving unit 104b that receives light that has passed through the slit 103 of the encoder scale 102, and a power supply unit. 104c is a transmissive optical sensor. The encoder sensor 104 is provided on the carriage 105 as shown in FIG. 6A and moves together with the carriage 105. As shown in FIG. 6B, the encoder sensor 104 is interposed between the light emitting unit 104a and the light receiving unit 104b. The encoder scale 102 is arranged.

  When the encoder sensor 104 is positioned on the transparent portion 103b, the light emitted from the light emitting portion 104a passes through the encoder scale 102 and reaches the light receiving portion 104b. Since the reached light turns on the transistors constituting the light receiving unit 104b, the voltage level reaching the CPU 108 side is close to the ground level.

  On the other hand, when the encoder sensor 104 is positioned at the black mark portion 103a of the encoder scale 102, the light emitted from the light emitting portion 104a is blocked by the black mark portion 103a on the encoder scale 102 and therefore does not reach the light receiving portion 104b. . If the light does not reach, the transistors constituting the light receiving unit 104b are turned off, so that the voltage level reaching the CPU 108 side is close to the power supply voltage level.

  The encoder sensor 104 outputs to the CPU 108, as an encoder signal, a pulse formed by a change in voltage level that reaches the CPU 108 side.

  The CPU 108 detects a change in the position and speed of the carriage 105 from the encoder signal, performs correction by calculation, converts the result into a control signal, and outputs the control signal to the motor driver 107. The motor driver 107 controls the position and speed of the DC motor 106, that is, the carriage 105, based on the input control signal.

  Next, the encoder signal will be described. FIG. 7A is a diagram showing an encoder signal output from the encoder sensor 104 of the conventional encoder device 101. FIG. 7B is a diagram showing an encoder signal (CPU recognition signal) recognized by the CPU 108. FIG. 8A is a diagram illustrating a CPU recognition signal having a long cycle and a timing for performing CPU arithmetic processing on the CPU recognition signal. FIG. 8B is a diagram illustrating a CPU recognition signal with a short cycle and timing for performing CPU arithmetic processing on the CPU recognition signal.

  As shown in FIG. 7A, when the encoder sensor 104 is positioned at the black mark portion 103a, the light from the light emitting portion 104a is blocked, so that the light does not reach the light receiving portion 104b, and the light receiving portion 104b is moved. The transistor to be configured is turned off. That is, since the voltage level reaching the CPU 108 side is close to the power supply voltage level, the encoder sensor output value is at a high level. On the other hand, when the encoder sensor 104 is positioned in the transparent portion 103b, the light from the light emitting portion 104a is transmitted and the light reaches the light receiving portion 104b, so that the transistors constituting the light receiving portion 104b are turned on. That is, since the voltage level reaching the CPU 108 side is close to the ground level, the encoder sensor output value is at a low level (low).

  Then, as shown in FIG. 7B, the CPU 108 sets the encoder signal output from the encoder sensor 104 to a high level among the pulses of the encoder signal that are equal to or higher than the CPU input threshold, and is equal to or lower than the CPU input threshold. Recognize pulse as low level signal (CPU recognition signal).

  When the period of the input encoder signal is long, the CPU 108 performs arithmetic processing on the encoder signal at a timing as shown in FIG. In this case, since the CPU 108 can perform an operation on all the pulses without missing the pulses of the input encoder signal, the encoder signal can be detected correctly.

  Therefore, the CPU 108 can generate a control signal for controlling the position and speed of the carriage 105 using the correctly detected encoder signal. Based on the control signal, the CPU 108 can control the position and speed of the carriage 105. Can be done correctly.

  In the inkjet printer 100, it is preferable to shorten the movement time of the carriage 105 from the home position to the printing start position in order to reduce the total printing time. That is, it is preferable to operate the carriage 105 at high speed from the home position to the print start position.

  However, the conventional encoder device 101 has the following problems when the carriage 105 is moved at high speed.

  When the carriage 105 is moved at a high speed, the number of black mark portions 103a read by the encoder device 101 provided in the carriage 105 per unit time increases, so that the frequency of the encoder signal output from the encoder sensor 104 increases. The cycle of the encoder signal is shortened.

  On the other hand, the period of the encoder signal that can be correctly detected by the CPU 108, that is, the period of the CPU recognition signal (detectable period) is determined in advance by the capability of the CPU 108. For this reason, when an encoder signal having a cycle shorter than the detectable cycle is input to the CPU 108, the CPU 108 cannot accurately detect the encoder signal, and the position of the carriage 105 or the like by the control signal obtained from the encoder signal The speed cannot be controlled properly.

  Further, even if the CPU 108 can accurately detect the encoder signal without missing each pulse of the encoder signal having a cycle shorter than the detectable cycle, the idle portion (3) shown in FIG. Since there is no room between the calculation process performed on the next pulse, the calculation load on the calculation unit (not shown) of the CPU 108 becomes heavy. As a result, the CPU 108 may affect other processes to be executed by the CPU 108.

  Specifically, when an encoder signal having a cycle shorter than the detectable cycle is input to the CPU 108, the cycle in which the CPU 108 recognizes each pulse of the encoder signal is shortened. In this case, as shown in FIG. 8B, the calculation processes (1) and (2) performed for each pulse are gradually delayed from the timing for recognizing each pulse of the encoder signal. There is a possibility that a pulse that cannot be processed because the calculation process is not in time can occur. That is, the CPU 108 may cause missing pulses. If a pulse is missed, the CPU 108 cannot perform an arithmetic process on all pulses of the input encoder signal, and thus cannot detect an accurate encoder signal.

