JP2005292156A - Distance-measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce drive current, to prevent reduction of a service life time of an element to allow lighting operation, and to allow far projection without reducing light quantity, when performing light projeection operation by use of a plurality of semiconductor light-emitting elements. <P>SOLUTION: By connecting the semiconductor laser elements 23a-23c performing the light projection by lenses 25a-25c independently of each other in series, and performing connection to a signal generation circuit 24 as a power source to perform pulse-lighting, the three elements can be simultaneously lighted by the drive current, corresponding to one element. A package of each the semiconductor laser element 23a-23c has three lead terminals, and the semiconductor laser element 23a-23c is electrically connected to two lead terminals, electrically insulated with respect to a metal base. When a light collecting point P is set at the midpoint of a range of a detection distance, the shifting quantity of laser light is reduced to the utmost, over nearly the whole area, to suppress reduction of the light quantity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention comprises a semiconductor light projecting device having an optical system for projecting light emitted from a plurality of semiconductor light emitting elements to a light projecting region, receiving reflected light from the object, and reducing the distance to the object. The present invention relates to a distance measuring device to measure.

  In recent years, light is projected toward a detection region by a semiconductor light emitting device configured using a semiconductor light emitting element such as a semiconductor laser element or a light emitting diode element, and the reflected light is received and the measurement object in the detection region is measured from the delay time. Distance measuring devices that measure the distance to an object have been developed.

  For example, such a distance measuring device is mounted on a vehicle to measure the distance between the vehicles and issue a warning when the distance between the vehicles is closer than a certain distance, or when other vehicles are parked A system that outputs a warning when the distance to an obstacle is measured and is closer than a certain distance, or a system that outputs a warning when light is blocked within a certain distance in the light projection area, etc. Has been used. In addition, a system has been considered in which these systems can be applied to control the traveling of an automobile so that the vehicle can travel or park safely and appropriately.

  In this case, the inter-vehicle distance measurement system is required to be able to measure the distance in the range of about 10 m to 100 m (for example, about 120 m) as the distance measurement range in consideration of the driving state such as an expressway. For this purpose, the semiconductor laser device requires a light output of about 20 to 80 W as a whole by pulse driving of several tens to several hundreds nsec (nanoseconds). In general, with one semiconductor laser element, an optical output of about 10 to 20 W can be obtained when the peak current value is about 20 A. In order to satisfy the above-described requirements, it is conceivable to drive one semiconductor laser element with a large current, or simultaneously drive a plurality of semiconductor laser elements to synthesize their optical outputs.

  When one semiconductor laser is driven and controlled with a large current, the lifetime of the element decreases in inverse proportion to the magnitude of the current, so it is not a good condition to employ one. Therefore, a method of increasing the amount of light by collecting the light using a plurality of semiconductor lasers is effective.

  As this method, it is generally considered that each semiconductor laser is connected to a power supply in parallel and individually driven to emit light and the light is condensed. However, in that case, since it is necessary to flow the drive currents corresponding to the number connected in parallel, the power consumption increases and the pulse waveform becomes dull, which is not preferable as a drive condition.

On the other hand, there are some which are shown in patent documents 1 to 3 in order to solve such problems. These are formed by laminating and integrating a plurality of semiconductor laser chips and driving them in a serial connection state. As a light source, a plurality of light emitting points are arranged at intervals of about 100 μm. This is condensed by a condenser lens, converted into parallel light, and projected toward a target light projection area.
JP-A-5-41561 JP-A-6-282807 Japanese Patent Laid-Open No. 7-307520

  In the above-described case, even if the interval between the light emitting points in the light source is 100 μm, the interval between the laser light spots from each semiconductor laser chip is proportional to the projection distance in the state where the light is condensed so as to be parallel light. Will spread. For example, as shown in FIG. 25, when a semiconductor laser device 1 formed by laminating three semiconductor laser chips 1a to 1c is placed at the focal position of a condenser lens 2 as an optical system to emit light, each laser chip When the laser beams emitted from the light emitting points La to Lc of 1a to 1c pass through the condensing lens 2, they are condensed and become parallel light Sa to Sc.

  At this time, if each spot diameter of the parallel light beams Sa to Sc is D, the same deviation as the arrangement interval of the laser chips 1a to 1c occurs at the position advanced by the focal length f. Since it becomes large, such a shift keeps the focused state with almost no problem. Then, when each of the parallel lights Sa to Sc travels to a distance to be measured, for example, about several tens of meters, the above-described deviation spreads to a level that cannot be ignored, and the detection distance due to the condensed light is increased. The effect of doing is totally lost.

  In this state, as shown in FIG. 26, when the detection distance x is increased, the spots are projected so that the spots overlap at about x1 in the figure, but when the detection distance x is increased to about x2 (> x1), Not only is the amount of light decreased, but a dark area B is formed where the distance between the spots is increased and no light strikes. In this case, the measurement object that happens to be located in the dark area B at the time of distance measurement will not be measured, and will be recognized as non-existent, and there is a problem that accurate measurement cannot be performed.

  The extent of the spread of the spot interval is proportional to the distance from the condensing lens 2 and simply increases as the distance increases. Therefore, as the distance is detected, the amount of light decreases or dark areas occur. This becomes a disadvantageous condition when it is desired to receive more reflected light from the object.

Specifically, for example, when the interval between the light emitting points La to Lc is 100 μm, the spread angle θ of the light source with respect to the focal length f of the condenser lens 2 is
θ = arctan (0.1 / f)
Therefore, when the focal length f is 22 mm, θ = 0.26 °. At a position 22 m away from the position of the condenser lens 2 which is 1000 times the focal length f, the distance between the center positions of the spots is about 10 cm. Although there is a relationship with the size of the spot diameter D, since the center position is not shifted, the light in the light projecting area spreads and the amount of light per unit area decreases, so the amount of reflected light decreases. Is certain.

  Therefore, when a distance of 100 m or more is set as the measurement distance range, the amount of light is largely insufficient and a dark area is generated. Therefore, the semiconductor laser device is driven with a larger current to increase the amount of light. However, in this case, there is a problem that it is impossible to avoid a decrease in the service life.

  In addition, when a configuration in which the range of the measurement distance is set up to a long distance of 100 m or more is obtained, strong light is output. When such strong light is output, this is human. When used in an environment where there is a possibility of being incident on the eyes, it is necessary to set the output level in consideration of safety, and in this respect as well, technical problems for increasing the output remain.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable light emission of a large output at a low current in a light projecting device constituted by using a plurality of semiconductor light emitting elements, and a light projecting distance. It is an object of the present invention to provide a distance measuring device capable of efficiently performing a distance measurement using a semiconductor light projecting device capable of performing an efficient light projecting operation according to the above.

  In addition, another object of the present invention is to use in an environment where there is a possibility of being incident on the human eye in a configuration that outputs strong light to project far away by achieving the above object. An object of the present invention is to provide a distance measuring device that measures distance measurement using a semiconductor light projecting device that can ensure the safety even when it is performed.

  According to the first aspect of the present invention, a plurality of optical devices are individually arranged with respect to the semiconductor light emitting elements so as to project light onto the light projecting region, and the plurality of semiconductor light emitting elements are connected to the power source. Since power is supplied in a state of being connected in series, the current can be made to flow by supplying the same current to all the semiconductor light emitting elements by supplying a current for one semiconductor light emitting element. It is possible to obtain the amount of light corresponding to the number of connected semiconductor light emitting elements. That is, in a semiconductor light emitting device, a light emission phenomenon usually occurs only by passing a current in one direction. Therefore, when connected in series, all the semiconductor light emitting devices emit light. In addition, the plurality of optical devices are configured in a state in which the optical axes are adjusted so that the light emitted from the plurality of semiconductor light emitting elements is condensed and projected onto one projection area. Even when light is emitted, light can be projected in a high light density state, and the light focused individually by the optical system is condensed. Therefore, more efficient light projection is provided by providing a condensing point at a position corresponding to the light projection distance. The operation can be performed.

  Further, the semiconductor light projecting device is used to project light onto the light projecting area, and the light receiving means receives reflected light from an object existing in the light projecting area. At this time, the detecting means receives the reflected light from the time of projecting. Since it is configured to measure the time to the point in time and detect the distance to the object, as described above, it is possible to efficiently collect the light to be projected and project it to the projection area. This makes it possible to accurately measure the distance up to a longer distance in the projection area. In other words, an efficient light projection operation can be performed within the target distance measurement range.

