Abstract:
The invention is based on a distance-measuring device, in particular a laser distance-measuring device ( 10 ) which is in the form of a handheld device, having a printed circuit board ( 18 ) and a transmitting or receiving unit ( 20, 22 ) which is provided for transmitting or receiving a measurement signal, and comprises a housing ( 30, 46, 82, 96, 130 ) which has a base surface ( 32, 48, 102, 140 ) which faces the printed circuit board ( 18 ), a side surface and a signal surface ( 38, 50, 98, 142 ). The invention proposes that the side surface is in the form of a signal surface ( 38, 50, 98, 142 ).

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2005 035 101.8 filed on Jul. 27, 2005. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a distance-measuring device, in particular a laser distance-measuring device designed as a hand-held device. 
     RELATED ART 
     Publication EP 1 351 070 A1 makes known a distance-measuring device with a printed circuit board, on which a laser diode for generating a measurement signal and a photodiode for receiving a measuring signal are installed. Each of these items includes a housing, which includes a glass cover that is permeable to a measurement signal. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a distance-measuring device, in particular a laser distance-measuring device designed as a hand-held device, with a printed circuit board and a transmitter or receiver unit provided for transmitting or receiving a measurement signal, and that includes a housing that includes a base surface facing the printed circuit board, a lateral surface, and a signal surface. 
     It is provided that the lateral surface is designed as a signal surface. It is advantageously possible to transmit or receive a measurement signal laterally through the housing of the transmitter or receiver unit. Particularly advantageously, transmission or receipt of a measurement signal oriented parallel to the printed circuit board may be attained with a simple design. To attain a high level of stability of the transmitter or receiver unit, the base surface may lie on the printed circuit board. In addition, the base surface may be installed directly on the printed circuit board. The housing may be bonded directly to the printed circuit board, thereby also resulting in a reliable electrical connection with the printed circuit board via the integral connection. The base surface is preferably designed as a flat surface. The base surface may be advantageously oriented parallel with the printed circuit board. In this context, a “lateral surface” refers to a surface of the housing that differs from the base surface and a cover surface located opposite to the base surface. The base surface and the lateral surface preferably form an angle between 30° and 120°. In addition, a “signal surface” refers to a surface that is located in a path of a measurement signal. The transmitter or receiver unit may be preferably provided for transmitting or receiving a visible light beam. The transmitter unit is advantageously designed as a laser diode, e.g., as a VCSEL (Vertical Cavity Surface Emitting Laser) diode. As an alternative, the transmitter or receiver unit may also be designed as transmitting or receiving means for further types of electromagnetic radiation, such as infrared or radar radiation, etc., or ultrasonic waves. 
     The housing advantageously includes at least two material layers, with an electrical connection being established between the material layers via a boundary surface. As a result, internal electrical connections of the housing may be easily and advantageously established, with a housing that is compact in design. The boundary surface may be formed by a contact surface, with which a material layer lies on an adjacent material layer. The housing may advantageously include a layering of several material layers, which are stacked as several levels of layers in a stacking direction. “Stacking direction” refers to a direction that is oriented transverse to the layer direction, and is perpendicular thereto in particular. A material layer may be located in a layer level. As an alternative, several adjoining material layers may be located in one layer level. An electrical connection may be established in one layer level or between two adjacent layer levels via a boundary surface between two material layers. To establish an electrical connection, the boundary surface is preferably coated with a conductive element, e.g., a soldering alloy. 
     The transmitter or receiver unit advantageously includes a diode chip, which is electrically connected with a boundary surface in at least two layer levels. As a result, electrical connections of the diode chip may be attained that are effectively insulated from each other electrically, e.g., by at least one layer thickness. 
     When the housing includes a soldering surface that is electrically connected with a boundary surface, and when the housing is soldered directly to the printed circuit board, a reliable electrical connection of the transmitter or receiver unit to the printed circuit board may be attained with minimal outlay. In addition, external connection elements for electrical contacting, e.g., leg-shaped connection pins, may be avoided, thereby resulting in a compact design of the transmitter or receiver unit. In addition, a good seal of the inner space of the housing to the outside may be attained, since this eliminates the need to feed external electrical connections into the interior through the housing. “Soldering surface” refers, in particular, to an outer surface of the housing that is coated with solder for soldering the housing to the printed circuit board. 
