Abstract:
A reflection encoder is disclosed having a light emitting element in a light receiving element that are separated by a light shielding body that prevents unwanted light from entering the light receiving element. In variations of the invention, the light shielding body may be integrally formed with a mold resin portion that holds the light emitting element and light receiving element, formed by a sheet or plate, or formed using an opaque liquid resin that is poured between transparent resin bodies that encapsulate the light emitter and receiver. In operation, light radiated from the light emitting element is reflected by a code wheel and then received by a light receiving element. Other variations include varying the height at which the light receiving and detecting elements are disposed relative to the code wheel and tilting these elements towards each other so as to increase light efficiency.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2004-217495 filed in Japan on Jul. 26, 2004, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a reflective encoder, which is an optical system of an optical sensor used as a part of an optical shaft angle encoder for generating an electric signal to indicate the angular position or angular change of a shaft. 
   2. Description of the Related Art 
     FIG. 11  shows a structural example of a conventional reflective encoder. 
   The reflective encoder is an optical encoder provided with a capsule-shaped reflective sensor  1100  that detects a modulated light beam Pa 1102  that is reflected from reflective regions  1104   a  of a code wheel  1104 . The reflective sensor  1100  includes a light emitting element  1101  that illuminates the reflective regions  1104   a  and non-reflective regions  1104   b  of the code wheel  1104 ; at least one light detecting element  1102  that is arranged on the same substrate as the light emitting element  1101 , in order to detect the modulated light beam Pa 1102  that is reflected from the code wheel  1104 ; a frame  1107  on which the light emitting element  1101  and the light detecting element  1102  are mounted; and an epoxy resin portion  1103  that covers the surface of both the light emitting element  1101  and the light detecting element  1102 , and protects the light emitting element  1101  and the light detecting element  1102 . 
   In order to prevent a light beam Pb 1102 , which is undesirably reflected at the phase boundary between the epoxy resin portion  1103  and air, from reaching directly onto the light detecting element  1102 , the reflective sensor  1100  contains a lens appropriately arranged between the light emitting element  1101  and the code wheel  1104 . The lens also enlarges the image towards the light detecting element  1102 , and thus by using a lens it is possible to use a more compact, less expensive light detecting element  1102 . 
   The capsule-shaped reflective sensor  1100  shown in  FIG. 11  includes individual lenses, namely a light emitting lens  1105  that covers the light emitting element  1101 , and a light detecting lens  1106  that covers the light detecting element  1102 . The light emitting element  1101  and the light detecting element  1102  are arranged in appropriate positions such that the light beam Pa 1101  from the light emitting element  1101  is enlarged by the light emitting lens  1105 , and is focused and emitted in the direction of the code wheel  1104 , and the modulated light beam Pa 1102  reflected from the code wheel  1104  is then enlarged and focused in the direction of the light detecting element  1102 . It should be noted that it is possible to use such a double lens structure, which is compact and inexpensive, provided that high accuracy is maintained. 
   However, as an example of such a reflective encoder, there is an optical encoder in which a light emitting device and a photodetector are enclosed within a single transparent medium (see for example, JP H6-221874A (1994)). 
   The reflective encoder shown in  FIG. 11  provides a number of advantages over reflective encoders that have been used up to now, namely being relatively inexpensive, and relatively compact, however there are problems, such as are indicated below, because the light emitting element and the light detecting element are both provided within the same transparent medium. 
   That is to say, the light beam Pb 1101  from the light emitting element  1101  is internally reflected by the epoxy resin portion  1103  that protects the light emitting element  1101 , and is irradiated as the light beam Pb 1102  onto the adjacent light detecting element  1102 . Thus, an undesired signal is generated in the light detecting element  1102 . 
     FIG. 12  is a graph showing an example of an output waveform when an undesired signal is generated in the light detecting element, and  FIG. 13  is a graph showing an example of an output waveform when an undesired signal is not generated in the light detecting element. In  FIG. 12  and  FIG. 13 , the vertical axis indicates voltage, and the horizontal axis indicates time. 
   As illustrated, the output signal waveform when an undesired signal is generated in the light detecting element is shifted upward by a noise component N, when compared to the output signal waveform when the undesired signal is not generated in the light detecting element. 
   In reflective encoders, the degree of accuracy of signal detecting has a great influence on the performance of the reflective encoder. Thus, precision loss due to internal reflection is a significant problem. Also, in order to overcome such internal reflection, it is necessary to use a relatively high current for emitting light, leading to an increase in power use. Furthermore, from the result of experiments, it has been found that the undesired signal that directly enters the light detecting element from the light emitting element induces a noise component shift in the output signal waveform that is about ⅙ the amplitude of the output signal waveform. Therefore it is necessary to remove the noise component. 
