Light receiving device and position detection method

Abstract

PURPOSE: To provide a light receiving device and a position detection method capable of correctly determining whether line beams received by the light receiving device are applied to a desired position.CONSTITUTION: A light receiving device includes: a photoelectric conversion section that has a first light reception surface and a second light reception surface that are adjacent while sandwiching a boundary line, and generates a first light reception signal obtained by converting light received by the first light reception surface to an electric signal and a second light reception signal obtained by converting light received by the second light reception surface to an electric signal; a notification section for giving notice about a predetermined mode when a ratio obtained by dividing a smaller one from among first light reception intensity shown by a first reception signal and second light reception intensity shown by the second light reception signal by a larger one is smaller than a determination threshold, or when a ratio obtained by dividing the larger one from among the first and second light reception intensities by the smaller one is larger than the determination threshold; and a determination threshold adjustment section for adjusting the magnitude of the determination threshold on the basis of the first light reception intensity and the second light reception intensity.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a light receiving device and a position detection method for detecting a position where light is irradiated. [Background technology]

[0002] One of the tasks performed at a construction site is marking out horizontal and vertical lines, etc., that serve as references for carrying out various tasks on the walls, ceilings, floors, etc. of a building, using line light as a laser beam.

[0003] Also, as a device used in such marking work, a laser marking device capable of emitting a line of light extending in the vertical direction or the horizontal direction, and a receiver for a laser marking device that detects the positional deviation of the line of light emitted from the laser marking device are known (see, for example, the description in paragraph 0068 of Patent Document 1). In this case, the receiver for a laser marking device is equipped with a first light receiving element that outputs a signal corresponding to the light receiving intensity received at one of the two light receiving surfaces obtained by dividing a rectangular light receiving surface by a dividing line, and a second light receiving element that outputs a signal corresponding to the light receiving intensity received at the other light receiving surface. In the receiver for a laser marking device, the laser receiver detects the laser light irradiation position based on the light receiving intensity received by the first and second light receiving elements when receiving the line of light irradiated from the laser marking device. The strength of the light receiving signals of the two light receiving elements is compared, and if they are equal or the difference is within a certain range, it is determined that the center of the laser light irradiation position is located at the center of the dividing line of the two light receiving elements. In marking work, the laser receiver is moved relative to the laser light to find the position where the amount of light received is equal. However, it is difficult to align it to a position where the strength of the two signals is exactly equal, so a certain tolerance, or threshold, is set for the difference between the two amounts of light received, and it is common to determine that the center of the laser light irradiation position is located within a width equivalent to this threshold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-085858 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned marking work, the longer the distance between the laser marking device and the receiver, the wider the line light becomes, and the smaller the intensity of the line light received by the receiver becomes. Therefore, when a fixed threshold value is set for the difference in the intensity of the line light received by the two light receiving elements to determine the irradiation position of the laser light, the allowable range of judgment varies depending on the distance between the laser marking device and the receiver, so it is not possible to accurately determine whether the line light is being irradiated to the desired position over a range from close to long distances between the laser marking device and the receiver.

[0006] Therefore, an object of the present invention is to provide a light receiving device and a position detection method that can correctly determine whether or not the line light received by the light receiving device is irradiated at a desired position, regardless of the distance between the source of the line light and the light receiving device. [Means for solving the problem]

[0007] The light receiving device of the present invention has a first light receiving surface and a second light receiving surface adjacent to each other across a boundary line, and has a photoelectric conversion unit that generates a first light receiving signal obtained by converting light received at the first light receiving surface into an electrical signal, and a second light receiving signal obtained by converting light received at the second light receiving surface into an electrical signal, a notification unit that issues a notification in a predetermined manner when a ratio obtained by dividing the smaller of a first light receiving intensity indicated in the first light receiving signal and a second light receiving intensity indicated in the second light receiving signal by the larger is smaller than a decision threshold, or when a ratio obtained by dividing the larger of the first light receiving intensity and the second light receiving intensity by the smaller of the first light receiving intensity and the second light receiving intensity is larger than the decision threshold, and a decision threshold adjustment unit that adjusts the magnitude of the decision threshold based on the first light receiving intensity or the second light receiving intensity.

[0008] Moreover, the light receiving device of the present invention has a first light receiving surface and a second light receiving surface adjacent to each other across a boundary line, and includes a photoelectric conversion unit that generates a first light receiving signal obtained by converting light received at the first light receiving surface into an electrical signal, and a second light receiving signal obtained by converting light received at the second light receiving surface into an electrical signal, a light receiving intensity acquisition unit that acquires a first light receiving intensity corresponding to the light intensity received at the first light receiving surface, and a second light receiving intensity corresponding to the light intensity received at the second light receiving surface, based on the first light receiving signal and the second light receiving signal, a notification unit that issues a notification in a predetermined manner when a difference between the first light receiving intensity and the second light receiving intensity is smaller than a decision threshold, and a decision threshold adjustment unit that adjusts the magnitude of the decision threshold based on the first light receiving intensity or the second light receiving intensity.

[0009] A position detection method according to the present invention acquires a first received light intensity and a second received light intensity, each of which individually represents the intensity of light received by a first light receiving surface and a second light receiving surface adjacent to each other on either side of a boundary line, and if a ratio obtained by dividing the smaller of the first received light intensity and the second received light intensity by the larger of the first received light intensity and the second received light intensity is smaller than a judgment threshold, or if a ratio obtained by dividing the larger of the first received light intensity and the second received light intensity by the smaller of the first received light intensity and the second received light intensity is larger than the judgment threshold, a notification is issued in a predetermined manner, and the magnitude of the judgment threshold is adjusted based on the first received light intensity or the second received light intensity. Effect of the Invention

