Apparatus with light-emitting element

Abstract: This invention relates to a light-emitting apparatus, a photosemiconductor apparatus and a method for producing a photosemiconductor wherein the light-emitting apparatus for emitting light on an object comprises a substrate; a light-emitting element provided on the substrate; an optical member provided on a predetermined position to the substrate; a light-receiving element provided on the substrate, the light-receiving element receiving a part of light beam emitted from the light-emitting element on the object via the optical member; and means for controlling a quantity of the beam projected from the light-emitting element on the object, based on an output signal from the light-receiving element.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a photosemiconductor apparatus having a light-emitting element according to the preamble of claim 1. More particularly, the invention relates to a light-emitting apparatus which is arranged to be able to control with high precision a quantity of emitted light from a light-emitting element such as a laser diode, a photosemiconductor element preferable for obtaining information about motion of a moving object by letting light beam outgoing from a light-emitting element such as a laser diode illuminate for example a moving object and detecting diffracted or scattered light subjected to phase modulation operation according to alteration or motion of the moving object, and methods for producing them. Related Background Art There are various conventional light-emitting apparatuses proposed, in which a light-emitting element such as a laser diode and a light-receiving element such as a photodiode are set in a single casing, a part of light beam from the light-emitting element is received by the light-receiving element, and a light quantity of outwardly emitted light from the light-emitting element is controlled utilizing output signals from the light-receiving element. Fig. 1 is a perspective view of major part in the structure of package for the laser diode as a conventional light-emitting apparatus of this type. In Fig. 1, reference numeral 1 designates a light-emitting element (laser diode), and 2 a light-receiving element (photodiode), which are mounted on a stem 3 also serving as a heat sink. They are covered with a cap 5 having an exit opening with a transparent glass plate 4, and the inside is filled with inert gas under hermetic seal. Each electrode for light-emitting element or light-receiving element is connected by wire bonding to a lead terminal which is led to the outside. Fig. 2 and Fig. 3 are cross sectional views as extracted and exploded to show the light-emitting element 1 and the light-receiving element 2 shown in Fig. 1. In case that the light-emitting element 1 is a laser diode, laser beams are emitted from both ends thereof. One beam 6 thereof is guided to the outside through the glass plate 4 on the package exit opening and is used as a light source. A part of another beam 7 is received by the light-receiving element 2 for a monitor. Such apparatus is generally used to obtain a constant-power laser beam, generally using a control circuit (APC: Automatic Power Control) for controlling a current in the laser diode such that a quantity of light entering the light-receiving element 2 is always constant. In the meantime, there are also various conventional proposals on apparatus in which light from a light-emitting element is made to illuminate an object (moving object) and diffracted or scattered light from the object is detected, whereby information as to object movement such as motion or displacement of object is attained with high precision, for example optical encoders, laser Doppler velocimeters, laser interferometers, and the like. In addition, a variety of apparatus such as compact disk, magneto-optical disk, CD-ROM, and the like have been proposed as apparatus for obtaining desired information by making light irradiate on an object. In either of the apparatuses, set in a single casing are the light-emitting element as a light source, the light-receiving element for receiving optical signals and converting them into electric signals, and other optical elements such as lens, beam splitter, mirror, and the like. Since either of the apparatus is constructed by assembling separate elements, precise adjustment is necessary for optical position upon positioning the elements, which requires much labor and time. Further, it is expected that the size of each optical element will be further miniaturized in the future. In this occasion, the precision of optical position for each element must be enhanced in proportion to the size reduction. For example, in JP-A-62-196880 it is proposed a photosemiconductor apparatus for CD pickup is designed such that the size of entire system is more reduced. JP-A-62-196880 discloses that a laser diode and a prism having a beam splitter function are respectively mounted on a semiconductor substrate on which a light-receiving unit is provided, signal light is guided to return on the same optical path as one through which light from the laser diode is guided to the outside, and the signal light is separated and reflected by the prism to obtain servo signals (signal light). There have been proposed that variety of conventional production methods of photosemiconductor