   As above, the problem of the effect due to internal reflection is greater with reflective encoders than with reflective photo interrupters. As shown in  FIG. 13 , in order to improve performance, it is important that there is substantially no noise component in the output signal waveform. 
   On the other hand, there is also the problem that if the distance between the lens of the light emitting element and the lens of the light detecting element is large, then the amount of light emitted by the light emitting element that reaches the light detecting element is reduced. 
   SUMMARY OF THE INVENTION 
   The present invention has been achieved with consideration of the above-described facts, and it is an object thereof to provide reflective encoders that are capable of improved optical properties through the elimination of undesired signals by a light shielding body, and to provide more compact, more accurate electronic devices through the incorporation of such reflective encoders. 
   A reflective encoder of the present invention is provided with a light emitting portion having a light emitting element capable of irradiating light and a light emitting side transparent resin body for covering and protecting the light emitting element, a light detecting portion having a light receiving element for detecting light that is irradiated from the light emitting element and that is reflected by a reflecting region of a code wheel, and a light receiving side transparent resin body for covering and protecting the light receiving element, and a light shielding body arranged between the light emitting side transparent resin body and the light receiving side transparent resin body for separating the light emitting portion and the light detecting portion. As a result, the light from the light emitting portion side is prevented from directly entering the light detecting portion side by the light shielding body, and thus undesired signals in the light receiving element can be eliminated. 
   The reflective encoder of the present invention may be further provided with a secondary mold resin portion for fixing the light emitting portion and the light detecting portion, so as to maintain a predetermined distance, wherein the light shielding body is molded in a single piece with the secondary mold resin portion. In the case of such a configuration, it is possible both to form the light shielding body without increasing manufacturing steps, and to accurately position the light emitting portion and the light detecting portion. 
   In the reflective encoder of the present invention, the light shielding body may be formed from a plate or sheet-shaped member. In the case of such a configuration, the lens of the light emitting portion and the lens of the light detecting portion may be formed in a closer arrangement, and thus it is possible ensure the light reflected by the code wheel is efficiently and accurately incident on the light detecting portion. 
   In the reflective encoder of the present invention, the light shielding body may be formed by injecting, and then curing a liquid opaque resin into the space between the light emitting side transparent resin body and the light receiving side transparent resin body. In the case of such a configuration, the lens of the light emitting portion and the lens of the light detecting portion may be formed in an even closer arrangement, and thus it is possible ensure the light reflected by the code wheel is more efficiently and accurately incident on the light detecting portion. 
   In the reflective encoder of the present invention, the height of a light emitting side frame of the light emitting portion on which the light emitting element is mounted, and the height of a light receiving side frame of the light detecting portion on which the light receiving element is mounted may be different. In the case of such a configuration, the arrangement of the light emitting element and the light receiving element may be adjusted to an optimal position or height, thus improving the optical properties of the reflective encoder. 
   In the reflective encoder of the present invention, it is possible that the code wheel has a circular shape, and the light emitting portion and the light detecting portion are arranged in a direction which is perpendicular with respect to the diametrical direction of the code wheel. In the case of such a configuration, even if the code wheel is small, it is possible to arrange the reflective encoder directly below the code wheel. 
   In the reflective encoder of the present invention, it is possible that the code wheel has a circular shape, and the light emitting portion and the light detecting portion are arranged along the diametrical direction of the code wheel. In the case of such a configuration, since the light that strikes the code wheel is distributed symmetrically to the left and right about the diametrical direction of the code wheel, the light that enters the light detecting portion is symmetrical to the left and right. Thus, the output waveform of the optical signal improves, and an accurate signal can be provided. 
   In the reflective encoder of the present invention, it is possible that the light receiving element has a light detecting region and a signal processing circuit, the light detecting region is arranged away from the center of the reflective encoder, and the signal processing circuit is arranged toward the center of the reflective encoder. In the case of such a configuration, it is possible to prevent the light detecting portion from becoming large due to the signal processing circuit. 
   In the reflective encoder of the present invention, it is possible that a light emitting side lens is formed on the top portion of the light emitting side transparent resin body, and a light receiving side lens is formed on the top portion of the light receiving side transparent resin body, and the light emitting portion and the light detecting portion are arranged such that the optical axis of at least one of the light emitting side lens and the light receiving side lens is tilted toward the top of the light shielding body. In the case of such a configuration, the light from the light emitting portion may be used effectively. 
