JP4928863B2 - Horizontal sensor - Google Patents

Description

  The present invention relates to a horizontal sensor used to detect a level of equipment, an apparatus, or an instrument, or to detect a degree of inclination.

  In general, a horizontal sensor detects a bubble level in a spirit level to detect the level and the degree of inclination. This bubble position detection method is an optical transmission type that irradiates light toward the level and detects the position of the projected light of the bubble with a light receiving element. An electrode is provided in the level, and between the electrodes that change depending on the bubble position. Examples thereof include a capacitance type for detecting capacitance, and a resistance type for detecting resistance between electrodes with the same configuration as the capacitance type. Of these, the optical transmission type is widely used because it is excellent in terms of the detection accuracy of the level and inclination, the workability of the level, and the like.

  As shown in Patent Document 1, such a conventional optical transmission type horizontal sensor is composed of a main part such as a light source composed of a light emitting diode, a level, four light receiving elements, and the like. There is known a horizontal sensor that is opposed to each other with a spirit level and is arranged so that the central axes of the light source, the spirit level, and the light receiving element are arranged in a substantially straight line. In this horizontal sensor, when the bubble diameter is constant, the diameter of the projection light of the bubble increases as the distance between the light source and the level decreases, and accordingly, the light receiving element needs to be increased accordingly. Therefore, conventionally, by providing a certain distance or more between the light source and the level and making the rays as parallel as possible, the bubble diameter and the bubble projection light diameter are made almost equal, and this projection light is received. A light receiving element having the same size as the diameter of the bubble has been used. That is, in order to make the size of the light receiving surface of each light receiving element approximately the same as the size of the bubbles, parallel light rays are required as much as possible. For this reason, it is necessary to provide a certain distance or more between the light source and the level and make the optical path longer, and it is difficult to reduce the size of the horizontal sensor.

  Here, with reference to FIGS. 19A and 19B, the positional relationship on the plane between the bubble 103a and the light receiving unit 102 as the light receiving element in the conventional horizontal sensor will be described. The light source irradiates the bubble 103 a (or the moved bubble 103 b) in the level 101 from the upper surface of the horizontal sensor, and the projection light (this shadow is called a bubble shadow) of the bubble 103 a constitutes the light receiving unit 102. The light is received by a substantially square light receiving diode 102a. The four light receiving diodes 102a are arranged so that the light receiving surface is formed in a square shape as a whole, the vertical and horizontal dimensions are set to be substantially the same as the diameter of the bubble 103a, and the detected amount of light received by the light receiving surface. The slopes can be detected by outputting the voltages corresponding to each of these and comparing these voltages. When the level of the horizontal sensor is maintained and the center of the bubble shadow of the bubble 103a coincides with the center of the light receiving surface of the light receiving unit 102, the light reception levels of the four light receiving diodes 102a coincide.

  In the horizontal sensor, when the bubble 103a moves from the center of the light receiving surface, the change in the light amount distribution on the light receiving surface before and after the movement is shown in FIG. The received light amount distribution P3 is a distribution when the bubble 103a does not move, and the received light amount distribution P4 (broken line) is a distribution when the bubble 103a moves to the bubble 103b. When the bubble 103a moves and moves to the bubble 103b, the position of the projection light of the bubble 103b deviates from the light receiving surface of the light receiving diode 102a, so that the amount of light received by the light receiving diode 102a changes, thereby detecting the movement. .

Next, in order to reduce the size of the light receiving portion 102 of the horizontal sensor, the same contents as described above when the size of the light receiving portion 102 is made smaller than the diameter of the bubble 103a are shown in FIGS. . If the light receiving diode 102b is made smaller than the above example, the light receiving areas of the light receiving diodes 102b of the four light receiving elements are smaller than the area of the bubble shadow of the bubble 103a. For this reason, the four light receiving diodes 102b remain in the bubble shadow of the bubble 103b even if the bubble 103a moves minutely to the position of the bubble 103b. Therefore, since the four light receiving diodes 102b remain in the bubble shadow in both the bubbles 103a and 103b, the amount of received light does not change and the inclination cannot be detected. For this reason, in the conventional horizontal sensor, the light receiving element cannot be made smaller than the size of the bubbles, which makes it more difficult to reduce the size of the horizontal sensor.
Japanese Patent No. 3370619

  The present invention has been made in order to solve the above-described problem, and is small and high-performance capable of detecting a minute inclination by reducing the light receiving portion and shortening the distance between the light source and the level. An object is to provide an optically transparent horizontal sensor.

