Position detection system and method
By using scales of different areas and light sensors to detect voltage output in a linear encoder, scale position detection is simplified, the processing delay problem in the prior art is solved, and efficient, power-saving position detection and fast AF function are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NISSHINBO MICROELECTRONICS CORP
- Filing Date
- 2023-12-21
- Publication Date
- 2026-07-14
AI Technical Summary
In the prior art, linear encoders require an additional pulse count structure when detecting the initial position of the scale, which leads to processing delay.
A linear encoder, simplified as an optical semiconductor device, uses first and second scales with different areas. Position is detected by detecting the voltage output corresponding to the area of the second scale. The encoder utilizes an optical sensor and a comparator for signal processing to achieve position detection.
While suppressing processing delays, it achieves efficient detection of the scale position, shortens the position detection time, and can restore position information without returning to the initial position after the device is started and shut down, thus achieving power saving and fast AF function.
Smart Images
Figure CN122396902A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to position detection using a linear encoder that utilizes an optical semiconductor device. Background Technology
[0002] Previously, a system was known in which a linear scale was connected to the device being measured, and the position was measured by detecting the scale's graduations. When using such a scale for position detection, information related to the scale's position in its initial state, which serves as a reference, is required.
[0003] To detect the position of a scale in such an initial state, Patent Document 1 discloses a scale device having multiple scale blocks with different numbers of graduations. The scale blocks are arranged on a scale at predetermined intervals. In Patent Document 1, a detection head is used to detect pulses corresponding to the number of graduations on each scale block, and each scale block is identified as an individual scale block based on the number of detected pulses, thereby detecting the position of the scale relative to the initial state. Existing technical documents
[0004] Patent Document 1: Japanese Patent Publication No. 7-63578
[0005] However, in Patent Document 1, the number of pulses needs to be counted in order to detect the position of the scale based on the initial state. Therefore, Patent Document 1 requires an additional structure for counting the number of pulses, and there is a possibility of processing delay caused by counting the number of pulses. Summary of the Invention
[0006] Therefore, the purpose of this invention is to detect the position of the scale while suppressing processing delay through a simple structure.
[0007] To achieve the above objectives, the position detection system and method of the present invention employ the following method: the position of a scale portion is detected based on a voltage output corresponding to the area of a second scale, the second scale having an area different from that of a plate-like component or slit of a first scale arranged at a predetermined period.
[0008] Specifically, the position detection system of the present invention comprises: The scale section includes a first scale and a second scale. The first scale has a plate-shaped member or slit arranged in a predetermined direction at a predetermined period, and the second scale has an area different from that of the plate-shaped member or slit. An incident section allows light to be incident on the scale section; The light-receiving part receives the light reflected or transmitted through the scale part and emits signals corresponding to the first scale and the second scale, respectively. The output unit receives a signal from the light-receiving unit corresponding to the second scale and outputs a voltage corresponding to the area of the second scale; and The position detection unit detects the position of the scale unit based on the voltage output corresponding to the area of the second scale.
[0009] Furthermore, the position detection method of the present invention is a position detection method for a scale portion having a first scale and a second scale, wherein the first scale has a plate-like member or slit arranged in a predetermined direction at a predetermined period, and the second scale has an area different from the plate-like member or slit, and the position detection method includes: The step of directing light onto the scale section; The step of receiving light reflected or transmitted through the scale portion and emitting signals corresponding to the first scale and the second scale respectively; The steps of receiving a signal corresponding to the second scale and outputting a voltage corresponding to the area of the second scale; and The step of detecting the position of the scale section based on the voltage output.
[0010] Therefore, by using a simple structure that detects the voltage output corresponding to the area of a second scale having a different area than the plate-shaped component or slit of the first scale, the position of the scale section can be detected while suppressing processing delay.
[0011] Alternatively, in the above structure, the second scale may have multiple plate-like components or slits with different widths in the predetermined direction. The output unit receives the signal corresponding to the second scale from the light-receiving unit and outputs voltages corresponding to the widths of the plurality of plate-shaped components or slits, respectively. The position detection unit detects the position of the scale unit based on voltage outputs corresponding to the widths of the plurality of plate-shaped components or slits.