  According to the invention of claim 2, in the above invention, when the spot shape in the light emitting region of the semiconductor light emitting element is an elliptical shape, the plurality of optical devices are arranged in the same plane. Since the plurality of semiconductor light emitting elements are arranged in parallel and at equal intervals so that the spots in the light projecting region overlap with each other in the major axis direction of the elliptical shape, light projection by irradiation of the semiconductor light emitting elements is performed. The overlapping state of the spots in the major axis direction in the region is shifted by the arrangement interval of the semiconductor light emitting elements. As a result, the overlapping area when irradiating a plurality of semiconductor light-emitting elements in parallel by an optical device, that is, the area that can be used as the strongest light has a large ratio with respect to the amount of deviation as the irradiation distance increases, and is strong. Irradiation can be effectively performed by increasing the degree of overlap in a distant place that requires light.

  According to the invention of claim 3, in the distance measuring apparatus described above, since the semiconductor light emitting element of the semiconductor light projecting device is pulse-lit by the detecting means, a high output light projecting operation can be performed efficiently, and the pulse It is possible to measure the distance by detecting the time difference between the light emitted by lighting and the reflected light received by the light receiving means from the difference in the rise time of the light projection signal and the light reception signal. Highly measurable measurement can be performed.

  According to the invention of claim 4, in the distance measuring device described above, the optical device adjusts the optical axis so that the light condensing point is located within the detection distance range of the light emitted from the plurality of semiconductor light emitting elements. Therefore, the shift of the center point of the light output from each semiconductor light emitting element within the range of the detection distance can be reduced, and a more accurate detection operation can be performed while preventing a decrease in the light amount as much as possible. It becomes like this.

  According to the fifth aspect of the present invention, since the position of the condensing point is adjusted to the farthest point within the range of the detection distance in the distance measuring device described above, the degree of condensing from each semiconductor light emitting element at the farthest point. Is the best and it is possible to suppress the occurrence of deviation of the center point of light, so that the farther the position, the higher the degree of condensing, and the reduction in the amount of light due to the deviation of the center point can be suppressed. In addition, at a position closer to the farthest point, the distance between the center points of the light is the arrangement interval at which each semiconductor light emitting element is arranged at the maximum, so the relationship between the arrangement interval and the spot diameter narrowed by the optical system is appropriate. By setting to, it is possible to obtain a condensing state with almost no deviation over the entire range within the measurement range, and it is possible to improve the detection accuracy within the distance measurement range.

  According to the invention of claim 6, in the distance measuring device according to claim 4, the position of the condensing point is adjusted to an intermediate point within the range of the detection distance. The center point of the light is almost the same at both the farthest point and the nearest point of the detection range, and the center point deviation of the spot light output from each semiconductor light emitting element over the entire detection range is the largest. It can be set as few conditions. Thereby, for example, by setting the distance with the highest detection frequency within the distance measurement range as the condensing point, the amount of light in the vicinity of the condensing point can be maximized to improve the detection accuracy.

  According to the invention of claim 7, in each of the distance measuring devices described above, the projection direction of the light is scanned within a predetermined range by the projection scanning means, and the distance of the object is projected from the reflected light detected by the detection means. Since it is obtained corresponding to the area, the range to be projected can be detected by dividing it into projection areas, and the position and distance of the detection target within the wide detection range are detected according to the projection position. be able to. As a result, the detection operation within a wide range can be performed more accurately.

  According to the invention of claim 8, in the above-described configuration, since the light projection direction is scanned two-dimensionally by the light projection scanning means, the degree of freedom of setting the range to be detected is increased and its application is used. Can also be widened.

  According to a ninth aspect of the present invention, in the distance measuring device according to any one of the first to eighth aspects, the distance measuring device is mounted on a moving body, and the distance of the light projecting area corresponding to the traveling direction is detected. Therefore, it is possible to detect the distance in the projection area corresponding to the traveling direction even in a moving body used as a transportation means such as an automobile, or a manned or unmanned moving body such as a transport device or a robot. The present invention can be applied to a wide range of uses such as detecting an obstacle that hinders the progress of a person or an object positioned in the traveling direction, or detecting a target object for tracking.

  According to the invention of claim 10, in the above-mentioned case, by installing this in an automobile, an obstacle in the traveling direction is detected and a dangerous case is notified in advance by an alarm or deceleration control is performed. When controlling other vehicles to take appropriate measures, or when tracking other vehicles traveling in front of the vehicle, this should be detected and used to control the vehicle while maintaining an appropriate inter-vehicle distance. You can also.

  According to the invention of claim 11, in the invention of claim 9 or 10, when the spot shape in the light emitting region of the semiconductor light emitting element is an elliptical shape, the spot of light emitted by the semiconductor light projecting device Is set so that the ellipse's major axis direction is oriented in the vertical direction with respect to the moving surface, so that the distance detection operation is performed, so that the horizontal detection resolution of the moving surface is increased. Will be able to. Thereby, for example, when used for a vehicle or the like, the direction and position of an object or the like located in the traveling direction can be detected with high accuracy.

  According to the twelfth aspect of the present invention, the plurality of optical devices are configured in a state in which the optical axes are adjusted so that light emitted from the plurality of semiconductor light emitting elements is projected onto the plurality of light projecting regions. The light projecting operation can be performed by individually using the light projecting by the elements, and even in this case, the semiconductor light emitting elements are connected in series, so that the power feeding operation can be performed efficiently. And this semiconductor light projecting device is provided, the reflected light from the objects existing in the plurality of light projecting areas of the semiconductor light projecting device is received by the light receiving means, respectively, and the objects present in each light projecting area are detected by the detecting means. Thus, it is possible to set a wide detection area and detect an object existing in the detection area.

  According to the inventions of claims 13 and 14, the above-described configuration is mounted on a moving body and detects an object in a light projecting area set around the mobile body. For example, in an automobile or an automatic guided vehicle It can be used to prevent the occurrence of damage by colliding with surrounding objects even in a narrow area when traveling without touching the surrounding objects or parking and stopping.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to an automobile distance measuring device will be described with reference to FIGS.

  The distance measuring device 11 is provided on the automobile 12 (see FIG. 7), and is disposed, for example, on the inner side of the dashboard or bonnet or on the bumper portion so as to perform a light projection operation toward the front of the vehicle body. Thus, as will be described later, a beam spot is scanned within a predetermined range in front, and the distance of an object existing within the range is detected.

  As shown in FIG. 4, the distance measuring device 11 includes a projector 13 as a semiconductor projector, a scanning unit 14 as a projection scanning unit for scanning the projection within a predetermined range, and a reflected light of a Fresnel type. A light receiving element 17 that receives light through the light receiving lens 16 and photoelectrically converts and outputs it, a preamplifier 18 that amplifies a light reception signal, an amplification factor variable amplifier 19, a time measurement circuit 20 that measures the time from light projection to light reception, and light projection operation , And a control circuit 21 for controlling the light receiving operation and the detecting operation.

  As shown in FIG. 1, the projector 13 includes, for example, three semiconductor laser elements 23 a to 23 c as semiconductor light emitting elements, and these are connected in series to a signal generation circuit 24 as a power source. It is connected. Each package has lead terminals for holding the case at the ground potential, and these lead terminals are connected to the ground terminals. Lenses 25a to 25c as optical devices for reducing the laser output to parallel light are respectively disposed on the front surfaces of the three semiconductor laser elements 23a to 23c.

  These three semiconductor laser elements 23a to 23c are arranged at a predetermined interval, and the optical axis is arranged so that the laser beam output projected from each through the lenses 25a to 25c is condensed at a predetermined distance. It has been adjusted. Here, as the predetermined distance, the distance Lo (for example, about 70 m) to the intermediate value position in the distance range Lmin to Lmax (for example, a range from 20 m to 120 m) to be measured by the distance measuring device 11. Distance) is set.

  The signal generation circuit 24 is configured to pass a pulsed current so as to cause the semiconductor laser elements 23a to 23c to perform pulse projection. At this time, the pulse current is set to emit light with a pulse width of 50 nsec and a repetition period of 5 kHz, and the peak current is set to about 14 A and the peak power per one of the semiconductor laser elements 23 a to 23 c is set to about 14 W. Has been.

  In this connection form, as shown in FIG. 5, the semiconductor laser elements 23a to 23c, that is, three laser diodes are connected to the signal generating circuit 24 in a state of being connected in series. Three currents are supplied with the same current that is supplied to the semiconductor laser elements 23a. In consideration of impedance matching and the like, a configuration that consumes power by interposing an adjustment resistor or the like is not required, so that power can be efficiently supplied with a small current.

  The light receiving element 17 is composed of, for example, a photodiode and photoelectrically converts the reflected light received through the light receiving lens 16 and outputs it as a light receiving signal. The light reception signal amplified through the preamplifier 18 and the amplification factor variable amplifier 19 is output to the time measurement circuit 20. The time measuring circuit 20 measures the delay time td from the light projecting pulse signal and the light receiving pulse signal respectively input from the light projector 13 and the amplification factor variable amplifier 19 and outputs it to the control circuit 21. The control circuit 21 drives and controls these circuits and elements, and calculates and stores the measurement distance for the light projection area at that time from the data of the delay time td given from the time measurement circuit 20.