[0010] In the light receiving device according to the present invention, first, first and second received light intensities corresponding to the intensities of the line light received on the first and second light receiving surfaces adjacent to each other across a boundary line as a target line to be aligned with the line light as the laser light are obtained. Then, when the ratio obtained by dividing the smaller of the first and second received light intensities by the larger is smaller than the judgment threshold, or when the ratio obtained by dividing the larger of the first and second received light intensities by the smaller is larger than the judgment threshold, the line light is judged to be irradiated on the target line in a manner that allows a predetermined positional deviation length, and a notification is given to indicate this. At this time, the light receiving device adjusts the value of the judgment threshold in accordance with the magnitude of the first and second received light intensities. This makes it possible to accurately judge whether the line light is irradiated on the target line, regardless of the distance between the source of the line light irradiation and the light receiving device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an external view that shows a schematic external appearance of a laser beam receiver 100 as a beam receiving device according to the present invention. [Diagram 2] 2 is a block diagram showing the internal configuration of a laser beam receiver 100. FIG. [Diagram 3] 1 is a diagram showing an example of a usage form of a laser beam receiver 100. FIG. [Figure 4A] 10 is a flowchart showing a procedure of a laser irradiation position determination process. [Figure 4B] 10 is a flowchart showing a procedure of a laser irradiation position determination process. [Figure 5A] FIG. 13 is a diagram illustrating an example of a function for calculating a determination threshold value from received light intensity. [Figure 5B] FIG. 13 is a diagram showing an example of a lookup table in which each range of received light intensity is associated with a determination threshold value. [Figure 6A] 13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the state of the buzzer sound when no line light is irradiated. FIG. [Figure 6B]13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the state of the buzzer sound when a line of light is irradiated to a position separated from the target line TL within the light-receiving surface F1. FIG. [Figure 6C] 13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when a line of light is irradiated to a position separated from the target line TL within the light-receiving surface F2. FIG. [Figure 6D] 13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the state of the buzzer sound when a line of light is irradiated to a position close to the target line TL within the light-receiving surface F1. FIG. [Figure 6E] 13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the state of the buzzer sound when a line of light is irradiated to a position close to the target line TL within the light-receiving surface F2. FIG. [Figure 6F] 13 is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when a line of light is irradiated onto a target line TL. FIG. [Figure 7] 4 is a block diagram showing another example of the internal configuration of the laser beam receiver 100. FIG. [Figure 8] 8 is a block diagram showing a modified example of the internal configuration of the laser beam receiver 100 shown in FIG. 7. [Figure 9] 10 is a flowchart showing another procedure of the laser irradiation position determination process. [Figure 10] FIG. 11 is a diagram illustrating another example of a function for calculating a determination threshold value from received light intensity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 1 is an external view that shows a schematic external appearance of a laser beam receiver 100 as a beam receiving device according to the present invention.

[0013] 1, exposed on the surface of the housing CA of the laser beam receiver 100 are light receiving surfaces F1 and F2, which are obtained by dividing a single light receiving surface into two halves with a linear target line TL as a boundary, which is a target for aligning the line light, and light emitting surfaces of the light emitting elements Lr, Ly, and Lg, which serve as indicators. Furthermore, a sound hole Bz is provided on the surface of the housing CA.

[0014] FIG. 2 is a block diagram showing the internal configuration of the laser beam receiver 100 formed in the housing CA.

[0015] As shown in FIG. 2, the laser light receiver 100 includes photoelectric conversion elements 21, 22, a selector 23, a bandpass filter (BPF) 24, a logarithmic conversion circuit 25, an analog-to-digital converter (ADC) 26, a controller 27, a sound generation circuit 28, a speaker 29, a lighting drive circuit 30, and light-emitting elements Lr, Ly, and Lg.

[0016] The photoelectric conversion element 21 has a light receiving surface F1 shown in FIG. 1, converts light received by the light receiving surface F1 into an electrical signal indicating the intensity of the light, and supplies this to the selector 23 as a first light receiving signal d1.

[0017] The photoelectric conversion element 22 has a light receiving surface F2 shown in FIG. 1, converts the light received by the light receiving surface F2 into an electrical signal indicating the intensity of the light, and supplies this to the selector 23 as a second light receiving signal d2.

[0018] The selector 23 alternately selects one of the received light signals d1 and d2 at a predetermined period in response to a selection signal SE supplied from the controller 27, and outputs this to the BPF 24.

[0019] The BPF 24 extracts signal components in a predetermined frequency band from the received light signal d 1 or d 2 supplied from the selector 23 , and supplies a received light signal df consisting of the extracted signal components to a logarithmic conversion circuit 25 .

[0020] The logarithmic conversion circuit 25 performs logarithmic conversion on the received light signal df and supplies the resulting signal to the ADC 26 as a received light intensity signal dlg indicating the intensity of the received light.

[0021] The ADC 26 converts the value indicated by the received light intensity signal dlg into a digital value to generate a received light intensity data signal DT, which is supplied to the controller 27 .

[0022] The controller 27 includes a ROM (Read Only Memory) 271 in which a laser irradiation position determination program is stored, and a RAM (Random Access Memory) 272.

[0023] The controller 27 supplies a selection signal SE to the selector 23 and retrieves a received light intensity data signal DT in accordance with a laser irradiation position determination program (described later) stored in the ROM 271.

[0024] In addition, the controller 27 generates a buzzer sound signal BS instructing no buzzer sound, or a buzzer sound signal BS instructing the output of a buzzer sound and specifying the scale of the buzzer sound (for example, the note "do") in accordance with the laser irradiation position determination program, and supplies this to the sound generation circuit 28.

[0025] Furthermore, the controller 27 generates a lighting control signal LS that instructs turning on one of the light-emitting elements Lr, Ly, and Lg, or a lighting control signal LS that instructs turning off all of the light-emitting elements Lr, Ly, and Lg, in accordance with the laser irradiation position determination program, and supplies this to the lighting drive circuit 30.

[0026] When the sound generating circuit 28 receives a buzzer sound signal BS instructing the output of a buzzer sound, it generates a sound signal having a waveform of a buzzer sound of the scale specified by the buzzer sound signal BS and supplies this to the speaker 29. As a result, the speaker 29 outputs a buzzer sound based on this sound signal to the outside through the sound hole Bz shown in Fig. 1. Also, when the sound generating circuit 28 receives a buzzer sound signal BS indicating no buzzer sound, it supplies a sound signal indicating no sound to the speaker 29. As a result, the speaker 29 goes into a silent state in which it does not output any sound.

[0027] When the lighting drive circuit 30 receives a lighting control signal LS instructing to light one of the light-emitting elements Lr, Ly, and Lg, it supplies a lighting drive signal to the light-emitting elements Lr, Ly, and Lg to light the one and turn off the other two. As a result, when the light-emitting element Lr is instructed to light, the light-emitting element Lr emits red light, and both the light-emitting elements Ly and Lg are turned off. When the light-emitting element Ly is instructed to light, the light-emitting element Ly emits yellow light, and both the light-emitting elements Lr and Lg are turned off. When the light-emitting element Lg is instructed to light, the light-emitting element Lg emits green light, and both the light-emitting elements Lr and Ly are turned off.