In order to achieve the above object, the invention of claim 1 comprises a level that encloses a liquid so that bubbles remain, a light source, and four or more light receiving elements that convert received light into an electrical signal, By irradiating light from a light source toward the level, projecting the shadow of the bubble on the light receiving element, and detecting the position of the projected light on the light receiving element with the light receiving element, the degree of horizontality and the degree of inclination are increased. The horizontal sensor to detect includes a surface light emitting unit having a light emitting area larger than the area of the projected light generated when the bubbles are projected by parallel light, and diffused from the surface light emitting unit toward the level The light quantity distribution of the projection light on the light receiving element has a minimum point near the central axis of the bubble, and monotonously increases as the distance from the central axis of the bubble is approximately the same as the radius of the bubble. Like having One in which the.

According to a second aspect of the present invention, in the horizontal sensor according to the first aspect, the light amount distribution of the projection light on the light receiving element has a minimum point near the central axis of the bubble by electrical correction , and the radius of the bubble In the substantially same range, the characteristic increases linearly as the distance from the central axis increases.

A third aspect of the present invention, the horizontal sensor according to claim 1, so as to be substantially uniformly surface radiation is reflected and refracted light incident from the light source, the surface light guide plate having an uneven or grooved shape transparent member It is arranged as a light emitting part .

According to a fourth aspect of the present invention, in the horizontal sensor according to the first or third aspect , a light source and a light receiving element are opposed to the level, and an optical axis of the light source, a central axis of the level, and the level sensor The optical axis of the light receiving element is disposed so as to be substantially in a straight line, and a sheet-like member having irregularities formed so as to have a diffusion effect is disposed between the light source and the level .

According to a fifth aspect of the present invention, in the horizontal sensor according to any one of the first, third, and fourth aspects, the horizontal sensor includes two or more light sources, and the light sources are substantially arranged with respect to a central axis of the level. The light source and the light receiving element are disposed at rotationally symmetric positions, and the central axis of the level and the optical axis of the light receiving element are substantially in a straight line, and the light of the light source The axis and the optical axis of the light receiving element are arranged so as to be substantially parallel .

According to a sixth aspect of the present invention, in the horizontal sensor according to any one of the first to third aspects, the light source and the light receiving element are disposed on the same side with respect to the level, and the light from the light source is incident. A light guide made of a transparent member so as to guide the light to a position where the light is irradiated toward the level, the light guide having a total reflection surface that totally reflects light from a light source, The reflecting surface is disposed so as to face the light source while being inclined with respect to the horizontal direction .

A seventh aspect of the present invention is the horizontal sensor according to any one of the first to sixth aspects, wherein the light is diffused on the surface of at least one level of the incident surface, the inner surface of the side wall, and the output surface. Concavities and convexities are formed .

The invention according to claim 8 is the horizontal sensor according to claim 1, claim 2, claim 6, or claim 7 , wherein the light from the light source is disposed on the side far from the light receiving element on the side surface of the level. Is provided with a light incident part, and a minute unevenness or groove is formed on the surface opposite to the light receiving element side of the level so that the light incident from the light incident part is reflected and refracted to irradiate the surface substantially uniformly. It has a shape, and the light incident part is formed such that the side end part close to the light source is depressed .

According to a ninth aspect of the present invention, in the horizontal sensor according to the sixth aspect, the light guide has a convex shape so that the light emitted from the light source is substantially parallel to the light incident surface of the light guide. The axis of this cylindrical part is parallel to the normal line of the plane including the optical axis of the light source and the axis formed by reflecting the optical axis of the light source with respect to the total reflection surface of the light guide. The cylindrical portion functions as a convex lens by having a convex cylindrical light incident surface .

According to a tenth aspect of the present invention, in the horizontal sensor according to the ninth aspect, the light guide includes a light-emitting plate-like surface light emitting portion, and the total reflection surface of the light guide includes an optical axis of the light source and light of the light source. A cross-sectional shape in a plane including an axis formed by reflection with respect to the total reflection surface forms a parabolic surface, and the focal point of the parabolic surface is formed in the vicinity of the entrance of the surface light emitting unit. The surface light emitting unit has a reflective surface having irregularities and grooves for reflecting light, and a light emitting surface for emitting light from the plane .