  Next, the configuration of the semiconductor laser elements 23a to 23c will be described in detail. In this embodiment, since the measurement distance is set to a wide range from about 20 m to about 120 m, the semi-semiconductor laser chip 26 is used as a semiconductor chip that can reliably project light to a farther detection area. The semiconductor laser element 23a (the same applies to 23b and 23c) has a structure as shown in FIGS. Note that the configuration of FIG. 3 is shown in a state slightly changed from the actual arrangement.

  The semiconductor laser chip 26 mounted on the package 27 employs a stripe type configuration having a wide stripe width of 100 μm or more as a structure suitable for high output. As the material, for example, a GaAs compound semiconductor substrate is used, and a plurality of compound semiconductor layers are laminated on the substrate together with an active layer. In this case, an active layer having a double hetero structure or a quantum well structure can be used. In addition to this, an InP substrate, a sapphire substrate, or the like can be used as the substrate material.

  The semiconductor laser chip 26 in this embodiment is formed by stacking GaAs / AlGaAs materials on an n-type GaAs substrate by epitaxial growth, and an AlGaAs layer is formed as an active layer. In addition to this, InGaAsP-InP system, InGaP-InGaAlP system, InGaAs-InAs system, GaAs-GaN system, GaAs-GaInNAs system, etc. can be adopted, and any one can be selected as necessary. it can. Hereinafter, a process of forming the semiconductor laser chip 26 will be briefly described.

  As a method for forming a compound semiconductor layer on a semiconductor substrate, an epitaxial growth method is used, which includes a liquid phase epitaxy (LPE) method, a molecular beam epitaxy (MBE) method, or an organometallic gas. There is a phase epitaxy (MOCVD: Metal Organic Chemical Vapor Deposition) method.

  On the substrate on which the epitaxial layer is formed, ohmic contact electrodes are formed on the upper surface and the lower surface, respectively. On the upper surface, that is, on the surface side, as a p-type electrode, a stacked structure of metals such as Au—Zn / Au, Cr / Au, Mo / Au, Ti / Pt / Au, Cr / Pt / Au, or the like is used for electron beam evaporation or sputtering. It is formed with a predetermined film thickness by a method or the like. When it is necessary to process the electrode shape, a photolithography process is performed as a patterning process, and a predetermined pattern is formed by chemical etching or ion beam etching. Subsequently, an ohmic contact is formed by annealing for alloying as necessary.

  Before forming the electrode on the lower surface side, the substrate is polished from the back surface side so as to make a chip easily, for example, to a plate thickness of about 100 μm. This plate thickness may be about 1/3 or less of the cavity length (resonator length), and the cavity length is about 300 μm to 1 mm, but considering the workability in consideration of the better heat dissipation as the thinner one is, It is preferable to be in the range of 50 μm to 200 μm. However, when the reflecting surface is formed by dry etching or the like without using a cleavage plane, this condition is not required, and therefore an appropriate plate thickness can be set.

  Thereafter, an n-type electrode is formed on the lower surface side, that is, the back surface side. The material is, for example, a laminated structure of metals such as Au-Ge / Ni / Au or Au-Sn / Au, and an ohmic contact is formed by performing an arrowing process after film formation. Next, a solder layer is formed on the surface of the back electrode by vapor phase growth. The material of the solder layer is, for example, Au—Sn or Pb—Sn, and the vapor phase growth method includes a method such as an electron beam evaporation method, a resistance heating evaporation method, a sputtering method, or an ion plating method. Are selected as appropriate.

  Next, chips are formed into a predetermined size. At this time, a mirror surface is necessary for laser oscillation as the output surface of the laser beam, so that it is a cleavage surface or is formed by dry etching to be a light emitting end surface. Further, in order to protect the end face and improve the light output, a thin film having a low reflectivity is formed on the output end face side and a thin film having a high reflectivity is formed on the reflective face side.

  In this case, the low reflectance thin film preferably has a reflectance in the range of about 2 to 25%, and the high reflectance thin film preferably has a reflectance in the range of 80 to 100%. The film configuration may be either a single layer film or a multilayer film. However, in the case of low reflectivity, for example, a single layer film such as Al2O3, SiO2, SiNx, SiC, C, or MgO is preferable, and high reflection is achieved. In the case of the rate, for example, a multilayer film structure in which Al 2 O 3, SiO 2, SiN x, C, MgO and the like and a film having a refractive index difference such as a-Si, Cr 2 O 3, TiO 2 is provided in multiple layers is preferable. In the case of forming a light emitting diode, which will be described later, it is not necessary to form a reflective film on the end face because a cleavage plane is not required, and therefore, a general dicing cut method can be used for chip formation. .

  The package 27 uses a three-terminal metal case for an optical element used for the purpose of mounting a transistor and two diode elements, for example, and has three lead terminals 29a, 29b, 29c on a metal base 28. The lead terminals 29a and 29b are provided in a state of being insulated from the metal base 28 via a sealing insulator 30 such as glass, and the lead terminal 29c is electrically connected to the metal base 28. It is provided in the state. This is illustrated in FIG.

  Of these lead terminals 29a to 29c, the lead terminals 29a and 29b insulated from the metal base 28 are electrically connected to the semiconductor laser chip 26, and the lead terminal 29c electrically connected to the metal base 28 is entirely at the ground potential. In order to hold it, it is connected to the ground.

  The metal pedestal 31 having a block shape is fixed in a state of being electrically connected to the metal base 28, and functions as a heat sink. For the metal pedestal 31, for example, a material having high thermal conductivity such as Fe or Cu is selected, and a metal having high conductivity such as Au is further formed on the surface by plating, vapor deposition or sputtering. .

  A GaAs insulating substrate 32 as an insulating plate is fixed on the metal base 31. In this GaAs insulating substrate 32, SiON films formed in an amorphous state on both the front and back surfaces are formed to a thickness of about 200 nm by a plasma CVD method or the like, and Cr / Ni / Au films are similarly formed on both surfaces by a vapor deposition method. The substrate is formed to have a thickness of about 50 nm / 300 nm / 500 nm, and is formed into a size of about 1 mm square by dicing and cutting the substrate.

  The GaAs insulating substrate 32 is bonded onto the metal pedestal 31 using Au—Sn solder foil, and the semiconductor laser chip 26 is fixed thereon. On the back side of the semiconductor laser chip 26, for example, an Au—Sn thin film of about 1.5 μm is formed, and this surface is connected to the GaAs insulating substrate 32. As a result, the back electrode of the semiconductor laser chip 26 is insulated from the metal pedestal 31, but is electrically connected to the outside by a conductor film 32a such as an electrode film and a solder layer formed on the surface of the GaAs insulating substrate 32. Conduction can be achieved.

  Examples of the insulating plate include an insulating plate made of ceramic such as alumina oxide, alumina nitride, silicon oxide, and silicon nitride, and a semi-insulating substrate in which impurities are diffused in a semiconductor such as Si and GaAs. Furthermore, it is also possible to use a film formed by depositing SiO2, SiNx, Ta2O3, a-C or the like on the surface of a semiconductor substrate such as metal, Si, GaAs, etc. by a method such as CVD, sputtering, vapor deposition, or thermal oxidation. it can. From the viewpoint of workability, ceramic substrate materials such as alumina oxide, alumina nitride, silicon oxide or silicon nitride are very hard, and it is difficult to cut about 1 mm square as described above. Therefore, a semiconductor substrate is used. It is an effective material in terms of practical use.

  In addition to the Au—Sn thin film described above, the bonding material may be a solder material such as Pb—Sn, or a general die bonding adhesive when electrical connection as described later is not required. it can.

  The semiconductor laser chip 26 and the lead terminals 29a and 29b are electrically connected by an Au wire 33 as a bonding wire. Two Au wires 33 are connected between the electrode on the upper surface of the semiconductor laser chip 26 and the bonding surface 34 of the lead terminal 29a, and the exposed portion of the GaAs insulating substrate 32 and the bonding surface 34 of the lead terminal 29b. Are also connected between the two. In addition to the Au wire 33, various wires such as an Au wire containing silicon, a Pt wire, an Al wire, or a Cu wire can be used as the bonding wire.

  Further, the bonding surfaces 34 of the cylindrical lead terminals 29a and 29b are formed flat so as to facilitate bonding, thereby improving the bonding strength. Therefore, it can be said that the bonding reliability is improved. It should be noted that the bonding positions of the electrodes on the upper surface of the semiconductor laser chip 26 are bonded one by one corresponding to both sides of the stripe portion which is the light emitting region.

  In the above configuration, the bonding surfaces 34 are not provided as shown in FIG. 9 or FIG. 10 in place of bonding with the flat bonding surfaces 34 provided on the side surfaces of the lead terminals 29a and 29b. As a configuration, bonding can also be performed by using flat portions of the end surfaces of the lead terminals 29a and 29b, whereby the step of forming the bonding surface 34 can be omitted.