[0028] Furthermore, when the lighting drive circuit 30 receives a lighting control signal LS instructing to turn off all of the light-emitting elements Lr, Ly, and Lg, it supplies a lighting drive signal to the light-emitting elements Lr, Ly, and Lg to turn off all of the light-emitting elements Lr, Ly, and Lg. As a result, all of the light-emitting elements Lr, Ly, and Lg are turned off.

[0029] FIG. 3 is a diagram showing an example of an installation form in which the above-mentioned laser beam receiver 100 is used for marking work.

[0030] In the example shown in FIG. 3, a laser light receiver 100 is used to irradiate a horizontally extending line of light LT emitted from a laser marking device 300 at a predetermined height on the wall surface of a building.

[0031] First, the user installs the laser beam receiver 100 on the wall surface of a building so that the target line TL shown in FIG. 1 reaches the above-mentioned predetermined height position.

[0032] When the power supply of the laser beam receiver 100 is turned on, the controller 27 executes a laser irradiation position determination program stored in the ROM 271.

[0033] 4A and 4B are flowcharts showing the procedure of a laser irradiation position determination process according to a laser irradiation position determination program executed by the controller 27. In FIG.

[0034] In FIG. 4A, first, the controller 27 sets the signal level of the received light signal d1 or d2 obtained in a state in which the photoelectric conversion element 21 or 22 is not receiving the above-mentioned line light LT in the usage environment of the laser light receiver 100 as the ambient illuminance LL in the usage environment of the laser light receiver 100 (step S20).

[0035] Next, the controller 27 sets a determination threshold DB having a predetermined initial value as a threshold for determining whether or not the irradiation position irradiated with the linear light LT coincides with the position of the target line TL (step S21).

[0036] Next, the controller 27 performs a measurement process to measure the intensity of the light irradiated on the light receiving surfaces F1 and F2 (step S22). In this measurement process, the controller 27 supplies a selection signal SE to the selector 23 to select the light receiving signal d1, thereby capturing the light receiving intensity data signal DT generated by the BPF 24, the logarithmic conversion circuit 25, and the ADC 26 based on the light receiving signal d1. The controller 27 then supplies a selection signal SE to the selector 23 to select the light receiving signal d2, thereby capturing the light receiving intensity data signal DT generated by the BPF 24, the logarithmic conversion circuit 25, and the ADC 26 based on the light receiving signal d2. In addition, in step S22, the controller 27 may repeatedly select and switch the light receiving signal using the selection signal SE multiple times, and may take in the average value of the light receiving intensity data signal DT based on the light receiving signal d1 as the light receiving intensity data signal DT corresponding to the final light receiving signal d1, and may take in the average value of the light receiving intensity data signal DT based on the light receiving signal d2 as the light receiving intensity data signal DT corresponding to the final light receiving signal d2.

[0037] After executing step S22, the controller 27 sets the received light intensity indicated by the light receiving intensity data signal DT based on the light receiving signal d1 of the two received light receiving intensity data signals DT as the received light intensity CH1, sets the received light intensity indicated by the light receiving intensity data signal DT based on the light receiving signal d2 as the received light intensity CH2, and writes each of them to the RAM 272 (step S23).

[0038] Next, the controller 27 determines whether or not both of the received light intensities CH1 and CH2 are equal to or lower than the environmental illuminance LL (step S24).

[0039] If it is determined in step S24 that both of the received light intensities CH1 and CH2 are equal to or lower than the ambient illuminance LL, the controller 27 supplies the lighting control signal LS to the lighting drive circuit 30 to instruct it to turn off all of the light-emitting elements Lr, Ly, and Lg (step S25).

[0040] On the other hand, if it is determined in step S24 that at least one of the received light intensities CH1 and CH2 is greater than the environmental illuminance LL, the controller 27 determines whether the received light intensity CH1 is greater than or equal to the environmental illuminance LL and the received light intensity CH2 is less than or equal to the environmental illuminance LL (step S26).

[0041] In step S26, if it is determined that the received light intensity CH1 is equal to or greater than the ambient illuminance LL and the received light intensity CH2 is equal to or less than the ambient illuminance LL, the controller 27 supplies a lighting control signal LS to the lighting drive circuit 30 to instruct it to turn on the light-emitting element Lr, and supplies a buzzer sound signal BS to the sound generation circuit 28 to instruct it to output a buzzer sound of the note "C" (step S27).

[0042] On the other hand, if it is determined in step S26 that the received light intensity CH1 is not equal to or greater than the ambient illuminance LL and the received light intensity CH2 is not equal to or less than the ambient illuminance LL, the controller 27 determines whether the received light intensity CH1 is equal to or less than the ambient illuminance LL and the received light intensity CH2 is equal to or greater than the ambient illuminance LL (step S28).

[0043] In step S28, if it is determined that the received light intensity CH1 is equal to or less than the ambient illuminance LL and the received light intensity CH2 is equal to or greater than the ambient illuminance LL, the controller 27 supplies the lighting drive circuit 30 with a lighting control signal LS to instruct the lighting element Lg to be turned on, and supplies the sound generation circuit 28 with a buzzer sound signal BS to instruct the sound generation circuit 28 to output a buzzer sound of the note "C" (step S29).

[0044] After executing the above-mentioned step S25, S27 or S29, the controller 27 returns to the execution of step S21 and performs the operations of each of the above-mentioned steps again.

[0045] During this time, if it is determined in step S28 that the received light intensity CH1 is not equal to or lower than the environmental illuminance LL and the received light intensity CH2 is not equal to or higher than the environmental illuminance LL, the controller 27 performs a determination threshold adjustment process (step S30).

[0046] In the determination threshold adjustment process, the controller 27 adjusts the magnitude of the determination threshold DB based on the larger of the received light intensities CH1 and CH2. That is, the controller 27 adjusts the value of the determination threshold DB so that the smaller the larger of the received light intensities CH1 and CH2 is, the smaller the value of the determination threshold DB becomes.

[0047] As a specific adjustment method, the controller 27 calculates the determination threshold DB from the received light intensity by using a function Fx as shown in Fig. 5A. Alternatively, the controller 27 may obtain the determination threshold DB corresponding to the received light intensity by dividing the range of the magnitude of the received light intensity into three stages as shown in Fig. 5B, for example, by using a lookup table in which a determination threshold DB having a value corresponding to the range of the received light intensity is stored in advance.

