Light-emitting device and distance measuring device

Abstract

To suppress an influence of deviation in irradiation range that respective light sources have as compared with a case in which the light sources are all turned on for any distance.SOLUTION: A light-emitting device comprises: a light-emitting part which has a first light source turned on to irradiate a first irradiation range and a second light source turned on to irradiate a second irradiation range, and irradiates, in a reference distance, the first irradiation range and second irradiation range side by side or one over the other; and a drive part which drives the light-emitting part such that when an object at a first distance different from the reference distance is irradiated by the light-emitting part, one of the first light source and second light source is turned on and the other is turned off.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a light-emitting device and a distance measuring device.

Background Art

[0002] Patent Document 1 describes a distance measuring device including a light source in which light-emitting regions are two-dimensionally arranged, and a light-receiving unit that receives reflected light reflected by a distance measurement target existing in a distance measurement region. In the distance measuring device, each light-emitting point of the light source is caused to emit light simultaneously with the same light amount for pre-emission, and the light emission amount of main emission is controlled based on the light reception amount for each light reception region measured by a region light amount measurement unit by the pre-emission. Patent Document 2 describes a detection device including a light source device that divides an irradiation region of light on a detection target by a plurality of light-emitting units into a plurality of irradiation regions and irradiates the detection target, a light source driving unit that switches a plurality of illuminance levels for each of the plurality of irradiation regions, and a control unit that integrates / synthesizes a plurality of detection data regarding the detection target detected by switching the plurality of illuminance levels for each of the plurality of irradiation regions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a distance measuring device that measures the distance to an object (sometimes referred to as "distance measurement") by the so-called Time of Flight (TOF) method, which measures the time from the emission of light by a light emitting unit to the reception of the light reflected by the object by a light receiving unit. In such a distance measuring device or the like, there is an aspect of designing the light emitting unit so that when a plurality of light sources are lit, the irradiation ranges of the respective light sources can irradiate a combined area in parallel or in an overlapping manner. In such an aspect, depending on the distance to the object, the deviation of the irradiation ranges of the respective light sources may increase, which may affect the distance measurement. An object of the present invention is to suppress the influence caused by the deviation of the irradiation ranges of the respective light sources as compared with the case where all the light sources are lit regardless of the distance.

Means for Solving the Problems

[0005] The invention according to claim 1 has a first light source that irradiates a first irradiation range and a second light source that irradiates a second irradiation range in a lit state, and at a reference distance, the first irradiation range and the second irradiation range are irradiated in parallel or in an overlapping manner. A light emitting unit, and when irradiating an object at a first distance different from the reference distance by the light emitting unit, one of the first light source and the second light source is in a lit state and the other is in an extinguished state. A driving unit that drives the light emitting unit, and a light emitting device characterized by comprising the driving unit. The invention according to claim 2 is such that the first light source includes a plurality of light emitting sections that emit light toward each of a plurality of irradiation sections obtained by dividing the first irradiation range, and the second light source includes a plurality of light emitting sections that emit light toward each of a plurality of irradiation sections obtained by dividing the second irradiation range. The driving unit drives the light emitting unit so that the light emitting sections that emit light toward adjacent irradiation sections emit light at different timings in each of the first light source and the second light source. The light emitting device according to claim 1. The invention according to claim 3 is such that the first light source has a first light-emitting section that irradiates a first irradiation section and a third light-emitting section that irradiates a third irradiation section adjacent to the first irradiation section, the second light source has a second light-emitting section that irradiates a second irradiation section and a fourth light-emitting section that irradiates a fourth irradiation section adjacent to the second irradiation section, at the reference distance, the first irradiation section and the second irradiation section are superimposed, and the third irradiation section and the fourth irradiation section are superimposed, and the driving unit drives the light-emitting section such that at the first distance where the first irradiation section and the fourth irradiation section are superimposed, one is in a lighting state and the other is in a non-lighting state. The light-emitting device according to claim 2 is characterized in that. The invention according to claim 4 is characterized in that which one is in the lighting state and which one is in the non-lighting state are determined based on the lighting history of the first light source and the second light source. The light-emitting device according to claim 1 is characterized in that. The invention according to claim 5 is such that when the driving unit irradiates an object at the first distance, among the first light source and the second light source, the one with the shorter total lighting time is in the lighting state and the one with the longer total lighting time is in the non-lighting state, and the driving unit drives the light-emitting section. The light-emitting device according to claim 4 is characterized in that. The invention according to claim 6 is such that each of the first light source and the second light source has a plurality of light-emitting sections that emit light toward the first irradiation range and the second irradiation range, and is driven to emit light at different timings for each group including at least one light-emitting section, and when the driving unit irradiates an object at the first distance, the one with less influence of the heat generated by the light emission of the previous group on the light emission of the next group is in the lighting state and the one with greater influence is in the non-lighting state, and the driving unit drives the light-emitting section. The light-emitting device according to claim 4 is characterized in that. The invention according to claim 7 is such that when an object is detected at the first distance, the driving unit drives the light-emitting section such that one of the first light source and the second light source is in the lighting state and the other is in the non-lighting state. The light-emitting device according to claim 1 is characterized in that. The invention according to claim 8 is the light-emitting device according to claim 1, characterized in that the first irradiation range and the second irradiation range overlap at the reference distance, and the first distance is closer than the reference distance. The invention according to claim 9 has a first light source that irradiates a first irradiation range and a second light source that irradiates a second irradiation range in a lighting state, and at a reference distance, a light-emitting unit that irradiates the first irradiation range and the second irradiation range in parallel or overlapping; a first mode for irradiating an object at a first distance different from the reference distance by the light-emitting unit; and a second mode for irradiating an object at a distance farther than the first distance, and the light-emitting unit can be driven by switching between them. In the first mode, the light-emitting unit is driven so that one of the first light source and the second light source is in a lighting state and the other is in a lighting-off state. In the second mode, the light-emitting unit is driven so that both the first light source and the second light source are in a lighting state. It is a light-emitting device characterized by having a driving unit. The invention according to claim 10 is the light-emitting device according to claim 9, characterized in that the driving unit drives the light-emitting unit in the first mode when the arrival of an object at the first distance is predicted. The invention according to claim 11 is a distance measuring device characterized by comprising the light-emitting device according to any one of claims 1 to 10, a light-receiving unit that receives light irradiated from the light-emitting device and reflected by an object, and a calculating unit that calculates the distance to the object based on the result of light reception in the light-receiving unit. The invention according to claim 12 is the distance measuring device according to claim 11, characterized in that the driving unit drives the light-emitting unit so that one of the first light source and the second light source is in a lighting state and the other is in a lighting-off state when an object is detected at the first distance or the arrival of an object at the first distance is predicted based on the result of light reception in the light-receiving unit or the result of calculation in the calculating unit.

Effects of the Invention

[0006] According to the invention of claim 1, it is possible to suppress the influence caused by the deviation of the irradiation range of each light source as compared with the case where all light sources are turned on regardless of the distance. According to the invention of claim 2, it is possible to suppress the interference to adjacent irradiation sections as compared with the case where all light sources are turned on regardless of the distance. According to the invention of claim 3, it is possible to suppress the interference to adjacent irradiation sections even under conditions where interference is likely to occur due to the overlap of irradiation ranges. According to the invention of claim 4, drive control according to the lighting state of each light source is performed as compared with the case where the light sources to be in the lighting state and the extinguished state are fixed. According to the invention of claim 5, the deviation of the total lighting time of each light source is suppressed as compared with the case where the light sources to be in the lighting state and the extinguished state are fixed. According to the invention of claim 6, the influence on the luminous efficiency due to the heat generated during light emission is suppressed as compared with the case where the light sources to be in the lighting state and the extinguished state are fixed. According to the invention of claim 7, the irradiation of each light source in a state where the irradiation range is deviated with respect to an object existing at the first distance is suppressed. According to the invention of claim 8, it is suppressed that the amount of light irradiated in the overlapping part and the non-overlapping part becomes non-uniform on the side closer to the light emitting part where the amount of light irradiated is larger than on the side farther from the light emitting part, and it is suppressed that the amount of light irradiated to the object becomes excessive. According to the invention of claim 9, the influence caused by the deviation of the irradiation range of each light source is suppressed as compared with the case where all light sources are turned on regardless of the distance. According to the invention of claim 10, the irradiation of each light source in a state where the irradiation range is deviated with respect to an object that has reached the first distance is suppressed. According to the invention of claim 11, it is possible to suppress the influence caused by the deviation of the irradiation range of each light source as compared with the case where all light sources are turned on regardless of the distance. According to the invention of claim 12, it is possible to detect an object without providing individual sensors and use it for control.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the technical scope of the present invention is not limited to the scope described as embodiments below. It is clear from the description of the claims that combinations of a plurality of embodiments and those obtained by making various changes or improvements to these embodiments are also included in the technical scope of the present invention.

[0009] [Embodiment 1] (Distance Measuring Device 1) FIG. 1 is a block diagram showing an example of the schematic configuration of the distance measuring device 1 to which the present embodiment is applied. The distance measuring device 1 measures the distance to an object based on the time from the timing when light is emitted from the light emitting unit 4 to the timing when the light reflected by the object is received by the light receiving unit 5. That is, the distance measuring device 1 is a device that measures distance based on the ToF method. The ToF method includes an indirect ToF (iToF: indirect ToF) method of measuring time from the difference between the phase of the emitted light and the phase of the received light, and a direct ToF (dToF: direct ToF) method of directly measuring the time from the emission to the reception of light. Although both are applicable, in the present embodiment, the distance measuring device 1 will be described as performing distance measurement based on the indirect ToF method.

[0010] As shown in FIG. 1, the distance measuring device 1 includes an optical device 3 and a control unit 8. The optical device 3 includes a light emitting unit 4 that irradiates light toward a predetermined range, a light receiving unit 5 that receives light reflected by an object existing in the range irradiated with light from the light emitting unit 4, a light emitting driving unit 6 that drives the light emitting unit 4, and a light receiving driving unit 7 that drives the light receiving unit 5. The light emitting unit 4 is an example of a light emitting device. The light emitting driving unit 6 is an example of a driving unit.

[0011] (Control unit 8) The control unit 8 controls the operations of the light emitting unit 4 and the light receiving unit 5 of the optical device 3. Further, the control unit 8 acquires the result of light reception in the light receiving unit 5, and measures the distance from the distance measuring device 1 to the object by the ToF method based on the result of this light reception. The control unit 8 is an example of a calculation unit.

[0012] The control unit 8 is composed of a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, and a RAM (Random Access Memory) 83. The CPU 81 is an example of a processor, and realizes each function described later by loading and executing various programs stored in the ROM 82 etc. into the RAM 83. The RAM 83 is a memory used as a working memory etc. of the CPU 81. The ROM 82 is a memory that stores various programs etc. executed by the CPU 81.

[0013] Here, the program executed by the CPU 81 can be provided in a state stored in a computer-readable recording medium such as a magnetic recording medium (magnetic tape, magnetic disk, etc.), an optical recording medium (optical disk, etc.), a magneto-optical recording medium, or a semiconductor memory. Also, the program executed by the CPU 81 may be provided using a communication means such as the Internet.

[0014] In addition, in the present embodiment, the processor refers to a processor in a broad sense, including a general-purpose processor (e.g., CPU: Central Processing Unit, etc.) and a dedicated processor (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.). Moreover, the operation of the processor in the present embodiment may be achieved not only by one processor but also by a plurality of physically separated processors cooperating with each other. Also, the order of each operation of the processor is not limited to the order described in the present embodiment and may be changed.

[0015] (Light emitting unit 4) FIG. 2 is a diagram showing the light sources 4A and 4B included in the light emitting unit 4 of the present embodiment and the irradiation ranges 100A and 100B which are the ranges irradiated with the light emitted from the light sources 4A and 4B. In the present embodiment, an example in which the light emitting unit 4 has two light sources is shown, but the number of light sources included in the light emitting unit 4 may be three or more. As an example of an aspect in which the light emitting unit 4 has three or more light sources, Embodiment 3 will be shown later. In FIG. 2, the front side of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the rightward direction of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively.

[0016] The light emitting unit 4 includes a light source 4A that irradiates the irradiation range 100A with light and a light source 4B that irradiates a different irradiation range 100B from the irradiation range 100A with light. The light emitting unit 4 irradiates the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B in parallel or in an overlapping manner. In this example, the light source 4A is an example of the first light source, the light source 4B is an example of the second light source, the irradiation range 100A is an example of the first irradiation range, and the irradiation range 100B is an example of the second irradiation range. In the light-emitting unit 4 of the present embodiment, the light sources 4A and 4B are arranged in parallel in the y direction. In this example, the light source 4A is arranged on the +y direction side with respect to the light source 4B.