   In the reflective encoder of the present invention, the light emitting element may be arranged on the optical axis of the light emitting side lens. In the case of such a configuration, light efficiently enters the light emitting side lens. 
   In the reflective encoder of the present invention, the light receiving element may be arranged on the optical axis of the light receiving side lens. In the case of such a configuration, the light that enters the light receiving side lens is efficiently focused onto the light receiving element. 
   An electronic device of the present invention is a device in which at least one reflective encoder such as has been described above is used. As a result, light can be efficiently and accurately detected, and the performance of the electronic device can be improved. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a cross-sectional view showing a reflective encoder associated with Embodiment 1 of the present invention. 
       FIG. 2  is a perspective view showing the reflective encoder of  FIG. 1 . 
       FIG. 3  is a cross-sectional view showing a modified example of the reflective encoder associated with Embodiment 1 of the present invention. 
       FIG. 4  is a cross-sectional view showing a reflective encoder associated with Embodiment 2 of the present invention. 
       FIG. 5  is a cross-sectional view showing a reflective encoder associated with Embodiment 3 of the present invention. 
       FIG. 6  is a cross-sectional view showing a reflective encoder associated with Embodiment 4 of the present invention. 
       FIG. 7(   a ) is an explanatory diagram showing a top view of a reflective encoder associated with Embodiment 5 of the present invention, and  FIG. 7(   b ) is a diagram showing a side view thereof. 
       FIG. 8(   a ) is an explanatory diagram showing a top view of a reflective encoder associated with Embodiment 6 of the present invention, and  FIG. 8(   b ) is a diagram showing a side view thereof. 
       FIG. 9  is a cross-sectional view showing a reflective encoder associated with Embodiment 7 of the present invention. 
       FIG. 10  is a cross-sectional view showing a reflective encoder associated with Embodiment 8 of the present invention. 
       FIG. 11  is an overview showing an example of a conventional reflective encoder. 
       FIG. 12  is a graph showing an example of an output signal waveform when an undesired signal is generated in a light detecting element. 
       FIG. 13  is a graph showing an example of an output signal waveform when an undesired signal is not generated in the light detecting element. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The embodiments of the present invention are described below with reference to the drawings. 
   Embodiment 1  
     FIG. 1  is a cross-sectional view showing a reflective encoder  100  associated with Embodiment 1 of the present invention, and  FIG. 2  is a perspective view of the reflective encoder  100  of  FIG. 1 . 
   The reflective encoder  100  is provided with a light emitting portion  120 , a light detecting portion  130 , and a secondary mold resin portion  107  that fixes the light emitting portion  120  and the light detecting portion  130 , for positioning the light emitting portion  120  and the light detecting portion  130 . 
   The light emitting portion  120  has a light emitting side frame  105 , a light emitting element  106  arranged on the light emitting side frame  105  and a light emitting side transparent resin body  101  that covers and protects the light emitting element  106 . The upper portion of the light emitting side transparent resin body  101  is molded into a light emitting side lens  101   a . The light detecting portion  130  has a light receiving side frame  104 , a light receiving element  103  arranged on the light receiving side frame  104  and a light receiving side transparent resin body  102  that covers and protects the light receiving element  103 . The upper portion of the light receiving side transparent resin body  102  is molded into a light receiving side lens  102   a.    
   The secondary mold resin portion  107  is formed using an opaque resin. Those parts of the secondary mold resin portion  107  that are formed between the light emitting portion  120  and the light detecting portion  130  function as a light shielding body  107   a    
   Because the reflective encoder  100  has this configuration, a light beam P 1  that is irradiated from the light emitting element  106  is focused by the light emitting side lens  101   a,  after which it is emitted toward a code wheel  108 , wherein it strikes reflective portions  108   a  and non-reflective portions  108   b  on the code wheel  108 . The light that hits the reflective portions  108   a  is reflected, and the light that hits the non-reflective portions  108   b  is not substantially reflected. As a result, when a reflected light beam P 2  that is reflected from the code wheel  108  is focused by the light receiving side lens  102   a  and strikes the light receiving element  103 , the intensity of the light varies. Thus, the rotational frequency and direction of the code wheel  108  can be determined by such light striking partitioned photodiodes (PD) that are formed on the light receiving element  103 . 