[0048] Then, the controller 27 sets the thus adjusted determination threshold DB as a new determination threshold.

[0049] After executing step S30, the controller 27 judges whether or not the value obtained by subtracting the received light intensity CH2 from the received light intensity CH1 is equal to or greater than the judgment threshold DB (step S31).

[0050] In step S31, if it is determined that the value obtained by subtracting the light receiving intensity CH2 from the light receiving intensity CH1 is equal to or greater than the judgment threshold DB, the controller 27 supplies the lighting drive circuit 30 with a lighting control signal LS to instruct the lighting drive circuit 30 to turn on the light-emitting element Lr, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct the output of a buzzer sound of the note "Mi" (step S32).

[0051] On the other hand, if it is determined in step S31 that the value obtained by subtracting the light receiving intensity CH2 from the light receiving intensity CH1 is not greater than or equal to the judgment threshold DB, the controller 27 determines whether the value obtained by subtracting the light receiving intensity CH1 from the light receiving intensity CH2 is greater than or equal to the judgment threshold DB (step S33).

[0052] In step S33, if it is determined that the value obtained by subtracting the light receiving intensity CH1 from the light receiving intensity CH2 is equal to or greater than the judgment threshold DB, the controller 27 supplies the lighting drive circuit 30 with a lighting control signal LS to instruct the lighting drive circuit 30 to turn on the light-emitting element Lg, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct the output of a buzzer sound of the note "Mi" (step S34).

[0053] On the other hand, if it is determined in step S33 that the value obtained by subtracting the light receiving intensity CH1 from the light receiving intensity CH2 is not greater than or equal to the judgment threshold DB, the controller 27 supplies the lighting control signal LS to the lighting drive circuit 30 to instruct it to turn on the light-emitting element Ly, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct it to output a buzzer sound of the note "G" (step S35).

[0054] After executing step S32, S34 or S35, the controller 27 returns to executing step S21 and performs the operations of each of the steps described above again.

[0055] Below, the state of the light-emitting elements (Lr, Ly, Lg) of the laser light receiver 100 and the buzzer sound based on the laser irradiation position determination process shown in Figures 4A and 4B will be explained for each irradiation position of the line light LT on the light receiving surfaces F1 and F2 of the laser light receiver 100.

[0056] FIG. 6A is a diagram showing the states of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the line of light LT is not irradiated onto either the light-receiving surfaces F1 or F2.

[0057] As shown in Fig. 6A, when the line light LT is not irradiated to either the light receiving surface F1 or the light receiving surface F2, the light receiving intensity CH1 received by the light receiving surface F1 and the light receiving intensity CH2 received by the light receiving surface F2 are both equal to or less than the ambient illuminance LL. As a result, step S25 shown in Fig. 4A is performed, the light emitting elements Lr, Ly, and Lg are all turned off, and no buzzer sound is output.

[0058] Therefore, the user can confirm that the line light LT is not irradiated onto either of the light receiving surfaces F1 or F2, since the light emitting elements Lr, Ly, and Lg are all off and no buzzer sound is being output.

[0059] FIG. 6B is a diagram showing the states of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the line light LT is irradiated only onto the light-receiving surface F1 of the light-receiving surfaces F1 and F2.

[0060] When the linear light LT is irradiated as shown in Fig. 6B, the light receiving surface F1 receives a light intensity CH1 equal to or greater than the environmental illuminance LL, and the light receiving surface F2 receives a light intensity CH2 equal to or less than the environmental illuminance LL. At this time, the controller 27 determines that the linear light LT is irradiated only to the light receiving surface F1 of the light receiving surfaces F1 and F2 (S26), and outputs the determination result (S27). As a result, only the light emitting element Lr of the light emitting elements Lr, Ly, and Lg is turned on, and a buzzer sound of the musical scale "C" is output.

[0061] Therefore, the user confirms that the light-emitting element Lr is lit, thereby shining a line of light LT onto the light-receiving surface F1, and that the buzzer sound of the note "C" is being output, thereby confirming that the line of light LT is being shining onto a position relatively far away from the target line TL.

[0062] FIG. 6C is a diagram showing the states of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the line light LT is irradiated only onto the light-receiving surface F2 out of the light-receiving surfaces F1 and F2.

[0063] When the linear light LT is irradiated as shown in Fig. 6C, the light receiving surface F2 receives a light intensity CH2 equal to or greater than the environmental illuminance LL, and the light receiving surface F1 receives a light intensity CH1 equal to or less than the environmental illuminance LL. At this time, the controller 27 determines that the linear light LT is irradiated only to the light receiving surface F2 of the light receiving surfaces F1 and F2 (S28) and outputs the determination result (S29). As a result, only the light emitting element Lg of the light emitting elements Lr, Ly, and Lg is turned on, and a buzzer sound of the musical scale "C" is output.

[0064] Therefore, the user confirms that the light-emitting element Lg is lit, causing the line of light LT to be projected onto the light-receiving surface F2, and that the buzzer sound of the note "C" is being output, causing the line of light LT to be projected onto a position relatively far away from the target line TL.

[0065] Figure 6D is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the center line CL of the line light LT extending along the extension direction of the line light LT is located on the light-receiving surface F1 and the line light LT is irradiated to both the light-receiving surfaces F1 and F2.

[0066] 6D, when the line light LT is irradiated, the difference obtained by subtracting the light receiving intensity CH1 from the light receiving intensity CH2 is equal to or greater than the judgment threshold DB. At this time, the controller 27 judges that the line light LT is irradiated to the light receiving surfaces F1 and F2 with the center line CL of the line light LT positioned on the light receiving surface F1 (S31), and outputs the judgment result (S32). As a result, only the light emitting element Lr of the light emitting elements Lr, Ly, and Lg is turned on, and a buzzer sound of the musical scale "Mi" is output.

[0067] Therefore, the user confirms that since the light-emitting element Lr is lit, the line of light LT is being projected onto the light-receiving surface F1, and since the buzzer sound of the note "Mi" is being output, the user confirms that the line of light LT is being projected onto a position near the target line TL.

[0068] Figure 6E is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the center line CL of the line light LT is located on the light-receiving surface F2 and the line light LT is irradiated to both the light-receiving surfaces F1 and F2.