apparatus in which elements constituting such photosemiconductor apparatus are arranged at high precision on a semiconductor substrate. An example method is a method in which a spherical collimating lens or the like is provided for a sealing cap of laser diode, the spherical lens on the cap is aligned with a light-emitting source, and then the lens is fixed. JP-A-63-127444 proposes a production method as shown in Figs. 4A to 4D and Figs. 5A to 5D. At the steps in Figs. 4A and 4B, a light detection element is formed for each of plural chips (11) on a silicon wafer (10). At the step in Fig. 4C, mounted on the silicon wafer (10) are rod chip bars (15) each having a plurality of semiconductor lasers aligned in parallel with the direction perpendicular to the longitudinal direction of the chips (11). Then at the step in Fig. 4D, the silicon wafer (10) is heated to have the chip bar (15) melt-bonded to the silicon wafer. Further at the step in Fig. 5A, rod prisms (16) are bonded onto the light detection elements so as to be in parallel with the chip bars (15). Then the bonded prisms (16) and the silicon wafer is cut together to obtain a plurality of laser couplers at the same time as shown in Fig. 5B. Fig. 5B shows a laser coupler. Each laser coupler is completed after die bonding process and wire bonding one as shown in Fig. 5C and Fig. 5D, respectively. In these production methods, the size of each optical element used is as small as a square of several mm to less than a square of 1 mm to obtain a smaller photosemiconductor apparatus. In the laser coupler shown in Figs. 4A, 4B, 4C, 4D and Figs. 5A, 5B, 5C, 5D, a prism in the size of about 1.8×1.6×0.6 mm has functions for bending an output beam from the laser diode and for beam-splitting an input light. According to JP-A-4 199 890, a surface emission type laser diode, a monitoring photodiode and a signal reproducing photodiode are provided on a common substrate. A shield member is not recognizable. JP-A-2 063 182 discloses a semiconductor laser device comprising a cap being filled with an inactive gas. Further light emitting devices are known from US-A-4 182 977 and JP-A-63-127 444. JP-A-3 192 783 shows a light emitting element which emits a signal light from its one end and a monitor light from its other end. A generic photosemiconductor apparatus is known from the JP-A-61 071 681. This documents shows a light emitting device with a light receiving element. This device comprises a light emitting element, a shielding member and a light receiving element which are provided on a common substrate. Light emitted from the light emitting element is directed to an object to be inspected and the light reflected from the object is incident on the light receiving element. Due to the presence of the shielding member, noise can be reduced. It is an object of the present invention to further develop a photosemiconductor apparatus according to the preamble of claim 1 such that always a constant quantity of light emitted from the light emitting element to the outside is kept by precisely monitoring the quantity of light emitted from the light emitting element to the outside. This object is achieved by a photosemiconductor apparatus having the features of claim 1. Advantageous further developments are set out in the dependent claims. According to the present invention, the light-emitting apparatus can keep always constant a quantity of light emitted from a light-emitting element to the outside by precisely monitoring the quantity of light emitted from the light-emitting element to the outside. The photosemiconductor apparatus is free of bad influence of noise light and can detect signal light with high precision. The apparatus having the light-emitting element of the present invention will be described in detail with an embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view to show a major part of a conventional light-emitting apparatus; Fig. 2 is an explanatory view to show a part of the apparatus shown in Fig. 1; Fig. 3 is an explanatory view to show a part of the apparatus shown in Fig. 1; Figs. 4A, 4B, 4C and 4D are schematic views to illustrate a conventional method for producing a photosemiconductor apparatus; Figs. 5A, 5B, 5C and 5D are schematic views to illustrate a conventional method for producing a photosemiconductor apparatus; Fig. 6 is a perspective view to show a major part of an Embodiment of photosemiconductor apparatus according to the present invention; Fig. 7 is a plan view to show a major part of the Embodiment of photosemiconductor apparatus according to the present invention; Fig. 8 is an explanatory view to show a part of the Embodiment of photosemiconductor apparatus according to the present invention; and Fig. 9 is a cross sectional view of the major part of the Embodiment of photosemiconductor apparatus according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 6 is a perspective view to show a major part of a portion of an Embodiment of an apparatus having a light-emitting element, and Fig. 15, Fig. 16 and Fig. 17 are a plan view of major part of the present invention, a schematic view of a portion, and a cross sectional view of major part, respectively, to show the Embodiment of photosemiconductor apparatus. In the drawings, numeral 101 designates a light-emitting element such as a laser diode, LED and SLD, which is