[0017] Here, the irradiation range 100A is a range irradiated with the light emitted from the light source 4A at a certain distance in the +z direction from the light-emitting unit 4. Similarly, the irradiation range 100B is a range irradiated with the light emitted from the light source 4B at a certain distance in the +z direction from the light-emitting unit 4. That the irradiation range 100A and the irradiation range 100B are parallel means that at a certain distance in the +z direction from the light-emitting unit 4, the irradiation range 100A and the irradiation range 100B are arranged side by side in a direction intersecting in the z direction. Also, that the irradiation range 100A and the irradiation range 100B overlap means that at a certain distance in the +z direction from the light-emitting unit 4, at least a part of the region of the irradiation range 100A and at least a part of the region of the irradiation range 100B overlap. In FIG. 2, the overlapping part of the irradiation range 100A and the irradiation range 100B is shown by hatching. Note that in the present embodiment, the distance in the +z direction from the light-emitting unit 4 more precisely means the distance from the light-emitting surfaces 41 (to be described later) of the light source 4A and the light-emitting surfaces 42 (to be described later) of the light source 4B in the light-emitting unit 4.

[0018] Also, FIG. 2 shows irradiation surfaces 210 and 220 that are orthogonal to the +z direction at a certain distance in the direction (+z direction) in which the light sources 4A and 4B emit light, and on which the light of the irradiation range 100A and the irradiation range 100B is irradiated. The irradiation surfaces 210 and 220 extend in the x direction and the y direction at a certain distance in the +z direction. Also, the irradiation surfaces 210 and 220 are arranged in order in the +z direction from the light sources 4A and 4B. Hereinafter, the distance in the +z direction from the light sources 4A and 4B to the irradiation surface 210 is denoted as a distance L1, and the distance in the +z direction from the light sources 4A and 4B to the irradiation surface 220 is denoted as a distance L2. Note that the relationship between the irradiation range 100A and the irradiation range 100B on the irradiation surfaces 210 and 220 will be described in detail later.

[0019] The light sources 4A and 4B have light emitting surfaces on which a plurality of vertical cavity surface emitting lasers (VCSELs) are arranged. Hereinafter, the light emitting surface of the light source 4A is denoted as the light emitting surface 41 (see FIG. 3 described later), and the light emitting surface of the light source 4B is denoted as the light emitting surface 42 (see FIG. 3 described later). The light rays emitted from the light sources 4A and 4B are spread and irradiated on a plane perpendicular to the emission direction by diffusion parts (not shown) of the light sources 4A and 4B. As the diffusion part, a diffusion plate provided on the optical path of light and diffusing light by scattering or the like, a diffractive optical element (DOE) that changes the angle of incident light and emits it, or / and an optical member such as a lens can be used.

[0020] The irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B expand in the ±x direction and the ±y direction as they go in the +z direction. In the present embodiment, as shown in FIG. 2, in a region where the distance in the +z direction from the light sources 4A and 4B is less than the distance L2, the irradiation range 100A is located on the +y direction side compared to the irradiation range 100B. Further, in the present embodiment, as the distance from the light sources 4A and 4B increases, the ratio of the overlapping portion of the irradiation range 100A and the irradiation range 100B in the combined range of the irradiation range 100A and the irradiation range 100B increases.

[0021] In the light emitting unit 4 of the present embodiment, the light sources 4A and 4B are independently driven by a light emitting drive unit 6 (see FIG. 1) to perform a light emitting operation. Additionally, the light sources 4A and 4B emit light when power is supplied to the VCSELs included in the light sources 4A and 4B by the light emitting drive unit 6. Note that the amount of light of the VCSELs included in the light sources 4A and 4B changes depending on the magnitude of the current value flowing through the VCSELs when power is supplied. That is, the light sources 4A and 4B emit more light as the supplied power increases and the current value flowing through the VCSELs increases. In the following description, the current values of the VCSELs constituting the light sources 4A and 4B may be simply referred to as the current values of the light sources 4A and 4B.

[0022] Here, "driven independently" means that each of the light sources 4A and 4B is driven to emit light. The light emission driving unit 6 drives the respective light sources 4A and 4B in accordance with a control signal from the control unit 8 (see FIG. 1). Therefore, the light sources 4A and 4B do not necessarily emit light simultaneously, and for example, a state where the light source 4A is emitting light but the light source 4B is not emitting light can be taken. In the present embodiment, the state where the light sources 4A and 4B are emitting light is referred to as the light sources 4A and 4B being in the lit state, and the state where the light sources 4A and 4B are not emitting light may be referred to as the light sources 4A and 4B being in the off state. The switching between the lit state and the off state of the light sources 4A and 4B will be described in detail later.

[0023] FIG. 3 is a diagram showing the light sources 4A and 4B included in the light emitting unit 4 of the present embodiment and the irradiation surfaces 210 and 220 irradiated with the light emitted from the light sources 4A and 4B. In FIG. 3, the right direction of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. In FIG. 3, the light emitting unit 4 and the irradiation surfaces 210 and 220 are shown shifted in the vertical direction (±y direction), but actually, the light emitting unit 4 and the irradiation surfaces 210 and 220 are arranged to face each other. In FIG. 3, the light emitting unit 4 is located in the front side direction (-z direction) of the paper surface, and the irradiation surface 210 and the irradiation surface 220 are sequentially located in the back side direction (+z direction) of the paper surface. That is, FIG. 3 shows the light emitting unit 4 emitting light as seen from the side opposite to the side from which the light emitting unit 4 is emitting light. In the irradiation surfaces 210 and 220 of FIG. 3, the hatched portion indicates the overlapping portion of the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B.

[0024] As shown in FIG. 3, in the light emitting unit 4, the light emitting surface 41 of the light source 4A and the light emitting surface 42 of the light source 4B are parallel in the y direction. In this example, the light emitting surface 41 of the light source 4A is parallel to the +y direction side with respect to the light emitting surface 42 of the light source 4B. In addition, the shapes of the light-emitting surfaces 41 and 42 as viewed in the z direction are rectangular shapes having sides extending in the x and y directions. Additionally, in the present embodiment, the shapes and areas of the light-emitting surfaces 41 and 42 as viewed in the +z direction are equal to each other.

[0025] As described above, the light-emitting unit 4 of the present embodiment spreads and irradiates the light rays emitted from the light sources 4A and 4B onto a plane perpendicular to the emission direction. Therefore, the areas of the irradiation surfaces 210 and 220 increase in the order of the irradiation surface 210 and the irradiation surface 220 arranged in the +z direction. In addition, the shapes of the irradiation ranges 100A and 100B on the irradiation surfaces 210 and 220 are substantially rectangular, corresponding to the shapes of the light-emitting surfaces 41 and 42.

[0026] The light-emitting unit 4 of the present embodiment irradiates light so that the overlap between the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B becomes large on the irradiation surface 220 where the distance in the +z direction from the light-emitting unit 4 is the distance L2. The distance L2 is an example of a reference distance. Hereinafter, it may be referred to as the reference distance L2. In this example, the light-emitting unit 4 irradiates light so that substantially the entire irradiation range 100A by the light source 4A and substantially the entire irradiation range 100B by the light source 4B overlap on the irradiation surface 220. In other words, when both the light source 4A and the light source 4B are in the lit state, almost the entire area of the irradiation surface 220 becomes an overlapping region 225 where the light from the light source 4A and the light from the light source 4B are overlapped and irradiated.

[0027] The irradiation surface 220 has a shape as viewed in the +z direction that is close to a rectangular shape corresponding to the shapes of the light-emitting surface 41 of the light source 4A and the light-emitting surface 42 of the light source 4B due to the entire irradiation range 100A and the entire irradiation range 100B overlapping. In the following description, the shape of the irradiation surface 220 as viewed in the +z direction may be referred to as a reference shape.

[0028] Also, on the irradiation surface 210 where the distance in the +z direction from the light emitting unit 4 is the distance L1 that is closer than the reference distance L2, the overlap between the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B becomes smaller compared to the irradiation surface 220. The distance L1 is an example of the first distance. Incidentally, the light emitting unit 4 irradiates light on the irradiation surface 210 such that the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B are displaced and arranged in a direction intersecting in the z direction. As a result, on the irradiation surface 210, although the ratio of the portion where the irradiation range 100A and the irradiation range 100B overlap exceeds 50%, the ratio of the portion where the irradiation range 100A and the irradiation range 100B do not overlap is also 10% or more. And the light amount distribution on the irradiation surface 210 is non-uniform.

[0029] In this example, the light emitting unit 4 irradiates light on the irradiation surface 210 such that the irradiation range 100A is displaced and arranged in the +y direction with respect to the irradiation range 100B. As a result, on the irradiation surface 210, a part of the region on the -y direction side in the irradiation range 100A and a part of the region on the +y direction side in the irradiation range 100B overlap. In other words, when both the light source 4A and the light source 4B are in the lit state, the irradiation surface 210 includes an irradiation region 211 where light from the light source 4A is irradiated and light from the light source 4B is not irradiated, an irradiation region 212 where light from the light source 4B is irradiated and light from the light source 4A is not irradiated, and an overlapping region 215 where light from the light source 4A and light from the light source 4B are superimposed and irradiated. On the irradiation surface 210, the irradiation region 211, the overlapping region 215, and the irradiation region 212 are arranged in order in the -y direction.

[0030] Also, due to the irradiation range 100A and the irradiation range 100B being displaced and arranged in the y direction, the shape seen in the +z direction of the irradiation surface 210 is a rectangular shape with a larger ratio of the length in the y direction to the length in the x direction compared to the above-described reference shape.

[0031] Also, although illustration is omitted, the light emitting unit 4 irradiates light such that the ratio of the overlapping portion of the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B increases slightly compared to the irradiation surface 220 at the reference distance L2 on the irradiation surface where the distance in the +z direction from the light emitting unit 4 is farther than the reference distance L2. In this example, the light emitting unit 4 irradiates light such that the irradiation range 100A is shifted in the -y direction with respect to the irradiation range 100B on the irradiation surface where the distance in the +z direction from the light emitting unit 4 is farther than the reference distance L2.

[0032] (Light receiving unit 5) The light receiving unit 5 has a light receiving surface that extends in the x direction and the y direction and on which a plurality of light receiving elements are arranged. Then, each light receiving element on the light receiving surface of the light receiving unit 5 receives the light emitted from the light sources 4A and 4B of the light emitting unit 4 and reflected by the object. Then, the light receiving unit 5 outputs an electrical signal corresponding to the light received by the light receiving element to the control unit 8. Examples of the light receiving element include a photodiode and a phototransistor.

[0033] (Drive control of the light emitting unit 4) Subsequently, the driving of the light emitting unit 4 performed by the light emission driving unit 6 based on the control by the control unit 8 will be described. As described above, when the distance in the +z direction from the light emitting unit 4 is different from the reference distance L2, the irradiation range 100A by the light source 4A and the irradiation range 100B by the light source 4B may shift, which may affect the distance measurement of the object. For example, an irradiation surface 210 at a distance L1 in the +z direction from the light emitting unit 4 that is closer than a reference distance L2 includes an irradiation region 211 irradiated with light from the light source 4A and not irradiated with light from the light source 4B, an irradiation region 212 irradiated with light from the light source 4B and not irradiated with light from the light source 4A, and an overlapping region 215 irradiated with the overlapping light from the light source 4A and the light source 4B. When both the light source 4A and the light source 4B are in the lit state, on the irradiation surface 210, the amount of light irradiated from the light emitting unit 4 is non-uniform in the irradiation regions 211 and 212 and the overlapping region 215. More specifically, on the irradiation surface 210, in the overlapping region 215, since light is irradiated from both the light source 4A and the light source 4B, the amount of light irradiated to the overlapping region 215 is larger than the amount of light irradiated to the irradiation regions 211 and 212.

[0034] When an object exists in the overlapping region 215 of the irradiation surface 210 when both the light source 4A and the light source 4B are in the lit state, the amount of light irradiated to the object becomes excessive. In this case, for example, signal saturation may occur in the light receiving element of the light receiving unit 5 that receives the light reflected by the object existing in the overlapping region 215, and it may not be possible to accurately measure the distance to the object.

[0035] In contrast, when the light emitting driving unit 6 of the present embodiment irradiates an object at a distance L1 different from the reference distance L2 with light by the light emitting unit 4, the light emitting unit 4 is driven so that one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state. FIGS. 4(a) to (b) are diagrams showing the irradiation surface 210 when one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state. FIG. 4(a) shows the irradiation surface 210 when the light source 4A is in the lit state and the light source 4B is in the extinguished state, and FIG. 4(b) shows the irradiation surface 210 when the light source 4A is in the extinguished state and the light source 4B is in the lit state.

[0036] As shown in FIGS. 4(a) and 4(b), by setting one of the light sources 4A and 4B in the lit state and the other in the off state, the overlapping region 215 (see FIG. 3) where the light from the light source 4A and the light from the light source 4B are superimposed and irradiated on the irradiation surface 210 is not formed. As a result, on the irradiation surface 210, it is suppressed that the amount of light irradiated becomes non-uniform, and it is suppressed that the amount of light irradiated to the object becomes excessive.