  That is, in the configuration of FIG. 9, a package in which the bonding surface 34 is provided only on one lead terminal 29a side is used. In this case, a bonding surface is not formed on the lead terminal 29b, but an Au wire 33 is bonded to a flat portion of the end surface portion. Further, in the configuration of FIG. 10, both the lead terminals 29a and 29b are not provided with a bonding surface, and the Au wire 33 is bonded to the flat portion of the end surface portion of each lead terminal 29a and 29b.

  When the bonding surface 34 is not provided in this way, the bonding direction on the semiconductor laser chip 26 side and the bonding direction on the lead terminals 29a and 29b side are twisted by 90 °, but in the actual bonding process, After one bonding, the support pedestal is rotated 90 ° to perform the other bonding, but the two Au wires 33 are not in contact with each other and are not subjected to an offset load. This can be done without any problems.

  In the above case, since the terminals are connected by two Au wires 33, the reliability of the operation is lowered even if the three semiconductor laser elements 23a to 23c are connected in series. Can be used without any problem. That is, for example, in the case of a failure due to the disconnection of the Au wire 33, the current can be maintained through the other remaining Au wires 33, and even in the case of a short-circuit failure that is expected to occur in the semiconductor laser chip 26 itself. The semiconductor laser elements 23a to 23c can be energized.

  A case 35 in the shape of a cylindrical container is for sealing a can, and is fixed to the metal base 28 so as to cover the semiconductor laser chip 26. A glass window 35 a for guiding laser light emitted from the end face of the semiconductor laser chip 26 to the outside is fitted on the upper surface of the case 35. As shown in FIG. 1, the semiconductor laser elements 23a to 23c having the above-described configuration are arranged at predetermined positions and the laser light emitting portions are arranged with the lenses 25a to 25c serving as an optical system as described above. The optical axis is adjusted so that the light is condensed at one point at the condensing point P.

  Since the package 27 employs the above-described configuration, the metal base 28 portion is not connected to any electrode of the semiconductor laser chip 26 and can be held at the ground potential. For example, the package 27 is mounted on the circuit board. Even when it is installed, the area occupied by the potential portion can be reduced, and the occurrence of short circuit accidents due to current leakage or contact between terminals can be suppressed to minimize the occurrence of circuit abnormality. Will be able to.

  Next, the operation of this embodiment will be described. As shown in FIG. 7, in the distance measuring device 11 mounted on the automobile 12 a, when the control circuit 21 controls the projector 13 to perform the projection operation, the projector 13 moves forward via the scanning unit 14. The laser beam is output while turning on the pulse.

  As shown in FIG. 8, the laser beam is projected in a reflecting mirror of the scanning unit 14 with respect to a predetermined two-dimensional detection range S in which the scanning unit 14 spreads the laser beam from the projector 13 in front of the automobile 12. Measure the distance to each projection area as a projection area arranged in a large number of grids as shown in the figure by scanning (scanning) by controlling the rotation of the projector and properly timing the projection pulse and timing. Can do.

  At this time, the pulsed laser light has a pulse width of about 50 nsec and a repetition period of 5 kHz as described above. The peak value of the pulse current for driving the semiconductor laser chip 26 is about 14A. Note that the peak power of the semiconductor laser chip 26 under these conditions was about 14 W. When light was projected under this condition, it was confirmed that an object existing 170 m ahead could be detected.

  When the laser beam output in this way is incident on a reflector (reflector) 22 attached to the rear part of another automobile 12b existing in front, the reflected light returns in the same direction as the incident direction. Reflect. When this reflected light is incident on the light receiving element 17 through the light receiving lens 16 of the distance measuring device 11, it is converted into a light receiving signal and output, and the light receiving signal amplified through the preamplifier 18 and the gain variable amplifier 19 is time-converted. The data is output to the measurement circuit 20.

  The time measurement circuit 20 receives a light projection pulse signal for driving the projected laser beam and also receives a light reception signal when it is received by the light receiving element 17. The time measuring circuit 20 measures the time from the rising timing of the light projection pulse to the rising timing of the received light signal with high accuracy. For example, if the time measurement can be performed with a resolution of about 10 nsec, the distance measurement resolution can be in m units.

When receiving the data of the delay time td, the control circuit 21 detects the distance to the object based on this. Now, as shown in FIG. 7, when the detection distance is Lx (m) and the delay time is td (sec), considering the speed of light c (= 3 × 108 m / sec), it is necessary to reciprocate the detection distance Lx. Therefore, the detected distance Lx is td.
Lx (m) = td × c / 2
It becomes.

  In this way, the distance to the object is detected based on the delay time td based on the light reception signal generated from the reflected light when the light is projected onto the detection area one after another. And what kind of target object exists in which position from the detection distance corresponding to each part in the detection range S is estimated. For example, in the case of another target automobile 12b, it is detected whether the distance is within a certain range, and control such as following the traveling of the automobile 12a with a certain distance is performed based on the detected data. Can be done.

  Next, setting of the optical system will be described. That is, when three semiconductor laser elements 23a to 23c are arranged and projected, where the respective laser beams are focused is greatly related to detection accuracy. FIG. 6 is an explanatory diagram for setting the condensing point P of three laser beams.

  The distance from the position of the projection lenses 25a to 25c from which the parallel laser light is output to the condensing point P is Lo, and the nearest point and the farthest point in the range of distance to be detected are Lmin, This is described as Lmax. Needless to say, at the position of the condensing point P, the amount of light is the largest, so the amount of reflected light also increases. Therefore, it is preferable to set within the detection distance range Lmin to Lmax.

  Then, when there is no particular portion where the sensitivity is most desired to be enhanced as the detection distance within the detection distance range, if the condensing point P is positioned in the middle of the detection distance range (Lo = (Lmin + Lmax) / 2), the laser beam The amount of deviation of the spot between the nearest point and the farthest point is equal, and the spot can be minimized over the entire range. In addition, when there is a distance in the detection distance range where the detection sensitivity is particularly desired to be increased, it is preferable to set the condensing point P at a position in the vicinity thereof.

  Furthermore, as a way of thinking, the amount of laser beam spot deviation can be relatively reduced by setting the condensing point P as the farthest point. That is, since the occurrence of the original spot deviation amount is caused by the deviation of the arrangement of the semiconductor laser elements 23a to 23c, the deviation amount of the arrangement is the largest, and this is the focus point P. When the light is condensed, the amount of deviation at the light condensing point P is minimum, that is, zero. Therefore, at any position closer than that, the spot interval can be set to any amount smaller than the arrangement interval of the semiconductor laser elements 23a to 23c. is there.

According to this embodiment, the following effects can be obtained.
First, the three semiconductor laser elements 23a to 23c are connected in series to the signal generating circuit 24 so as to be fed, and the respective laser beams are separated by lenses 25a to 25c which are independent optical systems. Since the light is condensed and projected so as to be parallel light, even when a plurality of semiconductor laser elements 23a to 23c are provided, the light emission operation can be performed with a current amount of one, In addition, it is possible to avoid power loss due to the provision of a resistance element for impedance adjustment, and the condensed laser light can be condensed within a target measurement distance range. It is possible to reduce the deviation of the light spot as much as possible to suppress the decrease in the light amount even at the farthest point, and to perform the distance measurement efficiently and accurately.

  In the above-described case, a configuration in which the three semiconductor laser elements 23a to 23c are connected in series is adopted. However, the semiconductor laser chip 26 is generally used in the case where a failure that prevents lighting for some reason occurs. Therefore, even if one of them is short-circuited, it does not electrically block the conduction state of other semiconductor laser elements. Rather, the same reliability as when connected in parallel can be ensured.

  Secondly, since the laser light from the semiconductor laser elements 23a to 23c, which is focused on the parallel light through the lenses 25a to 25c, is set in the middle of the detection distance range, the distance between the farthest point and the nearest point of the detection distance range. In both cases, the laser beam spot shift amount can be set to the smallest, and the amount of reflected light can be increased by suppressing the decrease in the amount of light as much as possible within a wide detection distance range, and the detection distance is extended. Thus, the detection accuracy can be improved.

  Thirdly, an operation unit 14 is provided so as to two-dimensionally scan the light projected by the light projector 13 within a predetermined area in front of the automobile 12, and the distance in each of the light projected areas scanned by pulsed laser light is set. Since it is possible to measure, even if the moving direction of a moving body such as an automobile without a track fluctuates left and right or up and down, the distance of an object existing in the moving direction is detected flexibly. Will be able to.

  Fourth, since the package 27 of the semiconductor laser elements 23a to 23c can be used as a three-terminal package, there is no need to newly manufacture a package for this purpose. The two electrodes of the semiconductor laser chip 26 are led out from the lead terminals 29a and 29b, so that they can be drawn out in a state of being insulated from the metal base 28, and the metal base 28 is connected to the ground terminal, so that mounting is possible. Alternatively, a stable operation can be performed on the circuit configuration.