The invention of claim 11 is the horizontal sensor according to claim 9 or claim 10 , wherein the light guide diffuses light in the axial direction of the cylindrical portion along the cylindrical surface of the cylindrical portion. And each groove of the plurality of grooves is on a plane orthogonal to the axis of the cylindrical portion, and is disposed on substantially the entire cylindrical surface at substantially equal intervals in the axial direction of the cylindrical portion. It is what has been .

A twelfth aspect of the present invention is the horizontal sensor according to any one of the ninth to eleventh aspects, wherein the light guide is parallel to a reflection surface of the surface light emitting portion and a cylindrical axis of the cylindrical portion. A plurality of grooves having a triangular cross section are formed, and the base angle of the light incident side surface of the grooves is 20 to 40 °, and the exit surface of the surface light emitting portion of the light guide and the level The sheet-like member on which a triangular prism with an apex angle of 90 ° is formed is arranged so that the ridge line of the prism is parallel to the ridge line of the groove of the light guide, and the reflection surface is disposed outside the reflection surface. Auxiliary reflector is provided in parallel .

According to a thirteenth aspect of the present invention, in the horizontal sensor according to any one of the tenth to twelfth aspects, the size of the surface light emitting portion of the light guide can be freely changed depending on the design of the light guide. It has a structure, and the thickness of the surface light emitting portion is 0.7 to 1.5 mm .

According to a fourteenth aspect of the present invention, in the horizontal sensor according to the twelfth or thirteenth aspect of the present invention, the surface light emitting portion is formed between the triangular grooves formed on the reflection surface of the surface light emitting portion of the light guide. A plane parallel to the surface light emitting portion is formed by totally reflecting the light incident on the surface of the surface light and causing the light to travel from the vicinity of the entrance of the surface light emitting portion to the back .

  According to the present invention, the light quantity distribution of the projection light on the light receiving element has a minimum point near the central axis of the bubble, and has a characteristic that monotonously increases as the distance from the central axis of the bubble is approximately the same as the radius of the bubble. Therefore, even if the light receiving element is made small, it is possible to satisfactorily detect a change in the amount of light when the bubble moves, and a small and highly accurate optical transmission type horizontal sensor can be obtained.

  Hereinafter, a horizontal sensor according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2, the horizontal sensor includes a light emitting diode 1 as a light source, a level 2 having a cylindrical container 2a in which a substantially transparent liquid 2w is sealed so that bubbles 21 remain, and projection of bubbles 21 by parallel light. A light receiving section 3 having a light receiving area smaller than light (referred to as bubble shadow) and comprising four light receiving elements 31 to 34 (see FIG. 4), and a light guide plate 4 for guiding light incident from the light emitting diode 1 to the level 2 With. The light guide plate 4 is formed of a transparent member, and includes a light incident surface 44 on which light from a light source enters, a reflection surface 41 serving as a light guide for totally reflecting and guiding incident light, and a minute light for making incident light surface emission. A reflective surface 42 having a rough surface or a groove-shaped uneven portion 46 on the surface, a light output surface 43 that emits light from the light guide plate 4, and a termination surface 45. The uneven portion 46 is further processed to diffuse light. Here, the light guide plate 4 should just have the micro unevenness | corrugation or groove | channel shape for surface light emission in the at least 1 surface of the transparent member which forms the light guide plate 4. FIG. The light emitting diode 1 and the light receiving unit 3 are both mounted on one printed circuit board 5 and arranged on the same side with respect to the level 2.

  The level 2 has its central axis and the optical axis of the light receiving unit 3 arranged in a substantially straight line, and is arranged between the light receiving unit 3 and the light exit surface 43 of the light guide plate 4. The cylindrical container 2a of the level 2 has a hollow inside, and at least one of the inside surfaces has a substantially rotationally symmetric curved surface shape, and has an upper bottom 2b having an emission surface 23 facing the light receiving unit 3. And a bottom part 2c having a light incident surface 22 and a light exit surface 26 on both sides of the bottom thickness, and a side wall part 2d. Further, the area of the light exit surface 43 of the light guide plate 4 is set to be substantially the same as the area of the incident surface 22 of the opposing level 2.