   By using the reflective encoder  100  of the present Embodiment 1, and by the use of the light shielding body  107   a  it is possible to prevent light from the light emitting element  106  from directly entering the light receiving element  103  via the light emitting side transparent resin body  101  and the light receiving side transparent resin body  102 . 
   It should be noted that the light shielding body  107   a  of the present Embodiment 1 is molded in a single piece with the secondary mold resin portion  107  at the same time when forming the secondary mold resin portion  107  using opaque resin. Furthermore, the secondary mold resin portion  107  also has the effect of accurately positioning the light emitting portion  120  and the light detecting portion  130 . 
   Modified Example of Embodiment 1  
   An embodiment in which a light emitting element and a light receiving element are directly mounted on the same substrate is described next with reference to the drawings. 
     FIG. 3  is a cross-sectional view showing a reflective encoder  100 A associated with a modified example of Embodiment 1 of the present invention. 
   In the reflective encoder  100 A, a light emitting element  111  and a light receiving element  115  are mounted on a single substrate  116 . The light emitting element  111  and the light receiving element  115  are covered by a light emitting side transparent resin body  112  and a light receiving side transparent resin body  114  respectively. A light shielding body  113  formed using an opaque resin is arranged on the boundary part between the light emitting side transparent resin body  112  and the light receiving side transparent resin body  114 . 
   Because the reflective encoder  100 A has such a configuration, the light emitted from a light emitting portion  120 A (portion including the light emitting element  111  and the light emitting side transparent resin body  112 ) is imparted with variable intensity due to the code wheel (not shown), and is received at the partitioned PD formed on the light receiving element  115  of a light detecting portion  130 A (portion including the light receiving element  115  and the light receiving side transparent resin body  114 ). 
   Thus, by directly mounting the light emitting element  111  and the light receiving element  115  on the substrate  116 , it is possible to decrease the thickness of the reflective encoder  100 A. Furthermore, by arranging electrodes on the rear of the substrate  116 , it is possible to make the reflective encoder  100 A leadless type. 
   Embodiment 2 
   Embodiment 2 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 4  is a cross-sectional view showing a reflective encoder  200  associated with Embodiment 2 of the present invention. 
   In the reflective encoder  100  of Embodiment 1, the light shielding body  107   a  is molded in a single piece with the secondary mold resin portion  107 , however in this case, if the light shielding body  107   a  does not have a certain thickness then there may be a problem, for example, in that the resin does not penetrate, resulting from the step of molding of the resin. Therefore, it is necessary to set the thickness of the light shielding body  107   a  such that the resin sufficiently penetrates. As a result, the distance between the light emitting portion  120  and the light detecting portion  130  may increase, possibly leading to a decrease in the optical properties such as the amount of light entering the light detecting portion  130  from the light emitting portion  120 . 
   Therefore, in the present Embodiment 2, in order to further reduce the distance between a light emitting portion  220  and a light detecting portion  230 , a secondary mold resin portion  204  is used only to fix the light emitting portion  220  and the light detecting portion  230 , and a light shielding body  203  is formed as a part that is separate from the secondary mold resin portion  204 . Thus, only a slight gap is provided between the light emitting portion  220  and the light detecting portion  230  in the secondary mold resin portion  204 , and the separate light shielding body  203  is inserted into the gap. 
   That is to say, firstly, the light emitting portion  220  is formed by placing a light emitting element  208  onto a light emitting side frame  206 , and then covering the light emitting element  208  with the light emitting side transparent resin body  201  in whose upper part a light emitting side lens  201   a  is formed. The light detecting portion  230  is formed by mounting a light receiving element  209  onto a light receiving side frame  207 , and then covering the light receiving element  209  with a light receiving side transparent resin body  202  in whose upper part a light receiving side lens  202   a  is formed. 
   Next, the reflective encoder  200  is formed by sandwiching the light emitting portion  220  and the light detecting portion  230  with the secondary mold resin portion  204  which is made from an opaque resin, so that a small gap remains between the light emitting portion  220  and the light detecting portion  230 . 
   A thin plate-shaped or sheet-shaped light shielding body  203  that does not allow the passage of light and that is of a size or thickness that will fit into the gap between the light emitting portion  220  and the light detecting portion  230  is inserted into the space between the light emitting portion  220  and the light detecting portion  230 . 
   With the present Embodiment 2, the distance between the light emitting portion  220  and the light detecting portion  230  can be made smaller than in the reflective encoder  100  shown in Embodiment 1, and as a result, light that enters the light detecting portion  230  from the light emitting portion  220  due to internal reflection can be eliminated, while at the same time the light from the light emitting portion  220  can be reflected at a code wheel  205  so as to be incident on the light detecting portion  230  effectively and accurately. 