  Fifth, since two Au wires 33 for bonding the semiconductor laser chip 26 are bonded to each other at each bonding point, it is usual to avoid a concentration of current on one Au wire 33. Even when one of them is disconnected for some reason, the lighting state of other semiconductor laser elements connected in series can be maintained. Therefore, it is possible to suppress the life of the light projecting operation as much as possible even when the disconnection occurs.

(Second Embodiment)
FIGS. 11 and 12 show a second embodiment of the present invention. The difference from the first embodiment is that a package 36 is provided instead of the package 27 of the semiconductor laser elements 23a to 23c. The package 36 includes two lead terminals 38a and 38b on a metal base 37 as shown in FIG. The metal pedestal 39 is disposed so as to be embedded in the metal base 37 and is provided in a state of being insulated from the metal base 37 through an insulator 40 such as glass. One of the lead terminals 38a and 38b is fixed to the metal base 37 via an insulator 40 such as glass, and the other lead terminal 38b is electrically connected to the metal base 39. It is fixed.

  In this embodiment, the semiconductor laser chip 26 is directly mounted on the metal base 39 as shown in FIG. At this time, the back electrode of the semiconductor laser chip 26 and the metal pedestal 39 are bonded and fixed using an Au—Sn solder foil or the like so as to be electrically connected. The lead terminal 38 a is formed with a partially flat bonding surface 41, and this portion and the upper electrode of the semiconductor laser chip 26 are bonded by two Au wires 33. The case 35 is the same as that described above, and is provided with a glass window 35a. The case 35 is attached to a metal base 37 and sealed in a can.

  In the second embodiment configured as described above, the same operational effects as those of the first embodiment can be obtained, and the dedicated package 36 is provided, so that the number of bonding steps of the Au wire 33 is reduced. In addition, the metal base 37 portion can be connected to the ground. In this case, the metal base 37 portion is not independent as a lead terminal, but can be mounted on a conductive portion such as a metal plate, and the lead terminals 38a and 38b are insulated from the metal base 37 and the case 35. Can be kept in a state.

  In the above embodiment, the semiconductor laser chip 26 is directly bonded and fixed to the metal pedestal (iron, steel, etc.) 39. For example, the semiconductor laser chip 26 may be bonded and fixed with another conductor plate or the like interposed therebetween. . In this case, it is possible to improve the reliability by selecting a material that matches the thermal expansion coefficient of the semiconductor laser chip 26 with the conductor plate.

  That is, if the semiconductor laser chip 26 is subjected to thermal stress due to a difference in thermal expansion coefficient between the metal pedestal 39 and the semiconductor laser chip 26, the semiconductor laser chip 26 is deteriorated. Therefore, the use of a conductor plate is intended to reduce thermal stress. More specifically, when the semiconductor laser chip 26 is mainly composed of GaAs, the conductor plate is made of GaAs made of the same material as the semiconductor laser chip 26, and the metal base 39 is made of a combination of iron so that the most stress is obtained. The effect of relaxation can be enhanced. Note that the insulating plate 32 shown in FIG. 2 also has a thermal stress relaxation function in the same manner as the conductor plate.

(Third embodiment)
FIG. 13 and FIG. 14 show a third embodiment of the present invention. The difference from the first embodiment is that a semiconductor laser chip 42 having a different electrode structure is provided in place of the semiconductor laser chip 26. That is, the semiconductor laser chip 42 is formed as a GaAs / AlGaAs laser chip by a large number of layers formed by an epitaxial method on a GaAs substrate which is an n-type substrate, and is the same as in the first embodiment. After the p-type electrode 43 is formed, a predetermined portion is removed by a dry etching method or the like until the n-type epitaxial layer 42a on the substrate is exposed. An n-type electrode 44 is formed.

  That is, as a result, the two electrodes 43 and 44 of the semiconductor laser chip 42 are formed so that both of the two electrodes formed on the semiconductor laser chip 26 are exposed on the same surface side. Accordingly, the bonding of the Au wire 33 is performed between the electrode 43 and the lead terminal 29a and between the electrode 44 and the lead terminal 29b. This also eliminates the need for the semiconductor laser chip 42 to be electrically connected to the insulating plate 32. Therefore, the semiconductor laser chip 42 is simply bonded and fixed.

  According to the third embodiment, the same effect as that of the first embodiment is obtained, and in addition to this, the semiconductor laser chip 42 has a structure suitable for series connection. Bonding can be performed directly, and there is no need to separately form a conductor film as a conductor pattern on the insulating plate 32.

  Since the semiconductor laser chip 42 is formed as shown in the figure, the end surface for emitting the laser light is the end surface of the portion etched for forming the electrode 44 as a reflecting mirror. In addition, the electrode 44 may be formed in a direction extending on both sides of the stripe, not limited to the formation of the electrode 44 on the side where the reflecting mirror is formed as described above. It can be formed by cleavage.

(Fourth embodiment)
FIG. 15 shows a fourth embodiment of the present invention. The difference from the first embodiment is that a light projector 45 is provided as a semiconductor light projecting device having the semiconductor laser elements 23a to 23c and each optical system integrally. A package 46 that can be used is used. Here, the basic configuration is the same as that of the first embodiment, but the three metal pedestals 48a to 48c are arranged at predetermined positions on the metal base 47 so that the three semiconductor laser chips 26a to 26c are mounted. The two lead terminals 50a and 50b are provided via an insulator 49 such as glass so as to be electrically insulated from the metal base 47.

  The semiconductor laser chips 26a to 23c are placed and fixed on the metal bases 48a to 48c through the insulating plates 32a to 32c in the same manner as described above. As shown in the figure, two Au wires 33 are bonded to each other so as to be connected in series between the semiconductor laser chips 26a to 26c, and the electrodes located at both ends are connected to the lead terminals 50a and 50b, respectively. The bonding surface 51 is bonded with an Au wire 33.

  In the case 52, three windows are formed corresponding to the three semiconductor laser chips 26a to 26c, and light projecting lenses 53a to 53c are fitted therein. These lenses 53a to 53c are adjusted so that the laser beam output points of the semiconductor laser chips 26a to 26c are located at the focal points. When the case 52 is attached and sealed, each lens 53a to 53c is positioned. The laser light emitted from 53c is converted into parallel light and is set to be condensed at a predetermined condensing point P.

  According to the fourth embodiment, in addition to the effects of the first embodiment, the package 46 for integrally providing the three semiconductor laser chips 26a to 26c and the lenses 53a to 53c as the optical system is provided. Since the projector 45 is configured by using the projector 45, it is possible to obtain the projector 45 which is provided with a compact configuration, and is easy to handle.

  In the case of using such a package 46, the position of the condensing point P cannot be changed after fabrication, but if the specification for the condensing point position is determined, troublesome optical axis adjustment and position Since there is no need to perform alignment, it is possible to fully enjoy the advantage of easy handling.

The optical system may be provided separately in consideration of optical axis adjustment and alignment. In this case, a glass window may be provided in place of the lenses 53a to 53c.
Further, the metal base 47 may be provided with a partition plate so that the laser beams from the respective semiconductor laser chips 26a to 26c do not interfere with each other. Furthermore, it is possible to add a configuration in which a monitor element is provided on the rear side of each of the semiconductor laser chips 26a to 26c to check the light emission state.

(Fifth embodiment)
16 and 17 show a fifth embodiment of the present invention, which will be described below. In this embodiment, a plurality of light emitting diodes are connected in series for lighting operation, and light projection by each of the light emitting diodes is performed corresponding to each light projecting region, and the light projecting regions that are relatively close to each other 1 shows a distance measuring device that detects the distance of an object in the interior.

  That is, as shown in FIG. 17, distance detection devices 56 a to 56 h are provided in the respective portions for the respective light projection areas 55 a to 55 h around the automobile 54. Each of the distance detection devices 56a to 56h includes light emitting diode elements 57a to 57h as semiconductor light emitting elements and a light receiver (not shown), and is configured to receive reflected light and detect the distance in the same manner as described above. ing.

  In this case, for example, the three light emitting diode elements 57a to 57c arranged relatively close to each other are connected to the signal generation circuit 58 in a state of being connected in series as shown in FIG. These three are supplied with power from the signal generation circuit 58 at the same time and are lit.

  Each of the light emitting diode elements 57 a to 57 c is mounted on a package 59 similar to a normal LED package, and two lead terminals 61 a and 61 b are fixed to a metal base 60. The lead terminal 61 a is fixed via a metal base 60 and an insulator 62, and the lead terminal 61 b is fixed so as to be electrically connected to the metal base 60.