[0012] Therefore, by using a simple structure that detects the voltage output corresponding to the width of the plate-shaped component or slit of the second scale, the position of the scale section can be detected while suppressing processing delay.
[0013] Furthermore, the above structure may also include: A light sensor, comprising the incident portion and the light-receiving portion; and An actuator moves either the scale section or the optical sensor relative to the predetermined direction. The output unit moves either the scale unit or the light sensor in the predetermined direction according to the actuator, receives a signal from the light-receiving unit corresponding to the second scale, and outputs a voltage corresponding to the area of the second scale.
[0014] Therefore, by moving either the scale section or the optical sensor relative to the other using an actuator, the area and width of the second scale can be detected, allowing the initial position of the scale section to be determined. Thus, even if the position information of the scale section is lost due to the device being turned on or off, it is not necessary to move the scale section to its initial position, thereby shortening the time required for position detection and saving power.
[0015] Alternatively, in the above structure, the position detection unit may, after the actuator is driven, exclude the initial voltage output from the output unit and detect the position of the scale unit based on the subsequent voltage output from the output unit.
[0016] This suppresses the width of the second scale that may be falsely detected.
[0017] Alternatively, in the above structure, the position detection unit may detect the position of the scale unit based on the second voltage output from the output unit after the actuator is driven, and exclude subsequent voltage outputs from the output unit.
[0018] This reduces the processing time of the position detection unit.
[0019] Alternatively, in the above structure, the position detection unit may receive a signal from the light-receiving unit corresponding to the first scale, which changes according to the predetermined direction moved by either the scale unit or the light sensor by the actuator, and calculate the displacement of the scale unit's position.
[0020] Therefore, the position of the scale section can be calculated using a simple structure.
[0021] Furthermore, in the above structure, the output unit may be a comparator that outputs a reset signal indicating that the second scale has been detected as a voltage when the voltage value corresponding to the second scale input from the light-receiving unit is greater than a predetermined value. The position detection unit detects the position of the scale unit based on the reset signal.
[0022] Therefore, a simple comparator can be used to detect the position of the scale section.
[0023] Furthermore, the above disclosures can be combined as much as possible.
[0024] According to the present invention, the position of the scale can be detected while suppressing processing delay through a simple structure. Attached Figure Description
[0025] Figure 1 This is a diagram illustrating the general structure of a position detection system according to an embodiment of the present invention. Figure 2 This diagram illustrates the processing of incremental signals based on the signal processing unit. Figure 3 This diagram illustrates the processing of incremental signals based on the signal processing unit. Figure 4 This is a graph illustrating the relationship between the current flowing through the reference PD and the current flowing through the reset PD. Figure 5 This is a diagram illustrating the detection of a comparator-based reset scale. Figure 6 This is a diagram illustrating the scale section of the association. Figure 7 This is a diagram illustrating the reset scale of the implementation method. Figure 8 This is a diagram illustrating the reset scale of the implementation method. Figure 9 This is a diagram illustrating the origin position detection of the position detection system according to an embodiment of the present invention. Figure 10 This is a diagram illustrating the origin position detection of the position detection system according to an embodiment of the present invention. Figure 11 This is a flowchart illustrating the origin position detection of the position detection system according to an embodiment of the present invention. Detailed Implementation
[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments shown below. These embodiments are merely illustrative, and the present invention can be implemented in various ways with modifications and alterations based on the knowledge of those skilled in the art. Furthermore, in this specification and the accompanying drawings, the same reference numerals denote identical constituent elements.
[0027] [First Implementation Method] Reference Figures 1 to 5 The position detection system 100 according to the first embodiment of the present invention will be described. Figure 1The position detection system 100 is described in general terms. The position detection system 100 includes a scale unit 10, a light sensor 20, and an actuator 30. The position detection system 100 is a system capable of detecting the position of various devices connected to the scale unit 10. For example, the position detection system 100 can be used as a linear encoder and can be mounted on various devices that require absolute position detection, such as single-lens reflex cameras, interchangeable lenses, cameras, robots, machine tools, and measuring instruments. Here, absolute position refers to the objective position of a device connected to various devices and subject to position detection, relative to those devices. According to the position detection system 100, for example, the position of an interchangeable lens connected to a camera body and moving back and forth relative to the body can be detected relative to the body. Thus, in this embodiment, the position of a device connected to a device and moving relative to that device body can be detected relative to the device body.