     In this context, it is also provided that the soldering surface is bounded by a boundary surface in the stacking direction. When the housing is provided with several soldering surfaces, via which an electrical connection is established with a boundary surface in a layer level, this results in effective electrical insulation between the boundary surfaces. 
     In one embodiment, the housing includes a recess with a soldering surface. When the housing is soldered to the printed circuit board, the solder may be prevented from spreading—which is undesirable—by allowing the solder, e.g., when reflow soldering is performed, to fill a space bounded by the recess and the printed circuit board. When the soldering surface is bounded in the stacking direction, an undesired contacting of a layer level beyond the limits of the soldering surface due to the solder spreading may be advantageously prevented. 
     In an advantageous refinement of the present invention, it is provided that the transmitter or receiver unit includes a fastening means, which is provided to install an outer surface—which differs from the base surface and the signal surface—on the printed circuit board. As a result, a range of application of the transmitter or receiver unit based on an orientation of the measurement signal relative to the printed circuit board may be advantageously increased. When the housing includes at least two fastening means that are designed as soldering surfaces and are located on two abutting outer surfaces, this flexibility may be easily attained, and a compact design of the transmitter or receiver unit may also be attained. The abutting outer surfaces are advantageously angled relative to each other. 
     It is furthermore provided that the transmitter or receiver unit includes redirecting means for redirecting the measurement signal, which is located in the housing. As a result, increased precision of distance measurements that are carried out for objects at close range and for which the measurement signal is oriented, e.g., at a parallactic angle relative to the printed circuit board, may be easily attained and with a compact design. 
     In this context, the manufacturing costs of the transmitter or receiver unit may be easily reduced by the fact that the redirecting means are integrally formed with the housing as a single piece. 
     Further advantages result from the description of the drawing, below. Exemplary embodiments of the present invention are shown in the drawing. The drawing, the description and the claims contain numerous features in combination. One skilled in the art will also advantageously consider the features individually and combine them to form further reasonable combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a distance-measuring device with a printed circuit board, a transmitter unit, and a receiver unit, 
         FIG. 2  shows the transmitter unit with a housing installed on the printed circuit board, 
         FIG. 3  shows an alternative housing of the transmitter unit, in a perspective view, 
         FIG. 4  shows the transmitter unit with the housing in  FIG. 3  on the printed circuit board, in a partial sectional view, 
         FIG. 5  shows a contact point of the housing in  FIG. 3 , 
         FIG. 6  shows the transmitter unit with the housing in  FIG. 3  on the printed circuit board, in a top view, 
         FIG. 7  shows an alternative housing with three recesses, 
         FIG. 8  shows the transmitter unit with an alternative housing with soldering surfaces, 
         FIG. 9  shows the receiver unit with redirecting means, and 
         FIG. 10  shows the receiver unit with alternative redirecting means. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a distance-measuring device designed as a laser distance-measuring device  10 . Laser distance-measuring device  10  includes a housing  12 , actuating elements  14  for switching the distance-measuring device on and off, and for starting and configuring a measuring procedure, and it includes a display  16 . A printed circuit board  18  is located inside housing  12 , on which a transmitter unit  20  designed as a laser diode and a receiver unit  22  designed as a photo diode are installed. To measure a distance of laser distance-measuring device  10  from a remote object, during operation  1 o of laser distance-measuring device  10 , a transmitted measurement signal in the form of a light beam is sent from transmitter unit  20  via transmission optics  26  in a beam direction  24  oriented parallel to printed circuit board  18 . The transmitted measurement signal reflected by a surface of the remote object is received as a received measurement signal by receiver unit  22  via receiving optics  28 . The distance in question may be ascertained by comparing the transmitted measurement signal with the received measurement signal. 