  In the above configuration, the light emitted from the light emitting diode 1 enters the light incident surface 44 of the light guide plate 4. This incident light is totally reflected by the reflection surface 41 for guiding the light to the level 2 in the light path in the light guide plate 4 and the traveling direction is changed to the right in the figure, and the reflection surface 42 and the light exit surface The light enters the region sandwiched by 43. Since the incident light has minute irregularities or groove-shaped irregularities 46 formed on the surface of the reflecting surface 42, the light hitting the reflecting surface 42 is reflected in the direction determined by the reflecting surface 42. The light exits from the light exit surface 43 and travels toward the level 2. At this time, the reflecting surface 42 diffuses incident light from the light emitting diode 1 and irradiates diffused light having a light amount distribution with a wide angle from the entire light emitting surface 43 with a substantially uniform light amount. As described above, the light exit surface 43 of the light guide plate 4 forms a surface light emitting portion that irradiates diffused light from the entire surface. The surface light emitting portion of the light exit surface 43 has a light emission area larger than the area of the bubble shadow formed when the bubble 21 is projected by parallel light, and irradiates diffused light toward the level 2. Here, since it is sufficient that the distance between the reflective surface 42 and the light exit surface 43 of the light guide plate 4 is about 0.5 mm to 1.5 mm, the thickness of the light guide plate 4 can be reduced, so that the light guide plate 4 is increased in size of the horizontal sensor. The thickness of the horizontal sensor (the size in the axial direction of the cylindrical level) can be kept small while reducing the size of the light receiving unit.

  The diffused light emitted from the entire light exit surface 43 is incident on the entrance surface 22 of the level 2 opposite to the light exit surface 43 and hits the interface between the liquid 2w and the bubble 21 in the level 2 and is refracted or totally reflected at this interface. The light is reflected, emitted from the emission surface 23 of the level 2, and enters the light receiving elements 31 to 34 of the light receiving unit 3. The projection light of the bubble 21 irradiated with the diffused light is projected onto the light receiving unit 3 and received by the light receiving elements 31 to 34. When the level 2 tilts and the bubble 21 in the level 2 moves, the position of the bubble shadow of the bubble 21 projected on the light receiving elements 31 to 34 changes, and as a result, the amount of light received by the light receiving elements 31 to 34. Changes. Therefore, the inclination angle can be detected by reading the amount of change.

  With reference to FIG. 3 (a), (b), the light reception distribution state in the light-receiving part 3 of the horizontal sensor of this embodiment is demonstrated. FIG. 3A shows a two-dimensional received light amount distribution (black and white distribution) on a plane in the light receiving unit 3, and FIG. 3B shows a one-dimensional horizontal direction with the center of the bubble 21 as a reference. The light quantity distribution is shown.

  The two-dimensional light amount distribution is determined by the amount of light detected by the light receiving elements 31 to 34 for the projection light of the bubble 21 irradiated by the diffused light from the light exit surface 43, and is whiter as the received light amount is larger and black as the smaller the received light amount. Diffused light from the light exit surface 43 is irradiated forward from the light exit surface 43 at almost any angle unlike parallel light. Therefore, this diffused light enters the bubble 21 in the level 2 from the incident surface 22 of the level 2 with a wide angle range. At this time, the incident light is reflected and refracted on the surface of the bubble 21, but since the bubble 21 is spherical, light incident at right angles to the tangent on the spherical surface travels straight, but otherwise the liquid 2 w and the bubble 21 Refracted and reflected between. Therefore, as shown in FIG. 3A, the two-dimensional received light amount distribution is small (black part) at the center and outer peripheral part of the bubble 21, and has a maximum point (white part) between the center and outer peripheral part. Distribution.

  Thereby, the light quantity distribution at the horizontal position of the projection light has a minimum point near the central axis of the bubble 21 as shown in FIG. 3B, and the center of the bubble 21 in the same range as the radius of the bubble 21. A characteristic that monotonously increases as the distance from the axis (the center of the bubble) increases can be obtained. With this characteristic, even if the light receiving unit 3 is smaller than the bubble shadow 21a having the diameter of the bubble 21, it is possible to detect a change in the amount of received light by the light receiving elements 31 to 34 during the minute movement of the bubble 21. In addition, by configuring this monotonically increasing characteristic to have a characteristic that increases linearly as it moves away from the central axis (including electrical correction, etc.), changes due to the position of bubbles can be detected linearly. As a result, the inclination detection accuracy error can be reduced.