  As a means for solving the above problem, it is conceivable to use a CPU having a higher processing capability in order to reduce the processing burden caused by the shortening of the cycle of the encoder signal, but this causes an increase in cost.

  On the other hand, in order to perform processing appropriately using an existing CPU, it is necessary to lengthen the cycle of the encoder signal. To realize this, the cycle of the encoder signal is divided outside the CPU. A separate configuration such as adding parts or using an encoder scale with a large slit interval is required, resulting in an increase in cost.

  The present invention has been made in view of the above-described conventional problems, and the object thereof is not to require a separate configuration even when the cycle of the encoder signal (mark detection signal) is short, In addition, a position detection device capable of detecting an appropriate encoder signal at low cost is realized.

  In order to solve the above-described problem, the position detection apparatus of the present invention includes an encoder scale on which a plurality of marks necessary for position detection of an object are formed, a light emitting element, and a light receiving element. A mark detection sensor that optically detects the mark by the amount of light reaching the light receiving element via the encoder scale in the light, and a position for detecting a variation amount of the position of the object from the detected mark In the detection device, the plurality of marks include marks having different amounts of light reaching the light receiving element when the amount of light from the light emitting element is fixed.

  According to the above configuration, the amount of light reaching the light receiving element varies depending on the mark mediated while the light from the light emitting element reaches the light receiving element. Therefore, the mark detection sensor output value (encoder sensor output value) output from the mark detection sensor also changes in accordance with the amount of light reaching the light receiving element.

  As a result, for example, a CPU input threshold value, which is a limit value of the mark detection sensor output value that can be recognized by the CPU, is the mark detection sensor output value output in response to the light reaching the light receiving element via a certain mark. If the amount of light emitted from the light emitting element is set so as to be smaller, the mark is not recognized by the CPU. Therefore, the period of the mark detection signal (encoder signal) composed of the mark detection sensor output value can be thinned by the amount of the mark.

  As described above, by appropriately changing the CPU input threshold value and the amount of light applied to the mark from the light emitting element, the cycle of the mark detection signal can be freely thinned. Even when the cycle of the mark detection signal is shortened, it is possible to detect an appropriate mark detection signal at a low cost without requiring a separate configuration.

  In the position detection device of the present invention, it is preferable that the light emitting element and the light receiving element are arranged to face each other via the encoder scale, and the mark is a mark having a different transmittance.

  According to the above configuration, since the light emitting element and the light receiving element are arranged symmetrically with respect to the encoder scale, the light emitted from the light emitting element passes through the encoder scale as linear light. The light is received by the light receiving element. Therefore, the light emitted from the light emitting element is less likely to be diffused, and thus is easily detected by the light receiving element.

  In the position detection device of the present invention, it is preferable that the light emitting element and the light receiving element are arranged on the same side with respect to the encoder scale, and the mark is a mark having a different reflectance.

  According to the above configuration, the light emitting element and the light receiving element are arranged on the same side with respect to the encoder scale, and the light emitted from the light emitting element is reflected by the encoder scale and received by the light receiving element. Therefore, the irradiated light is difficult to detect by the light receiving element, and although the light quantity of the light emitting element and the sensitivity of the light receiving element are limited, the arrangement of the encoder scale is facilitated as compared with the transmission type configuration.

  In the position detection device of the present invention, it is preferable that the encoder scale has a strip shape, and the plurality of marks are formed at arbitrary intervals in the longitudinal direction of the encoder scale.

  According to the above configuration, for example, a position detection device that optically detects a plurality of marks formed at arbitrary intervals in the longitudinal direction of the encoder scale by moving the mark detection sensor in the longitudinal direction of the encoder scale. In this case, the fluctuation amount corresponding to the detected mark can be detected as the fluctuation amount of the position of the object. Therefore, the position detection device of the present invention is effective when the object moves linearly such as a carriage.

  In the position detection device of the present invention, it is preferable that the encoder scale has a disk shape, and the plurality of marks are formed at arbitrary intervals in a circumferential direction of the encoder scale.

  According to the above configuration, for example, the plurality of marks are formed at arbitrary intervals in the circumferential direction of the encoder scale by rotating the encoder scale, and the plurality of marks are detected by the fixed mark detection sensor. In the case of a position detection device that detects optically, it is possible to detect that the amount of rotation corresponding to the detected mark is the amount of change in the position of the object. Therefore, the position detection device of the present invention is effective when the object rotates and moves like a paper feed mechanism in a printer or the like.

  Moreover, it is preferable that the transmittance or the reflectance of each mark in the position detection device of the present invention is defined by a color density.

  According to the above-described configuration, the transmittance or the reflectance can be reduced, for example, by increasing the color of a part of the mark, that is, by increasing the density, thereby reducing the transmittance at the mark portion or reducing the reflectance. be able to. Furthermore, the transmittance of the mark portion can be increased or the reflectance can be increased only by making the color of the other part of the mark light, that is, by reducing the density. Thereby, the transmittance and reflectance of the mark can be easily changed. As a result, since the mark detection sensor output value output from the mark detection sensor changes depending on the transmittance or reflectance of the mark mediated, the amount of light emitted from the light emitting element to the mark is appropriately changed. Thus, the period of the mark detection signal can be easily thinned out without providing a separate configuration for thinning out the period of the mark detection signal.

  In the position detection device of the present invention, it is preferable that the transmittance or the reflectance of each mark is defined by the material forming each mark.