[0028] Specifically, the position detection system 100 has the following features: The scale section 10 includes an incremental scale 11 and a reset scale 12. The incremental scale 11 has a plate-shaped member or slit arranged in a predetermined direction at a predetermined period, and the reset scale 12 has an area different from the plate-shaped member or slit. The light-emitting part 21 allows light to be incident on the scale part 10; Increment PD22 and reset PD24 receive light reflected or transmitted through scale section 10 and emit signals corresponding to increment scale 11 and reset scale 12, respectively. Comparator 25 receives the signal from reset PD24 corresponding to reset scale 12 and outputs a voltage corresponding to the area of reset scale 12; and The signal processing unit 26 detects the position of the scale unit 10 based on the voltage output corresponding to the area of the reset scale 12.
[0029] The scale section 10 is provided on the device that is the object to be detected as having an absolute position, but cannot move relative to it. For example, when the position of a change lens connected to the camera body and moving back and forth relative to the body becomes the object to be detected, the scale section 10 is configured to not move relative to the change lens, but can move relative to the camera body. The scale section 10 includes an incremental scale 11 and a reset scale 12. The scale section 10 is configured to reflect light from the light sensor 20. For example, the scale section 10 may also be configured to coincide with the light sensor 20 when viewed from above. The incremental scale 11 and the reset scale 12 can move integrally in a predetermined direction relative to the device body to which the device that is the object to be measured as having a position is connected. In the following description, the direction of movement of the incremental scale 11 and the reset scale 12 relative to the device body is sometimes simply referred to as the "movement direction of the scale section 10". In addition, the scale section 10 may also be about 70 mm in its movement direction. The movement direction of the scale section 10 is an example of a "predetermined direction".
[0030] The incremental scale 11 is composed of multiple plate-shaped members formed in an elongated shape and capable of reflecting light signals from a light sensor. These plate-shaped members are arranged at equal intervals in the moving direction of the scale section 10. In other words, the incremental scale 11 is a reflector with multiple slits formed in an elongated shape at equal intervals. When the scale section 10 is in its initial position, the end point located in the moving direction of the scale section 10 (at...) Figure 1 The plate-shaped component (either the left or right end) overlaps with the light sensor 20. Furthermore, the initial state of the scale section 10 can be arbitrarily set; for example, the initial state can be set to the position where the center of the scale section 10 overlaps with the light sensor 20 in a predetermined direction. The incremental scale 11 functions as a "first scale."
[0031] The reset scale 12 is configured to have a width different from that of each plate-shaped member of the incremental scale 11 in the moving direction of the scale portion 10. In other words, the reset scale 12 has an area different from that of each plate-shaped member of the incremental scale 11 when viewed from above. In this embodiment, the reset scale 12 is configured to be wider than the width of each plate-shaped member of the incremental scale 11 in the moving direction of the scale portion 10. The width of the reset scale 12 may also be narrower than the width of the incremental scale 11 in the moving direction of the scale portion 10. Furthermore, the reset scale 12 is separated from the plate-shaped member located at the end of the incremental scale 11 in the moving direction of the scale portion 10. Information on how much the reset scale 12 has moved away from the plate-shaped member located at the end of the incremental scale 11 is pre-stored in the memory of the light sensor 20. That is, information on how much the reset scale 12 has moved away from the plate-shaped member that was initially aligned is pre-stored in the memory of the light sensor 20. The specific configuration and number of the reset scale 12 will be described later. The reset scale 12 functions as a "second scale".
