JP5955593B2 - Abnormality detection mechanism and vehicle front illumination device including the same - Google Patents

Description

  The present invention relates to a vehicle front illumination device such as a headlight or a fog lamp using a semiconductor laser element as an excitation source, and more particularly to an abnormality detection mechanism for an instrumentation system for eye safety interlock.

  Attempts have been made to adopt light-emitting diodes (LEDs) instead of halogen bulbs or high-pressure mercury bulbs as light sources for vehicle front lighting devices (hereinafter referred to as headlamps). In recent years, it can be said that some high-end cars are already in the stage of practical application because they already have LED-type headlamps, but these are currently used for low beams (higher beams) and are more expensive. It has not been adopted in high beams (running beams) that require light source brightness. Therefore, research on using a semiconductor laser element as an excitation source as a light source with even higher luminance has become active.

  In Patent Document 1, a light emitting part including a phosphor provided apart from a semiconductor laser element is used as an optical center, and light generated from the light emitting part is irradiated forward by a concave reflecting mirror. A headlamp that generates high light is disclosed.

  However, the irradiation light from the semiconductor laser element has a high spatial and temporal energy density, so that it must be handled with care from the viewpoint of eye-safety. In Patent Document 2, the light emitting element detects light emitted from a phosphor mixed with a light-transmitting member that is provided apart from the semiconductor laser element, thereby detecting the detachment of the phosphor layer. A light-emitting device for a lighting fixture that can prevent exposure to laser light by performing an interlock treatment is disclosed.

JP 2005-150041 A JP 2009-16543 A

Japanese Patent Laid-Open No. 2004-260688 performs control such as light emission stop by detecting whether or not the light emitted from the semiconductor laser element returns to the excitation source direction from the translucent resin containing the phosphor by the light receiving element. Although it is possible to discriminate completely unusable situations such as dropping and breakage of the optical member, it uses the presence or absence of fluorescence emitted from the phosphor and returning to the excitation source direction. Since it is impossible to detect damage (such as some cracks), it is not possible to perform an interlock process for laser light leakage or the like.
Furthermore, since the light receiving element has no light receiving sensitivity with respect to the light wavelength region of the semiconductor laser device as the excitation source, it has sensitivity only in the light wavelength region wavelength-converted by the phosphor, so that light is selectively captured. It is necessary to provide a wavelength selective filter that can be used, and an inexpensive Si photodiode cannot be used, which is expensive.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a light source unit abnormality detection method for interlocking related to eye safety in a headlamp using a semiconductor laser element as an excitation source. In other words, it is to provide a headlamp that ensures safety.

In order to achieve the above object, according to the first aspect of the present invention, the semiconductor laser element as the excitation source and the wavelength of at least a part of the light from the semiconductor laser element are converted into white light to the outside. A translucent wavelength conversion member that can be taken out, and an abnormality detection mechanism that detects an abnormality of the light emitting unit in a headlamp that uses the light emitting unit of the wavelength conversion member as a light source , the wavelength converting member, The top surface including the light emitting unit, a bottom surface that is a light incident surface, and one or more side surfaces that are in contact with the top surface and the bottom surface, are provided in front of the emission direction of the beam light from the semiconductor laser element, and the wavelength A support member that supports the bottom surface of the conversion member and has an opening for allowing the light beam from the semiconductor laser element to pass therethrough, and a plurality of light receiving elements that are disposed to face the side surface of the wavelength conversion member with a space therebetween And before Covering the top surface of the wavelength conversion member, having an opening at a position corresponding to the light emitting portion of the top surface of the wavelength conversion member, a shielding member joined to the support member, a preamplifier connected to the light receiving element, The above-described object is achieved by providing an abnormality detection mechanism for detecting an abnormality of the light emitting unit, which includes at least a determination device connected to an amplifier .

According to the invention described in claim 2 of the present invention, the light receiving element used in the abnormality detection mechanism is a Si photodiode, and the operating point of the Si photodiode is set to the short-circuit mode. The influence of noise due to dark current can be suppressed , and stable detection can be performed in a high temperature environment such as a headlamp.