  The diode chip 63 is formed by laminating multiple layers of GaAs / AlGaAs epitaxial layers on an n-type GaAs substrate, and is a surface-emitting type chip. The diode chip 63 is bonded and fixed to the metal base 59 so as to be electrically conductive, and two Au wires 33 are bonded and electrically connected between the electrode formed on the surface side and the lead terminal 60a. To do. The whole is molded with a light-transmitting resin to form a package 59. Note that the lens 64 is integrally formed on the upper surface portion of the diode chip 63 by this translucent resin.

  Each of the set of the light emitting diode elements 57d and 57e and the set of the light emitting diode elements 57f to 57h is driven in a state of being connected in series in the same manner as described above to perform a lighting operation. In addition, the reason why all the light emitting diode elements 57a to 57h are not connected in series is to prevent the wire harness from becoming longer and to reduce the time and effort at the time of installation.

  By adopting the above configuration, since the three light emitting diode elements 57a to 57c are simultaneously driven in series, it is possible to perform the lighting operation for three pieces with the current amount of one piece, and to drive efficiently. In addition, it can be used for applications such as detecting an object in each detection region to prevent a collision.

  In this case, according to the results obtained by the inventors, for example, the detection distances in the light projecting regions 55a to 55h by the light emitting diode elements 57a to 57h could be detected up to about 10 m. Therefore, for example, a notification operation such as displaying a lamp to the user while recognizing that an object is approaching from about several meters is performed, and further closer to about 30 cm, there is a danger of a collision. In such a case, it can be applied to a system that prompts the user by sounding an alarm.

  In the above case, the number of light emitting diode elements connected in series can be set as appropriate, and the light projecting region is not necessarily separated, and there may be a case where overlapping regions are formed. .

(Sixth embodiment)
FIGS. 18 to 24 show a sixth embodiment of the present invention. Hereinafter, parts different from the first embodiment will be described. When the distance measurement device in an automobile is configured so that the detection distance can be increased by increasing the output of the laser light as in the first embodiment, the laser light is in the human eye in consideration of the distance measurement environment. Therefore, if the output of the laser beam is increased, it is necessary to sufficiently consider this point. Therefore, this embodiment is mainly configured to be a distance measuring device capable of sufficiently satisfying the safety standard even when entering the human eye.

  In addition, in order to be able to set a long detection distance, it is necessary to increase the light density by efficiently irradiating a plurality of laser beams so as to overlap in the distance, and depending on the spot shape of the laser beam The efficiency of the irradiation region varies greatly depending on the arrangement. In this embodiment, in consideration of such points as well, a configuration capable of performing a distance measurement operation as efficiently and accurately as possible even when the spot shape in the laser light projection region is an elliptical shape. I will provide a.

  FIG. 18 schematically shows a cross-sectional structure of the semiconductor laser chip 65 mounted in the semiconductor laser elements 23a to 23c, using the material briefly described as a modification in the description of the first embodiment. Yes. That is, the semiconductor laser chip 65 is formed of a GaAs-GaInNAs-based material. In addition, although what was formed with this type | system | group material is demonstrated here, InP-GaInPAs type | system | group material which can implement | achieve the light emission wavelength of a long wavelength side is used as a material which satisfy | fills an eye safe condition so that it may mention later. You can also.

  Each of the following semiconductor layers is sequentially stacked on an n-GaAs (conductivity type n-type GaAs) substrate 66 which is a semiconductor substrate. First, a buffer layer 67 made of an n-GaAs layer having a thickness of about 0.1 μm is laminated on the GaAs substrate 66, and an n-Alx Ga1-x having a thickness of 0.5 to 1.0 μm is formed thereon. A clad layer 68 made of an As layer is laminated, and a light guide layer 69 made of an n-Aly Ga1-y As layer having a thickness of 0.1 to 1.0 μm is laminated thereon. The composition ratio values x and y in the cladding layer 68 and the light guide layer 69 are set so that each layer can obtain a refractive index necessary for its function.

  An active layer 70 is stacked on the light guide layer 69. The active layer 70 has a multiple quantum well structure by alternately stacking a plurality of layers (for example, 2 to 10 layers) of a GaInNAs layer having a thickness of 5 to 20 nm and an AlGaAs layer having a thickness of 5 to 10 nm. Formed. In this case, the equivalent bandgap energy Eg can be set by selecting the lamination conditions such as the film thickness and the number of laminations of the GaInNAs layer and the AlGaAs layer or the setting conditions of the composition ratio of each layer. The laser emission wavelength can be changed.

  When the wavelength is 1.4 μm or more, which is the condition of the eye-safe laser, for example, by setting the composition ratio of the GaInNAs layer to Ga0.87In0.13N0.04As0.96, the emission wavelength may be 1.45 μm. it can. The AlGaAs layer that constitutes the active layer 70 is set to the same composition ratio as that of the AlGaAs layer that constitutes the light guide layer 69 or to a composition ratio under the condition that the band gap energy Eg is smaller than that.

  The wavelength of 1.4 μm or more, which is the condition of the eye safe laser, was obtained based on the following criteria. When extracting the safety standard of the laser beam with the exposure time (pulse width) of 1 to 100 ns from the data of the safety standard MPE shown in JIS-C6802 as shown in FIG. Become. From FIG. 20, in the case of 1.4 μm or more, the exposure amount of several orders of magnitude or more is allowed for light on the shorter wavelength side, and it is a condition that hardly affects human eyes. I understand that.

  In the case where the active layer 70 does not employ a quantum well structure, the active layer 70 may have a double heterojunction structure in which a GaInNAs layer is formed in a single layer structure with a thickness of about 20 to 100 nm. In the case of a single layer structure, the light emission efficiency is improved as the film thickness is increased. However, since the influence of the resistance component is increased at a thickness greater than this, it is not practical.

  On the active layer 70, a p-Aly Ga1-y As layer having a thickness of 0.1 to 1.0 [mu] m is laminated as the light guide layer 71, and on this, a thickness of 0.5 to 1.0 [mu] m is formed. An Alx Ga1-x As layer is laminated as the cladding layer 72. On top of this, a p-GaAs layer having a film thickness of 0.3 to 0.5 μm is laminated as a cap layer 73. The semiconductor layers 68 to 73 including the above-described cladding layer 68 and located above the semiconductor layer 68 to 73 as a whole are formed in a mesa shape in the lateral direction in the drawing, and are perpendicular to the cross-sectional view shown in the drawing. Is formed in a stripe shape extending this shape.

  An insulating film 74 such as SiO2 is formed on the surface of the mesa-shaped portion. On the upper surface of the cap layer 73, an opening 74a is formed in the insulating film 74 with a predetermined stripe width (100 μm or more, for example, a width dimension of 400 μm), and for the p-type over the front surface together with the upper surface of the cap layer 73. An electrode 75 is coated. An n-type electrode 76 is formed on the back surface (lower side) of the n-GaAs substrate 66. The materials for the p-type electrode 75 and the n-type electrode 76 are the same as described above, and form ohmic contacts with the cap layer 73 and the n-GaAs substrate 66, respectively.

About the formation method of the above-mentioned semiconductor laser chip 65, the manufacturing process similar to having described in 1st Embodiment is used, The description is abbreviate | omitted here.
Next, advantages of using a GaInNAs-based material that outputs laser light having a wavelength in the above-described eye-safe region will be briefly described. FIGS. 19A and 19B show band diagrams for GaInNAs-based and GaInPAs-based materials. Here, a composition ratio with a wavelength of 1.3 μm is shown as an example. Regarding the wavelength band of the eye-safe laser, the composition ratio slightly changes, but basically the same effect can be obtained.

  In a semiconductor laser using GaInNAs as an active layer, the wavelength is not limited to 1.4 μm or more, and by changing the composition of N, the emission wavelength can be set in a wide range up to about 0.8 μm. In addition, since GaAs, which has been conventionally used as a semiconductor laser, is used as a substrate, there is also an advantage that the process becomes easy because many special processes are not used in the element manufacturing process.

  As shown in FIG. 5A, when the difference in energy of the band offset generated at the junction between the GaInNAs region and the AlGaAs region is seen, the energy difference ΔEc (= 570 meV) of the conduction band (conduction band). ) Is larger than the energy difference ΔEv (= 60 meV) in the valence band. This increases the effect of confining electrons in the GaInNAs region serving as the well layer, and this energy difference ΔEc makes it possible to sufficiently confine electrons in the active layer 70 even in a high temperature operating state.

  Therefore, even during high-temperature operation, both electrons and holes can be reliably confined in the GaInNAs emission region, the characteristic temperature To can be improved to the ideal value of the semiconductor laser, and an efficient light-emitting operation can be performed. . As a result, the self-heating of the element when operating at high output and the temperature characteristics are good even when used in a high temperature environment, almost no decrease in light output at the same current can be eliminated, and stable operation is performed. Will be able to. In particular, it is very effective when it is assumed to be used in an environment with a large temperature difference such as an automobile.