[0069] 6E, when the line light LT is irradiated, the difference obtained by subtracting the light receiving intensity CH2 from the light receiving intensity CH1 is equal to or greater than the judgment threshold DB. At this time, the controller 27 judges that the line light LT is irradiated to the light receiving surfaces F1 and F2 with the center line CL of the line light LT positioned on the light receiving surface F2 (S33), and outputs the judgment result (S34). As a result, only the light emitting element Lg of the light emitting elements Lr, Ly, and Lg is turned on, and a buzzer sound of the musical scale "Mi" is output.

[0070] Therefore, the user confirms that since the light-emitting element Lg is lit, the line of light LT is being projected onto the light-receiving surface F2, and since the buzzer sound of the note "Mi" is being output, the user confirms that the line of light LT is being projected onto a position near the target line TL.

[0071] Figure 6F is a diagram showing the state of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound when the line of light LT is irradiated onto both the light receiving surfaces F1 and F2 so that the center line CL of the line of light LT approximately overlaps with the target line TL.

[0072] When the line light LT is irradiated as shown in Fig. 6F, the difference between the received light intensity CH1 and the received light intensity CH2 is smaller than the judgment threshold DB. At this time, the controller 27 judges that the line light LT is irradiated onto the target line TL (S33) and outputs the judgment result (S35). As a result, only the light-emitting element Ly of the light-emitting elements Lr, Ly, and Lg is turned on, and a buzzer sound of the musical scale "G" is output.

[0073] Therefore, the user confirms that the line of light LT is irradiated onto the target line TL because the light emitting element Ly is lit and the buzzer sound of the musical scale "G" is being output.

[0074] In this way, the laser beam receiver 100 obtains the difference between the light receiving intensities CH1 and CH2 obtained by performing logarithmic conversion processing on the light receiving signals d1 and d2 obtained by photoelectrically converting the light irradiated on the light receiving surfaces F1 and F2, respectively, as the ratio of the magnitude of the light intensity irradiated on the light receiving surfaces F1 and F2, respectively (S31, S33). In other words, the ratio of the light receiving intensities of the two is obtained from the logarithmic difference between the light receiving signals d1 and d2. Then, when the difference between the light receiving intensities CH1 and CH2 is smaller than the judgment threshold DB, the laser beam receiver 100 judges that the center line CL of the line light LT coincides with the position of the target line TL, that is, that the line light LT is irradiated on the target line TL (S33), and outputs the judgment result (S35).

[0075] Therefore, by using the laser light receiver 100 for marking out work, even if the user cannot visually see the line light LT projected onto the wall surface of a building, etc., the user can check whether the line light LT is being projected onto the desired position by monitoring the status of the light-emitting elements (Lr, Ly, Lg) and the buzzer sound.

[0076] Furthermore, the laser beam receiver 100 can distinguish between cases where the position where the line light LT is irradiated is significantly deviated from the desired position (the position of the target line TL) (FIGS. 6A to 6C) and cases where the positional deviation is small (FIGS. 6D and 6E). This makes it possible to shorten the time spent on adjusting the irradiation direction of the line light LT on the laser marking device 300 side.

[0077] Here, as described above, in the laser light receiver 100, when the difference between the received light intensities CH1 and CH2 is smaller than the judgment threshold DB, the laser light receiver 100 outputs a judgment result (S35) that the line light LT is irradiated to the desired position (target line TL).

[0078] In other words, when the difference between the received light intensity CH1 and the received light intensity CH2 is zero, the position of the center line CL of the line light LT and the position of the target line TL should perfectly match, but the laser light receiver 100 uses a judgment threshold DB to perform a match judgment (S31, S33) that allows for positional deviation within a predetermined tolerance range.

[0079] Incidentally, the light intensity of the line light LT received by the light receiving surfaces F1 and F2 decreases as the distance between the laser marking device 300 and the laser light receiver 100 increases, and the width of the line light LT also increases. Therefore, when the distance between the laser marking device 300 and the laser light receiver 100 is long, the difference between the light receiving intensity CH1 and the light receiving intensity CH2 also becomes smaller than when the distance is short. In this case, even if the positional deviation length (hereinafter referred to as the positional deviation length ML) of the center line CL of the line light LT with respect to the target line TL exceeds a predetermined allowable range, the difference between the light receiving intensity CH1 and the light receiving intensity CH2 becomes smaller than the judgment threshold DB, and it is erroneously judged that the line light LT is irradiated to the desired position (target line TL).

[0080] Therefore, the laser light receiver 100 adjusts (S30) the magnitude of the judgment threshold DB based on the larger of the received light intensities CH1 and CH2. In other words, the smaller the received light intensity, the smaller the judgment threshold DB is adjusted. Therefore, even if the received light intensity (CH1, CH2) becomes small because the distance between the laser marking device 300 and the laser light receiver 100 is long, the judgment threshold DB also becomes small following the received light intensity. This makes it possible to always keep the position deviation length ML within a predetermined allowable range when the difference between the received light intensities CH1 and CH2 becomes smaller than the judgment threshold DB.

[0081] Therefore, according to the laser light receiver 100, it is possible to determine whether or not the line light LT is being irradiated onto the desired target line while allowing for a predetermined positional deviation length ML, regardless of the distance between the laser marking device 300 and the laser light receiver 100.

[0082] In the above embodiment, the internal configuration of the laser beam receiver 100 is shown in Fig. 2, but is not limited to this configuration. For example, the selector 23, BPF 24, logarithmic conversion circuit 25, and ADC 26 shown in Fig. 2 may be omitted, and the light receiving signals d1 and d2 may be converted into digital values ​​and directly acquired as the light receiving intensities CH1 and CH2 by the controller 27. In this case, the controller 27 may determine the difference between the light receiving intensity indicated by the light receiving signal d1 and the light receiving intensity indicated by the light receiving signal d2, and compare this with the determination threshold DB as described above to perform a match determination (S31, S33).

[0083] 2, the controller 27 performs the various operations shown in Fig. 4A and Fig. 4B by software, but such operations may be realized by hardware. In the example shown in Fig. 2, the selector 23, BPF 24, logarithmic conversion circuit 25, etc. are realized by hardware, but the light receiving signals d1 and d2 from the photoelectric conversion elements 21 and 22, respectively, may be A / D converted, and the subsequent signal processing (selector 23, BPF 24, logarithmic conversion circuit 25) may be realized by software.