  According to a third aspect of the present invention, the semiconductor laser element is stopped from emitting light based on an increase or decrease in the abnormality detection mechanism and a light receiving element of the abnormality detection mechanism from a certain range. Or it can be set as the highly safe headlamp by which the instrumentation circuit for eye safety interlocks was incorporated by setting it as the headlamp which comprises the light emission control means which can reduce light emission intensity.

  According to the present invention, in a headlamp using a semiconductor laser element as an excitation source, it is possible to provide a light source unit abnormality detection method for interlocking with respect to eye safety at a low cost, and thus to provide a highly safe headlamp. it can.

FIG. 1 is a diagram showing an example of a headlamp composition incorporating an abnormality detection mechanism for interlock control according to the present invention. FIG. 2 is a functional block diagram showing the optical and electrical connections of the abnormality detection mechanism that is the gist of the present invention. FIG. 3 is a diagram showing a specific embodiment of the abnormality detection mechanism in the present invention. FIG. 4 is a diagram showing an example of a preamplifier unit to be combined with the light receiving element of the abnormality detection mechanism in the present invention. FIG. 5 is a diagram illustrating an example of a determination unit that determines the detection output value of the abnormality detection mechanism according to the present invention. FIG. 6 is a diagram illustrating an example of an arrangement relationship between the wavelength conversion member and the light receiving elements when the number of the light receiving elements to be used is reduced and the number of the light receiving elements is three with respect to the embodiment illustrated in FIG. 3. FIG. 7 is a diagram illustrating an example of the arrangement relationship of the light receiving elements when the wavelength conversion unit illustrated in FIG. 6 is modified. FIG. 8 is a diagram showing a state in which two light receiving elements are connected in parallel to the preamplifier shown in FIG. FIG. 9 is a diagram illustrating an arrangement example of the preamplifiers when the preamplifiers and the light receiving elements illustrated in FIG. 8 are connected.

(Aspect of headlamp in which the present invention is used)
FIG. 1 shows an example of a headlamp composition incorporating an abnormality detection mechanism for interlock control according to the present invention. The headlamp 1 emits light that is converted into white light through the wavelength conversion member 15 by using the semiconductor laser element 10 as a light source and is appropriately light-distributed forward by the reflecting lens 21 by the prism lens 22 on the front surface of the illumination device.

  Light emitted from the semiconductor laser element 10 is collimated by a collimator lens 11 installed in a lens barrel 14 made of a black anodized aluminum material, and then, if necessary, a cylindrical lens or an anamorphic prism. The aspect ratio of the beam shape is adjusted through the beam shaper 12 using the above and the like, and the light is condensed on the incident surface 151 of the plate-like wavelength conversion member 15 by the condenser lens 13. In addition, the shaping of the beam shape is not set to an extremely low aspect, but is set in accordance with the light distribution required for the headlamp.

  The wavelength conversion unit 15 is preferably made based on an inorganic material in order to ensure heat resistance and heat diffusibility, and is made of, for example, a phosphor-dispersed glass or a translucent phosphor ceramic plate. The phosphor is particularly preferably a nitride-based Ca-α sialon-based phosphor that has a low degree of thermal deterioration phenomenon and temperature quenching phenomenon and is free of moisture resistance and corrosion due to hydrogen sulfide.

  The semiconductor laser device 10 has a light emission wavelength in a purple to blue region, and has a broad stripe structure that is a basic structure of a high-power semiconductor laser. Accordingly, the intensity distribution of the beam cross section has a plurality of undulations due to a large number of mixed horizontal and transverse modes of oscillation, and it is difficult to say that it is suitable as a light source for illumination. Functions as a light-emitting portion having a smoothed light intensity distribution. Although not shown, the semiconductor laser element 10 is subjected to heat radiation treatment with a heat sink or a heat pipe in order to ensure the life.