[0032] The light sensor 20 is configured to be movable relative to the device that is the absolute position of the object being detected. For example, when a changeable lens connected to the camera body and moving back and forth is the absolute position of the object being detected, the light sensor 20 is configured to be movable relative to the changeable lens but not relative to the camera body. The light sensor 20 includes a light-emitting unit 21, an incremental PD (photodiode) 22, a reference PD (photodiode) 23, a reset PD (photodiode) 24, a comparator 25, and a signal processing unit 26. The light sensor 20 is a reflective semiconductor light sensor device, configured such that the incremental PD 22 and the reset PD 24 receive light emitted by the light-emitting unit 21 and reflected by the scale unit 10. Furthermore, the scope of the present invention is not limited to using a reflective semiconductor light sensor device to detect the scale position; it can also be configured to use an MR (magnetic resistance) sensor device to detect the scale position. Additionally, the light sensor 20 can also be a transmissive semiconductor light sensor device.
[0033] The light-emitting part 21 is configured to emit light. The light-emitting part 21 is, for example, an LED. The light emitted from the light-emitting part 21 is reflected by the incremental scale 11 and the reset scale 12. Thus, in this embodiment, only one light source is provided, but two or more light sources may also be provided. The light-emitting part 21 functions as an "incident part".
[0034] The incremental PD22 is set in correspondence with the incremental scale 11. Specifically, the incremental PD22 is positioned to receive light emitted by the light-emitting unit 21 and reflected by the incremental scale 11. The incremental PD22 is configured such that current flows when light shines on the light-receiving surface.
[0035] like Figure 2 As shown in the graph above, the signal processing unit 26 detects the current flowing through the incremental PD22 and converts it into an analog incremental voltage signal. Specifically, the signal processing unit 26 outputs two analog incremental signals, a sine and a cosine, that are 90 degrees out of phase.
[0036] like Figure 2 As shown in the graph below, the signal processing unit 26 performs arctangent processing on the two analog incremental signals, sine and cosine. Therefore, for the device that is the object of position detection, it is possible to calculate the change in position corresponding to one cycle of the arrangement of the plate-shaped components of the incremental scale 11.
[0037] like Figure 3As shown, the signal processing unit 26 calculates the displacement from a specific position by adding the position variations over one cycle. Therefore, it is possible to calculate the change in position of a device connected to and moving relative to the device body relative to the device body.
[0038] In other words, the signal processing unit 26 receives a signal from the increment PD22 corresponding to the increment scale 11, which changes according to the predetermined direction of either the scale unit 10 or the light sensor 20 being moved by the actuator 30, thereby enabling it to calculate the displacement of the scale unit 10.
[0039] However, in order to specifically determine the position of the device that moves relative to the device body, information related to the position of the device relative to the device body at the time when the optical sensor 20 begins position measurement is needed. Therefore, in this embodiment, the position of the device relative to the device body at the time when the optical sensor begins position measurement is determined using the reset signal obtained from the reset PD24. That is, in this embodiment, by knowing the position of the reset scale 12, it is determined how much the device and scale section 10, which are the objects of position measurement, have moved from their initial positions. In the following description, the position of the scale section 10 in the initial state is referred to as the origin position. At the origin position, the plate-shaped member located at the end of the incremental scale 11 coincides with the optical sensor 20. A more detailed method for knowing the origin position of the device and scale section 10, which are the objects of position measurement, will be described later.
[0040] Reference PD23 is configured to receive light from light-emitting unit 21 without passing through scale unit 10, thereby allowing a certain current to flow. The current flowing through reference PD23 is converted into voltage using a general current-to-voltage conversion circuit or the like.
[0041] The reset PD24 is configured to correspond to the reset scale 12. Specifically, the reset PD24 is positioned to receive light emitted by the light-emitting unit 21 and reflected by the reset scale 12. The reset PD24 is configured such that current flows when light shines on the light-receiving surface. The current flowing through the reset PD24 is converted into voltage using a general current-to-voltage conversion circuit. Furthermore, as... Figure 4 As shown, the design ensures that when the reset PD24 receives reflected light from the reset scale 12, the current flowing through the reset PD24 is greater than the current flowing through the reference PD23. Since the voltage value is proportional to the current value, the voltage corresponding to the current flowing through the reset PD24 is greater than the voltage corresponding to the current flowing through the reference PD23. The incremental PD22 and the reset PD24 function as "light-receiving units".