[0084] In addition, in the above embodiment, the laser light receiver 100 receives laser light as the line light LT, but the line light LT received by the laser light receiver 100 is not limited to laser light, and may be, for example, light (lens focused light, slit light) emitted by a point light source such as an LED or an incandescent lamp.

[0085] In short, the laser beam receiver 100 shown in FIG. 2 may be configured to realize at least the following photoelectric conversion unit, received light intensity acquisition unit, notification unit, and determination threshold adjustment unit.

[0086] That is, the photoelectric conversion unit (21, 22) has a first light receiving surface (F1) and a second light receiving surface (F2) adjacent to each other across a boundary line (TL), and generates a first light receiving signal (d1) obtained by converting the light received at the first light receiving surface into an electrical signal, and a second light receiving signal (d2) obtained by converting the light received at the second light receiving surface into an electrical signal.

[0087] The light receiving intensity acquisition unit (23 to 26, S23, 272) acquires a first light receiving intensity (CH1) corresponding to the light intensity received at the first light receiving surface and a second light receiving intensity (CH2) corresponding to the light intensity received at the second light receiving surface based on the first and second light receiving signals.

[0088] The notification unit (27, 30, S31, S33, S35) performs notification in a predetermined manner (Ly lighting) when the difference between the first received light intensity and the second received light intensity is smaller than the determination threshold (DB).

[0089] The determination threshold adjustment section (S30) adjusts the magnitude of the determination threshold based on the first and second received light intensities.

[0090] That is, the laser light receiver 100 may be configured with either hardware or software as long as it realizes the operations shown in the above-mentioned light receiving intensity acquisition unit, notification unit, and judgment threshold adjustment unit. In short, the light receiving device of the present invention may be configured to acquire first and second light receiving intensities representing the intensities of light received at the first and second light receiving surfaces adjacent to each other across a boundary line, and when the ratio obtained by dividing the larger of the first and second light receiving intensities by the smaller one is smaller than the judgment threshold, or when the ratio obtained by dividing the larger by the smaller one is larger than the judgment threshold, to perform a notification in a predetermined manner, and to adjust the magnitude of the judgment threshold based on the first or second light receiving intensity.

[0091] In the above embodiment, the laser beam receiver 100 obtains the difference (|CH1-CH2|) between the received light signals d1 and d2 after logarithmic transformation, i.e., the logarithmic difference, as the ratio of the received light signals d1 and d2. However, the ratio between the received light signals d1 and d2 may be obtained by dividing the received light signals d1 and d2 by each other.

[0092] FIG. 7 is a block diagram showing another example of the internal configuration of the laser beam receiver 100 that has been made in consideration of the above points, and FIG. 8 is a block diagram showing a modified example of the configuration shown in FIG.

[0093] 7 is the same as that shown in Fig. 2 except that the logarithmic conversion circuit 25 is omitted from the configuration shown in Fig. 2 and a controller 27A is used instead of the controller 27. The BPF 24 shown in Fig. 7 extracts signal components in a predetermined frequency band from the light reception signal d1 or d2 supplied from the selector 23 and supplies a light reception signal df consisting of the extracted signal components to the ADC 26. The ADC 26 converts the value indicated by the light reception signal df into a digital value to supply a light reception intensity data signal DT to the controller 27A.

[0094] On the other hand, the configuration shown in FIG. 8 is the same as that shown in FIG. 2 except that the logarithmic conversion circuit 25 and the selector 23 are omitted from the configuration shown in FIG. 2, and the controller 27, the BPF 24, and the ADC 26 are replaced with a controller 27B, a BPF 24a, an ADC 26a, and an ADC 26b. The BPF 24a extracts a signal component of a predetermined frequency band from the light receiving signal d1, and supplies a light receiving signal df1 consisting of the extracted signal components to the ADC 26a. The ADC 26a supplies a light receiving intensity data signal DT1, which is a value indicated by the light receiving signal df1 converted into a digital value, to the controller 27B. The BPF 24b extracts a signal component of a predetermined frequency band from the light receiving signal d2, and supplies a light receiving signal df2 consisting of the extracted signal components to the ADC 26b. The ADC 26b supplies a light receiving intensity data signal DT2, which is a value indicated by the light receiving signal df2 converted into a digital value, to the controller 27B.

[0095] Each of the controllers 27A and 27B, similar to the controller 27, executes a laser irradiation position determination program stored in the ROM 271 in response to power-on. That is, the controller 27A (27B) first sequentially executes steps S20 to S29 shown in FIG. 4A.

[0096] In steps S22 and S23, the controller 27A, like the controller 27, sequentially receives the light receiving intensity data signal DT while supplying the selection signal SE to the selector 23 to alternately select the light receiving signals d1 and d2. At this time, the controller 27A writes the light receiving intensity indicated by the light receiving intensity data signal DT based on the light receiving signal d1 to the RAM 272 as the light receiving intensity CH1, and writes the light receiving intensity indicated by the light receiving intensity data signal DT based on the light receiving signal d2 to the RAM 272 as the light receiving intensity CH2. On the other hand, in steps S22 and S23, the controller 27B writes the light receiving intensity indicated by the light receiving intensity data signal DT1 to the RAM 272 as the light receiving intensity CH1, and writes the light receiving intensity indicated by the light receiving intensity data signal DT based on the light receiving signal d2 to the RAM 272 as the light receiving intensity CH2.

[0097] Here, in step S28 shown in FIG. 4A, if it is determined that the received light intensity CH1 is equal to or less than the environmental illuminance LL and the received light intensity CH2 is not equal to or greater than the environmental illuminance LL, the controller 27A (27B) executes steps S40 to S43 shown in FIG. 9 instead of steps S30 to S33 shown in FIG. 4B.

[0098] That is, when the controller 27A (27B) determines in step S28 shown in Fig. 4A that the received light intensity CH1 is not greater than the environmental illuminance LL and the received light intensity CH2 is not greater than the environmental illuminance LL, the controller 27A (27B) performs a determination threshold adjustment process shown in Fig. 9 (step S40). In the determination threshold adjustment process in step S40, the controller 27A (27B) adjusts the value of the determination threshold DB according to the function Fx2 or Fx3 shown in Fig. 10 based on the larger of the received light intensities CH1 and CH2. Then, the controller 27A (27B) sets the thus adjusted determination threshold DB as a new determination threshold.

[0099] After executing step S40, the controller 27A (27B) determines whether the received light intensity CH1 is greater than the received light intensity CH2 (step S41).