  With reference to FIGS. 4 (a) and 4 (b), the manner in which the received light amount is detected when the bubble 21 of the horizontal sensor having the received light amount distribution moves will be described in more detail. FIG. 4A shows a positional relationship between the bubble 21 on the plane and the light receiving elements 31 to 34 of the light receiving unit 3 when viewed from the upper surface of the horizontal sensor of the present embodiment. The diffused light from the surface light emitting part of the light exit surface 43 of the light guide 4 irradiates the bubble 21 in the level 2, and the light receiving diodes 31 to 34 which are four substantially square light receiving elements constituting the light receiving part 3. Is received. The four light receiving diodes 31 to 34 are arranged symmetrically with respect to the center of the light receiving surface so that the light receiving surface becomes a square shape as a whole, so that the vertical and horizontal dimensions are smaller than the diameter of the bubble 21. Is set. And the voltage corresponding to the detection amount of the light received by the light receiving surface is output, and the inclination can be detected by comparing these voltages. When the level of the horizontal sensor is maintained and the center of the bubble shadow of the bubble 21 coincides with the center of the light receiving surface of the light receiving unit 3, the light receiving levels of the four light receiving diodes 31 to 34 match.

  FIG. 4B shows a change in the light amount distribution on the light receiving surface before and after the movement of the bubble shadow 21a when the light receiving unit 3 is smaller than the bubble shadow 21a in the horizontal sensor. . The received light amount distribution P1 is a distribution when the bubble 21 does not move, and the received light amount distribution P2 (broken line) is a distribution when the bubble 21 moves and the bubble shadow 21a shifts to the bubble shadow 21b. As shown in FIGS. 3A and 3B, the received light amount distribution P1 has a minimum point in the vicinity of the central axis of the bubble 21, and as the distance from the central axis of the bubble 21 increases in the same range as the radius of the bubble. It has the characteristic of increasing monotonously in a straight line, and forms a substantially V-shaped curve that increases from the center to the left and right. Accordingly, the received light amount distribution P1 is minimum at the center of the light receiving surface, and the received light level always changes with distance from the center. Before the bubble 21 moves in the horizontal state, the light receiving amounts of the light receiving elements 31 to 34 are all the same and balanced at the level 11 of the light receiving amount distribution P1. On the other hand, after the movement of the bubble 21, the received light amount distribution P1 shifts to the received light amount distribution P2, so that the received light amount of the light receiving elements 31 to 32 becomes the level 12 of the received light amount distribution P2, and the light receiving elements 33 to 34 The amount of received light is greatly shifted to level 13 of the received light amount distribution P2. Thus, when the light receiving levels of the light receiving elements 31 to 32 and the light receiving elements 33 to 34 are different, the amount of light received by each of the light receiving diodes 31 to 34 is changed, thereby detecting the movement. This is detected in the same way even if it deviates in other directions.

  Therefore, the change in the amount of light received by each of the light receiving elements 31 to 34 can be finely detected with respect to the minute movement of the bubble 21. Each of the light receiving elements 31 to 34 outputs a voltage corresponding to the amount of light received, and compares these voltages to detect a finer inclination.

  As described above, the horizontal sensor according to the present embodiment is configured so that the light receiving unit 3 occupying a large mounting area is made smaller than the bubble shadow 21a of the bubble 21 and a thin surface light emitting unit capable of irradiating diffused light is formed. An optical system in which the light amount distribution of the projection light on the element has a minimum point near the central axis of the bubble 21 and obtains a light distribution characteristic that monotonously increases as the distance from the central axis of the bubble 21 is approximately the same as the radius of the bubble 21. Therefore, a small and highly accurate sensor can be obtained.

  In the horizontal sensor, in the formation of diffused light, a sheet-like member 6 provided with minute irregularities having a function of diffusing light between the light exit surface 43 of the light guide plate 4 and the incident surface 22 of the level 2. By disposing (hereinafter abbreviated as a sheet-like member) (see FIG. 5A described later), the concavo-convex shape of the reflective surface 42 of the light guide plate 4 or the groove-shaped concavo-convex shape portion 46 is processed for diffusion. Therefore, the amount of light emitted from the entire light exit surface 43 can be made more uniform.

  Further, instead of arranging the sheet-like member 6, diffused light may be formed by making the incident surface 22 of the level 2 rough.