[0037] Also, as shown in FIG. 4(a), when the light source 4A is in the lit state and the light source 4B is in the off state, the shape of the irradiation surface 210 as viewed in the +z direction is a rectangular shape corresponding to the shape of the light emitting surface 41 (see FIG. 3) of the light source 4A. That is, when the light source 4A is in the lit state and the light source 4B is in the off state, the shape of the irradiation surface 210 as viewed in the +z direction is substantially equal to the reference shape. Similarly, as shown in FIG. 4(b), when the light source 4A is in the off state and the light source 4B is in the lit state, the shape of the irradiation surface 210 as viewed in the +z direction is a rectangular shape corresponding to the shape of the light emitting surface 42 (see FIG. 3) of the light source 4B. That is, when the light source 4A is in the off state and the light source 4B is in the lit state, the shape of the irradiation surface 210 as viewed in the +z direction is substantially equal to the reference shape.

[0038] Here, when the light emitting drive unit 6 irradiates light to an object whose distance in the +z direction from the light emitting unit 4 is the reference distance L2, the light emitting unit 4 may be driven so that both the light sources 4A and 4B are in the lit state. As described above, on the irradiation surface 220 where the distance in the +z direction from the light emitting unit 4 is the reference distance L2, when both the light source 4A and the light source 4B are in the lit state, the entire irradiation range 100A by the light source 4A and the entire irradiation range 100B by the light source 4B overlap. That is, on the irradiation surface 220, the entire area is an overlapping region 225 where the light from the light source 4A and the light from the light source 4B are irradiated, and the amount of light irradiated from the light emitting unit 4 is uniform. In this case, the influence due to the non-uniform amount of light irradiated from the light emitting unit 4 in the irradiation regions 211 and 212 and the overlapping region 215, as in the irradiation surface 210, is unlikely to occur. However, when a problem occurs even if the amount of light is not non-uniform, for example, when there is an object with a high reflectance such as a mirror or a white board on the irradiation surface and the light incident on the light receiving unit 5 becomes excessive and a problem occurs, even when irradiating an object existing at the reference distance L2, the light emitting unit 4 may be driven so that one of the light sources 4A and 4B is in the lit state and the other is in the off state.

[0039] When an object is detected at a distance different from the reference distance L2, the light emission driving unit 6 of the present embodiment can drive the light emitting unit 4 so that one of the light sources 4A and 4B is in the lit state and the other is in the off state. The detection of the object is performed by the control unit 8 based on, for example, the light reception result by the light receiving unit 5. As described above, at a distance different from the reference distance L2 (for example, the distance L1), the amount of light irradiated on the irradiation surface 210 becomes non-uniform, so that the amount of light irradiated on the object may become excessive. In this case, the amount of light received by the light receiving unit 5 that receives the light reflected by the object increases. The control unit 8 detects the entry of an object to a distance different from the reference distance L2 when the amount of light received by the light receiving unit 5 exceeds a predetermined threshold value. As the threshold value of the amount of light received used for detecting the object by the control unit 8, for example, it can be set to the amount of light at which signal saturation occurs in the light receiving element of the light receiving unit 5. Further, the control unit 8 may detect the entry of an object to a distance different from the reference distance L2 (for example, the distance L1) by a detection sensor provided separately from the optical device 3.

[0040] Also, the light emission driving unit 6 of the present embodiment preferably does not change the magnitude of the power supplied to the light sources 4A and 4B that are turned on between the case where both the light sources 4A and 4B are turned on to irradiate an object existing on the irradiation surface 220 and the case where one of the light sources 4A and 4B is turned on and the other is turned off to irradiate an object existing on the irradiation surface 210. In other words, the light emission driving unit 6 preferably switches the light sources 4A and 4B between the lit state and the off state while keeping the current values of the light sources 4A and 4B fixed.

[0041] Here, as another method for eliminating the excessive light amount irradiated to the object in the overlapping region 215 of the irradiation surface 210, for example, a method of reducing the current values of both the light sources 4A and 4B while keeping both the light sources 4A and 4B in the lit state can be considered. In this case, by reducing the current value, the light amount emitted from the light sources 4A and 4B decreases, and the light amount irradiated to the object in the overlapping region 215 decreases. However, generally, when the current values of the light sources 4A and 4B are changed, conditions such as the rise time and fall time when light is emitted from the light sources 4A and 4B change. Therefore, in order to accurately perform distance measurement using the light emitted from the light sources 4A and 4B, it is necessary to set correction parameters for correcting the control signal for driving the light sources 4A and 4B for each current value of the light sources 4A and 4B. In this case, the drive control of the light sources 4A and 4B performed by the light emission drive unit 6 based on the control signal from the control unit 8 tends to become complicated.

[0042] On the other hand, the light emission drive unit 6 of the present embodiment suppresses the complication of the drive of the light sources 4A and 4B by the light emission drive unit 6 by switching the light sources 4A and 4B between the lit state and the extinguished state while keeping the current values of the VCSELs constituting the light sources 4A and 4B fixed.

[0043] In the present embodiment, when the control unit 8 sets one of the light sources 4A and 4B to the lit state and the other to the extinguished state, it is preferable to determine which of the light sources 4A and 4B is to be in the lit state and which is to be in the extinguished state based on the lighting history of the light sources 4A and 4B. Thereby, when one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state, compared with the case where the light sources 4A and 4B in the lit state and the extinguished state are fixed, drive control of the light emitting unit 4 according to the lighting situation of the light sources 4A and 4B can be performed. Here, the lighting history means the situation where the light sources 4A and 4B are switched between the lit state and the extinguished state before performing the control of setting one of the light sources 4A and 4B to the lit state and the other to the extinguished state.

[0044] As an example of the lighting history of the light sources 4A and 4B, the control unit 8 can determine which of the light sources 4A and 4B is to be in the lit state and which is to be in the extinguished state based on the total lighting time of the light sources 4A and 4B. More specifically, when one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state, the control unit 8 causes the light emitting unit 4 to be driven by the light emission driving unit 6 such that the one with the shorter total lighting time among the light sources 4A and 4B is in the lit state and the other with the longer total lighting time is in the extinguished state. Thereby, when one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state, the bias in the total lighting time of the light sources 4A and 4B is suppressed as compared with the case where the light sources 4A and 4B to be in the lit state and the extinguished state are fixed.

[0045] Further, as an example of the lighting history of the light sources 4A and 4B, the control unit 8 can determine which of the light sources 4A and 4B is to be in the lit state and which is to be in the extinguished state based on the lighting status of the light sources 4A and 4B immediately before one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state. For example, when one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state, the control unit 8 causes the light emitting unit 4 to be driven by the light emission driving unit 6 such that the one with the shorter immediately preceding lighting time among the light sources 4A and 4B is in the lit state and the other with the longer immediately preceding lighting time is in the extinguished state. Here, in the light sources 4A and 4B, heat may be generated due to the light emission of the VCSEL when in the lit state. And the light sources 4A and 4B may have their temperature rise due to the heat generated by the light emission of the VCSEL as the duration of the lit state continues, which may affect the light emission efficiency. In contrast, by determining which of the light sources 4A and 4B is to be in the lit state and which is to be in the extinguished state based on the lighting status of the light sources 4A and 4B immediately before one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state, the influence on the light emission efficiency due to heat generation is suppressed.

[0046] In addition, in the present embodiment, the case where the light emitting unit 4 has two light sources 4A and 4B has been described as an example. However, the number of light sources included in the light emitting unit 4 is not limited to two, and the light emitting unit 4 may have three or more light sources provided so that the irradiation ranges overlap at the reference distance L2. Further, when the light emitting unit 4 has three or more light sources, the light emission driving unit 6 may vary the number of light sources to be in the lit state and the number of light sources to be in the extinguished state according to the distance in the +z direction from the light emitting unit 4 where the object exists. For example, the light emission driving unit 6 may decrease the number of light sources to be in the lit state and increase the number of light sources to be in the extinguished state as the distance in the +z direction from the light emitting unit 4 where the object exists is closer.

[0047] (Other aspects of driving control of the light emitting unit 4) Subsequently, other aspects of driving the light emitting unit 4 by the light emission driving unit 6 based on the control by the control unit 8 will be described. In the above, when irradiating an object at a distance different from the reference distance L2 (for example, distance L1) by the light emitting unit 4, it has been described that the light emission driving unit 6 drives the light emitting unit 4 such that one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state. The light emission driving unit 6 may drive the light emitting unit 4 by switching between the following first mode and second mode regardless of the actual distance from the light emitting unit 4 to the object.

[0048] The first mode is a mode for irradiating an object at a first distance different from the reference distance L2, and is a mode of driving the light emitting unit 4 such that one of the light sources 4A and 4B is in the lit state and the other is in the extinguished state. As the first distance, for example, a distance shorter than the reference distance L2 can be used, and the above-described distance L1 can be exemplified. Further, the second mode is a mode for irradiating an object at a distance farther than the first distance, and is a mode of driving the light emitting unit 4 such that both of the light sources 4A and 4B are in the lit state.

[0049] The light emission driving unit 6 can switch between the first mode and the second mode of the light emitting unit 4 based on, for example, the distance from the light emitting unit 4 to the object detected by the control unit 8 based on the light reception result by the light receiving unit 5. Additionally, when it is predicted that the object will reach the first distance (for example, distance L1) based on the detection result of the object from the light emitting unit 4, the light emission driving unit 6 can drive the light emitting unit 4 in the first mode. In this case, it is possible to suppress the irradiation in a state where the irradiation range 100A of the light source 4A of the light emitting unit 4 and the irradiation range 100B of the light source 4B are displaced with respect to the object that has reached the first distance. Examples of the case where it is predicted that the object will reach the first distance include cases where the distance of the object detected by the control unit 8 based on the light reception result by the light receiving unit 5 approaches the first distance from a distance farther than the first distance as time elapses.

[0050] The switching between the first mode and the second mode of the light emitting unit 4 by the light emission driving unit 6 may be performed by an operation by the user who uses the distance measuring device 1. Also, the mode of switching the light emitting unit 4 between the first mode and the second mode by the light emission driving unit 6 may be applied to Embodiment 2 and Embodiment 3 described later.

[0051] [Embodiment 2] Subsequently, Embodiment 2 of the present invention will be described. The configuration of the light emitting unit 4 and the light receiving unit 5 included in the optical device 3 of Embodiment 2 is different from that of Embodiment 1. In Embodiment 2, the same reference numerals are used for the same configurations as in Embodiment 1, and detailed descriptions thereof are omitted here.

[0052] (Light Emitting Unit 4) FIG. 5 is a diagram showing the light sources 4C and 4D included in the light emitting unit 4 of Embodiment 2 and the irradiation surface 230 irradiated with the light emitted from the light sources 4C and 4D. In FIG. 5, the right direction of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. Note that in FIG. 5, the light emitting unit 4 and the irradiation surface 230 are shown shifted in the vertical direction (±y direction), but actually, the light emitting unit 4 and the irradiation surface 230 are arranged to face each other. In FIG. 5, the light emitting unit 4 is located in the front side direction (-z direction) of the paper surface, and the irradiation surface 230 is located in the back side direction (+z direction) of the paper surface. That is, FIG. 5 shows the light emitting unit 4 emitting light as seen from the side opposite to the side from which the light emitting unit 4 emits light. Also, here, it is assumed that the distance in the +z direction from the light sources 4C and 4D to the irradiation surface 230 is the above-described reference distance L2 (see FIG. 2).

[0053] The light emitting unit 4 of the present embodiment includes a light source 4C that irradiates light to an irradiation range 100C (see FIG. 6 described later) and a light source 4D that irradiates light to an irradiation range 100D (see FIG. 6 described later) different from the irradiation range 100C. The light emitting unit 4 irradiates light by juxtaposing or superimposing the irradiation range 100C by the light source 4C and the irradiation range 100D by the light source 4D. In this example, the light source 4C is an example of a first light source, the light source 4D is an example of a second light source, the irradiation range 100C is an example of a first irradiation range, and the irradiation range 100D is an example of a second irradiation range. In the light emitting unit 4 of the present embodiment, the light source 4C is arranged on the +y direction side with respect to the light source 4D.

[0054] The light sources 4C and 4D of the present embodiment each have a light emitting surface 43 and 44 on which a plurality of VCSELs are arranged. In this example, the light emitting surface 43 of the light source 4C is juxtaposed in parallel on the +y direction side with respect to the light emitting surface 44 of the light source 4D. The light emitting surfaces 43 of the light source 4C and 44 of the light source 4D are each divided into a plurality of light emitting sections including at least one VCSEL. The light emitting surface 43 of the light source 4C is divided, for example, into a total of 12 light emitting sections C1 to C12, 4 in the x direction and 3 in the y direction. In this example, the light emitting sections C1 to C12 are located in order from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the light emitting surface 43. Similarly, the light emitting surface 44 of the light source 4D is divided, for example, into a total of 12 light emitting sections D1 to D12, 4 in the x direction and 3 in the y direction. In this example, the light emitting sections D1 to D12 are located in order from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the light emitting surface 44.