  According to the above configuration, the transmittance or the reflectance is, for example, a part of the plurality of marks is formed of a material having a high transmittance and / or reflectance, and the other part of the mark is transmittance or It can be formed of a material having a low reflectance. Thereby, the transmittance or reflectance of the mark can be easily changed. As a result, since the mark detection sensor output value output from the mark detection sensor varies depending on the transmittance or reflectance of the mark mediated, the mark is irradiated from the CPU input threshold and the light emitting element. By appropriately changing the amount of light to be obtained, it is possible to easily thin out the cycle of the mark detection signal without providing a separate configuration for thinning out the cycle of the mark detection signal.

  In addition, the transmittance or the reflectance of each mark in the position detection device of the present invention is such that a region that transmits light from the light emitting element has an area of a black region that does not transmit light that each mark has. It is preferable that the ratio is defined by the proportion occupied.

  According to the above configuration, in the transmission-type position detection device, when a transparent portion is formed in a polka dot shape in the black mark region of the encoder scale, by increasing the proportion of the polka dot in the mark region The transmittance of the mark increases. In the reflection type position detection device, for example, when a reflective member is provided at the lower part of the encoder scale and a transparent portion is formed in a polka-dot shape in the area of the black mark, the polka-dot-shaped area in the mark area. Increasing the proportion of the transparent portion increases the reflectance.

  Thereby, the transmittance or reflectance of the mark can be easily changed. As a result, the mark detection sensor output value output from the mark detection sensor changes depending on the transmittance or reflectivity of the mark mediated, so that the amount of light emitted from the light emitting element to the mark is appropriately changed. Thus, the period of the mark detection signal can be easily thinned out without providing a separate configuration for thinning out the period of the mark detection signal.

  Moreover, it is preferable that the position detection device of the present invention further includes a light amount switching unit that switches a light amount emitted from the light emitting element.

  According to the said structure, the light quantity irradiated from the said light emitting element can be changed automatically, and the light quantity which reaches | attains the said light receiving element is changed in connection with this. That is, since the mark detection sensor output value changes, the cycle of the mark detection signal can be changed. For example, when the position detection target is moved at high speed, the light amount switching means switches the light amount from the light emitting element so that a part of the mark detection sensor output value becomes equal to or less than the CPU input threshold value. By doing so, the cycle of the mark detection signal can be thinned out.

  An electronic apparatus according to the present invention includes a position detection target, and uses the position detection device according to the present invention to detect the amount of change in the position of the target.

  The object is preferably an ink ejecting unit.

  According to the above configuration, the position detection device according to the present invention can freely thin out the cycle of the mark detection signal. Therefore, in a scene where the cycle of the mark detection signal is shortened by moving the object at high speed. However, it is possible to detect an appropriate mark detection signal at low cost without adding a separate configuration to an electronic apparatus such as an ink jet printer.

  As described above, the position detection device of the present invention includes an encoder scale on which a plurality of marks necessary for position detection of an object are formed, a light emitting element, and a light receiving element, and includes the light from the light emitting element. A position detection device that includes a mark detection sensor that optically detects the mark based on the amount of light that reaches the light receiving element via the encoder scale, and that detects a variation in the position of the object from the detected mark; The plurality of marks include marks having different amounts of light reaching the light receiving element when the amount of light from the light emitting element is fixed.

  Therefore, even when the object moves at high speed and the cycle of the mark detection signal is shortened, an appropriate mark detection signal is detected at a low cost without requiring a separate configuration. There is an effect of realizing a position detecting device capable of performing the above.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 5 as follows.

  FIG. 1 is a schematic configuration diagram of an encoder device 1 (position detection device). FIG. 2 is a schematic configuration diagram of the entire inkjet printer 10. FIG. 3 is a perspective view showing the external appearance of the peripheral portion of the encoder device 1 in the inkjet printer 10.

  As shown in FIG. 2, the ink jet printer 10 of the present embodiment includes an encoder device 1, a carriage 5 (ink ejecting unit), a DC motor 6, a motor driver 7, a CPU 8, and a paper feed mechanism 9 (see FIG. 2). 3) and a light quantity switching unit 12 (FIG. 1).

  The ink jet printer 10 according to the present embodiment includes an encoder device 1 having an encoder scale 2 formed with a gray mark portion 3b (FIG. 1) in which the amount of transmitted light changes depending on the amount of light irradiated. According to the above configuration, when it is desired to operate the carriage 5 or the paper feed mechanism 9 at a high speed such as when printing is started, the light amount switching unit 12 (light amount switching unit) and the light emitting unit in the encoder sensor 4 (mark detection sensor). It is possible to switch so that the amount of light emitted from 4a (light emitting element) increases. Thereby, since the amount of light transmitted through the gray mark portion 3b can be increased, the encoder sensor output value corresponding to the light transmitted through the gray mark portion 3b can be made smaller than the CPU input threshold value. As a result, the period of the encoder signal recognized by the CPU 8 can be thinned out.

  Here, the CPU input threshold is a characteristic that the CPU has in advance, and if the encoder signal (mark detection signal) output from the encoder sensor 4 is equal to or less than the CPU input threshold, the CPU 8 recognizes it as a low level, If it is above the CPU input threshold, it is recognized as a high level. A signal composed of signals recognized as high level by the CPU is called a CPU recognition signal, for example, the one shown in the bottom diagram of FIG.