mounted on a sub-mount 102. The light-emitting element 101 emits a light beam 101a from one end face and a light beam 101b from the other end face. The sub-mount 102 is provided on the surface of semiconductor substrate 108. Numeral 105 denotes a reflecting prism with a reflective surface of slant surface, in which three reflecting prisms 105a, 105b, 105c are incorporated through light absorbing members 105d, 105e in between. Among them, the reflecting prism 105b reflects an output light beam 101a emitted from the light-emitting element 101, and thereafter enters a lens 131b in optical unit 103 as described below. Numeral 103 is an optical unit, which includes three lenses 131a, 131b, 131c corresponding to the three reflecting prisms 105a, 105b, 105c on one surface thereof and three gratings 132a, 132b, 132c corresponding to the three lenses 131a, 131b, 131c on the other surface thereof. Among them, the lens 131b condenses the light beam (output beam) 101a emitted from the light-emitting element 101 and then reflected by the reflecting prism 105b and forms the light beam as parallel one to enter the grating 132b. Numeral 106 denotes a light shield member, in a portion of which three openings 106a, 106b, 106c are provided corresponding to the three reflecting prisms 105a, 105b, 105c. The light shield member 106 is formed for example by applying etching to a metal plate or by perforating a light-shielding film. Numeral 151 is a light-guide prism, in which three prisms 151a, 151b, 151c each with reflective surface having slant surface are incorporated through light absorbing members 151d, 151e in between. The light-guide prism 151 reflects by its reflective surface a beam passing through an opening in the light shield member 106 and thereafter guides it to a light-receiving element (140, 141a, 141c) as described below. Numeral 140 designates a light-receiving element for APC (Automatic Power Control), and 141 (141a, 141c) light-receiving elements for signal light. The light-receiving elements 140, 141a, 141c are provided on the surface of the same semiconductor substrate 108. Numeral 107 represents a package. In the present embodiment, the output light 101a emitted from the light-emitting element 101 is reflected by the reflecting prism 105b, the reflected light is condensed by the lens 131b to be changed into a parallel beam, and the parallel beam then enters the grating 132b. The grating 132b diffracts the output light 101a and the diffracted light irradiates an object (not shown) located in a predetermined direction. For example, the object corresponds to a moving object in case that the photosemiconductor apparatus of the present invention is applied to a linear encoder or the like. Signal light reflected by the object passes through the grating 132a (132c), diffracted light is condensed by the lens 131a (131c), the condensed light is reflected by the reflecting prism 105a (105c), and thereafter the reflected light enters the opening 106a (106c) in the light shield member 106. The light-guide prism 151a (151c) guides the signal light passing through the opening 106a (106c) in the light shield member 106, onto the light-receiving element 141a (141c). Information as to movement of the moving object is detected using signals from the light-receiving element 141a (141c). On the other hand, the light beam 101b emitted from the other end of light-emitting element 101 passes through the opening 106b in the light shield member 106 and then passes through the light-guide prism 151b to enter the light-receiving element 140 for APC. An amount of light emitted from the light-emitting element 101 is controlled using signals from the light-receiving element 140. In the present embodiment, the projecting light path where the output light 101a is emitted from the light-emitting element 101 to be incident on the object is made different from the receiving light path where the returning light is reflected by the object to be returned the light-receiving element 141a (141c). In the present embodiment, there is provided the light shield member 106 having the openings 106a, 106c corresponding to the spot size of signal light in front of the light-guide prism 151 to thereby separate the signal light from the output light 101a, whereby noise light can be effectively prevented from entering the light-receiving element 140 for APC or the light-receiving elements 141a, 141c for signal light. This permits the light-receiving elements 141a, 141c to obtain signals having a high S/N ratio. In the Embodiment of photosemiconductor apparatus according to the present invention, as described above, if a plurality of light-receiving portions are required, they can be formed on a single semiconductor substrate, which can obviate adjustment of mutual positional relation in mounting them. Further, if amplifiers and processing circuits are built between the light-receiving elements in the substrate, the size of apparatus can be further reduced. Also, by separating the projecting light optical path from the receiving light optical path and providing the light shield members having the shielding function to independently separate these optical paths, the apparatus can have a high S/N ratio even if its size is compact, can be constructed of a less number of stages of amplifier, and can have a high response frequency and the like.