[0055] Each of the light emitting sections C1 to C12 of the light source 4C and each of the light emitting sections D1 to D12 of the light source 4D are independently driven to emit light by the light emission driving unit 6. The light emission driving unit 6 drives each light emitting section of the light sources 4C and 4D in response to a control signal from the control unit 8. Therefore, each of the light emitting sections C1 to C12 of the light source 4C and each of the light emitting sections D1 to D12 of the light source 4D do not necessarily all emit light at the same time, and a state where a part of them emits light and the rest does not emit light can be taken. In the present embodiment, when each of the light emitting sections C1 to C12 of the light source 4C and each of the light emitting sections D1 to D12 of the light source 4D emits light, it is said that the light emitting section is in a lit state. Also, when each of the light emitting sections C1 to C12 of the light source 4C and each of the light emitting sections D1 to D12 of the light source 4D is not emitting light, it is said that the light emitting section is in an extinguished state.

[0056] Figs. 6(a) to (b) are diagrams showing irradiation ranges 100C and 100D which are the ranges irradiated with light by the light sources 4C and 4D. Fig. 6(a) shows the irradiation range 100C by the light source 4C, and Fig. 6(b) shows the irradiation range 100D by the light source 4D. Figs. 6(a) to (b) are views of the irradiation ranges 100C and 100D at a certain distance in the +z direction from the light emitting unit 4 as seen in the +z direction. As shown in Fig. 6(a), the irradiation range 100C includes irradiation sections P1 to P12 irradiated with the light emitted from the light-emitting sections C1 to C12 of the light source 4C. The irradiation sections P1 to P12 are sequentially located from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the irradiation range 100C. And for a certain irradiation section Pi (i = 1 to 12) of the irradiation range 100C, the light emitted from the light-emitting section Ci with the same number i is irradiated. The shapes of the respective irradiation sections P1 to P12 of the irradiation range 100C are rectangular corresponding to the shapes of the respective light-emitting sections C1 to C12 of the light-emitting surface 43. Also, the shape of the entire irradiation range 100C is rectangular corresponding to the shape of the light-emitting surface 43.

[0057] As shown in Fig. 6(b), the irradiation range 100D includes irradiation sections Q1 to Q12 irradiated with the light emitted from the light-emitting sections D1 to D12 of the light source 4D. The irradiation sections Q1 to Q12 are sequentially located from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the irradiation range 100D. And for a certain irradiation section Qi (i = 1 to 12) of the irradiation range 100D, the light emitted from the light-emitting section Di with the same number i is irradiated. The shapes of the respective irradiation sections Q1 to Q12 of the irradiation range 100D are rectangular corresponding to the shapes of the respective light-emitting sections D1 to D12 of the light-emitting surface 44. Also, the shape of the entire irradiation range 100D is rectangular corresponding to the shape of the light-emitting surface 44.

[0058] The light-emitting unit 4 of the present embodiment irradiates light so that the overlap between the irradiation range 100C by the light source 4C and the irradiation range 100D by the light source 4D becomes large on the irradiation surface 230 where the distance in the +z direction from the light-emitting unit 4 is the reference distance L2. In this example, as shown in FIG. 5, the light emitting unit 4 irradiates light such that the entire irradiation range 100C by the light source 4C and the entire irradiation range 100D by the light source 4D overlap on the irradiation surface 230. In this case, on the irradiation surface 230, the irradiation sections P1 to P12 (see FIG. 6(a)) of the irradiation range 100C by the light source 4C and the irradiation sections Q1 to Q12 (see FIG. 6(b)) of the irradiation range 100D by the light source 4D overlap with each other. Additionally, on the irradiation surface 230, the irradiation section Pi of the irradiation range 100C and the irradiation section Qi of the irradiation range 100D with the same number i assigned thereto overlap.

[0059] Also, on the irradiation surface 230 of the present embodiment, the irradiation section Pi of the irradiation range 100C and the irradiation section Qj of the irradiation range 100D with a number j different from the number i do not overlap. For example, on the irradiation surface 230, the irradiation section P1 of the irradiation range 100C and the irradiation section Q1 of the irradiation range 100D overlap. On the other hand, on the irradiation surface 230, the irradiation section P1 of the irradiation range 100C and the irradiation sections Q2, Q5, and Q6 adjacent to the irradiation section Q1 in the irradiation range 100D do not overlap.

[0060] Thereby, in the light emitting unit 4 of the present embodiment, when the light sources 4C and 4D are simultaneously lit by the light emission driving unit 6, the light emitting sections C1 to C12 of the light source 4C and the light emitting sections D1 to D12 of the light source 4D are independently driven, so that the irradiation surface 230 can be divided into a plurality of sections and light can be irradiated. In the following description, on the irradiation surface 230, a plurality of sections that can be divided by the light sources 4C and 4D to irradiate light are denoted as sections R1 to R12 of the irradiation surface 230. On the irradiation surface 230, when the light emitting section Ci of the light source 4C and the light emitting section Di of the light source 4D are in a lit state, for the section Ri with the same number i, the light from the light emitting section Ci and the light from the light emitting section Di are overlapped and irradiated. That is, in the section Ri of the irradiation surface 230, the irradiation section Pi of the irradiation range 100C by the light source 4C and the irradiation section Qi of the irradiation range 100D by the light source 4D overlap.

[0061] Regarding the relationship between the irradiation sections P1 to P12 of the irradiation range 100C by the light source 4C and the irradiation sections Q1 to Q12 of the irradiation range 100D by the light source 4D on the irradiation surface (the irradiation surface 240 described later) where the distance in the +z direction from the light emitting section 4 is different from the reference distance L2, it will be described later.

[0062] (Light receiving section 5) FIG. 7 is a diagram for explaining an example of the configuration of the light receiving section 5 to which the second embodiment is applied, and is a diagram showing the light receiving surface 50 of the light receiving section 5 and the above-described irradiation surface 230. In FIG. 7, the right direction on the paper surface is the +x direction, the upper direction on the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. In FIG. 7, the light receiving section 5 and the irradiation surface 230 are shown shifted in the vertical direction (±y direction), but actually, the light receiving section 5 and the irradiation surface 230 are arranged to face each other. In FIG. 7, the light receiving section 5 is located in the front side direction (-z direction) of the paper surface, and the irradiation surface 230 is located in the back side direction (+z direction) of the paper surface.

[0063] The light receiving section 5 includes a light receiving surface 50 that extends in the x direction and the y direction and in which a plurality of light receiving elements are arranged. The light receiving surface 50 is divided into a plurality of light receiving sections A1 to A12 corresponding to the sections R1 to R12 of the irradiation surface 230. Specifically, the light receiving surface 50 is divided into a total of 12 light receiving sections A1 to A12, 4 in the x direction and 3 in the y direction. In this example, the light receiving sections A1 to A12 are located in order from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the light receiving surface 50. Each of the light receiving sections A1 to A12 receives light emitted from the light emitting sections C1 to C12 of the light source 4C and the light emitting sections D1 to D12 of the light source 4D and reflected by an object existing in the section Ri with the same number. Each of the light receiving sections A1 to A12 is independently driven by a light receiving driving section 7 (see FIG. 1) to perform a light receiving operation.

[0064] (Drive control of the light emitting section 4) Subsequently, the driving of the light emitting section 4 performed by the light emitting driving section 6 based on the control by the control section 8 will be described. The light emission driving unit 6 of the present embodiment drives the light sources 4C and 4D so that, for example, on the irradiation surface 230, light is irradiated to adjacent ones of the sections R1 to R12 at different timings. In other words, the light emission driving unit 6 drives the light sources 4C and 4D so that the light emitting sections C1 to C12 of the light source 4C and the light emitting sections D1 to D12 of the light source 4D that emit light toward adjacent ones of the sections R1 to R12 on the irradiation surface 230 emit light at different timings.

[0065] Figs. 8(a) to 8(b) are diagrams showing an example of the state of the irradiation surface 230 when the light sources 4C and 4D are driven so that light is irradiated to adjacent ones of the sections R1 to R12 at different timings. In Figs. 8(a) to 8(b), the right direction of the paper surface is taken as the +x direction, the upward direction of the paper surface is taken as the +y direction, and the back side of the paper surface is taken as the +z direction, with the opposite directions being the -x, -y, and -z directions, respectively. Also, in Figs. 8(a) to 8(b), among the sections R1 to R12 of the irradiation surface 230, the sections R1 to R12 irradiated with light by the light sources 4C and 4D are indicated by hatching.

[0066] The light emission driving unit 6 drives the light sources 4C and 4D so that, for example, on the irradiation surface 230, light is irradiated to a set consisting of the sections R1, R3, R6, R8, R9, and R11 arranged in a staggered pattern and a set consisting of the sections R2, R4, R5, R7, R10, and R12 at different timings.

[0067] Specifically, the light emission driving unit 6 sets the light emitting sections C1, C3, C6, C8, C9, and C11 of the light source 4C to the lit state and the light emitting sections D1, D3, D6, D8, D9, and D11 of the light source 4D to the lit state at a predetermined first timing, and sets the light emitting sections C2, C4, C5, C7, C10, and C12 of the light source 4C to the extinguished state and the light emitting sections D2, D4, D5, D7, D10, and D12 of the light source 4D to the extinguished state. As a result, at the first timing, as shown in FIG. 8(a), for each of the sections R1, R3, R6, R8, R9, R11 of the irradiation surface 230, the light emitted from the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D is irradiated.

[0068] In a certain section Ri of the irradiation surface 230, as described above, the irradiation section Pi of the irradiation range 100C and the irradiation section Qi of the irradiation range 100D with the same number i are superimposed. On the other hand, in the section Gi, the irradiation section Pi of the irradiation range 100C and the irradiation section Qj of the irradiation range 100D with a number j different from the number i do not overlap, and the irradiation section Qi of the irradiation range 100D and the irradiation section Pk of the irradiation range 100C with a number k different from the number i do not overlap. Therefore, at the first timing, for the sections R2, R4, R5, R7, R10, R12 of the irradiation surface 230, the light emitted from the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D is not irradiated.

[0069] Further, the light emission driving unit 6 turns on the light-emitting sections C2, C4, C5, C7, C10, C12 of the light source 4C and turns on the light-emitting sections D2, D4, D5, D7, D10, D12 of the light source 4D at a second timing different from the first timing, and turns off the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and turns off the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D. As a result, at the second timing, as shown in FIG. 8(b), for each of the sections R2, R4, R5, R7, R10, R12 of the irradiation surface 230, the light emitted from the light-emitting sections C2, C4, C5, C7, C10, C12 of the light source 4C and the light-emitting sections D2, D4, D5, D7, D10, D12 of the light source 4D is irradiated.

[0070] Also, at the second timing, with respect to the sections R1, R3, R6, R8, R9, and R11 of the irradiation surface 230, the light emitted from the light-emitting sections C2, C4, C5, C7, C10, and C12 of the light source 4C and the light-emitting sections D2, D4, D5, D7, D10, and D12 of the light source 4D is not irradiated. Note that the second timing can be, for example, a timing following the first timing.

[0071] Thus, according to the light-emitting unit 4 of the present embodiment, on the irradiation surface 230 where the distance in the +z direction from the light-emitting unit 4 is the reference distance L2, the set consisting of the sections R1, R3, R6, R8, R9, and R11 and the set consisting of the sections R2, R4, R5, R7, R10, and R12 adjacent thereto can be irradiated with light at different timings. Then, the light-receiving unit 5 obtains the light reflected by the irradiation surface 230 at different timings for the set consisting of the light-receiving sections A1, A3, A6, A8, A9, and A11 and the set consisting of the light-receiving sections A2, A4, A5, A7, A10, and A12, thereby obtaining the light-receiving results for each of the sections R1 to R12 of the irradiation surface 230. Thereby, in the distance measuring device 1 of the present embodiment, compared with the case where the light-emitting sections C1 to C12 of the light source 4C and the light-emitting sections D1 to D12 of the light source 4D are simultaneously turned on to irradiate the sections R1 to R12 of the irradiation surface 230 with light at the same time, the distance measurement of the object existing on the irradiation surface 230 can be performed more accurately.

[0072] Here, in the second embodiment, as in the first embodiment, when the distance in the +z direction from the light-emitting unit 4 is different from the reference distance L2, the irradiation range 100C by the light source 4C and the irradiation range 100D by the light source 4D may be displaced, which may affect the distance measurement of the object. Figs. 9(a) and 9(b) are diagrams for explaining the irradiation ranges 100C of the light source 4C and the irradiation range 100D of the light source 4D on the irradiation surface 240 where the distance in the +z direction from the light emitting part 4 is the distance L1 (see Fig. 2) closer than the reference distance L2. In Figs. 9(a) and 9(b), the right direction of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the back side of the paper surface is the +z direction, with the opposite directions being the -x, -y, and -z directions, respectively. Also, in Figs. 9(a) and 9(b), the irradiation range 100C of the light source 4C is shown by a solid line, and the irradiation range 100D of the light source 4D is shown by a dashed line.