  The encoder device 1 is a linear encoder device including an encoder scale 2 and an encoder sensor 4. The encoder device 1 optically detects a plurality of mark portions formed as scales on an encoder scale 2 which is a fixed band-shaped transparent scale by an encoder sensor 4 that moves together with the carriage 5, whereby the carriage 5 The amount of change in position and speed is detected.

  On the encoder scale 2, there are a mark portion 3a (hereinafter referred to as a black mark portion) provided with a black tape and a mark portion 3b (hereinafter referred to as a gray mark portion) provided with a gray tape having a lighter density than black. The encoder scale 2 is formed at regular intervals in the longitudinal direction. The encoder scale 2 is provided with a black mark portion 3a, a gray mark portion 3b, and a transparent portion 3c on which nothing is formed, so that a slit 3 is formed. Specifically, the black mark portions 3a are continuously formed at equal intervals of the distance L. One gray mark portion 3b is provided at each position obtained by dividing the black mark portion 3a into three equal parts. That is, as shown in FIG. 1, one of the gray mark portions 3b is formed at a position separated from the black mark portion 3a by a distance L / 3 obtained by dividing the distance L between the black mark portions 3a into three equal parts, and Further, another gray mark portion 3b is formed at a position further away from the gray mark portion 3b by a distance L / 3. Moreover, since the said mark part has width, the said distance says the distance of the center points of the black mark part 3a and the gray mark part 3b.

  The black mark portion 3a is provided with a black portion having a light transmittance (hereinafter referred to as transmittance) of 0% on a transparent scale, and does not transmit light. The gray mark portion 3b is a portion where the transmittance C% is provided on the transparent scale, and the amount of light transmitted varies depending on the amount of light irradiated. Here, C is an arbitrary value belonging to the range of 0 <C <100. The transparent portion 3c is a portion where nothing is provided on the transparent scale, and has a transmittance of 100%, and thus transmits all light.

  Further, the position information represented by only the black mark portions 3a separated from each other by the distance L as the scale is the position information parameter X, and the mark portions separated from each other by the distance L / 3 (the black mark portions 3a and the gray mark portions 3b). The position information represented as a scale is defined as a position information parameter Y. The relationship between the position information parameter X and the position information parameter Y is that, in the position information parameter X, a position advanced by two scales, that is, a position advanced by 2L, and a parameter Y advanced by six scales, that is, L / 3 ×. Corresponds to a position advanced by six. These positional information parameters X and Y and the correspondence between the positional information parameter X and the positional information parameter Y are determined in advance. In the position information parameter X, the distance between the scales, that is, the interval between the black mark portions 3a is large. Therefore, the position information parameter X is determined when the carriage 5 is moved at high speed, that is, when the light amount switching unit 12 is switched so that the light emission amount at the light emitting unit 4a is large (light amount A). This is used for position control of the carriage 5 when thinning is performed. On the other hand, in the position information parameter Y, the distance between the scales, that is, the interval between the mark portions is small at L / 3. Therefore, the position information parameter Y is determined when the carriage 5 is moved at a low speed, that is, when the light amount switching unit 12 is switched so that the light emission amount at the light emitting unit 4a is small (light amount B). This is used for the position control of the carriage 5 when not thinning out.

  The encoder sensor 4 optically detects the mark portions 3a and 3b formed on the encoder scale 2, and as shown in FIG. 1, a light emitting portion 4a that irradiates light toward the encoder scale 2, and an encoder This is a transmissive optical sensor including a light receiving unit 4b that receives light transmitted through the scale 2 and a power supply unit 4c.

  In the encoder sensor 4, the light emitting diode that constitutes the light emitting unit 4a emits light by the current flowing from the power supply 17 side, and the light emitted from the light emitting unit 4a is disposed between the light emitting unit 4a and the light receiving unit 4b. Only the light that has been irradiated onto the scale 2 and has passed through the encoder scale 2 among the irradiated light reaches the light receiving unit 4b. When the light reaches the light receiving unit 4b, the encoder sensor 4 switches the ON / OFF state of the transistors constituting the light receiving unit 4b in accordance with the amount of light that has reached. In order to turn on the transistor constituting the light receiving unit 4b (light receiving element), the amount of light reaching the light receiving unit 4b needs to be equal to or greater than a predetermined value M. The predetermined value M is a characteristic value that the encoder sensor 4 has in advance.

  More specifically, if the amount of light reaching the light receiving unit 4b is less than M, the phototransistor constituting the light receiving unit 4b is in an OFF state, so the encoder sensor 4 does not flow the current from the power supply unit 4c to the ground side. . That is, the current I flowing from the power supply unit 4c to the ground side is I = 0. In this case, since the voltage level reaching the CPU 8 side is close to the power supply voltage level, the encoder sensor output value is at a high level as shown in FIG.

  Here, the current I refers to a current that flows from the power supply unit 4c to the ground side via the light receiving unit 4b.

  On the other hand, if the amount of light reaching the light receiving unit 4b is more than M, the phototransistor serving as the light receiving unit 4b is turned on, and the encoder sensor 4 causes the current I to flow from the power supply unit 4c to the ground side. In this case, since the voltage level reaching the CPU 8 side is close to the ground, the encoder sensor output value is at a low level as shown in FIG.

  The CPU 8 detects and controls the speed of the carriage 5 and the paper feed mechanism 9, the position control unit 14 that detects and controls the positions of the carriage 5 and the paper feed mechanism 9, and the light quantity switching unit 12 (FIG. 1). ), And a calculation unit 16 that calculates and corrects encoder signals detected from the speed control unit 13 and the position control unit 14.