     Printed circuit board  18  and receiver unit  22  are shown in a sectional view in  FIG. 2 . Receiver unit  22  includes a housing  30 , which includes a base surface  32  soldered to printed circuit board  18 , a cover surface  34  located opposite to base surface  32 , a first lateral surface  36 , a second lateral surface designed as a signal surface  38 , and a diode chip  40  located in housing  30  for receiving the received measurement signal. Signal surface  38  is located on an optical axis  42 —oriented parallel to printed circuit board  18 —for the received measurement signal, and it is formed by a glass cover  44  that is permeable to the received measurement signal. 
     A further embodiment of a housing  46  of receiver unit  22  is shown in a perspective view in  FIG. 3 . In the state in which receiver unit  22  is installed on printed circuit board  18 , as shown in  FIG. 6 , a base surface  48  of housing  46  is installed on printed circuit board  18 . Housing  46  also includes a lateral surface, which is designed as a signal surface  50 , as shown in  FIG. 4 . To enable base surface  48  to be soldered to printed circuit board  18 , housing  46  is provided with two recesses  52 ,  54 , each of which includes a soldering surface  56  and  58 . Soldering surfaces  56 ,  58  are each coated with a soldering alloy, which is depicted schematically as shading. When receiver unit  22  is installed on printed circuit board  18 , as shown in  FIG. 6 , and when reflow soldering is employed, a space bounded by recess  52  and  54  and printed circuit board  18  is filled with the soldering alloy. Housing  46  also includes a recess  60 , in which a diode chip  62  shown in  FIG. 4  is located, in the assembled state of receiver unit  22 . 
     Receiver unit  22  with housing  46  is shown in a partial sectional view in  FIG. 4  in its assembled state and installed on printed circuit board  18 . Housing  46  includes four material layers  64 ,  66 ,  68 ,  70 , which are stacked in a stacking direction  72 . Material layers  64 ,  66 ,  68 ,  70  are made of ceramic. Diode chip  62 , which is soldered to boundary surface  74 , is located in recess  60 . Diode chip  62  is electrically connected with boundary surface  74  via the soldered connection. Furthermore, diode chip  62  is also electrically connected with a boundary surface  78 , i.e., via a bonding wire  76 , which is soldered to diode chip  62  and boundary surface  78 . Boundary surface  74  and  78  includes a soldering alloy so that diode chip  62  and bonding wire  76  may be soldered. As shown in detail in  FIG. 5 , this soldering alloy is in contact with soldering surface  56  and  58 . As a result, an electrical connection is established between boundary surface  74  and  78  and soldering surface  56  and  58 . Diode chip  62  is therefore electrically connected with printed circuit board  18  via boundary surface  74 , and soldering surface  56  is electrically connected with printed circuit board  18  in a first layer level and via boundary surface  78 , and soldering surface  58  is electrically connected with printed circuit board  18  in a second layer level. Recess  60  is insulated to the outside by a glass cover  80 , which forms signal surface  50 . In one embodiment, housing  46  may be made of a single-pieced plastic part that is provided with a pressed screen. In this case, housing  46  includes material layers that are stacked in several layer levels in a stacking direction, which is oriented parallel to one of the screen axes. Adjacent material layers in two different layer levels and/or within one layer level may abut each other with a boundary surface, a boundary surface being formed by boundary surfaces of elementary screen cells. The pressed screen is preferably made of a conductive material, thereby enabling an internal electrical connection to be established in housing  46  and enabling an electrical connection with a soldering surface for soldering housing  46  to printed circuit board  18  to be established via the pressed screen. 
       FIG. 5  shows a further side view of housing  46 , including material layers  64 ,  66 ,  68 ,  70  and recess  52  with soldering surface  56 . Boundary surface  74 , on which diode chip  62  is soldered ( FIG. 4 ), is coated with a soldering alloy, which is continuous under material layer  66  to a contact point  81  with soldering surface  56 . 
       FIG. 6  shows the positioning of receiver unit  22  with housing  46  on printed circuit board  18 , in a top view. 