  Here, a plurality of light receiving elements 16 and a shielding member 17 which are arranged close to the lateral side surface of the plate-like wavelength conversion member 15 indicate an abnormality detection mechanism part which is a main part of the present invention. 16, a part of the laser light incident on the light incident surface 151 of the wavelength conversion member 15 is always detected as diffuse propagation light in the side surface direction of the wavelength conversion member 15.

  The light receiving element 16 is desirably a Si photodiode having a maximum sensitivity wavelength of 800 nm or more, preferably around 900 nm. The Si photodiode has a sensitivity region of 400 nm or more, and can convert a laser light used as an excitation source into light having a wide spectral width converted into a photocurrent. If the operating point is set to the short-circuit mode, the short-circuit current Isc has excellent linearity with respect to the amount of incident light, does not generate noise due to dark current, and has a wide dynamic range. Further, in the case of incident light in the visible region that is shorter than the maximum sensitivity wavelength, the variation characteristic of sensitivity with temperature is almost zero. Although the maximum sensitivity wavelength shifts to the short wavelength side as the temperature rises, if the maximum sensitivity wavelength is 800 nm or more at room temperature, it is considered that the wavelength region of the detection light can be substantially included even in the temperature environment of the headlamp.

The shielding member 17 is a plate material provided with an opening in the center corresponding to the light emitting portion on the upper surface of the wavelength conversion member 15, and fixes the wavelength conversion member 14 to the support member 20 provided with the opening , and disturbs the light receiving element 16. It also has a function as a shielding means for preventing incidence of light and stray light. The shielding member 17 is made of a rigid metal material (for example, SUS304, SUS305, etc.), and is coated with a highly heat-resistant black paint (matte cashew resin paint, ceramic tyrano coat, etc.) in order to prevent reflection and scattering of light. The support member 20 is made of a metal plate (for example, galvanized steel plate SECC, SEHC, etc.), and is coated with the same black paint as the shielding member 17.

(Function block diagram)
The present invention receives a slight change in the amount of light propagation in the lateral direction of the wavelength converter 15 when the wavelength converter 15 is damaged by the laser beam condensed in the headlamp shown in the example of FIG. By detecting with the element 16, the abnormality of the apparent light source formed on the surface of the wavelength conversion unit 15 is detected, and the interlock is operated through the instrumentation circuit included in the control unit in the driving unit of the semiconductor laser light source. It is the purpose.
FIG. 2 is a functional block diagram showing optical and electrical connections of the abnormality detection mechanism that is the gist of the present invention.

  FIG. 3 shows a specific embodiment of the anomaly detection mechanism according to the present invention centering on the wavelength conversion member 15. The wavelength conversion member 15 is a plate-like member having a deformed octagonal shape in which the four corners of a square are cut off at an angle of 45 degrees. Is done. The light emitting surface 151 is formed with a convex portion serving as a light emission center target. The laser beam is set to be focused with this position as a target.

An opening is provided in the center of the shielding member 17 to regulate the size of the apparent light source formed on the light emitting surface 151 of the wavelength conversion member 15. The support member 20 is provided with an opening in accordance with the beam incident position on the light incident surface 152, and regulates the thickness of the laser beam.

  The four light receiving elements 16a to 16d are installed so that the light receiving windows face the four side faces corresponding to the four directions of the wavelength conversion member 20, and the shielding member 17 is formed by the provided U-shaped cutouts. The position of 16d is fixed, and ambient light entering the light receiving element from the surroundings is shielded.

  Reference numeral 19 denotes a circuit board on which the preamplifiers 18a to 18d are formed. An organic substrate is used intentionally so as to reduce the tilt caused by heat from the support member 20. The substrate 19 is subjected to moisture-proof coating with a fluororesin coating agent after the electronic circuit constituting the preamplifier is mounted. The connection from the preamplifier to the next-stage determination device formed on the main control board (not shown) is wired from the board 19 through a hole provided at a predetermined position of the support member 20 by a cable. The

(Preamplifier)
As described above, it is preferable that the light receiving elements 16a to 16d use Si photodiodes and set their operating points to the short-circuit mode. In this case, as shown in FIG. 4, the combination with a transimpedance amplifier circuit using an operational amplifier is the best so that the apparent load becomes zero. (In practice, Rf / A corresponds to the load resistance. Here, Rf is a feedback resistance and A is an operational amplifier open gain.)