[0042] Comparator 25 is a general comparator, such as... Figure 5As shown, it has two input terminals. Comparator 25 is a circuit that outputs a predetermined value based on the voltage applied to the negative input terminal. The negative input terminal is connected to the reference PD23, and the positive input terminal is connected to the reset PD24. That is, in this embodiment, the output of comparator 25 is switched based on the voltage from the reference PD and the voltage from the reset PD24. Specifically, when the voltage of the positive input terminal connected to the reset PD24 is greater than the voltage of the negative input terminal connected to the reference PD23, a high-level signal is output. On the other hand, when the voltage of the positive input terminal is less than the voltage of the negative input terminal, a low-level signal is output. Here, the high-level signal and the low-level signal are voltage signals. For example, the light sensor 20 can be designed so that the low-level signal = 0 (V) and the high-level signal = the power supply voltage (V). The high-level signal and the low-level signal output from comparator 25 are sent to the signal processing unit 26. In the following description, these high-level and low-level signals will be referred to as reset signals. Comparator 25 functions as the "output".
[0043] In other words, if the voltage value corresponding to the reset scale 12 input from the reset PD24 is greater than a predetermined value, the comparator 25 outputs a reset signal indicating that the reset scale 12 has been detected.
[0044] Thus, in this embodiment, a general and simple comparator can be used to detect the presence of reset PD24.
[0045] The signal processing unit 26 detects the presence and width of the reset scale 12 in the moving direction of the scale unit 10 based on the duration of the high-level signal. In other words, the signal processing unit 26 detects the presence and area of the reset scale 12. That is, in this embodiment, the area of the reset scale is detected based on the voltage output of the comparator 25 corresponding to the area of the reset scale 12. Based on the detection results of the presence and width of the reset scale 12, the signal processing unit 26 indirectly determines the origin position. That is, the signal processing unit 26 determines how much the device and the scale unit 10, which are the objects of position measurement, have moved from the origin position by calculating the presence and width of the reset scale 12. The detailed method for determining the origin position will be described later. The signal processing unit 26 functions as a "position detection unit".
[0046] As described above, in this embodiment, The reset scale 12 has multiple plate-shaped components or slits with different widths in the moving direction of the scale section 10. Comparator 25 receives the signal from reset PD24 corresponding to reset scale 12 and outputs voltages corresponding to the widths of the multiple plate-shaped components or slits respectively. The signal processing unit 25 detects the position of the scale unit 10 based on the voltage output corresponding to the width of each of the multiple plate-shaped components or slits.
[0047] In particular, it includes an actuator 30 that moves either the scale section 10 or the light sensor 20 in a predetermined direction relative to the other. The comparator 25 moves either the scale section 10 or the light sensor 20 in a predetermined direction according to the actuator 30, and outputs a voltage corresponding to the area of the second scale.
[0048] With this structure, the origin position can be indirectly determined by detecting the position and width of the reset scale 12, which is located at the position separated from the end of the incremental scale 11, in the moving direction of the scale section 10. Therefore, even if the position information of the scale section 10 is lost due to the start-up and shutdown of the device, it is not necessary to move the scale section 10 to the origin position, thereby shortening the time for position detection and saving power.
[0049] Furthermore, the scale section 10 and the device connected to the scale section 10, which is the object of position measurement, are configured to automatically move relative to the light sensor 20 and the main body of the device via the actuator 30. With such a structure, for example, when the position detection system 100 is mounted on a camera with an interchangeable lens, the origin position can be determined without moving the scale section 10 to the origin position, thereby enabling a faster AF (Auto Focus) function.
[0050] Furthermore, the shape of the reset scale 12 is not limited to a quadrilateral; the shape of the reset scale 12 includes all shapes that can determine the position of the origin based on its area. For example, the reset scale 12 can also be formed as a triangle when viewed from above.
[0051] Furthermore, the reset scale 12 can also be formed as a slit cut in a manner that has a predetermined area when viewed from above. Even in this case, the presence of the slit and the area cut can be detected by using a simple comparator to detect the difference between the voltage value from the reset PD24 and the voltage value that serves as a reference.