  Here, the speed control in the speed controller 13 is performed by detecting the speed fluctuation amount of the carriage 5 from the CPU recognition signal that is the position fluctuation amount of the carriage 5 and the time component of the CPU 8.

  In the CPU 8, a limit value that can be recognized by the CPU 8, that is, a CPU input threshold value t is set in advance. An output value smaller than the CPU input threshold t is not recognized as a pulse by the CPU 8.

  As shown in FIG. 1, the light amount switching unit 12 includes a transistor 12 a therein, and flows to the light emitting unit 4 a of the encoder sensor 4 by switching the transistor 12 a on and off based on an instruction from the light amount switching control unit 15. This circuit switches the amount of current. The light amount switching unit 12 switches the amount of light (light emission amount) emitted from the light emitting unit 4a by switching the amount of current flowing through the light emitting unit 4a.

  In accordance with the control instruction of the light amount switching control unit 15, the light amount switching unit 12 changes the light emission amount from the light emitting unit 4a between A having a large light emission amount (hereinafter, light amount A) and B having a small light emission amount (hereinafter, light amount B). Switch to 2 stages. Here, the light amount A is set such that the light amount that passes through the gray mark portion 3b and reaches the light receiving portion 4b is larger than the predetermined value M, that is, the encoder sensor output value is always greater than the CPU input threshold value t. Is set to a low level. The amount of light B is set so that the amount of light that passes through the gray mark portion 3b and reaches the light receiving portion 4b is smaller than the predetermined value M, that is, the encoder sensor output value is always greater than the CPU input threshold value t. It is set to be high level.

The light quantity switching operation by the light quantity switching unit 12 will be specifically described as follows. Here, as shown in FIG. 1, the current flowing through the light emitting unit 4a is i, and the current limiting resistors for setting the current value flowing through the current i are R ₁ and R ₂ .

The light amount switching unit 12 turns off the transistor 12a when switching the light emission amount from the light emitting unit 4a to the light amount B. When the transistor 12a and the OFF state, the current flowing from the power source 17 flows to the ground 1 through only _{R 1.}

On the other hand, when the light amount switching unit 12 switches the light emission amount from the light emitting unit 4a to the light amount A, the light amount switching unit 12 turns on the transistor 12a. When the transistor 12a in an ON state, current flows from the power supply 17, via _{R 1} and _{R 2,} respectively flows to the ground 1 and ground 2. Here, R ₁ and R ₂ are in a parallel relationship, and when the combined resistance of R ₁ and R ₂ and R ₁ are compared, the combined resistance of R ₁ and R ₂ is smaller than R ₁ . That is, since the combined resistance of R ₁ and R ₂ <R ₁ , the current i flowing through the light emitting unit 4a when the transistor 12a is in the ON state is greater than the current i flowing through the light emitting unit 4a when the transistor 12a is in the OFF state. ,growing.

  That is, when the transistor 12a is turned on, the light emission amount of the light emitting unit 4a can be switched to the light amount A having a large light amount, and when the transistor 12a is turned off, the light amount B can be switched to a light amount B having a small light amount. it can.

  Next, the control operation of the inkjet printer 10 will be described in detail with reference to FIGS.

  FIG. 4 is a diagram showing an encoder signal and a CPU recognition signal when the light amount emitted from the light emitting unit 4a is small, that is, when the light amount switching unit 12 switches to the light amount B. FIG. 5 is a diagram illustrating an encoder signal and a CPU recognition signal when the light amount emitted from the light emitting unit 4a is large, that is, when the light amount switching unit 12 switches to the light amount A.

  First, the control operation of the inkjet printer 10 when moving the carriage 5 at high speed at the start of printing will be described.

  When the CPU 8 detects the print start signal, the speed control unit 13 switches the movement speed of the carriage 5 at a high speed so as to move the carriage 5 from the home position to the print start position at a high speed. At that time, the CPU 8 switches the position information parameter used for position control of the carriage 5 to the high-speed position information parameter X in the position control unit 14, and the light amount switching control unit 15 emits the light emitting unit 4 a in the encoder sensor 4. The light amount switching unit 12 is controlled so that the light emission amount becomes the light amount A.

  The light amount switching unit 12 switches the transistor 12a to the ON state based on a control instruction from the light amount switching control unit 15. Thereby, the light emission amount of the light emitting unit 4a becomes the light amount A.

  In the encoder device 1, the encoder scale 2 is irradiated with light of the light amount A emitted from the light emitting unit 4 a in the encoder sensor 4. Of the irradiated light, only the light transmitted through the encoder scale 2 is received by the light receiving unit 4b. Further, in the encoder sensor 4, only when the light of the predetermined value M or more reaches the light receiving unit 4b, the transistor constituting the light receiving unit 4b is turned on, and the encoder output value output from the encoder sensor 4 is low level. Or it becomes a level close to the low level. That is, when the amount of light reaching the light receiving unit 4b is equal to or less than the above-described constant value M, the transistors constituting the light receiving unit 4b are turned off, and the encoder sensor output value is at a high level or a level close to a high level. Detailed description of the operation in the encoder device 1 will be described later.

  Then, the position control unit 14 in the CPU 8 recognizes the encoder signal input from the encoder device 1 and detects the variation amount of the carriage 5 using the CPU recognition signal and the position information parameter X. Then, the calculation unit 16 of the CPU 8 corrects the fluctuation amount by calculation, converts it into a control signal for the motor driver 7, and outputs it to the motor driver 7. The motor driver 7 moves the carriage 5 via the DC motor 6.