[0100] In step S41, when it is determined that the received light intensity CH1 is greater than the received light intensity CH2, the controller 27A (27B) determines whether or not the division result (CH1 / CH2) obtained by dividing the received light intensity CH1 by CH2 is smaller than the judgment threshold DB adjusted based on the function Fx2 shown in Fig. 10 (step S42). In step S42, when it is determined that the division result (CH1 / CH2) is not smaller than the judgment threshold DB, the controller 27A (27B) executes step S32 shown in Fig. 4B. That is, the controller 27A (27B) supplies the lighting control signal LS to the lighting drive circuit 30 to instruct the lighting element Lr to be turned on, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct the output of a buzzer sound of the musical scale "Mi".

[0101] Furthermore, if it is determined in step S41 that the received light intensity CH1 is not greater than the received light intensity CH2, the controller 27A (27B) determines whether or not the division result (CH1 / CH2) obtained by dividing the received light intensity CH1 by CH2 is greater than the judgment threshold DB adjusted based on the function Fx3 shown in Fig. 10 (step S43). If it is determined in step S43 that the division result (CH1 / CH2) is not greater than the judgment threshold DB, the controller 27A (27B) executes step S34 shown in Fig. 4B. That is, the controller 27A (27B) supplies the lighting control signal LS to the lighting drive circuit 30 to instruct the lighting element Lg to be turned on, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct the output of a buzzer sound of the musical scale "Mi".

[0102] Also, when it is determined in step S42 that the division result of the received light intensity CH1 by CH2 (CH1>CH2) is smaller than the judgment threshold DB, or when it is determined in step S43 that the division result of the received light intensity CH1 by CH2 (CH1≦CH2) is larger than the judgment threshold DB, the controller 27A (27B) executes step S35 shown in Fig. 4B. That is, the controller 27A (27B) supplies the lighting control signal LS to the lighting drive circuit 30 to instruct the lighting element Ly to be turned on, and supplies the buzzer sound signal BS to the sound generation circuit 28 to instruct the output of a buzzer sound of the musical scale "G".

[0103] After executing step S32, S34, or S35, the controller 27A (27B) returns to the execution of step S21 shown in FIG. 4A, and performs the operations of the above-mentioned steps again.

[0104] In this way, in the laser light receiver 100 having the internal configuration shown in FIG. 7 or 8, the ratio of the magnitude of the light intensity irradiated on the light receiving surfaces F1 and F2 is obtained by dividing the light receiving intensities CH1 and CH2. At this time, if the light receiving intensity CH1 is greater than the light receiving intensity CH2, it is determined whether the ratio obtained by dividing CH1 by CH2 is smaller than the judgment threshold DB (S42). Here, if it is determined that this ratio is smaller than the judgment threshold DB, it is determined that the center line CL of the line light LT coincides with the position of the target line TL, that is, the line light LT is irradiated on the target line TL, and the judgment result is output (S35). On the other hand, if the light receiving intensity CH1 is equal to or less than the light receiving intensity CH2, it is determined whether the ratio obtained by dividing CH1 by CH2 is larger than the judgment threshold DB (S43). Here, if it is determined that this ratio is greater than the judgment threshold DB, it is determined that the center line CL of the line light LT coincides with the position of the target line TL, that is, the line light LT is irradiated onto the target line TL, and the judgment result is output (S35).

[0105] In other words, when the ratio between the received light intensity CH1 and the received light intensity CH2 is essentially 1, the position of the center line CL of the line light LT and the position of the target line TL will perfectly coincide, but in the configuration of the laser light receiver 100 shown in Figure 7 or Figure 8, a coincidence judgment (S42, S43) is performed that allows for a deviation of ± the judgment threshold DB from the ratio of 1.

[0106] 7 or 8, the magnitude of the decision threshold DB is adjusted based on the larger of the received light intensities CH1 and CH2, for example, according to the function Fx2 or Fx3 shown in Fig. 10. That is, when the ratio between the received light intensities CH1 and CH2 is calculated by dividing the received light intensity CH1 by the received light intensity CH2, if the received light intensity CH1 is larger than CH2, the value of the decision threshold DB is adjusted according to the function Fx2 shown in Fig. 10 so that the smaller the received light intensity CH1 is, the smaller the value of the decision threshold DB becomes (a ratio larger than 1). On the other hand, if the received light intensity CH1 is equal to or smaller than CH2, the value of the decision threshold DB is adjusted according to the function Fx3 shown in Fig. 10 so that the smaller the received light intensity CH2 is, the larger the value of the decision threshold DB becomes (a ratio smaller than 1).

[0107] According to such an adjustment of the judgment threshold DB, since the width of the line light LT increases with a decrease in the received light intensity as the distance between the laser marking device 300 and the laser light receiver 100 increases, even if the ratio between the received light intensities CH1 and CH2 fluctuates, the value of the judgment threshold DB is adjusted to follow the fluctuation of this ratio. Therefore, regardless of the distance between the laser marking device 300 and the laser light receiver 100, it is possible to accurately determine whether or not the line light LT is irradiated onto the target line while allowing for a predetermined positional deviation length.

[0108] In the configuration shown in Fig. 7 or 8, the controller 27A or 27B performs the various operations shown in Fig. 4A and 9 by software, but such operations may be realized by hardware. Also, in the example shown in Fig. 7 or 8, the selector 23, BPF 24, 24a, 24b, etc. are realized by hardware, but the light receiving signals d1 and d2 from the photoelectric conversion elements 21 and 22, respectively, may be A / D converted, and the subsequent signal processing (selector 23, BPF 24, 24a, 24b) may be realized by software.

[0109] In short, the laser beam receiver 100 having the internal configuration shown in FIG. 7 or FIG. 8 may be configured to realize at least the following photoelectric conversion unit, notification unit, and determination threshold adjustment unit.

[0110] That is, the photoelectric conversion unit (21, 22) has a first light receiving surface (F1) and a second light receiving surface (F2) adjacent to each other across a boundary line (TL), and generates a first light receiving signal (d1) obtained by converting the light received at the first light receiving surface into an electrical signal, and a second light receiving signal (d2) obtained by converting the light received at the second light receiving surface into an electrical signal.