[0073] Fig. 9(a) shows the relationship between the irradiation sections P1, P3, P6, P8, P9, P11 of the irradiation range 100C and the irradiation sections Q1, Q3, Q6, Q8, Q9, Q11 of the irradiation range 100D on the irradiation surface 240. Incidentally, in Fig. 9(a), when the light emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D are in the lit state, the portions on the irradiation surface 240 where light is irradiated are shown by hatching. Fig. 9(b) shows the relationship between the irradiation sections P2, P4, P5, P7, P10, P12 of the irradiation range 100C and the irradiation sections Q2, Q4, Q5, Q7, Q10, Q12 of the irradiation range 100D on the irradiation surface 240. Incidentally, in Fig. 9(b), when the light emitting sections C2, C4, C5, C7, C10, C12 of the light source 4C and the light emitting sections D2, D4, D5, D7, D10, D12 of the light source 4D are in the lit state, the portions on the irradiation surface 240 where light is irradiated are shown by hatching.

[0074] As shown in Figs. 9(a) and 9(b), the light emitting part 4 of the present embodiment irradiates light on the irradiation surface 240 such that the irradiation range 100C of the light source 4C is shifted in the +y direction and arranged with respect to the irradiation range 100D of the light source 4D. In this case, on the irradiation surface 240, the irradiation section Pi of the irradiation range 100C and the irradiation section Qi of the irradiation range 100D given the same number i are shifted in the +y direction and arranged.

[0075] For example, as shown in FIG. 9(a), when the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D with the same numbers are simultaneously turned on, on the irradiation surface 240, the irradiation sections P1, P3, P6, P8, P9, P11 and the irradiation sections Q1, Q3, Q6, Q8, Q9, Q11 are arranged shifted in the y direction. In this case, on the irradiation surface 240, the irradiation sections P1, P3, P6, P8, P9, P11 and the irradiation sections Q1, Q3, Q6, Q8, Q9, Q11 overlap in a partial region in the y direction and do not overlap in a partial region in the y direction.

[0076] Also, as shown in FIG. 9(b), when the light-emitting sections C2, C4, C5, C7, C10, C12 of the light source 4C and the light-emitting sections D2, D4, D5, D7, D10, D12 of the light source 4D with the same numbers are simultaneously turned on, on the irradiation surface 240, the irradiation sections P2, P4, P5, P7, P10, P12 and the irradiation sections Q2, Q4, Q5, Q7, Q10, Q12 are arranged shifted in the y direction. In this case, on the irradiation surface 240, the irradiation sections P2, P4, P5, P7, P10, P12 and the irradiation sections Q2, Q4, Q5, Q7, Q10, Q12 overlap in a partial region in the y direction and do not overlap in a partial region in the y direction.

[0077] FIGS. 10(a) to (b) are diagrams for explaining the overlap between the irradiation range 100C by the light source 4C and the irradiation range 100D by the light source 4D on the irradiation surface 240. In FIGS. 10(a) to (b), the right direction of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, -z directions, respectively. Also, in FIGS. 10(a) to (b), the irradiation range 100C of the light source 4C is shown by a solid line, and the irradiation range 100D of the light source 4D is shown by a dashed line. Also, FIG. 10 shows the irradiation sections P1, P5 of the irradiation range 100C and the irradiation sections Q1, Q5 of the irradiation range 100D among the irradiation range 100C and the irradiation range 100D on the irradiation surface 240.

[0078] In Fig. 10(a), the light-emitting section C1 of the light source 4C and the light-emitting section D1 of the light source 4D are in the lit state, while the light-emitting section C5 of the light source 4C and the light-emitting section D5 of the light source 4D are in the off state. Also, in Fig. 10(b), the light-emitting section C5 of the light source 4C and the light-emitting section D5 of the light source 4D are in the lit state, while the light-emitting section C1 of the light source 4C and the light-emitting section D1 of the light source 4D are in the off state. Then, in Figs. 10(a) to 10(b), the irradiation sections P1 and P5 irradiated with light by the light-emitting sections C1 and C5 of the lit light source 4C, and the irradiation sections Q1 and Q5 irradiated with light by the light-emitting sections D1 and D5 of the lit light source 4D are indicated by hatching.

[0079] As shown in Figs. 10(a) to 10(b), the light-emitting unit 4 of the present embodiment irradiates light on the irradiation surface 240 such that the irradiation section P1 is shifted in the +y direction with respect to the irradiation section Q1. As a result, on the irradiation surface 240, a partial region on the -y direction side in the irradiation section P1 and a partial region on the +y direction side in the irradiation section Q1 overlap. Similarly, the light-emitting unit 4 irradiates light on the irradiation surface 240 such that the irradiation section P5 is shifted in the +y direction with respect to the irradiation section Q5. As a result, on the irradiation surface 240, a partial region on the -y direction side in the irradiation section P5 and a partial region on the +y direction side in the irradiation section Q5 overlap.

[0080] Also, on the irradiation surface 240, since the irradiation section Q1 is shifted in the -y direction with respect to the irradiation section P1, a partial region on the -y direction side in the irradiation section Q1 and a partial region on the +y direction side of the irradiation section P5 adjacent to the -y direction side of the irradiation section P1 overlap. Furthermore, on the irradiation surface 240, since the irradiation section P5 is shifted in the +y direction with respect to the irradiation section Q5, a partial region on the +y direction side in the irradiation section P5 and a partial region on the -y direction side of the irradiation section Q1 adjacent to the +y direction side of the irradiation section Q5 overlap.

[0081] Here, in the light-emitting unit 4 of Embodiment 2, consider the case where at a predetermined third timing, the light-emitting section C1 of the light source 4C and the light-emitting section D1 of the light source 4D are simultaneously turned on, and the light-emitting section C5 of the light source 4C and the light-emitting section D5 of the light source 4D are turned off. In this case, as shown in FIG. 10(a), on the irradiation surface 240, since the irradiation section Q1 and the irradiation section P1 overlap, light from the light-emitting section D1 of the light source 4D irradiates the irradiation section P5 where light is not irradiated by the light-emitting sections C1 and C5 of the light source 4C. In this example, the light-emitting section C5 of the light source 4C is an example of a first light-emitting section that irradiates the irradiation section P5 which is a first irradiation section, and the light-emitting section C1 of the light source 4C is an example of a third light-emitting section that irradiates the irradiation section P1 which is a third irradiation section adjacent to the irradiation section P5. Also, the light-emitting section D5 of the light source 4D is an example of a second light-emitting section that irradiates the irradiation section Q5 which is a second irradiation section, and the light-emitting section D1 of the light source 4D is an example of a fourth light-emitting section that irradiates the irradiation section Q1 which is a fourth irradiation section adjacent to the irradiation section Q5.

[0082] Next, in the light-emitting unit 4 of Embodiment 2, consider the case where at a fourth timing different from the third timing, the light-emitting section C5 of the light source 4C and the light-emitting section D5 of the light source 4D are simultaneously turned on, and the light-emitting section C1 of the light source 4C and the light-emitting section D1 of the light source 4D are turned off. In this case, as shown in FIG. 10(b), on the irradiation surface 240, light from the light-emitting section C5 of the light source 4C irradiates the irradiation section Q1 where light is not irradiated by the light-emitting sections D1 and D5 of the light source 4D.

[0083] Thus, in the light-emitting unit 4 of Embodiment 2, when the light-emitting section Ci of the light source 4C that irradiates the irradiation section Pi and the light-emitting section Di of the light source 4D that irradiates the irradiation section Qi with the same number are simultaneously turned on, even when the light-emitting section Cj of the light source 4C that irradiates the irradiation section Pj adjacent to the irradiation section Pi in the -y direction is turned off, the irradiation section Pj is irradiated with light. In this case, on the irradiation surface 240, unlike the irradiation surface 230 at the reference distance L2 described above, it becomes difficult to irradiate the irradiation sections Pi, Qi and the adjacent irradiation sections Pj, Qj with light at different timings.

[0084] Therefore, the light emission driving unit 6 of the present embodiment drives the light emitting unit 4 so that, at a distance L1 different from the reference distance L2, one of the light emitting sections Ci of the light source 4C that irradiates the irradiation section Pi and the light emitting section Di of the light source 4D that irradiates the irradiation section Qi with the same number is in the lighting state and the other is in the extinguished state at a predetermined third timing. At the third timing, the light emission driving unit 6 drives the light emitting unit 4 so that the light emitting section Cj of the light source 4C that irradiates the irradiation section Pj adjacent to the irradiation section Pi and the light emitting section Dj of the light source 4D that irradiates the irradiation section Qj adjacent to the irradiation section Qj are in the extinguished state.

[0085] Also, at a fourth timing different from the third timing, the light emitting unit 4 is driven so that one of the light emitting section Cj of the light source 4C that irradiates the irradiation section Pj adjacent to the irradiation section Pi and the light emitting section Dj of the light source 4D that irradiates the irradiation section Qj adjacent to the irradiation section Qi is in the lighting state and the other is in the extinguished state. At the fourth timing, the light emission driving unit 6 drives the light emitting unit 4 so that the light emitting section Ci of the light source 4C that irradiates the irradiation section Pi and the light emitting section Di of the light source 4D that irradiates the irradiation section Qi are in the extinguished state.

[0086] FIG. 11 is a diagram for explaining an example of the drive control of the light emitting unit 4 by the light emission driving unit 6 at the above-described third timing. In FIG. 11, the portions of the irradiation surface 240 irradiated with light by the light emitting unit 4 are indicated by hatching. In FIG. 11, the light emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C are in the lighting state, and the light emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D are in the extinguished state, while the light emitting sections C2, C4, C5, C7, C10, C12 of the light source 4C and the light emitting sections D2, D4, D5, D7, D10, D12 of the light source 4D are in the extinguished state.

[0087] As shown in FIG. 11, the light emission driving unit 6 drives the light emitting unit 4 so that, at a distance L1 different from the reference distance L2, one of the light emitting sections Ci of the light source 4C and the light emitting section Di of the light source 4D with the same number is in the lighting state and the other is in the extinguished state, thereby making it possible to irradiate the irradiation sections Pi, Qi and the irradiation sections Pj, Qj adjacent thereto with light at different timings. Thereby, when the light emission driving unit 6 sets the light emitting section Ci of the light source 4C and the light emitting section Di of the light source 4D with the same number to the lighting state at the same time at a distance L1 different from the reference distance L2, the distance measurement of the object existing on the irradiation surface 240 can be performed more accurately.

[0088] Here, in the present embodiment, similar to the first embodiment, it is possible to determine which of the light emitting section Ci of the light source 4C and the light emitting section Di of the light source 4D is in the lighting state and which is in the extinguished state based on the lighting history of the light sources 4C and 4D. For example, in the above-described example, the sum of the total lighting times of the light emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the sum of the total lighting times of the light emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D are compared, and the light emitting unit 4 may be driven by the light emission driving unit 6 so that the one with the shorter sum of the total lighting times is in the lighting state and the other with the longer sum of the total lighting times is in the extinguished state. Thereby, when one of the light emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D is in the lighting state and the other is in the extinguished state, the bias of the total lighting times of the light sources 4C and 4D is suppressed as compared with the case where the light emitting sections to be in the lighting state and the extinguished state are fixed. Note that it is not necessary to strictly compare the total lighting time itself with the sum of the times during which the light emitting sections of each light source have been lit in the lighting history of each light source. For example, among the times during which the light emitting sections of each light source have been lit, the total lighting time may be compared after omitting the times during which the light emitting sections have been lit at an output that has little influence on the life of the light source. Further, when the light emitting sections of each light source emit light in pulses at the same time intervals, the total number of lighting times of the light emitting sections of each light source may be compared as the lighting history of the light source.

[0089] [Embodiment 3] Next, Embodiment 3 of the present invention will be described. The configurations of the light emitting unit 4 and the light receiving unit 5 of the optical device 3 in Embodiment 3 are different from those in Embodiments 1 and 2. In Embodiment 3, the same reference numerals are used for the same configurations as in Embodiments 1 and 2, and detailed descriptions thereof are omitted here.

[0090] (Light emitting unit 4) Figs. 12(a) to (c) are diagrams for explaining the configurations of the light sources 4E, 4F, and 4G of the light emitting unit 4 in Embodiment 3. In Figs. 12(a) to (c), the right direction on the paper surface is the +x direction, the upward direction on the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. Figs. 12(a) to (c) show the light sources 4E, 4F, and 4G of the light emitting unit 4 emitting light as viewed from the side opposite to the side where the light emitting unit 4 emits light.

[0091] Fig. 13 is a diagram showing the light sources 4E, 4F, and 4G of the light emitting unit 4 in Embodiment 3 and the irradiation surface 250 irradiated with the light emitted from the light sources 4E, 4F, and 4G. In Fig. 13, the right direction on the paper surface is the +x direction, the upward direction on the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. In Fig. 13, the light emitting unit 4 and the irradiation surface 250 are shown shifted in the vertical direction (±y direction), but actually, the light emitting unit 4 and the irradiation surface 250 are arranged to face each other. In Fig. 13, the light emitting unit 4 is located in the front side direction (-z direction) of the paper surface, and the irradiation surface 250 is located in the back side direction (+z direction) of the paper surface. That is, Fig. 13 shows the light emitting unit 4 emitting light as viewed from the side opposite to the side where the light emitting unit 4 emits light. Here, it is assumed that the distance in the +z direction from the light sources 4E, 4F, and 4G of the light emitting unit 4 to the irradiation surface 250 is the above-mentioned reference distance L2 (see Fig. 2).