     An alternative embodiment of a housing  82  of receiver unit  22  is shown in a perspective view in  FIG. 7 . The description below is limited to the differences between the designs of housings  46  and  82 . Identical parts of housings  46  and  82  are provided with the same reference numerals. Housing  82  includes three recesses  84 ,  86 ,  88 , each of which includes a soldering surface  90 ,  92 ,  94  for soldering base surface  48  to printed circuit board  18 . In the state in which receiver unit  22  is installed on printed circuit board  18 , an electrical connection between printed circuit board  18  and diode chip  62  is established via soldering surfaces  90 ,  94  and boundary surfaces  74 ,  78  in two layer levels and, in fact, in the manner described above with reference to  FIGS. 4 and 5 . A ground connection of diode chip  62  to printed circuit board  18  is established via a boundary surface  95  on a third layer level, which is lower in stacking direction  72 , the third layer level being electrically connected with diode chip  62  and soldering surface  92 . To attain effective electrical insulation between the lower layer level and the upper layer levels, soldering surface  92  is bounded by boundary surface  78 , and soldering surfaces  90 ,  94  are bounded by boundary surface  74  in stacking direction  72 . 
     Receiver unit  22  is depicted schematically in  FIG. 8  with a further embodiment of a housing  96 . Housing  96  includes a signal surface  98 , which is permeable to a measurement signal received by a diode chip  100 , and it includes a base surface  102 , which is soldered to printed circuit board  18 . Housing  96  also includes outer surfaces  104 ,  106 ,  108 ,  110 , which differ from base surface  102  and signal surface  98 . Base surface  102  and outer surfaces  104 ,  106 ,  108 ,  110  are provided with fastening means  112 ,  114 ,  116 ,  118 ,  120 ,  124 ,  126 ,  128 , which are designed as soldering surfaces. In one assembly variant, one of the outer surfaces  104 ,  106 ,  108 ,  110  may be soldered to printed circuit board  18  using one of the fastening means  112 ,  114 ,  116 ,  118 ,  120 ,  124 , thereby enabling a different orientation of a measurement signal generated by diode chip  100  relative to printed circuit board  18  to be attained. 
     In all of the exemplary embodiments described above, transmitter unit  20  and receiver unit  22  are identical in terms of design and in the manner in which they are installed on printed circuit board  18 . Identical reference numerals are used for identical parts of transmitter unit  20  and receiver unit  22 . 
     An alternative embodiment of a housing  130  of receiver unit  22  is shown in a sectional view in  FIG. 9 . Housing  130 , which includes several material layers  132 ,  134 ,  136 ,  138 , is soldered via a base surface  140  to printed circuit board  18 . A lateral surface of housing  130  is designed as signal surface  142 , and it is formed by a glass cover  144 , which is permeable to the received measurement signal. As an alternative, it is feasible to eliminate glass cover  144 , or for signal surface  142  to be formed by a casting compound. A diode chip  146  soldered to a boundary surface  148  is located in housing  130 . As described above for receiver unit  22  with reference to  FIG. 4 , diode chip  146  is electrically connected with boundary surface  148  and via a bonding wire  150  with a boundary surface  152 . Boundary surfaces  148 ,  152  are electrically connected with soldering surfaces—not shown—of housing  130 , via which housing  130  is soldered to printed circuit board  18 . As a result, diode chip  146  is electrically connected to printed circuit board  18 . When measuring the distance of an object located at close range, a received measurement signal in the form of a light beam  153  may be strike signal surface  142  at a parallactic angle relative to printed circuit board  18 . Receiver unit  22  is provided with redirecting means  154   1 o allow a received measurement signal of this type to be received by diode chip  146 . Redirecting means  154  are formed by an extension of material layer  138 , which is also coated with reflecting means. 
     An embodiment of receiver unit  22  is shown in  FIG. 10 . It includes redirecting means  156 , which are located in housing  130 . 
     In a further exemplary embodiment, transmitter unit  20  is designed and is installed on printed circuit board  18  in the manner described above for receiver unit  22 .