  For example, regarding the control operation of the ink jet printer 10 when the speed is reduced at the time of printing or the like, first, when printing is started, the speed control unit 13 performs control to switch the moving speed of the carriage 5 to a low speed.

  When the speed control unit 13 switches the moving speed of the carriage 5 to a low speed, the CPU 8 switches the position information parameter used for the position control of the carriage 5 to the low-speed position information parameter Y in the position control unit 14, and the light quantity. In the switching control unit 15, the light amount switching unit 12 is controlled so that the light emission amount of the light emitting unit 4 a in the encoder sensor 4 becomes the light amount B.

  In the light amount switching unit 12, the transistor 12a is turned off so that the light emission amount of the light emitting unit 4a becomes the light amount B based on an instruction from the light amount switching control unit 15. When the transistor 12a is turned off, the current i flowing through the light emitting unit 4a becomes small, and the light emission amount of the light emitting unit 4a becomes the light amount B smaller than the light amount A.

  In the encoder device 1, in response to the current i, light of a light amount B is emitted from the light emitting unit 4 a in the encoder sensor 4, irradiated to the encoder scale 2, and transmitted through the encoder scale 2 out of the irradiated light. Only the received light is received by the light receiving unit 4b. In addition, when the amount of light equal to or more than the predetermined amount M reaches the light receiving unit 4b, the encoder sensor 4 turns on the transistors constituting the light receiving unit 4b, and the encoder sensor output value becomes low level or a level close to low level. . On the other hand, when the amount of light reaching the light receiving unit 4b is equal to or less than the predetermined value M, 4b is turned off, and the encoder sensor output value is at a high level or a level close to a high level. Detailed description of the operation in the encoder device 1 will be described later.

  Then, the position control unit 14 in the CPU 8 recognizes the encoder signal input from the encoder device 1 (CPU recognition signal), and detects the fluctuation amount of the carriage 5 using the CPU recognition signal and the position information parameter Y. To do. Then, the calculation unit 16 of the CPU 8 corrects the fluctuation amount by calculation, converts it into a control signal for the motor driver 7, and outputs it to the motor driver 7. The motor driver 7 moves the carriage 5 via the DC motor 6.

  Here, a specific operation in the encoder device 1 will be described.

  First, the case where the amount of light B is switched when the carriage 5 is moved at a low speed will be described with reference to FIG.

  In the encoder device 1, when the encoder sensor 4 is positioned at the black mark portion 3 a of the encoder scale 2, the transmittance of the black mark portion 3 a is 0%, so that the total amount of light emitted from the light emitting portion 4 a is the encoder scale. 2 is blocked by the black mark portion 3a on the top 2. Therefore, the light emitted from the light emitting unit 4a does not reach the light receiving unit 4b. In this case, since the phototransistor constituting the light receiving unit 4b is turned off, the encoder sensor 4 outputs a high level signal to the CPU 8 as indicated by the n1th pulse shown in FIG.

  Further, when the encoder sensor 4 is located in the transparent portion 3c of the encoder scale 2, the transmittance of the transparent portion 3c is 100%, so that the light emitted from the light emitting portion 4a is transmitted through the encoder scale 2 in the total amount. To reach the light receiving unit 4b. In this case, since the phototransistor constituting the light receiving unit 4b is in the ON state, the output level of the encoder sensor 4 is a low level as represented between the n1th pulse and the n2th pulse in FIG. Become.

  Further, when the encoder sensor 4 is located at the gray mark portion 3b of the encoder scale 2, since the transmittance is C%, only a part of the light emitted from the light emitting portion 4a is allowed to pass through the gray mark portion 3b. The light passes through and reaches the light receiving unit 4b. Here, since the light quantity B is set in advance so that the light quantity that passes through the gray mark portion 3b, that is, the mark portion having the transmittance C% and reaches the light receiving portion 4b is smaller than the predetermined value M, the light receiving portion 4b. Is turned off. Therefore, the output level of the encoder sensor 4 outputs a high level signal to the CPU 8 as indicated by the n2 th pulse or the n3 th pulse in FIG.

  From the above, when the light amount emitted from the light emitting unit 4a is the light amount B, the encoder sensor output value when the encoder sensor is located in the gray mark unit 3b is larger than the CPU input threshold value t. The mark 3b is detected as a pulse by the CPU 8.

  As a result, when the light amount is set to B, the cycle of the encoder signal output from the encoder device 1 is not thinned out and is also recognized by the CPU 8 as it is, so the CPU 8 recognizes the cycle of the output encoder signal. The period of the pulse (CPU recognition period) is the same.

  Next, a case where the amount of light A is switched when the carriage 5 is moved at high speed will be described with reference to FIG.

  When the encoder sensor 4 is positioned at the black mark portion 3a of the encoder scale 2, the transmittance of the black mark portion 3a is 0%, so that the total amount of light emitted from the light emitting portion 4a is on the encoder scale 2. Is blocked by the black mark portion 3a. Therefore, the light emitted from the light emitting unit 4a does not reach the light receiving unit 4b, and the phototransistor constituting the light receiving unit 4b is turned off. Therefore, the encoder sensor 4 outputs a high level signal as indicated by the n1 th pulse in FIG.

  When the encoder sensor 4 is positioned on the transparent portion 3c of the encoder scale 2, the total amount of light emitted from the light emitting portion 4a passes through the encoder scale 2 and reaches the light receiving portion 4b. Is turned on. Therefore, the output level of the encoder sensor 4 becomes a low level as shown between the n1 th pulse and the n2 th pulse in FIG.