  The operational amplifier used here is of a low input bias current type, but it should be selected from bipolar operational amplifiers, for example, avoiding a common FET input operational amplifier as a low input bias current type (for example, AD620 from Analog Devices). AD706 etc.). This is because the operation of the headlamp in which this product is installed requires high-temperature operation, and the FET input type operational amplifier, in which the input bias current increases extremely at high temperatures, has a photocurrent detection error. It will be bigger.

(Determinator)
As the determiner, for example, a window comparator circuit as shown in FIG. 4 is used. In the case of the configuration of the detector as shown in FIG. 2, a total of four determinators are required to determine the outputs of the preamplifiers 18a to 18d. Since the output of the preamplifiers 18a to 18d is reduced in impedance, the installation location of the window comparator is separated from the preamplifiers 18a to 18d by a control unit including a laser CW drive unit and an interlock instrumentation circuit. It may be on a main board (not shown) to be mounted.

  In the window comparator of FIG. 4, the two are set to be between two reference voltages (high and low) in normal times and the output is H level, but the wavelength conversion member 15 is cracked or the like. When the amount of light diffused and propagated in the direction of the light receiving elements 16a to 16d decreases, the output of COMP2 becomes L and the output to the control unit also becomes L level. The direction of the light receiving elements 16a to 16d is due to the generation of stray laser light due to an abnormality of the optical system in the lens barrel 14 or the radiation output from the laser light source 10 itself (abnormality of the constant current driver of the driving unit). When the amount of light diffused and propagated increases, the output of COMP1 becomes L and the output to the control unit also becomes L level.

  Therefore, when normal, it is H level, and when there is an abnormality due to two failure modes for each threshold, both outputs become L level, and the interlock instrumentation circuit after the control unit (for example, the laser light output is suppressed to an intrinsically safe level, Alternatively, a signal is output to the laser light emission stop due to power supply line interruption.

  Although Example 1 is an example of an abnormality detection mechanism using four light receiving elements as shown in FIG. 2, the arrangement and number of light receiving elements are not limited to this. For example, FIG. 6 shows an example of the arrangement relationship between the wavelength conversion member 315 and the light receiving elements when there are three light receiving elements. In this case, the wavelength converting member 315 has a shape in which three vertex portions are cut off from a substantially regular triangle at right angles to the center direction to provide three planes, and the light receiving elements 16a to 16c are arranged so that the plane and the light receiving surface face each other. It is arranged in. The treatment after the preamplifiers 18a to 18c is the same as that of the first embodiment.

  In this case, the wavelength converting member 315 is not limited to this shape, and the shape is appropriately determined in accordance with the arrangement of the light receiving elements so that the detection efficiency of the amount of light diffused and propagated from the laser light incident position in the lateral direction is increased. Shape optimization may be performed. For example, the wavelength conversion member 3155 in FIG. 7 is obtained by deforming three sides of an equilateral triangle that is an envelope shape that is a base of the wavelength conversion member 315 in FIG. The condensing rate of the light diffused and propagated in the lateral direction from the incident position of the laser light to the directly facing surface is improved.

  In the abnormality detection mechanism described with reference to FIG. 2 in the first embodiment, the preamplifier is arranged using four light receiving elements, but the arrangement of the light receiving elements 16a to 16d and the wavelength conversion member 15 is the original. It is also possible to reduce the number of sets after the preamplifier.

  FIG. 8 shows a structure in which two light receiving elements are connected in parallel to the operational amplifier input based on the preamplifier shown in FIG. In this circuit, the operation of the light receiving element is in the short-circuit mode, and the light receiving element functions as a current source.

Accordingly, the number of the pre-amplifiers can be reduced from four to two if the configuration of the light-receiving element in FIG. 2 is not provided separately for the light-receiving elements. Since the determiner is also configured with the preamplifier, the number is similarly reduced from four to two.
In this way, with the configuration of the preamplifier according to FIG. 4, the number of sets after the preamplifier can be reduced by using a plurality of light receiving elements connected to the operational amplifier input.