[0052] Furthermore, contrary to this embodiment, the light sensor 20 may also be provided in a device that is the absolute position of the detection object but cannot move relative to it. For example, when the position of a change lens connected to the camera body and moving back and forth relative to the body becomes the detection object, the light sensor 20 is configured to not move relative to the change lens, but can move relative to the camera body via an actuator. In this case, the scale section 10 may also be configured to be movable relative to the device that is the absolute position of the detection object. For example, the scale section 10 is configured to be movable relative to the change lens but not relative to the camera body.
[0053] [Second Implementation] Next, refer to Figures 6 to 8 The reset scale of the second embodiment will be explained. First, based on... Figure 6 The associated position detection system is described below. The associated position detection system includes a scale unit 10A and a light sensor 20A.
[0054] The scale section 10A is equipped with an incremental scale. This allows for the calculation of the change in position of the device connected to and moving relative to the main body. However, the scale section 10A lacks a special structure for determining the origin position. Therefore, if the position information of the scale section 10A is lost due to the start-up or shutdown of the equipment, it is necessary to move the scale section 10A back to the origin position.
[0055] On the other hand, such as Figure 7 As shown, in this embodiment, the scale section 10 includes a reset scale 13 in addition to the incremental scale 11. The reset scale 13, like the reset scale 12 in the first embodiment, is configured to be wider than the width of each plate-shaped member of the incremental scale 11 in the moving direction of the scale section 10. That is, the reset scale 12 has a different area than each plate-shaped member of the incremental scale 11 when viewed from above.
[0056] In this embodiment, the optical sensor 20 determines the presence and width of the reset scale 13 based on the reset signal output by the comparator 25. Therefore, even if the position information of the scale section 10 is lost due to the device being turned on or off, the origin position can be determined without moving the scale section 10 to the origin position.
[0057] Furthermore, the number of reset scales does not need to be one. For example, in Figure 8The diagram illustrates an example where the scale section 10 includes multiple reset scales 14. The multiple reset scales 14 are arranged at equal intervals along the movement direction of the scale section 10. This allows for the configuration of multiple reset scales 14, enabling the origin position to be determined by counting reset signals as pulses. Furthermore, the number of reset scales 14 is not limited to two; it can be three or more. Additionally, the number of reset scales 14 can vary depending on the device equipped with the position detection system 100.
[0058] Furthermore, the shapes of reset scales 13 and 14 are not limited to quadrilaterals, and the shape of reset scale 12 includes all shapes that can determine the origin position based on its area. Additionally, reset scales 13 and 14 can also be formed as slits cut in a manner that have a predetermined area when viewed from above. Even in this case, the presence of the slits and the cut area can be detected by using a simple comparator to detect the difference between the voltage value from reset PD24 and the reference voltage value.
[0059] [Third Implementation Method] Next, refer to Figures 9 to 11 The origin position detection method of the position detection system 100 according to an embodiment of the present invention will be described. In this embodiment, the scale unit 10 includes multiple reset scales 15 in addition to the incremental scale 11.
[0060] Specifically, the position detection method of the present invention is a position detection method for a scale portion 10, the scale portion 10 comprising an incremental scale 11 and a reset scale 15, the incremental scale 11 having a plate-like component or slit arranged in a predetermined direction at a predetermined period, and the reset scale 15 having an area different from the plate-like component or slit, the position detection method comprising: The step of directing light onto the scale section 10; The step of receiving light reflected or transmitted through the scale section 10 and emitting signals corresponding to the incremental scale 11 and the reset scale 12 respectively; The steps of receiving the signal corresponding to the reset scale 12 from the reset PD24 and outputting a voltage corresponding to the area of the reset scale 12; and The step of detecting the position of the scale section 10 based on the voltage output corresponding to the area of the reset scale 12.
[0061] Multiple reset scales 15 have different widths in the movement direction of the scale portion 10. Specifically, reset scales 15A, 15B, 15C, 15D, 15E, 15F, and 15G have widths of 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, and 160μm, respectively, in the movement direction of the scale portion 10. In other words, each reset scale 15 has a different area. Information related to the width and area of each reset scale 15 is pre-stored in the memory of the light sensor 20.