  Further, when the encoder sensor 4 is located at the gray mark portion 3b of the encoder scale 2, since the transmittance is C%, only a part of the light emitted from the light emitting portion 4a is allowed to pass through the gray mark portion 3b. The light passes through and reaches the light receiving unit 4b. Here, the light amount A is set in advance so that the light amount that passes through the gray mark portion 3b, that is, the mark portion having the transmittance C% and reaches the light receiving portion 4b is larger than the predetermined value M, and therefore the light receiving portion 4b. Is turned on. Therefore, the output level of the encoder sensor 4 becomes a low level as shown by the n2 th pulse and the n3 th pulse in FIG.

  At this time, as shown in FIG. 5, since the CPU 8 detects only a pulse greater than or equal to the CPU input threshold value t, that is, a pulse corresponding to the black mark portion 3a, the position information parameter X having only the black mark portion 3a as a scale is used. Thus, the carriage 5 is controlled.

  From the above, when the light amount emitted from the light emitting unit 4a is the light amount A, the encoder sensor output value detected according to the light amount that passes through the gray mark portion 3b and reaches the light receiving unit 4b is the CPU input. Since it is smaller than the threshold value t, the mark of the gray mark portion 3b is not detected as a pulse by the CPU 8.

  As a result, the period of the encoder signal recognized by the CPU 8 when the amount of light emitted from the light emitting unit 4a is switched to the light amount A is, as shown in FIG. It is thinned out by the gray mark portion 3b that is not detected. Therefore, the CPU 8 can recognize the encoder signal with a period of 1/3 of the period of the encoder signal output from the encoder device 1.

  According to the above configuration, in the encoder device 1 according to the present embodiment, the amount of light transmitted through the gray mark portion 3b can be increased by increasing the amount of light emitted from the encoder sensor 4. Therefore, the CPU 8 can thin out the cycle of the signal output from the encoder device 1 by the gray mark portion 3b, and the cycle of the CPU recognition signal can be lengthened.

  Therefore, in the encoder device 1 according to the present embodiment, the period of the CPU recognition signal can be lengthened, and even if the carriage 5 is moved at such a high speed that the CPU 8 cannot detect it, the CPU 8 misses the pulse of the encoder signal. The operation can be performed without any problem. Accordingly, the encoder device 1 can appropriately detect the encoder signal, and the position and speed of the carriage 5 can be accurately controlled by various control signals generated based on the encoder signal.

  Further, in the encoder device 1 of the present embodiment, by using a mark portion (gray mark portion 3b) whose transmission amount can be changed by the amount of light that irradiates a part of the mark formed on the encoder scale 2, The period of the CPU recognition signal can be thinned out. That is, since the period of the CPU recognition signal can be lengthened by switching the amount of light applied to the encoder scale 2, no separate external configuration is required for lengthening the period, and an existing CPU is used. Since the period can be lengthened, the manufacturing cost can be reduced.

  In this embodiment, the encoder device 1 that controls the position and speed of the carriage 5 has been described. However, the present invention is not limited to this, and the position and speed control of the paper feed mechanism 9 as shown in FIG. The present invention can also be applied to a rotary encoder device 1 ′ to be performed. In this case, the encoder scale 2 of the encoder device 1 corresponds to the encoder wheel 2 'of the encoder device 1', and the encoder sensor 4 corresponds to the encoder sensor 4 '.

  At this time, mark portions are formed on the encoder wheel 2 'at regular intervals in the circumferential direction of the encoder wheel 2'.

  In this encoder apparatus 1 ', the encoder sensor 4' is fixed, the encoder wheel 2 'is rotated together with the paper feed mechanism 9, and the mark portion formed on the encoder wheel 2' is optically detected by the encoder sensor 4 '. By doing so, the position and speed of the printing paper 11 are controlled.

  In the paper feed mechanism 9, it is preferable to move the printing paper 11 to the printing start position at high speed during paper feeding at the start of printing. Therefore, in this case, the light amount of the light emitting portion 4a of the encoder sensor 4 'in the present embodiment is set to the light amount A. Since the subsequent operation is the same as that of the encoder device 1, the description thereof is omitted.

  In the present embodiment, the amount of light emitted from the light emitting unit 4a of the encoder sensor 4 can be switched between two steps of the light amount A and the light amount B, and the black mark portion 3a and the gray mark portion 3b on the encoder scale 2 Since the mark portions having two different transmittances are formed, the period of the CPU recognition signal can be switched to two types. However, the present invention is not limited to this, and the light amount switching unit 12 in the encoder sensor 4 can switch the light amount in three steps, and on the encoder scale 2, in addition to the black mark portion 3a and the gray mark portion 3b. Further, by providing a light gray mark portion 3d (not shown) having a higher transmittance than the gray mark portion 3b, the cycle of the CPU recognition signal may be switched to three types. In addition, the light quantity switching unit 12 can switch three or more kinds of light quantities, and three or more kinds of marks having different transmittances are formed on the encoder scale 2 so as to correspond thereto, thereby reducing the period of the CPU recognition signal. It may be configured to switch to three or more types.

  In the present embodiment, the light transmittance is changed by the shade of the color of the gray mark portion or the like, but the present invention is not limited to this, and the ratio of the area occupied by the black portion that does not transmit light in the area of the mark portion The light transmittance may be changed by changing. In the present invention, the light transmittance and reflectance of the mark portion may be changed by using materials having different transmittance and reflectance for the mark portion.

  In this embodiment, a transmissive encoder device is used. However, the present invention is not limited to this, and a reflective encoder device may be used.