[0092] The light emitting unit 4 of the present embodiment includes a light source 4E that irradiates light onto the irradiation range 100E, a light source 4F that irradiates light onto an irradiation range 100F different from the irradiation range 100E, and a light source 4G that irradiates light onto an irradiation range 100G different from the irradiation ranges 100E and 100F. The light emitting unit 4 irradiates light by arranging or overlapping the irradiation range 100E by the light source 4E, the irradiation range 100F by the light source 4F, and the irradiation range 100G by the light source 4G in parallel. In the light emitting unit 4 of the present embodiment, the light sources 4E, 4F, and 4G are arranged in this order in the -y direction.

[0093] The light sources 4E, 4F, and 4G of the present embodiment each have light emitting surfaces 45, 46, and 47 in which a plurality of VCSELs are arranged. In this example, the light emitting surface 45 of the light source 4E, the light emitting surface 46 of the light source 4F, and the light emitting surface 47 of the light source 4G are arranged in parallel in this order in the -y direction. The light emitting surface 45 of the light source 4E is divided into a total of 24 light emitting sections Emn (m is a natural number from 1 to 6, n is a natural number from 1 to 4) in the x direction and 4 in the y direction as an example. m represents the position of the light emitting section Emn in the x direction on the light emitting surface 45, and n represents the position of the light emitting section Emn in the -y direction on the light emitting surface 45. For example, the light emitting section E11 is arranged at the first position in the x direction and the first position in the -y direction from the upper left (-x direction side and +y direction side end) of the light emitting surface 45 on the light emitting surface 45. The same applies to the light emitting sections Fmn of the light source 4F and the light emitting sections Gmn of the light source 4G described below.

[0094] The light emitting surface 46 of the light source 4F is divided into a total of 24 light emitting sections Fmn (m is a natural number from 1 to 6, n is a natural number from 1 to 4) in the x direction and 4 in the y direction as an example. The light emitting surface 47 of the light source 4G is divided into a total of 24 light emitting sections Gmn (m is a natural number from 1 to 6, n is a natural number from 1 to 4) in the x direction and 4 in the y direction as an example.

[0095] Each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G are independently driven by the light-emitting driving unit 6 to emit light. The light-emitting driving unit 6 drives each light-emitting section of the light sources 4E, 4F, and 4G in response to a control signal from the control unit 8. Therefore, each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G do not necessarily all emit light at the same time, and a part of them may emit light while the rest do not. In this embodiment, the state where each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G emits light is referred to as the lighting state of that light-emitting section. Also, the state where each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G does not emit light is referred to as the extinguished state of that light-emitting section.

[0096] The light-emitting driving unit 6 of this embodiment divides each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G into three groups and drives them to emit light at different timings for each group. In this example, each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G are divided into a first group that irradiates light on sections S1n, S4n on the irradiation surface 250, a second group that irradiates light on sections S2n, S5n, and a third group that irradiates light on sections S3n, S6n. The light-emitting driving unit 6 causes each light-emitting section Emn of the light source 4E, each light-emitting section Fmn of the light source 4F, and each light-emitting section Gmn of the light source 4G belonging to each group to emit light, for example, in the order of the first group, the second group, and the third group.

[0097] Specifically, the first group includes the light-emitting sections E11, E12, E13, E14, E41, E42, E43, E44 of the light source 4E, the light-emitting sections F11, F12, F13, F14, F41, F42, F43, F44 of the light source 4F, and the light-emitting sections G11, G12, G13, G14, G41, G42, G43, G44 of the light source 4G. In addition, the second group includes the light-emitting sections E21, E22, E23, E24, E51, E52, E53, E54 of the light source 4E, the light-emitting sections F21, F22, F23, F24, F51, F52, F53, F54 of the light source 4F, and the light-emitting sections G21, G22, G23, G24, G51, G52, G53, G54 of the light source 4G. In addition, the third group includes the light-emitting sections E31, E32, E33, E34, E61, E62, E63, E64 of the light source 4E, the light-emitting sections F31, F32, F33, F34, F61, F62, F63, F64 of the light source 4F, and the light-emitting sections G31, G32, G33, G34, G61, G62, G63, G64 of the light source 4G.

[0098] In addition, the light-emitting unit 4 of the present embodiment irradiates light so that the entire irradiation range 100E by the light source 4E, the entire irradiation range 100F by the light source 4F, and the entire irradiation range 100G by the light source 4G overlap on the irradiation surface 250 where the distance in the +z direction from the light-emitting unit 4 is the reference distance L2. In this case, on the irradiation surface 250, the light from the light-emitting section Emn of the light source 4E with the same numbers m and n, the light from the light-emitting section Fmn of the light source 4F, and the light from the light-emitting section Gmn of the light source 4G are irradiated onto the same range on the irradiation surface 250. Hereinafter, on the irradiation surface 250, the range irradiated with the light from the light-emitting section Emn of the light source 4E, the light from the light-emitting section Fmn of the light source 4F, and the light from the light-emitting section Gmn of the light source 4G is denoted as the section Smn. Incidentally, the irradiation surface 250 is divided into a total of 24 sections Smn, 6 in the x direction and 4 in the y direction.

[0099] Although not shown, the light-emitting unit 4 of the present embodiment irradiates light so that the irradiation range 100E by the light source 4E, the irradiation range 100F by the light source 4F, and the irradiation range 100G by the light source 4G are shifted and arranged in a direction (for example, the y direction) intersecting in the z direction on an irradiation surface at a distance (for example, the distance L1) different from the reference distance L2 from the light-emitting unit 4, in the same manner as in the first and second embodiments. In this case, if the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G, which are given the same number, are simultaneously turned on, it becomes difficult to divide the irradiation surface into a plurality of sections and irradiate adjacent sections with light at different timings, similar to the case of Embodiment 2.

[0100] Therefore, the light-emitting drive unit 6 of the present embodiment does not simultaneously turn on the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G, which are given the same number. Instead, one of the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G, which are given the same number, is turned on, and the remaining two are turned off.

[0101] More specifically, the light-emitting drive unit 6 of the present embodiment turns on one of the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G belonging to the first group and turns off the remaining two at the timing of causing the first group to emit light. Note that the light-emitting drive unit 6 turns off the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G belonging to the second group and the third group at the timing of causing the first group to emit light.

[0102] Further, after causing the first group to emit light, the light-emitting drive unit 6 turns on one of the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G belonging to the second group and turns off the remaining two at the timing of causing the second group to emit light. Note that the light-emitting drive unit 6 turns off the light-emitting sections Emn of the light source 4E, the light-emitting sections Fmn of the light source 4F, and the light-emitting sections Gmn of the light source 4G belonging to the first group and the third group at the timing of causing the second group to emit light.

[0103] Furthermore, after causing the first group and the second group to emit light, the light emission driving unit 6, at the timing of causing the third group to emit light, sets one of the light emission sections Emn of the light source 4E belonging to the third group, the light emission section Fmn of the light source 4F, and the light emission section Gmn of the light source 4G to the lit state, and sets the remaining two to the extinguished state. Note that at the timing of causing the third group to emit light, the light emission driving unit 6 sets the light emission sections Emn of the light source 4E belonging to the first group and the second group, the light emission section Fmn of the light source 4F, and the light emission section Gmn of the light source 4G to the extinguished state.

[0104] Here, in the present embodiment, at the timing of causing each group to emit light, the light emission driving unit 6 drives the light emitting unit 4 so that the light emission sections of the light sources belonging to each group are in the lit state and the extinguished state according to the following criteria. That is, the light emission driving unit 6 drives the light emitting unit 4 so that the light emission sections of the light sources with less influence of the heat generated by the light emission of the previous group on the light emission of the next group are in the lit state, and the light emission sections of the light sources with greater influence are in the extinguished state.

[0105] Specifically, for example, at the timing of causing the first group to emit light, the light emission driving unit 6 controls the light emitting unit 4 so that among the light sources 4E, 4F, and 4G, the light emission sections E11, E12, E13, E14, E41, E42, E43, E44 of the light source 4E are in the lit state, and the light emission sections F11, F12, F13, F14, F41, F42, F43, F44 of the light source 4F and the light emission sections G11, G12, G13, G14, G41, G42, G43, G44 of the light source 4G are in the extinguished state. In this case, in the light source 4E, heat is generated along with the light emission of the light emission sections E11, E12, E13, E14, E41, E42, E43, E44 that are in the lit state.

[0106] Next, at the timing when the light emission driving unit 6 causes the second group to emit light after causing the first group to emit light, among the light sources 4E, 4F, and 4G, the light emission sections F21, F22, F23, F24, F51, F52, F53, F54 of the light source 4F, which are less affected by the heat generated by the light emission of the light emission sections E11, E12, E13, E14, E41, E42, E43, E44 of the light source 4E in the first group, or the light emission sections G21, G22, G23, G24, G51, G52, G53, G54 of the light source 4G are controlled to be in the lighting state so as to control the light emitting unit 4. In this example, at the timing when the light emission driving unit 6 causes the second group to emit light, the light emission sections F21, F22, F23, F24, F51, F52, F53, F54 of the light source 4F are in the lighting state, and the light emission sections E21, E22, E23, E24, E51, E52, E53, E54 of the light source 4E and the light emission sections G21, G22, G23, G24, G51, G52, G53, G54 of the light source 4G are in the extinguished state so as to control the light emitting unit 4. In this case, in the light source 4F, heat is generated due to the light emission of the light emission sections F21, F22, F23, F24, F51, F52, F53, F54 that are in the lighting state.

[0107] Next, at the timing when the light emission driving unit 6 causes the third group to emit light after causing the first group and the second group to emit light, among the light sources 4E, 4F, and 4G, the light emission sections G31, G32, G33, G34, G61, G62, G63, G64 of the light source 4G, which are less affected by the heat generated by the light emission of the light emission sections E11, E12, E13, E14, E41, E42, E43, E44 of the light source 4E in the first group and the light emission sections F21, F22, F23, F24, F51, F52, F53, F54 of the light source 4F in the second group, are controlled to be in the lighting state so as to control the light emitting unit 4. Incidentally, the light emission driving unit 6 controls the light emitting unit 4 such that the light emitting sections G31, G32, G33, G34, G61, G62, G63, G64 of the light source 4G are in the lit state and the light emitting sections E31, E32, E33, E34, E61, E62, E63, E64 of the light source 4E and the light emitting sections F31, F32, F33, F34, F61, F62, F63, F64 of the light source 4F are in the extinguished state at the timing of causing the third group to emit light.

[0108] As described in Embodiment 1 as well, when the light emitting section of the light source is in the lit state, heat may be generated due to the light emission of the VCSEL. Then, due to the heat generated by the light emission of the VCSEL, the temperature of the light emitting section in the lit state and the light emitting section adjacent to the light emitting section in the lit state increases. And when the temperature of the light emitting section increases, when this light emitting section is in the lit state, the light emission efficiency of the VCSEL may be affected. The light emission driving unit 6 of the present embodiment sets the light emitting section of the light source, in which the influence of the heat generated by the light emission of the previous group on the light emission of the next group is small, in the lit state, and sets the light emitting section of the light source, in which the influence is large, in the extinguished state, so that, for example, compared with the case where the light sources in the lit state and the extinguished state are fixed, the influence of the heat generated by the light emission on the light emission efficiency is suppressed.

[0109] In the above-described Embodiment 1 and Embodiment 2, the reference distance is the distance at which substantially the entire irradiation ranges by the two light sources overlap on the irradiation surface. When an object is at a distance closer than the reference distance, one light source is in the lit state and the other light source is in the extinguished state. However, the reference distance is not limited to this, and the distance to be set as the reference distance may be set according to the required accuracy or the like. For example, even when an object is at a distance such that the ratio of the overlapping portion of the irradiation ranges by a plurality of light sources on the irradiation surface is less than 50%, and when the ranging accuracy is not required so much, both light sources may be in the lit state without setting one light source in the lit state and the other light source in the extinguished state. Also, whether to set one light source in the lit state and the other light source in the extinguished state, or to set a plurality of light sources in the lit state simultaneously, may be switched not only according to the required distance but also according to the accuracy.