[0062] In the following description, as an embodiment of the position detection system 100, we will describe the case where the position detection system 100 is configured for AF (Auto Focus) of a camera's interchangeable lens. That is, the scale section 10 is connected to the camera's interchangeable lens. The position detection system 100 detects the AF point by turning on (ON) the power to the camera body. Here, the AF point refers to the position of the scale section 10 (i.e., the interchangeable lens) corresponding to the position where the subject and the lens are in focus.
[0063] In the following description, the scale section 10 is initially in its initial state. Furthermore, as... Figure 10 As shown, the relative positions of the scale section 10 and the light sensor 20 change in the order of (A), (B), (C), and (D).
[0064] First, the user turns on the power of the camera equipped with the position detection system 100 (step S1).
[0065] In this state, the position detection system 100 detects the AF point by driving the actuator 30 (step S2). Specifically, the position detection system 100 moves the scale unit 10 from the initial state to the AF point while the signal processing unit 26 observes the change in the relative position of the scale unit 10 with respect to the optical sensor 20 based on the incremental signal (step S3). In this embodiment, the initial AF point exists between the third reset scale 15C and the fourth reset scale 15D.
[0066] With the scale 10 at the AF point, the user takes a photo or video (step S4). Furthermore, the shooting method is not limited to manual shooting by the user; the device can also automatically perform the shooting. Afterward, the user turns off the camera (step S5).
[0067] The user turns the camera power on again (ON) (step S6). In this state, the actuator 30 moves the scale section 10 left, right, or both sides, thereby the signal processing unit 26 detects the presence and width of one or both of the reset scales 15C and 15D. Specifically, the signal processing unit 26 detects the presence and width of one or both of the reset scales 15C and 15D by comparing the data related to the width of the reset scales pre-stored in the memory with the measured value. Based on this, the signal processing unit 26 determines the origin position based on the detection result (step S7). In this embodiment, the reset scales 15A to 15G each have different widths, so the origin position can be indirectly determined by detecting the width of any one of the reset scales 15A to 15G.
[0068] Subsequently, the position detection system 100 moves the scale section 10 to the next AF point, using either the reset scales 15C or 15D as a starting point (step S8). With the scale section 10 at the AF point, the user takes a photo or video (step S9). Figure 10 (D) indicates the case where there is a next AF point between the fifth reset scale 15E and the sixth reset scale 15F.
[0069] Thus, in this embodiment, when the power is turned on after being turned off, it is not necessary to move the scale section 10 to the origin position, thereby significantly reducing the time until the next AF point detection. As a result, for example, it is possible to improve the performance of cameras and other devices that use linear actuators.
[0070] Furthermore, in this embodiment, the reset scales 15A to 15G each have different widths depending on their position relative to the origin. Therefore, even without providing a memory to store the position information of the scale section 10 when the power is off, the position detection system 100 can properly determine the origin position without causing the scale section 10 to return to the origin position.
[0071] Alternatively, when the power is turned on again, and the scale unit 10 is moved left, right, or to the left and right, the signal processing unit 26 may exclude the detection result corresponding to the initial reset signal sent from the reset PD. That is, after the actuator 30 is driven, the signal processing unit 26 may exclude the initial voltage output from the comparator 25 and detect the position of the scale unit 10 based on the subsequent voltage output from the comparator 25. This suppresses the false detection of the width of the reset scale 15 when, in a top-view situation, any one of the reset scales 15 is in a position coinciding with the light sensor 20, and the power is turned off.
[0072] Furthermore, once the origin position is determined, it is not necessary to re-determine the origin position while the scale section 10 moves to the AF point. Therefore, the signal processing unit 26 can be configured not to perform the detection and reset of the presence and width (area) of the scale 12 during this period. That is, the signal processing unit 26 can also detect the position of the scale section 10 based on the second voltage output from the comparator 25 after the actuator 30 is driven, and exclude subsequent voltage outputs from the comparator 25. As a result, the processing time of the signal processing unit 26 can be shortened.