[0111] The notification unit (27A, 27B, S42, S43, S35) notifies of a predetermined mode (Ly on) when the ratio obtained by dividing the larger of the first light receiving intensity (CH1) indicated by the first light receiving signal and the second light receiving intensity (CH2) indicated by the second light receiving signal by the smaller is smaller than the judgment threshold (DB) (S42, S35). Also, the notification unit notifies of a predetermined mode (Ly on) when the ratio obtained by dividing the larger of the first light receiving intensity (CH1) and the second light receiving intensity (CH2) by the smaller is larger than the judgment threshold (DB) (S43, S35).

[0112] The determination threshold adjustment section (S40) adjusts the magnitude of the determination threshold based on the first and second received light intensities. [Explanation of symbols]

[0113] 21, 22 Photoelectric conversion element 25 Logarithmic conversion circuit 27, 27A, 27B Controller 100 Laser light receiver F1, F2 light receiving surface TL target line

Claims

1. a photoelectric conversion unit having a first light receiving surface and a second light receiving surface adjacent to each other across a boundary line, the photoelectric conversion unit generating a first light receiving signal by converting light received at the first light receiving surface into an electrical signal, and a second light receiving signal by converting light received at the second light receiving surface into an electrical signal; a notification unit that performs a notification in a predetermined manner when a ratio obtained by dividing a smaller one of a first light receiving intensity indicated by the first light receiving signal and a second light receiving intensity indicated by the second light receiving signal by the larger one is smaller than a determination threshold value, or when a ratio obtained by dividing a larger one of the first light receiving intensity and the second light receiving intensity by the smaller one is larger than the determination threshold value; a determination threshold adjustment section that adjusts the magnitude of the determination threshold based on the first received light intensity or the second received light intensity.

2. The light receiving device according to claim 1, characterized in that, when the first received light intensity is greater than the second received light intensity, the judgment threshold adjustment unit adjusts the judgment threshold so that the value becomes smaller as the first received light intensity is smaller, and, when the first received light intensity is equal to or less than the second received light intensity, the judgment threshold adjustment unit adjusts the judgment threshold so that the value becomes smaller as the second received light intensity is smaller.

3. The light receiving device according to claim 2, characterized in that the judgment threshold adjustment unit sets the first light receiving intensity or the second light receiving intensity obtained when the first light receiving surface and the second light receiving surface do not receive the alignment target light as an ambient illuminance, and adjusts the judgment threshold when both the first light receiving intensity and the second light receiving intensity obtained when the alignment target light is received by the first light receiving surface and the second light receiving surface are greater than the ambient illuminance.

4. the boundary line is a target line serving as a target for aligning the line light, 2. The light receiving device according to claim 1, further comprising a judgment unit that judges that the center line of the line light is located on the target line when a ratio obtained by dividing the smaller of the first received light intensity and the second received light intensity by the larger of the first received light intensity and the second received light intensity is smaller than the judgment threshold value, or when a ratio obtained by dividing the larger of the first received light intensity and the second received light intensity by the smaller of the first received light intensity and the second received light intensity is larger than the judgment threshold value.

5. a photoelectric conversion unit having a first light receiving surface and a second light receiving surface adjacent to each other across a boundary line, the photoelectric conversion unit generating a first light receiving signal by converting light received at the first light receiving surface into an electrical signal, and a second light receiving signal by converting light received at the second light receiving surface into an electrical signal; a light receiving intensity acquiring unit that acquires a first light receiving intensity corresponding to the light intensity received at the first light receiving surface and a second light receiving intensity corresponding to the light intensity received at the second light receiving surface based on the first light receiving signal and the second light receiving signal; a notification unit that issues a notification in a predetermined manner when a difference between the first received light intensity and the second received light intensity is smaller than a determination threshold; a determination threshold adjustment section that adjusts the magnitude of the determination threshold based on the first received light intensity or the second received light intensity.

6. 6. The light receiving device according to claim 5, wherein the determination threshold adjustment section adjusts the determination threshold so as to decrease the determination threshold as the greater of the first and second received light intensities decreases.

7. The light receiving device according to claim 6, characterized in that the judgment threshold adjustment unit sets the first light receiving intensity or the second light receiving intensity obtained when the first light receiving surface and the second light receiving surface do not receive the alignment target light as the ambient illuminance, and adjusts the judgment threshold when both the first light receiving intensity and the second light receiving intensity obtained when the alignment target light is received by the first light receiving surface and the second light receiving surface are greater than the ambient illuminance.

8. the boundary line is a target line serving as a target for aligning the line light, 6. The light receiving device according to claim 5, further comprising a determination unit that determines that the center line of the line of light is located on the target line when a difference between the first received light intensity and the second received light intensity is smaller than a determination threshold value.

9. The notification unit includes a display and a speaker.

6. The light receiving device according to claim 5, wherein the predetermined mode is lighting of the display and output of a sound of a predetermined scale from the speaker.

10. a selector that receives the first light receiving signal and the second light receiving signal, and alternately selects and outputs the first light receiving signal and the second light receiving signal every predetermined period; A light receiving device as described in any one of claims 1 to 9, characterized in that it includes a memory that, when the first light receiving signal is output from the selector, holds this as the first light receiving intensity, and, when the second light receiving signal is output from the selector, holds this as the second light receiving intensity.

11. a selector that receives the first light receiving signal and the second light receiving signal, and alternately selects and outputs the first light receiving signal and the second light receiving signal every predetermined period; a logarithmic conversion circuit that performs logarithmic conversion on the first light receiving signal or the second light receiving signal output from the selector and outputs the logarithmic conversion signal as a light receiving intensity signal representing a light receiving intensity; a memory for holding, when the logarithmic conversion circuit outputs the light receiving intensity signal based on the first light receiving signal, the light receiving intensity represented by the output light receiving intensity signal as the first light receiving intensity, and for holding, when the logarithmic conversion circuit outputs the light receiving intensity signal based on the second light receiving signal, the light receiving intensity represented by the output light receiving intensity signal as the second light receiving intensity.

12. acquiring a first light receiving intensity and a second light receiving intensity, each of which individually represents the intensity of light received by a first light receiving surface and a second light receiving surface adjacent to each other across a boundary line; A position detection method characterized by providing a notification in a predetermined manner when a ratio obtained by dividing the smaller of the first received light intensity and the second received light intensity by the larger of the first received light intensity and the second received light intensity is smaller than a judgment threshold, or when a ratio obtained by dividing the larger of the first received light intensity and the second received light intensity by the smaller of the first received light intensity and the second received light intensity is larger than the judgment threshold, and adjusting the magnitude of the judgment threshold based on the first received light intensity or the second received light intensity.

Images