[0110] Also, when irradiating light by dividing the irradiation surface into a plurality of sections as in Embodiment 2, in the above-described example, the light-emitting section Di of the light source 4D having the same number as the light-emitting section Ci of the light source 4C is not simultaneously turned on, but the present invention is not limited to this. If it is possible to divide and irradiate light to a plurality of sections of the irradiation surface, the light-emitting section Di of the light source 4D having the same number as the light-emitting section Ci of the light source 4C may be simultaneously turned on. For example, as shown in FIG. 9(a), when the light-emitting section D1 of the light source 4D is turned on, although a part of the region of the irradiation section Q1 irradiated with the light from the light-emitting section D1 overlaps with the irradiation section P5, there remains a non-irradiated area in the irradiation section P5 where the light from the light-emitting section D1 is not irradiated. Therefore, even when the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D are simultaneously turned on, it is barely possible to perform divided irradiation between the irradiated areas irradiated with the light from these light-emitting sections and the non-irradiated areas not irradiated with light. In this case, taking the distance at which divided irradiation is barely possible as the reference distance, the light-emitting section Di of the light source 4D having the same number as the light-emitting section Ci of the light source 4C may be simultaneously turned on. On the other hand, compared with the example shown in FIG. 9(a), in a region where the irradiation section Pi and the irradiation section Qi with the same number i do not overlap and the area is large, and when the light-emitting sections C1, C3, C6, C8, C9, C11 of the light source 4C and the light-emitting sections D1, D3, D6, D8, D9, D11 of the light source 4D are simultaneously turned on, divided irradiation cannot be performed at a distance where the entire irradiation surface 240 is irradiated with light. In this case, either the light-emitting section Ci of the light source 4C or the light-emitting section Di of the light source 4D with the same number may be turned off.

[0111] [Embodiment 4] Next, Embodiment 4 of the present invention will be described. The distance measuring device 1 according to Embodiment 4 is different from those of Embodiments 1 to 3 in the configurations of the light-emitting unit 4 and the light-receiving unit 5 included in the optical device 3. In Embodiment 4, the same reference numerals are used for the same configurations as those in Embodiments 1 to 3, and detailed descriptions thereof are omitted here.

[0112] (Light-emitting unit 4) FIG. 14 is a diagram showing the light sources 4H and 4I included in the light-emitting unit 4 of Embodiment 4 and the irradiation ranges 100H and 100I where the light emitted from the light sources 4H and 4I is irradiated. In FIG. 14, the front side of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the right direction of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively.

[0113] The light-emitting unit 4 includes a light source 4H that irradiates light to the irradiation range 100H and a light source 4I that irradiates light to an irradiation range 100I different from the irradiation range 100H. The light-emitting unit 4 irradiates light so that the irradiation range 100H and the irradiation range 100I are parallel at a certain distance (a reference distance L4 described later) in the direction (+z direction) in which the light sources 4H and 4I emit light. In this example, the light source 4H is an example of a first light source, the light source 4I is an example of a second light source, the irradiation range 100H is an example of a first irradiation range, and the irradiation range 100I is an example of a second irradiation range. In the light-emitting unit 4 of the present embodiment, the light sources 4H and 4I are arranged in parallel in the y direction. In this example, the light source 4H is arranged on the +y direction side with respect to the light source 4I.

[0114] FIG. 15 is a diagram for explaining the configurations of the light sources 4H and 4I included in the light-emitting unit 4 of Embodiment 4. In FIG. 15, the right direction of the paper surface is the +x direction, the upward direction of the paper surface is the +y direction, and the back side of the paper surface is the +z direction, and the opposite directions are the -x, -y, and -z directions, respectively. FIG. 15 shows the light sources 4H and 4I of the light-emitting unit 4 that are emitting light as viewed from the side opposite to the side where the light-emitting unit 4 is emitting light.

[0115] The light sources 4H and 4I of the present embodiment each have light-emitting surfaces 48 and 49 in which a plurality of VCSELs are arranged. In this example, the light-emitting surface 48 of the light source 4H is parallel to the light-emitting surface 49 of the light source 4I on the +y direction side. The light emitting surfaces 48 of the light source 4H and 49 of the light source 4I are each divided into a plurality of light emitting sections including at least one VCSEL. The light emitting surface 48 of the light source 4H is divided into a total of six light emitting sections H1 to H6, three in the x direction and two in the y direction, for example. In this example, the light emitting sections H1 to H6 are located in order from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the light emitting surface 48. Similarly, the light emitting surface 49 of the light source 4I is divided into a total of six light emitting sections I1 to I6, three in the x direction and two in the y direction, for example. In this example, the light emitting sections I1 to I6 are located in order from the upper left (-x direction side and +y direction side end) to the lower right (+x direction side and -y direction side end) of the light emitting surface 49. Incidentally, in the light emitting unit 4 of the present embodiment, the light emitting sections H4, H5, and H6 on the light emitting surface 48 of the light source 4H are adjacent in the y direction to the light emitting sections I1, I2, and I3 on the light emitting surface 49 of the light source 4I.

[0116] Each of the light emitting sections H1 to H6 of the light source 4H and each of the light emitting sections I1 to I6 of the light source 4I are independently driven to emit light by the light emission driving unit 6 (see FIG. 1). The light emission driving unit 6 drives each of the light emitting sections of the light sources 4H and 4I in response to a control signal from the control unit 8 (see FIG. 1). Therefore, each of the light emitting sections H1 to H6 of the light source 4H and each of the light emitting sections I1 to I6 of the light source 4I do not necessarily all emit light at the same time, and a state where some of them emit light and the rest do not emit light can be taken. In the present embodiment, a state where each of the light emitting sections H1 to H6 of the light source 4H and each of the light emitting sections I1 to I6 of the light source 4I emit light is referred to as a lighting state of the light emitting section. Also, a state where each of the light emitting sections H1 to H6 of the light source 4H and each of the light emitting sections I1 to I6 of the light source 4I do not emit light is referred to as a non-lighting state of the light emitting section.

[0117] In Fig. 14, at a certain distance in the direction in which the light sources 4H and 4I emit light (+z direction), there are shown irradiation surfaces 260 and 270 that are orthogonal to the +z direction and on which the light of the irradiation ranges 100H and 100I is irradiated. The irradiation surfaces 260 and 270 extend in the x direction and the y direction at a certain distance in the +z direction. Also, the irradiation surfaces 260 and 270 are arranged in order from the light sources 4H and 4I in the +z direction. Hereinafter, the distance in the +z direction from the light sources 4H and 4I to the irradiation surface 260 is denoted as distance L3, and the distance in the +z direction from the light sources 4H and 4I to the irradiation surface 270 is denoted as distance L4. The light rays emitted from the light sources 4H and 4I are refracted by an optical system (not shown) that the light sources 4H and 4I have and are spread and irradiated on a plane perpendicular to the emission direction.

[0118] When viewed from the +x direction side, the light emitting unit 4 of the present embodiment irradiates light so that the irradiation ranges 100H and 100I intersect at a certain distance L5 in the +z direction. In this case, as shown in Fig. 14, in the region where the distance in the +z direction from the light sources 4H and 4I is less than the distance L5, the irradiation range 100H is located on the +y direction side compared to the irradiation range 100I. Also, in the region where the distance in the +z direction from the light sources 4H and 4I exceeds the distance L5, the irradiation range 100H is located on the -y direction side compared to the irradiation range 100I. In the distance measuring device 1 of the present embodiment, the object existing in the range where the distance in the +z direction from the light emitting unit 4 exceeds the distance L5 is irradiated with the light from the light sources 4H and 4I.

[0119] Figs. 16(a) to (b) are diagrams for explaining the irradiation surfaces 260 and 270. Fig. 16(a) shows the irradiation surface 270 where the distance in the +z direction from the light emitting unit 4 is the distance L4. Also, Fig. 16(b) shows the irradiation surface 260 where the distance in the +z direction from the light emitting unit 4 is the distance L3 that is closer than the distance L4. In Figs. 16(a) to (b), the right direction of the paper surface is taken as the +x direction, the upward direction of the paper surface is taken as the +y direction, and the back side of the paper surface is taken as the +z direction, and the opposite directions are taken as the -x, -y, and -z directions, respectively.

[0120] As shown in FIGS. 16(a) to (b), on the irradiation surfaces 260 and 270, the irradiation range 100H includes irradiation sections T1 to T6 irradiated with light emitted from the light-emitting sections H1 to H6 of the light source 4H. The irradiation sections T1 to T6 are sequentially located from the lower right (+x direction side and -y direction side end) to the upper left (-x direction side and +y direction side end) of the irradiation range 100H. In the present embodiment, the arrangement of the irradiation sections T1 to T6 in the irradiation range 100H is inverted in the x direction and the y direction with respect to the arrangement of the light-emitting sections H1 to H6 on the light-emitting surface 48 of the light source 4H. Similarly, on the irradiation surfaces 260 and 270, the irradiation range 100I includes irradiation sections U1 to U6 irradiated with light emitted from the light-emitting sections I1 to I6 of the light source 4I. The irradiation sections U1 to U6 are sequentially located from the lower right (+x direction side and -y direction side end) to the upper left (-x direction side and +y direction side end) of the irradiation range 100I. In the present embodiment, the arrangement of the irradiation sections U1 to U6 in the irradiation range 100I is inverted in the x direction and the y direction with respect to the arrangement of the light-emitting sections I1 to I6 on the light-emitting surface 49 of the light source 4I.

[0121] As shown in FIG. 16(a), on the irradiation surface 270 where the distance in the +z direction from the light-emitting unit 4 is the distance L4, the irradiation range 100H by the light source 4H and the irradiation range 100I by the light source 4I are parallel in the y direction. Additionally, on the irradiation surface 270, the irradiation range 100H and the irradiation range 100I do not overlap. In the present embodiment, the distance L4, which is the distance at which the irradiation range 100H and the irradiation range 100I are parallel on the irradiation surface 270, is an example of a reference distance. Hereinafter, it may be denoted as the reference distance L4.

[0122] Further, as shown in FIG. 16(b), on the irradiation surface 260 where the distance in the +z direction from the light emitting unit 4 is the distance L3 which is closer than the reference distance L4, a partial region of the irradiation range 100H by the light source 4H and a partial region of the irradiation range 100I by the light source 4I overlap. In other words, in the present embodiment, when the distance in the +z direction from the light emitting unit 4 is closer than the reference distance L4, a deviation occurs with respect to the positional relationship between the irradiation ranges 100H and 100I that are parallel at the reference distance L4, and a partial region of the irradiation range 100H and a partial region of the irradiation range 100I overlap. On the irradiation surface 260, the irradiation sections T4 to T6 of the irradiation range 100H and the irradiation sections U1 to U3 of the irradiation range 100I that are adjacent in the +y direction to the irradiation sections T4 to T6 overlap with each other. More specifically, on the irradiation surface 260, a partial region on the +y direction side in the irradiation sections T4 to T6 of the irradiation range 100H and a partial region on the -y direction side in the irradiation sections U1 to U3 of the irradiation range 100I overlap with each other.

[0123] (Light receiving unit 5) Although illustration is omitted, the light receiving unit 5 (see FIG. 1) of Embodiment 4 includes a light receiving surface on which a plurality of light receiving elements are arranged. This light receiving surface is divided into a plurality of light receiving sections corresponding to the irradiation sections T1 to T6 and the irradiation sections U1 to U6. Specifically, the light receiving surface is divided into a total of 12 light receiving sections, 3 in the x direction and 4 in the y direction. Each light receiving section receives light that is emitted from the light emitting sections H1 to H6 of the light source 4H and the light emitting sections I1 to I6 of the light source 4I and is reflected by an object existing in the irradiation sections T1 to T6 and the irradiation sections U1 to U6. Each light receiving section is independently driven by the light receiving drive unit 7 (see FIG. 1) to perform a light receiving operation. Thereby, the light receiving unit 5 of the present embodiment can acquire a light receiving result for each of the irradiation sections T1 to T6 and the irradiation sections U1 to U6.

[0124] (Drive control of the light emitting unit 4) Subsequently, the driving of the light emitting unit 4 performed by the light emitting drive unit 6 based on the control by the control unit 8 will be described. When the light emission driving unit 6 of the present embodiment irradiates light on the irradiation surface 260 where the distance in the +z direction from the light emitting unit 4 is a distance L3 closer than the reference distance L4, the light emitting driving unit 6 drives the light emitting unit 4 so that the light emitting sections of the light emitting sections adjacent to each other between the irradiation range 100H and the irradiation range 100I emit light at different timings. Specifically, the light emission driving unit 6 causes the light emitting section H4 of the light source 4H that emits light toward the irradiation section T4 and the light emitting section I1 of the light source 4I that emits light toward the irradiation section U1 adjacent to the irradiation section T4 to emit light at different timings. Further, the light emission driving unit 6 causes the light emitting section H5 of the light source 4H that emits light toward the irradiation section T5 and the light emitting section I2 of the light source 4I that emits light toward the irradiation section U2 adjacent to the irradiation section T5 to emit light at different timings. Furthermore, the light emission driving unit 6 causes the light emitting section H6 of the light source 4H that emits light toward the irradiation section T6 and the light emitting section I3 of the light source 4I that emits light toward the irradiation section U3 adjacent to the irradiation section T6 to emit light at different timings.