Claims: A photosemiconductor apparatus comprising: a light-emitting element (101) provided on a substrate (108), said light-emitting element (101) able to emit a signal light (101a) from one end on an object; a light shield member (106) having non-shielding portions (106a, 106b, 106c) provided on said substrate (108); and a first light-receiving element (141a, 141c) provided on said substrate (108), said light-receiving element (141a, 141c) receiving said signal light (101a) emitted from said light-emitting element (101) to said object and reflected from said object through a non-shielding portion (106a, 106c) of said light shield member (106), wherein noise light except for signal light is removed by said light shield member (106), characterized in that said light-emitting element (101) is adapted to emit another light beam (101b) from another end of said light-emitting element, wherein said photosemiconductor apparatus further comprises a second light-receiving element (140) arranged on a side of said light shield member (106) opposite to said light-emitting element (101), for receiving said other light beam (101b) via a non-shielding portion (106b) of said light shield member (106) other than said non-shielding portion (106a, 106c) for said first light-receiving element (141a, 141c) and for detecting signals of said other light beam so as to control an amount of light emitted from the light-emitting element (101), so that said light shield member (106) prevents noise light also from entering said second light-receiving element (140). A photosemiconductor apparatus according to claim 1, characterized by a reflecting prism device (105) being set at the signal light exit side of said light emitting element (101), so that said signal light emitted from said light emitting element (101) and said signal light reflected from said object is reflected at said reflecting prism device (105), an optical unit (103) comprising lens portions (131a, 131b, 131c) on an inner side and grating portions (132a, 132b, 132c) on an outer side, said optical unit (103) being set between said reflecting prism device (105) and said object, and a light guide prism device (151) being set between said light shield member (106) and said light first and second light receiving elements (140, 141a, 141c). A photosemiconductor apparatus according to claim 1 or 2, characterized in that said reflecting prism device (105) consists of three reflecting prisms (105a, 105b, 105c) separated by light absorbing elements (105d, 105e), wherein one of the three reflecting prisms reflects said signal light emitted from said light emitting element (101) while the remaining reflecting prisms reflect said signal light reflected from said object, wherein said lens portions (131a, 131b, 131c) and said grating portions (132a, 132b, 132c) of said optical unit (103) are provided corresponding to the three reflecting prisms (105a, 105b, 105c) and wherein said light guide prism device (151) consists of three reflecting prisms (151a, 151b, 151c) separated by light absorbing members (151c, 151d). A photosemiconductor apparatus according to claim 3, characterized in that two first light receiving elements (141a, 141c) are provided on opposite sides of said second light receiving element (140). A photosemiconductor apparatus according to any of claims 1 to 4, characterized in that said light emitting device (101) is mounted on a sub mount (102) provided on said substrate (108).

Inventors: ISHII SATOSHI, ISHIZUKA KOH, KONDO HIROSHI, NISHIMURA TETSUHARU, ISHII, SATOSHI, ISHIZUKA, KOH, KONDO, HIROSHI, NISHIMURA, TETSUHARU, ISHII, SATOSHI, C/O CANON KABUSHIKI KAISHA, ISHIZUKA, KOH, C/O CANON KABUSHIKI KAISHA, KONDO, HIROSHI, C/O CANON KABUSHIKI KAISHA, NISHIMURA, TETSUHARU, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: H01L33
IPC codes: H01L31, G01S7, H01L33, H01S5, G11B7