   Embodiment 3 
   Embodiment 3 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 5  is a cross-sectional view showing a reflective encoder  300  associated with Embodiment 3 of the present invention. 
   The reflective encoder  300  of the present Embodiment 3 is an encoder in which a light shielding body  303  is formed using an opaque liquid resin instead of the sheet-shaped or plate-shaped light shielding body  203  as in the reflective encoder  200  of the above noted Embodiment 2. 
   That is to say, firstly, a light emitting portion  320  is formed by mounting a light emitting element  308  onto a light emitting side frame  306 , and then covering the light emitting element  308  with the light emitting side transparent resin body  301  in whose upper part a light emitting side lens  301   a  is formed. A light detecting portion  330  is formed by mounting a light receiving element  309  onto a light receiving side frame  307 , and then covering the light receiving element  309  with a light receiving side transparent resin body  302  in whose upper part a light receiving side lens  302   a  is formed. 
   Next, the reflective encoder  300  is formed by sandwiching the light emitting portion  320  and the light detecting portion  330  with the secondary mold resin portion  304  which is made from an opaque resin, so that a small gap remains between the light emitting portion  320  and the light detecting portion  330 . 
   The opaque liquid resin is then poured into the space between the light emitting portion  320  and the light detecting portion  330 , and cured to form the light shielding body  303 , which does not allow the passage of light, between the light emitting portion and the light detecting portion  330 . 
   According to the present Embodiment 3, the light shielding body  303  is originally a liquid, so that the distance between the light emitting portion  320  and the light detecting portion  330  can be reduced further than in Embodiment 2, and as a result, light that enters the light detecting portion  330  from the light emitting portion  320  due to internal reflection can be eliminated, while at the same time the light from the light emitting portion  320  can be reflected at a code wheel  305  so as to be incident on the light detecting portion  330  effectively and accurately. 
   Embodiment 4 
   Embodiment 4 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 6  is a cross-sectional view showing a reflective encoder  400  associated with Embodiment 4 of the present invention. 
   In the reflective encoder  400  of the present Embodiment 4, a light emitting portion  420  and a light detecting portion  430  are molded separately. Utilizing this fact, the height of a lead frame (a light emitting side frame)  402  in the light emitting portion  420  on which a light emitting element  401  is mounted, and the height of a lead frame (a light receiving side frame)  404  in the light detecting portion  430  on which a light receiving element  403  is mounted are altered. That is to say, the height from the bottom surface of a light emitting side transparent resin body  405  to the light emitting side frame  402  is made to differ from the height from the bottom surface of a light receiving side transparent resin body  406  to the light receiving side frame  404 . 
   As a result, the distance from the light emitting element  401  to a light emitting side lens  405   a  can be made different from the distance from the light receiving element  403  to a light receiving side lens  406   a.    
   For example when the light receiving element  403  approaches the light receiving side lens  406   a,  the intensity of the light when it is received is greater, and the amplitude (voltage value) of the output signal increases. On the other hand, when the position or height of the light emitting element  401  is adjusted, the direction and the focal properties of the light emitted from the light emitting side lens  405   a  can be changed. 
   Since the reflective encoder  400  is configured as such, the optical properties of the reflective encoder  400  can be improved by altering the height of the lead frame (the light emitting side frame)  402  on which the light emitting element  401  is mounted, or the height of the lead frame (the light receiving side frame)  404  on which the light receiving element  403  is mounted in order to adjust them to the most appropriate position or height. 
   Embodiment 5 
   Embodiment 5 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 7(   a ) and  FIG. 7(   b ) are explanatory diagrams showing a reflective encoder  601  associated with Embodiment 5 of the present invention, where  FIG. 7(   a ) is a top view and  FIG. 7(   b ) is a lateral view. 
   In Embodiment 5 of the present invention, the reflective encoder  601  is used for detecting the rotational speed or rotational direction of a shaft  603  of a motor or the like. 
   Moreover, the alignment direction of a light emitting portion  604  and a light detecting portion  605 , which are constituent elements of the reflective encoder  601 , is parallel to a direction D 2 , which is perpendicular to a diametrical direction D 1  of a code wheel  602 . 