[0125] Here, when irradiating the irradiation surface 260 with light, if the light emitting section H4 of the light source 4H and the light emitting section I1 of the light source 4I emit light at the same timing, the irradiation section T4 of the irradiation surface 260 includes a region irradiated with light from the light emitting section H4 and not irradiated with light from the light emitting section I1, and a region irradiated with the superposition of the light from the light emitting section H4 and the light from the light emitting section I1. As a result, the amount of light irradiated to the irradiation section T4 becomes non-uniform. Similarly, if the light emitting section H4 of the light source 4H and the light emitting section I1 of the light source 4I emit light at the same timing, the irradiation section U1 of the irradiation surface 260 includes a region irradiated with light from the light emitting section I1 and not irradiated with light from the light emitting section H4, and a region irradiated with the superposition of the light from the light emitting section H4 and the light from the light emitting section I1. As a result, the amount of light irradiated to the irradiation section U1 becomes non-uniform. In this case, when an object exists in the irradiation section T4 or the irradiation section U1 on the irradiation surface 260, it may not be possible to accurately measure the distance to the object.

[0126] Although detailed description is omitted, when the light-emitting sections H5 and H6 of the light source 4H and the light-emitting sections I2 and I3 of the light source 4I emit light at the same timing, the amount of light irradiated on the irradiation sections T5, T6, U2, and U3 of the irradiation surface 260 also becomes non-uniform. In this case, it may not be possible to accurately measure the distance to the object.

[0127] On the other hand, in the present embodiment, when irradiating the irradiation surface 260 at a distance L3 where the distance in the +z direction from the light-emitting unit 4 is closer than the reference distance L4, by causing the light-emitting sections that emit light toward adjacent irradiation sections between the irradiation range 100H and the irradiation range 100I to emit light at different timings, it is possible to suppress the light from the light-emitting section of the light source 4H and the light from the light-emitting section of the light source 4I from being superimposed and irradiated in the irradiation section. As a result, it is possible to suppress the amount of light irradiated on the irradiation section from becoming non-uniform.

[0128] Here, when irradiating the irradiation surface 270 where the distance in the +z direction from the light-emitting unit 4 is the reference distance L4, the light-emitting drive unit 6 may drive the light-emitting unit 4 so that the light-emitting sections that emit light toward adjacent irradiation sections between the irradiation range 100H and the irradiation range 100I emit light at the same timing. As described above, on the irradiation surface 270 where the distance in the +z direction from the light-emitting unit 4 is the reference distance L4, the adjacent irradiation sections between the irradiation range 100H and the irradiation range 100I do not overlap. As a result, in each of the adjacent irradiation sections between the irradiation range 100H and the irradiation range 100I, the amount of light irradiated from the light-emitting unit 4 is uniform. In this case, the influence due to the non-uniform amount of light irradiated on the irradiation section as in the irradiation surface 260 is less likely to occur.

[0129] As described above, the embodiments of the present invention have been described, but the technical scope of the present invention is not limited to the scope described in the above-described embodiments. It is clear from the description of the claims that those obtained by making various changes or improvements to the above-described embodiments are also included in the technical scope of the present invention.

[0130] <Supplementary Note> (((1))) A light emitting device having a first light source that irradiates a first irradiation range and a second light source that irradiates a second irradiation range in a lighting state, and at a reference distance, irradiating the first irradiation range and the second irradiation range in parallel or overlapping; When irradiating an object at a first distance different from the reference distance by the light emitting unit, a driving unit that drives the light emitting unit so that one of the first light source and the second light source is in a lighting state and the other is in a lighting state. Is in the off state; A light emitting device, characterized in that it comprises. (((2))) The first light source includes a plurality of light emitting sections that emit light toward each of a plurality of irradiation sections obtained by dividing the first irradiation range. The second light source includes a plurality of light emitting sections that emit light toward each of a plurality of irradiation sections obtained by dividing the second irradiation range. The driving unit drives the light emitting unit so that the light emitting sections that emit light toward adjacent irradiation sections emit light at different timings in each of the first light source and the second light source. The light emitting device according to (((1))), characterized in that. (((3))) The first light source has a first light emitting section that irradiates a first irradiation section and a third light emitting section that irradiates a third irradiation section adjacent to the first irradiation section. The second light source has a second light emitting section that irradiates a second irradiation section and a fourth light emitting section that irradiates a fourth irradiation section adjacent to the second irradiation section. At the reference distance, the first irradiation section and the second irradiation section are superimposed, and the third irradiation section and the fourth irradiation section are superimposed. The driving unit drives the light emitting unit so that one is in a lighting state and the other is in an extinguished state at the first distance where the first irradiation section and the fourth irradiation section are superimposed. The light emitting device according to (((2))), characterized in that. (((4))) Which one is in the lit state and which one is in the extinguished state are determined based on the lighting history of the first light source and the second light source. The light emitting device according to any one of ((1)) to ((3)). (((5))) When irradiating an object at the first distance, the driving unit drives the light emitting unit such that, among the first light source and the second light source, the one with the shorter total lighting time is in the lit state and the other with the longer total lighting time is in the extinguished state. The light emitting device according to ((4)). (((6))) Each of the first light source and the second light source has a plurality of light emitting sections that emit light toward the first irradiation range and the second irradiation range, and is driven to emit light at different timings for each group including at least one light emitting section. When irradiating an object at the first distance, the driving unit drives the light emitting unit such that, among the first light source and the second light source, the one with less influence of the heat generated by the light emission of the previous group on the light emission of the next group is in the lit state and the other with greater influence is in the extinguished state. The light emitting device according to ((4)). (((7))) When an object is detected at the first distance, the driving unit drives the light emitting unit such that one of the first light source and the second light source is in the lit state and the other is in the extinguished state. The light emitting device according to any one of ((1)) to ((6)). (((8))) The first irradiation range and the second irradiation range overlap at the reference distance. The first distance is closer than the reference distance. The light emitting device according to any one of ((1)) to ((7)). (((9))) A light emitting unit having a first light source that irradiates the first irradiation range and a second light source that irradiates the second irradiation range in the lit state, and irradiating the first irradiation range and the second irradiation range in parallel or overlapping at the reference distance. The light emitting unit can be switched between a first mode for irradiating an object at a first distance different from the reference distance and a second mode for irradiating an object at a distance farther than the first distance, and can drive the light emitting unit. In the first mode, the light emitting unit is driven so that one of the first light source and the second light source is in a lit state and the other is in an extinguished state. In the second mode, the light emitting unit is driven so that both the first light source and the second light source are in a lit state. It has a driving unit. A light emitting device characterized by this. (((10))) The driving unit drives the light emitting unit in the first mode when the arrival of an object at the first distance is predicted. The light emitting device according to (((9))). (((11))) The light emitting device according to any one of (((1))) to (((10))), A light receiving unit that receives light irradiated from the light emitting device and reflected by an object, A calculating unit that calculates the distance to the object based on the result of light reception in the light receiving unit, A distance measuring device characterized by comprising. (((12))) When an object is detected at the first distance or the arrival of an object at the first distance is predicted based on the result of light reception in the light receiving unit or the result of calculation in the calculating unit, the driving unit drives the light emitting unit so that one of the first light source and the second light source is in a lit state and the other is in an extinguished state. The distance measuring device according to (((11))).

[0131] According to the light emitting device according to (((1))), the influence due to the deviation of the irradiation range of each light source can be suppressed as compared with the case where all the light sources are lit regardless of the distance. According to the light emitting device according to (((2))), the interference to the adjacent irradiation section can be suppressed as compared with the case where all the light sources are lit regardless of the distance. According to the light-emitting device according to ((3)), even under conditions where interference is likely to occur due to the overlap of irradiation ranges, interference with adjacent irradiation sections can be suppressed. According to the light-emitting device according to ((4)), compared with the case where light sources that are turned on and off are fixed, drive control according to the lighting state of each light source is performed. According to the light-emitting device according to ((5)), compared with the case where light sources that are turned on and off are fixed, the deviation of the total lighting time of each light source is suppressed. According to the light-emitting device according to ((6)), compared with the case where light sources that are turned on and off are fixed, the influence on the luminous efficiency due to heat generated during light emission is suppressed. According to the light-emitting device according to ((7)), irradiation in a state where the irradiation ranges of the respective light sources are shifted with respect to an object existing at the first distance is suppressed. According to the light-emitting device according to ((8)), on the side closer to the light-emitting part where the amount of light irradiated is larger than on the side farther from the light-emitting part, it is suppressed that the amount of light irradiated in the overlapping part and the non-overlapping part becomes non-uniform, and it is suppressed that the amount of light irradiated to the object becomes excessive. According to the light-emitting device according to ((9)), compared with the case where all the light sources are turned on regardless of the distance, the influence due to the deviation of the irradiation ranges of the respective light sources is suppressed. According to the light-emitting device according to ((10)), irradiation in a state where the irradiation ranges of the respective light sources are shifted with respect to an object that has reached the first distance is suppressed. According to the distance measuring device according to ((11)), compared with the case where all the light sources are turned on regardless of the distance, the influence due to the deviation of the irradiation ranges of the respective light sources can be suppressed. According to the distance measuring device according to ((12)), an object can be detected without providing individual sensors and used for control.

Explanation of reference numerals

[0132] 1... Distance measuring device, 3... Optical device, 4... Light emitting unit, 4A, 4B, 4C, 4D, 4E, 4F, 4G... Light sources, 5... Light receiving unit, 6... Light emission driving unit, 7... Light reception driving unit, 8... Control unit, 100A, 100B, 100C, 100D, 100E, 100F, 100G... Irradiation ranges

Claims

1. A light emitting unit having a first light source that irradiates a first irradiation range and a second light source that irradiates a second irradiation range in a lit state, and irradiating the first irradiation range and the second irradiation range in parallel or in an overlapping manner at a reference distance; A drive unit that drives the light emitting unit such that when irradiating an object at a first distance different from the reference distance by the light emitting unit, one of the first light source and the second light source is in a lit state and the other is in an extinguished state; A light emitting device comprising the same.

2. The first light source includes a plurality of light emitting sections that emit light toward respective ones of a plurality of irradiation sections obtained by dividing the first irradiation range, The second light source includes a plurality of light emitting sections that emit light toward respective ones of a plurality of irradiation sections obtained by dividing the second irradiation range, The drive unit drives the light emitting unit such that, in each of the first light source and the second light source, the light emitting sections that emit light toward adjacent irradiation sections emit light at different timings. The light emitting device according to claim 1, characterized in that.

3. The first light source has a first light emitting section that irradiates a first irradiation section and a third light emitting section that irradiates a third irradiation section adjacent to the first irradiation section, The second light source has a second light emitting section that irradiates a second irradiation section and a fourth light emitting section that irradiates a fourth irradiation section adjacent to the second irradiation section, At the reference distance, the first irradiation section and the second irradiation section are overlapped, and the third irradiation section and the fourth irradiation section are overlapped, The drive unit drives the light emitting unit such that at the first distance where the first irradiation section and the fourth irradiation section are overlapped, one is in a lit state and the other is in an extinguished state. The light emitting device according to claim 2, characterized in that.

4. The light emitting device according to claim 1, characterized in that which one is in a lit state and which one is in an extinguished state is determined based on the lighting history of the first light source and the second light source.

5. When irradiating an object at the first distance, the drive unit drives the light emitting unit such that, of the first light source and the second light source, the one with the shorter total lighting time is in a lit state and the one with the longer total lighting time is in an extinguished state.

6. Each of the first light source and the second light source has a plurality of light-emitting sections that emit light toward the first irradiation range and the second irradiation range, and is driven to emit light at different timings for each group including at least one light-emitting section. When irradiating an object at the first distance, the driving unit drives the light-emitting unit such that one of the previous group's light emission that causes less influence on the next group's light emission is in the lit state and the other with greater influence is in the extinguished state. The light-emitting device according to claim 4, characterized in that.

7. The driving unit drives the light-emitting unit such that when an object is detected at the first distance, one of the first light source and the second light source is in the lit state and the other is in the extinguished state, according to the light-emitting device described in claim 1.

8. The first irradiation range and the second irradiation range overlap at the reference distance. The light-emitting device according to claim 1, characterized in that the first distance is closer than the reference distance.

9. A light-emitting unit having a first light source that irradiates the first irradiation range and a second light source that irradiates the second irradiation range in the lit state, and irradiating the first irradiation range and the second irradiation range in parallel or overlapping at the reference distance, The light-emitting unit can switch between a first mode for irradiating an object at a first distance different from the reference distance and a second mode for irradiating an object at a distance farther than the first distance, and drive the light-emitting unit. In the first mode, the light-emitting unit is driven such that one of the first light source and the second light source is in the lit state and the other is in the extinguished state. In the second mode, the light-emitting unit is driven such that both the first light source and the second light source are in the lit state, and a driving unit. A light-emitting device characterized by that.

10. The driving unit drives the light-emitting unit in the first mode when the arrival of an object at the first distance is predicted, according to the light-emitting device described in claim 9.

11. The light-emitting device according to any one of claims 1 to 10, A light-receiving unit that receives the light irradiated from the light-emitting device and reflected by the object, A calculating unit that calculates the distance to the object based on the result of light reception in the light-receiving unit, A distance measuring device characterized by comprising.

12. The drive unit drives the light emitting unit so that when an object is detected at the first distance or when it is predicted that the object will reach the first distance, based on the result of light reception in the light receiving unit or the result of calculation in the calculation unit, one of the first light source and the second light source is in a lit state and the other is in an extinguished state. The distance measuring device according to claim 11, characterized in that.

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