  Now, the semiconductor laser chip 65 formed in this way is mounted in the same manner inside the three semiconductor laser elements 23a-23c. Next, a projector 77 as a semiconductor projector with the semiconductor laser elements 23a to 23c mounted thereon will be described with reference to FIG.

  The projector 77 is mounted side by side so that the three semiconductor laser elements 23a to 23c are positioned on one straight line at a predetermined interval L (for example, L = 5 to 15 mm). At this time, each of the semiconductor laser elements 23a to 23c is arranged in a state in which the direction of the active layer 70 of the semiconductor laser chip 65 is orthogonal to the aligned linear direction. This is because, as will be described later, the arrangement of the beam spot in the light projection area is characterized by an elliptical shape.

  These three semiconductor laser elements 23a to 23c are configured to be electrically connected in series to a signal generation circuit 24 that is a power source, as described above. Projection lenses 79a to 79c, which are integrally supported by a lens holder 78, are provided as optical devices for the semiconductor laser elements 23a to 23c. As shown in the drawing, these light projecting lenses 79a to 79c project the light of each of the semiconductor laser elements 23a to 23c so as to spread at a certain spread angle, and the directions of the optical axes thereof are parallel to each other. Is set.

  Accordingly, as shown in the figure, when the laser beams from the respective semiconductor laser elements 23a to 23c are projected to positions separated by a distance d through the light projecting lenses 79a to 79c, the respective beam spots A1 to A3 are shifted by L, respectively. It will be projected in the state. The amount of deviation of the beam spots A1 to A3 is always constant regardless of the distance d. As will be described later, this contributes to a configuration that does not reduce the light density when measuring a long distance.

  In general, the shape of the beam spot projected by the semiconductor laser chip is an ellipse, and in the vicinity of the light emitting part, an elliptical shape extending in the width direction of the beam emitting part of the active layer 70 is formed, and the position is slightly apart. Is an elliptical shape whose major axis is oriented in a direction orthogonal to the active layer 70. Then, the beam spot is projected by a projection lens 79a to 79c with a predetermined spread angle. Therefore, when these beam spots are projected, the elliptical shape of each beam spot is formed in a state shifted by a distance L so that the major axis direction is directed in the vertical direction. The elliptical shape of the beam spot is set so that the vertical dimension, that is, the major axis “a” is about 2.5 to four times the lateral dimension, ie, the minor axis “b”.

  As a projection pattern of the projector 77, for example, when the spread angle is set to 1 °, the length dimension a in the vertical direction is about 10 m at a distance of 10 m when using three semiconductor laser elements 23a to 23c as shown in this example. 17 cm, and the length dimension c in the vertical direction of the region where the three projection regions overlap is 15 cm because it is reduced by L in the vertical direction. Therefore, the degree of overlap of the projection areas in this case is about 88%. At a distance of 50 m, the length dimension a in the vertical direction is about 87 cm, and the length dimension c in the vertical direction of the overlapping region is 85 cm. Therefore, in this case, the degree of overlap of the projection areas is as large as 97% or more. Thus, in other words, it can be seen that, by using the configuration of the projector 77, the overlapping region becomes wider as the distance d becomes longer.

  When the projection distance is short, the light density is still high, so that sufficient distance measurement is possible even with the light quantity of one semiconductor laser element even if the degree of overlap of the projection areas is relatively small. And the longer the projection distance, the lower the light density, and the greater the degree of overlap of the projected areas, and the distance measurement with the combined light quantity of the three semiconductor laser elements is sufficiently possible. Can be performed with higher accuracy.

  The above relationship is shown in a generalized manner with reference to FIG. That is, the degree of overlap of the projection areas is calculated for each of the measurement points D1 and D2 whose distances from the projector 77 are d1 and d2 (d2> d1). Although the number of semiconductor laser elements is three in the illustrated state, it is assumed that n semiconductor laser elements are provided. As for the beam spot shape of the semiconductor laser element, the vertical dimension a corresponding to the major axis of the ellipse is assumed to be k times the lateral dimension b corresponding to the minor axis (a = kb), and the unit distance do Let ao be the vertical dimension a.

  First, the vertical dimension a1 of the beam spot at the measurement point D1 is expressed by the following equation (1), and the dimension c1 of the overlapping portion of the projection area is expressed by equation (2). When the degree r1 of the overlapping portion is calculated from these values, Equation (3) is obtained.

a1 = d1 · ao (1)
c1 = a1-L (n-1) (2)
r1 = c1 / a1
= 1-L (n-1) / a1
= 1−L (n−1) / (d1 · ao) (3)
Next, when the values a2, c2, and r2 at the measurement point D2 are obtained in the same manner, equations (4) to (6) are obtained.

a2 = d2 · ao (4)
c2 = a2-L (n-1) (5)
r2 = c2 / a2
= 1-L (n-1) / a2
= 1−L (n−1) / (d2 · ao) (6)
As a result, it can be seen that the degree of overlap r increases as the value subtracted from 1 on the right side of Equation (6) decreases at the measurement point D2 of the distance d2. From this result, it can be seen that reducing the distance L between the semiconductor laser elements and reducing the number contribute to increasing the value of the degree of overlap r.

  Since there is no deviation in the horizontal direction, the area S of the overlapping portion of the projection areas is larger in the projection area S2 in the case of the distance d2 than in the case of the distance d1 as shown in FIG. It is clear that the degree of overlap is greater than the area of the elliptical spot.

  Next, another advantage of arranging the elliptical shape of the beam spot in such a manner that the major axis is oriented in the vertical direction will be described. FIG. 24 shows a state of light projection by the light projector 77, which corresponds to that of FIG. 8 in the first embodiment. In the case of FIG. 8, the beam spot is assumed to be circular, but in this embodiment, the beam spot is set so that the major axis is oriented in the vertical direction. Therefore, it can be used in a state where the beam spread in the lateral direction is the narrowest.

  This makes it possible to increase the number of measurement points that can be detected so that the beam spot does not protrude into an adjacent region in one horizontal scan, and the detection resolution can be increased. When driving on a road surface such as an automobile, the distance distribution in the horizontal direction is detailed in terms of the relationship between setting the travel route and the like more accurately than detecting the distribution in the distance detection in the vertical direction in detail. In this embodiment, the detection is more effective.

  According to the sixth embodiment, since the emission wavelength is set to 1.4 μm or more by using a GaAs-GaInNAs-based material as the semiconductor laser chip 65, there is a possibility that the semiconductor laser chip 65 may enter the human eye. Even when used in a certain environment, the safety standard can be sufficiently satisfied, and the light intensity can be increased and output when measuring a long distance.

  In addition, the projector 77 is arranged so that the semiconductor laser elements 23a to 23c are arranged so that their optical axes are parallel and equidistant in the same plane as described above, and they are shifted so as to overlap in the major axis direction of the elliptical shape. Therefore, the farther the irradiation is, the higher the degree of overlap of the beam spots from the semiconductor laser elements, and the longer distance measurement can be performed efficiently.

  Further, since the elliptical shape of the beam spot to the light projection area by the light projector 77 is set so that the major axis is directed in the vertical direction with respect to the ground, the detection resolution for scanning in the horizontal direction can be improved. This makes it possible to effectively measure the direction and distance with respect to the traveling direction of the automobile.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be modified or expanded as follows.

An EL element (electroluminescence element) or the like may be used as the semiconductor light emitting element.
The shape of the lead terminal of the package and the shape of the bonding surface are not limited to this shape, and can be changed as appropriate as long as a flat surface is provided.

  It is good also as a structure which provides a monitor element integrally in the semiconductor laser elements 23a-23c. For example, in the first embodiment, a monitor element such as a photodiode for detecting that the semiconductor laser chip 26 emits light is integrated in the package 27 so as to be opposite to the laser light emitting direction of the semiconductor laser chip 26. The laser beam leaking in the direction may be detected. As a result, even if a short circuit accident occurs and the output of the laser beam is stopped, this state can be detected from the detection output of the monitor element. It becomes possible to easily recognize that the light output is reduced.

  The number of semiconductor laser elements is not limited to three, and two or four or more semiconductor laser elements may be provided. If necessary. Further, the usage is not limited to condensing all the semiconductor laser elements 23a to 23c, and some of them may be condensed and used alone without condensing other semiconductor laser elements. .

Although the case where the detection target range by the projector 13 is scanned two-dimensionally has been described, a configuration may be adopted in which detection is performed by scanning one-dimensionally.
Although the case where the semiconductor light projecting device is applied to the distance measuring device has been described, the present invention is not limited to this, and it is used for a device that detects an object that blocks the light in a state where light is projected by the semiconductor light projecting device. You can also. Accordingly, it can be applied to a security system that detects an unauthorized intruder and issues an alarm.

  In addition to automobiles, mobile objects equipped with distance measuring devices can be mounted on mobile objects such as motorcycles and trains, and mobile objects such as helicopters and airplanes. Further, the present invention can also be applied to a transport vehicle or a mobile robot that moves unmanned on or in a track.