   As the reflective encoder  601  contains such a structure, it is possible to provide the reflective encoder  601  closer to the shaft  603 . As a result, even if the code wheel  602  is small, the reflective encoder  601  may be provided within the code wheel  602 , and it is possible to reduce the size of the device, and more specifically, to miniaturize the motor in which such a reflective encoder  601  is incorporated. Further, it is also possible to achieve more compact electronic devices that use these reflective encoders. 
   Embodiment 6 
   Embodiment 6 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 8(   a ) and  FIG. 8(   b ) are explanatory diagrams showing a reflective encoder  701  associated with Embodiment 6 of the present invention, where  FIG. 8(   a ) is a top view and  FIG. 8(   b ) is a lateral view. 
   In the present Embodiment 6, the reflective encoder  701  is used for detecting the rotational speed or rotational direction of a shaft  703  of a motor or the like. 
   Furthermore, a light emitting portion  704  and a light detecting portion  705 , which are constituent elements of the reflective encoder  701 , are aligned along a diametrical direction D 1  of a code wheel  702 . 
   With such a structure, since the light that strikes the code wheel  702  is distributed symmetrically to the left and right about the diametrical direction D 1 , and the light that enters the light detecting portion  705  is symmetrical to the left and right, as a result, the waveform of the output signal has a more preferable shape. 
   Embodiment 7 
   Embodiment 7 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 9  is a cross-sectional view showing a reflective encoder  900  associated with Embodiment 7 of the present invention. 
   A light beam P 901  that is emitted from a light emitting element  901  of a light emitting portion  920  becomes a reflected light beam, P 902  by reflection at a code wheel  905 , and enters a light detecting region  902   a  on top of a light receiving element  903  of a light detecting portion  930 . 
   In the present Embodiment 7, the light receiving element  903  has the light detecting region  902   a  and a signal processing circuit  902   b.  The light detecting region  902   a  of the light receiving element  903  is arranged away from the center P of the reflective encoder  900 , and the signal processing circuit  902   b  is arranged toward the center P of the reflective encoder  900 . 
   With such a structure, it is possible to prevent the light detecting portion  930  from becoming large due to the signal processing circuit  902   b.    
   Embodiment 8 
   Embodiment 8 of the reflective encoder of the present invention is described next with reference to the drawings. 
     FIG. 10  is a cross-sectional view showing a reflective encoder  1000  associated with Embodiment 8 of the present invention. 
   In Embodiment 8, a light emitting element  1001  of a light emitting portion  1020  is arranged on the optical axis of a light emitting side lens  1002   a  of a light emitting side transparent resin body  1002 , and a light beam P 1001  that is emitted from the light emitting element  1001  is effectively exited from the light emitting side lens  1002   a.  The light beam P 1001  is reflected by a code wheel  1006  to become a reflected light beam P 1002 . The principal light beam of the reflected light beam P 1002  strikes along the optical axis of, and is focused by a light receiving side lens  1005   a  that is formed on the upper portion of a light receiving side transparent resin body  1005 . The light is then received by a light receiving element  1004  that is arranged on the optical axis of the light receiving side lens  1005   a  of the light detecting portion  1030 . 
   Thus, as well as arranging the light emitting element  1001  and the light receiving element  1004  on the optical axis of the light emitting side lens  1002   a  and the light receiving side lens  1005   a  respectively, the light emitting portion  1020  and the light detecting portion  1030  are arranged at a slant such that they face toward each other (that is, a secondary mold resin portion  1007  fixes the light emitting portion  1020  and the light detecting portion  1030  such that the optical axis of the light emitting side lens  1002   a  and the light receiving side lens  1005   a  intersect at those regions of the code wheel  1006  surface above a light shielding body  1007   a ). Thus, the light may be used more efficiently. It should be noted that the light emitting portion  1020  and the light detecting portion  1030  may be easily and accurately arranged at a slant by fixing the light emitting portion  1020  and the light detecting portion  1030  with the secondary mold resin portion  1007 . 
   It should be noted that the electronic device of the present invention is a device in which at least one of any of the reflective encoders described in Embodiment 1 to Embodiment 8 is included. A more compact, more accurate electronic device may be obtained by having such a configuration. 
   With regard to industrial applicability, the reflective encoder and the electronic device in which the reflective encoder is used, of the present invention may be ideally utilized in, or as, electronic devices such as consumer devices or factory automating apparatuses. 
   The present invention can be embodied and practiced in other different forms without departing from the spirit and essential characteristics thereof Therefore, the above-described embodiments are considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All variations and modifications falling within the equivalency range of the appended claims are intended to be embraced therein.