  However, in the case of the connection according to FIG. 8, since the substantial detection sensitivity to the abnormality is reduced to about ½, the number of light receiving elements connected to the input of the operational amplifier is not additionally connected, but a detection margin The number must be determined while evaluating This is because, as the number of light receiving elements connected in parallel increases, the threshold setting of the determination unit becomes a troublesome operation, and as a result, it is expected that the stability of the abnormality detection function is impaired. As shown in FIG. 8, it is safe to accommodate the light receiving elements in about two at most.

FIG. 9 shows an arrangement example when the preamplifier and the light receiving element are connected according to FIG. The wavelength conversion member 15 and the light receiving elements 16a to 16d are the same as the arrangement in FIG. Only the preamplifier unit is 418a and 418b, the light receiving elements 16a and 16d are connected to the preamplifier unit 418a, and the light receiving elements 16b and 16c are connected to the preamplifier unit 418b.
In this example, two adjacent light receiving elements are adjacent to each other. Of course, although the wiring of the substrate portion on which the preamplifier is formed is complicated, the light receiving elements that form a pair may be two facing each other.

The arrangement and configuration of the wavelength conversion member and the light receiving element in the above embodiment, and the combination of the light guide member are merely examples, and are not limited thereto. For example, the wavelength conversion member may be a three-dimensional shape instead of a simple flat plate, and the coupling portion of the light receiving element may be provided in another space not on the holding member.
Based on the present invention, the above-described procedure will be a possible modification for those skilled in the art.

  The present invention relates to a safety interlock detection mechanism necessary for a high luminous flux white illumination device using a semiconductor laser element as a light source. In addition to a headlight for a vehicle, a front illumination device for a fog lamp, a projector device, etc. It can also be used as a light source abnormality detection mechanism.

DESCRIPTION OF SYMBOLS 1 Headlamp 10 Semiconductor laser element 11 Collimator lens 12 Cylindrical lens or anamorphic prism 13 Condensing lens 14 Lens barrel 15,315, 3155 Wavelength conversion member 16,16a, 16b, 16c, 16d, Light receiving element 17 Shielding member 18a, 18b, 18c, 18d, 418a, 418b Preamplifier 19 Circuit board 20 Support member 21 Reflector 22 Prism lens 151 Light incident surface of wavelength conversion member 152 Light emission surface of wavelength conversion member

Claims (3)

Semiconductor laser element as excitation source, translucent wavelength conversion member capable of converting wavelength of at least part of light from semiconductor laser element and taking out to outside as white light, and light emitting portion of said wavelength conversion member An abnormality detection mechanism for detecting an abnormality of the light emitting unit in a vehicle front illumination device using a light source as a light source ,
The wavelength conversion member includes a top surface including the light emitting unit, a bottom surface that is a light incident surface, and one or more side surfaces in contact with the top surface and the bottom surface,
A support member provided in front of the emission direction of the beam light from the semiconductor laser element, supporting a bottom surface of the wavelength conversion member, and having an opening for passing the beam light from the semiconductor laser element;
A plurality of light receiving elements installed so as to face each other on the side surface of the wavelength conversion member,
A shielding member that covers the top surface of the wavelength conversion member, has an opening at a location corresponding to the light emitting portion of the top surface of the wavelength conversion member, and is joined to the support member;
A preamplifier connected to the light receiving element;
A determiner connected to the preamplifier;
An abnormality detection mechanism for detecting an abnormality in the light emitting unit .
The abnormality detection mechanism according to claim 1, wherein the light receiving element is a Si photodiode, and an operating point of the Si photodiode is set in a short-circuit mode .
An abnormality detection mechanism according to claim 1 and a light emission control means capable of stopping light emission or reducing light emission intensity of the semiconductor laser element based on a detection value of a light receiving element of the abnormality detection mechanism. A vehicle front lighting device characterized by:

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