The light projecting area to be detected can be arranged not only in the traveling direction of the moving body but also in the left-right direction and the rear to measure the distance.
The distance measuring device is not limited to a moving body such as an automobile, but can be mounted on a building or a robot.

  In the configuration of the semiconductor laser chip 65 according to the sixth embodiment, the light guide layers 69 and 71 are described. However, the semiconductor laser chip 65 may be configured so as to be directly sandwiched between clad layers.

  Even when the semiconductor laser chip 65 using a GaInNAs-based material or a GaInPAs-based material is used, the eye-safe wavelength can be set to a wavelength of 1.4 μm or less. In this case, the eye-safe problem can be solved by using the output at a reduced output or in an environment where there is no possibility of being incident on the human eye when the output is high.

  As the projector 77, the semiconductor laser elements 23 a to 23 c are arranged on a straight line at equal intervals L, and the projected beam spots are overlapped so that the elliptical shapes of the projected beam spots are shifted by the arrangement interval L in the major axis direction. Since the optical axes are adjusted by arranging the lenses 79a to 79c, the degree of overlapping of the projection areas can be increased as the distance increases, and an efficient light projecting operation can be performed by measuring the distance over long distances. The detection accuracy can be improved.

  Furthermore, since the direction of the beam spot projected by the projector 77 is set so that the major axis of the ellipse is oriented in the vertical direction, the detection resolution in the lateral direction can be improved, and as a measurement condition when applied to an automobile It can be used effectively.

  In the sixth embodiment, the case of setting the three arrangement relationships when the beam spot shape in the light projection region by the semiconductor laser element is an elliptical shape has been described. When adjusting to be a spot, the same effect can be expected even if the arrangement condition for the semiconductor laser element is arranged so as to be positioned at the apex of the equilateral triangle as in the first embodiment.

The electrical block diagram of the principal part which shows the 1st Embodiment of this invention. Exploded perspective view showing internal configuration of semiconductor laser device (Part 1) Schematic vertical side view of a semiconductor laser device Schematic block diagram of distance measuring device Equivalent circuit diagram of the projector The figure explaining the relationship between a semiconductor laser element and a condensing point Diagram explaining the positional relationship of distance measurement The figure which shows the detection range which scans a laser beam Exploded perspective view showing internal configuration of semiconductor laser device (Part 2) Exploded perspective view showing internal configuration of semiconductor laser device (Part 3) FIG. 2 equivalent view showing the second embodiment of the present invention 3 equivalent diagram FIG. 2 equivalent view showing the third embodiment of the present invention Schematic sectional view of the semiconductor laser chip 42 FIG. 2 equivalent view showing a fourth embodiment of the present invention FIG. 3 equivalent view showing the fifth embodiment of the present invention The figure which shows the arrangement | positioning state of a distance detection apparatus Schematic sectional view of a semiconductor laser chip showing a sixth embodiment of the present invention Band diagram of the active layer to explain the band gap The figure which shows the relationship of the safety standard MPE with respect to the light emission wavelength of a laser beam with a pulse width of 1-100 nm. The figure which shows MPE with respect to the eye in the observation state in a beam shown by the relationship between light emission wavelength and exposure time The figure which shows the relationship between the arrangement state of a projector and the projection state of a beam spot The figure explaining the relationship between the projection distance and overlap of a semiconductor laser element Equivalent to FIG. The figure explaining the amount of deviation of the spot of the laser beam showing a conventional example (short distance) Illustration explaining the amount of laser beam spot deviation (far)

Explanation of symbols

11, 56a to 56h are distance measuring devices, 12 is an automobile (moving body), 13 and 45 are projectors (semiconductor projectors), 14 is a scanning unit (projecting scanning means), 16 is a light receiving lens, and 17 is a light receiving element. (Light receiving means), 20 is a time measuring circuit, 21 is a control circuit, 22 is a reflector, 23a to 23c are semiconductor laser elements (semiconductor light emitting elements), 24 and 58 are signal generation circuits (power supplies), and 25a to 25c are lenses. (Optical device), 26 and 42 are semiconductor laser chips, 27, 36, 46 and 59 are packages, 28, 37, 47 and 60 are metal bases, 29a to 29c, 38a and 38b, 50a, 50b, 61a and 61b are Lead terminals, 30, 40, 49, 62 are insulators, 31, 39, 48a to 48c are metal bases, 32 is an insulating plate, 33 is an Au wire (bonding wire), 34, 41, 51 Bonding surface, 35 and 52 are cases, 35a is a glass window, 53 is a lens (optical system), 55a to 55h are projection areas, 57a to 57c are light emitting diode elements (semiconductor light emitting elements), 63 is a diode chip, and 64 is A lens, 65 is a semiconductor laser chip, 66 is an n-GaAs substrate, 69 and 71 are light guide layers, 70 is an active layer, 77 is a projector, 78 is a lens holder, and 79a to 79c are projector lenses.

Claims (14)

A plurality of semiconductor light emitting elements, and a plurality of optical devices that are provided for each of the plurality of semiconductor light emitting elements and guide emitted light to a predetermined light projecting region, The optical axis is adjusted so that light emitted from a plurality of semiconductor light emitting elements is condensed and projected to one light projecting area, and the plurality of semiconductor light emitting elements are connected to a power source. A semiconductor light projecting device configured with a power supply path for supplying power in a state of being connected in series;
A light receiving means for receiving reflected light from an object existing in a light projecting region of the semiconductor light projecting device;
And detecting means for detecting a distance to an object existing in the light projecting region by measuring a time from a light projecting time by the semiconductor light projecting device to a light receiving time of the reflected light by the light receiving device. A distance measuring device. The distance measuring device according to claim 1,
When the spot shape in the light emitting region of the semiconductor light emitting device is an elliptical shape,
The plurality of optical devices are arranged in a state where respective optical axes are arranged in parallel and at equal intervals in the same plane,
The distance measuring device, wherein the plurality of semiconductor light emitting elements are arranged such that spots in a light projecting region are overlapped with each other in a major axis direction of an elliptical shape. The distance measuring device according to claim 1 or 2,
The distance measuring device is characterized in that the detecting means controls the semiconductor light projecting device to light a pulse. The distance measuring device according to claim 3,
The distance measuring device, wherein the optical device is configured in a state in which an optical axis is adjusted so that a light condensing point is positioned within a detection distance range of light emitted from the plurality of semiconductor light emitting elements. . The distance measuring device according to claim 4,
The distance measuring device, wherein the position of the condensing point set by the optical device is adjusted to the farthest point within the range of the detection distance. The distance measuring device according to claim 4,
The distance measuring device, wherein the position of the condensing point set by the optical device is adjusted to an intermediate point within the range of the detection distance. The distance measuring device according to any one of claims 3 to 6,
A light projecting scanning means for scanning a light projecting direction of light emitted by the semiconductor light projecting device within a predetermined range;
The detection means detects the distance while scanning the light projection area of the semiconductor light projection device via the light projection scanning means, and detects the distance corresponding to each of the scanned light projection areas. A distance measuring device that is configured. The distance measuring device according to claim 7,
The distance measuring device, wherein the light projecting scanning unit is configured to two-dimensionally scan a light projecting direction of light emitted by the semiconductor light projecting device. The distance measuring device according to any one of claims 1 to 8,
A distance measuring apparatus mounted on a moving body and configured to detect a distance of a light projecting area corresponding to the traveling direction thereof. The distance measuring device according to claim 9,
The distance measuring apparatus, wherein the moving body is an automobile. The distance measuring device according to claim 9 or 10,
When the spot shape in the light emitting region of the semiconductor light emitting device is an elliptical shape,
A distance measuring device characterized in that a spot of light emitted by the semiconductor light projecting device is set so as to be directed in a direction perpendicular to a plane on which an elliptical major axis direction is moving. A plurality of semiconductor light emitting elements, and a plurality of optical devices that are provided for each of the plurality of semiconductor light emitting elements and guide emitted light to a predetermined light projecting region, A state in which the optical axis is adjusted so that light emitted from a plurality of semiconductor light emitting elements is projected to a plurality of light projecting regions, and the plurality of semiconductor light emitting elements are connected in series to a power source A semiconductor light emitting device characterized in that a power feeding path for feeding power is configured;
A light receiving means provided to receive each reflected light from an object existing in a plurality of light projecting regions of the semiconductor light projecting device;
And detecting means for detecting a distance to an object existing in the light projecting region by measuring a time from a light projecting time by the semiconductor light projecting device to a light receiving time of the reflected light by the light receiving device. A distance measuring device. The distance measuring device according to claim 12, wherein
Mounted on a moving body and configured to detect distances of a plurality of light projecting areas set around the moving body based on light reception signals of the plurality of light receiving means. apparatus. The distance measuring device according to claim 13,
The distance measuring apparatus, wherein the moving body is an automobile.

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