[0073] Furthermore, the number of reset scales 15 can vary depending on the device equipped with the position detection system 100. Moreover, the shape of the reset scales 15 is not limited to a quadrilateral; the shape of the reset scales 15 includes all shapes capable of determining the origin position based on their area. Additionally, the reset scales 15 can also be formed as slits cut in a manner that have a predetermined area when viewed from above. Even in this case, the presence of the slit and the cut area can be detected by using a simple comparator to detect the difference between the voltage value from the reset PD24 and the reference voltage value.
[0074] The apparatus of the present invention can also be implemented by a computer and a program, which can be stored in a storage medium or provided via a network. The program of the present invention is a program for enabling a computer to implement the various functions of the apparatus of the present invention, and a program for enabling a computer to execute the various steps of the method performed by the apparatus of the present invention. Explanation of reference numerals in the attached figures
[0075] 10, 10A: Scale section 11: Incremental Scale 12, 13, 14, 15, 15A, 15B, 15C, 15D, 15E, 15F, 15G: Reset the ruler 20, 20A: Optical sensor 21: Light-emitting part 22: Incremental PD 23: Refer to PD 24: Reset PD 25: Comparator 26: Signal Processing Department 30: Actuator 100: Position detection system.
Claims
1. A position detection system, wherein, have: The scale section includes a first scale and a second scale. The first scale has a plate-shaped member or slit arranged in a predetermined direction at a predetermined period, and the second scale has an area different from that of the plate-shaped member or slit. An incident section allows light to be incident on the scale section; The light-receiving part receives the light reflected or transmitted through the scale part and emits signals corresponding to the first scale and the second scale, respectively. The output unit receives a signal from the light-receiving unit corresponding to the second scale and outputs a voltage corresponding to the area of the second scale. as well as The position detection unit detects the position of the scale unit based on the voltage output corresponding to the area of the second scale.
2. The position detection system according to claim 1, wherein, The second scale has multiple plate-like components or slits with different widths in the predetermined direction. The output unit receives the signal corresponding to the second scale from the light-receiving unit and outputs voltages corresponding to the widths of the plurality of plate-shaped components or slits, respectively. The position detection unit detects the position of the scale unit based on voltage outputs corresponding to the widths of the plurality of plate-shaped components or slits.
3. The position detection system according to claim 2, wherein, It also has: A light sensor, comprising the incident portion and the light-receiving portion; and An actuator moves either the scale section or the optical sensor relative to the predetermined direction. The output unit moves either the scale unit or the light sensor in the predetermined direction according to the actuator, receives a signal from the light-receiving unit corresponding to the second scale, and outputs a voltage corresponding to the area of the second scale.
4. The position detection system according to claim 3, wherein, After the actuator is driven, the position detection unit excludes the initial voltage output from the output unit and detects the position of the scale unit based on the subsequent voltage output from the output unit.
5. The position detection system according to claim 4, wherein, After the actuator is driven, the position detection unit detects the position of the scale unit based on the second voltage output from the output unit, and excludes subsequent voltage outputs from the output unit.
6. The position detection system according to claim 3, wherein, The position detection unit receives a signal from the light-receiving unit corresponding to the first scale, which changes according to the predetermined direction moved by either the scale unit or the light sensor by the actuator, and calculates the displacement of the scale unit's position.
7. The position detection system according to any one of claims 1 to 6, wherein, The output unit is a comparator that outputs a reset signal indicating that the second scale has been detected as a voltage when the voltage value corresponding to the second scale input from the light-receiving unit is greater than a predetermined value. The position detection unit detects the position of the scale unit based on the reset signal.
8. A position detection method comprising a scale portion having a first scale and a second scale, wherein the first scale has a plate-like component or slit arranged in a predetermined direction at a predetermined period, and the second scale has an area different from that of the plate-like component or slit, wherein... The location detection method includes: The step of directing light onto the scale section; The step of receiving light reflected or transmitted through the scale portion and emitting signals corresponding to the first scale and the second scale respectively; The steps of receiving the signal and outputting a voltage corresponding to the area of the second scale; and The step of detecting the position of the scale section based on the voltage output.