  In the present embodiment, the period of the encoder signal recognized by the CPU is freely switched by changing the light transmittance at the mark portion of the encoder scale and the amount of light applied to the encoder scale. However, the present invention is not limited to this, and in the case of a reflective encoder device, an encoder signal recognized by the CPU by changing the reflectance of light at the mark portion of the encoder scale and the amount of light applied to the encoder scale. It is possible to freely switch the period.

  In the reflection type encoder device as described above, for example, a light emitting unit and a light receiving unit are provided on the same side with respect to the encoder scale, and a reflection member that totally reflects light is provided below the encoder scale. Thereby, the light emitted from the light emitting part and transmitted through the encoder scale is reflected by the reflecting member and reaches the light receiving part provided on the same side as the light emitting part side. That is, in the transparent part in the encoder scale, the reflectance is 100%, and the light receiving part receives the total amount of light emitted by the light emitting part. Further, since the black mark portion does not transmit light, the reflectance is 0%, and the light emitted from the light emitting portion does not reach the light receiving portion. Further, in the gray mark portion, the reflectance changes depending on the shade of the color, and when the amount of light emitted from the light emitting portion is increased, the amount of reflected light increases and the amount of light reaching the light receiving portion also increases.

  In this embodiment, the linear encoder device that moves linearly, which is mainly used for the position and speed control of the carriage, has been described. However, the present invention is not limited to this, and the position of the paper feed mechanism and The present invention can also be applied to a rotary encoder device used for speed control or the like.

  In the present embodiment, as an example of increasing the carriage moving speed, the movement from the home position at the start of printing to the printing start position has been described as an example. However, the present invention is not limited to this. For example, since it is preferable to move the carriage at a high speed for printing and to move the carriage at a low speed for printing an image, the present invention can also be applied to control the switching of the speed according to this. Is possible.

  In this embodiment, an ink jet printer has been described. However, the present invention is not limited to this, and can be used for a FAX, a scanner, or the like.

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

  The present invention can be applied to control of the position and speed of a DC motor or the like in an apparatus such as a printer or a scanner.

It is a schematic block diagram which shows one Embodiment of the encoder apparatus in this invention. It is a schematic block diagram which shows the structure of an inkjet printer provided with the said encoder apparatus. It is an external view of a part of structure of the said inkjet printer. It is a timing chart which shows the encoder output signal output from the said encoder apparatus, and the CPU recognition signal recognized by CPU. It is another timing chart which shows the encoder output signal output from the said encoder apparatus, and the CPU recognition signal recognized by CPU. (A) is a schematic block diagram which shows an inkjet printer provided with the conventional encoder apparatus, (b) is a schematic block diagram which shows the conventional encoder apparatus. It is a timing chart which shows the encoder output signal output from the conventional encoder apparatus, and the CPU recognition signal recognized by CPU. It is a timing chart which shows the CPU recognition signal recognized with the conventional CPU, and the timing of the arithmetic processing performed with CPU.

Explanation of symbols

1, 1 'encoder device (position detection device)
2, 2 'encoder scale 3 slit 3a black mark part 3b gray mark part 3c transparent part 4, 4' encoder sensor (mark detection sensor)
4a Light emitting part (light emitting element)
4b Light receiving part (light receiving element)
4c Power supply unit 5 Carriage (ink ejection unit)
6 DC motor 7 Motor driver 8 CPU
9 Paper feeding mechanism 10 Inkjet printer 11 Printing paper 12 Light quantity switching unit (light quantity switching means)
12a transistor 13 speed control unit 14 position control unit 15 light quantity switching control unit 16 calculation unit 17 power supply

Claims (11)

An encoder scale on which a plurality of marks necessary for detecting the position of an object are formed;
A mark detection sensor that includes a light-emitting element and a light-receiving element, and that optically detects the mark by the amount of light reaching the light-receiving element via the encoder scale in the light from the light-emitting element, and is detected In the position detection device that detects the amount of change in the position of the object from
The position detection device, wherein the plurality of marks include marks having different amounts of light reaching the light receiving element when the amount of light from the light emitting element is fixed. The light emitting element and the light receiving element are arranged to face each other via the encoder scale,
The position detection apparatus according to claim 1, wherein the marks are marks having different transmittances. The light emitting element and the light receiving element are arranged on the same side with respect to the encoder scale,
The position detection apparatus according to claim 1, wherein the mark is a mark having a different reflectance.   4. The position detection device according to claim 1, wherein the encoder scale has a strip shape, and the plurality of marks are formed at arbitrary intervals in a longitudinal direction of the encoder scale. 5. .   The position according to any one of claims 1 to 3, wherein the encoder scale has a disk shape, and the plurality of marks are formed at arbitrary intervals in a circumferential direction of the encoder scale. Detection device.   6. The position detection device according to claim 2, wherein the transmittance or the reflectance of each mark is defined by a color density.   6. The position detection device according to claim 2, wherein the transmittance or the reflectance of each of the marks is defined by a material that forms each of the marks.   The transmittance or reflectance of each mark is defined by a ratio of a region transmitting light from the light emitting element to an area of a black region that does not transmit light of each mark. The position detection device according to claim 2, wherein the position detection device is a feature.   The position detection device according to claim 1, further comprising a light amount switching unit that switches a light amount emitted from the light emitting element. In an electronic device equipped with an object for position detection,
An electronic apparatus using the position detection device according to any one of claims 1 to 9, in order to detect a variation amount of the position of the object.   The electronic device according to claim 10, wherein the object is an ink ejecting unit.

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