  Further, by arranging a sheet-like or plate-like highly reflecting member on the reflecting surface 41 or the reflecting surface 42 of the light guide plate 4, the ratio of the amount of light incident on the light incident surface 44 and the amount of light emitted from the light emitting surface 43 is increased. can do. As a result, the current of the light emitting diode 1 serving as a light source can be reduced in order to obtain the required tilt detection accuracy, and the power consumption of the horizontal sensor can be reduced. Further, as in the present embodiment, the light-emitting diode 1 and the light-receiving unit 3 are arranged on the same side with respect to the level 2, and the light guide plate 4 generally having a flat plate shape is a total reflection surface from the light source to the surface light-emitting unit. If the construction of the light guide portion having a portion (here, the portion from the light incident surface 44 including the reflection surface 41 to the reflection plate 42) is increased, the size (thickness) of the sensor in the direction of the level of the spirit level is greatly increased. It can be made smaller. Moreover, although the example which has arrange | positioned the light emitting diode 1 and the light-receiving part 3 on the same side with respect to the level 2 was shown here, it is not limited to this. For example, when both are arranged on a substantially straight line in the level axis direction, the size of the horizontal sensor in the horizontal direction perpendicular to the axis direction of the level 2 can be reduced.

  Next, a horizontal sensor according to a second embodiment of the present invention will be described with reference to FIGS. The horizontal sensor has a light receiving area smaller than the projection light produced by the parallel light of the bubble 21, the light emitting diode 1 as a light source, the level 2 having a cylindrical container 2 a filled with a substantially transparent liquid 2 w so that the bubble 21 remains. The light receiving unit 3 includes four light receiving elements 31 to 34 and the sheet-like member 6. The optical axis of the light emitting diode 1, the central axis of the level 2, and the optical axis of the light receiving unit 3 are arranged so as to be substantially in a straight line, and the level 2 is interposed between the light emitting diode 1 and the light receiving unit 3. Has been placed. Further, a light diffusing sheet-like member 6 is disposed between the light emitting diode 1 and the level 2 and functions as a surface light emitting portion.

  The cylindrical container 2a of the level 2 has a hollow inside, and at least one of the inside surfaces has a substantially rotationally symmetric curved surface shape, and has an upper bottom 2b having an emission surface 23 facing the light receiving unit 3. And a bottom part 2c having a light incident surface 22 and a light exit surface 26 on both sides of the bottom thickness, and a side wall part 2d. The light emitting diode 1, the sheet-like member 6, the level 2 and the light receiving elements 31 to 34 are assembled by a frame not shown.

  In the above configuration, the light 11 emitted from the light emitting diode 1 is diffused by the sheet-like member 6 to become diffused light 12. The diffused light 12 is incident on the incident surface 22 of the level 2, hits the interface between the liquid 2 w and the bubble 21 in the level 2, is refracted or totally reflected at the interface, and is emitted from the exit surface 23 of the level 2. , Enters the light receiving elements 31 to 34. Thereby, the projection light of the bubble 21 is projected on the light receiving elements 31 to 34, and the amount of received light is detected.

  At this time, the light irradiated by the bubbles 21 is diffused light obtained by diffusing the light of the light-emitting diode 1 by the sheet-like member 6, and therefore is shown in FIGS. 3A and 3B in the light receiving unit 3. The same light distribution characteristics as those obtained can be obtained. Therefore, when the level 2 is tilted and the bubbles 21 in the level 2 are slightly moved, the change amount can be read and the tilt angle can be detected as described above.

  As described above, the horizontal sensor of the present embodiment includes the sheet-like member 6 between the light emitting diode 1 and the level 2, and makes the light receiving area of the light receiving unit 3 smaller than the bubble shadow of the bubble 21. Similar light quantity distribution characteristics can be obtained. Therefore, with this light quantity distribution characteristic, it is possible to detect a change in the light quantity of the light receiving elements 31 to 34 during the minute movement of the bubble 21, and to obtain a highly accurate detection characteristic.

  In addition, since the light receiving unit 3 that requires a large mounting area among the electronic components used in the sensor can be reduced while ensuring the high-precision detection characteristics, the width and length of the mounting substrate can be reduced. This can contribute to downsizing of the horizontal sensor. Furthermore, since the diffused light can be efficiently formed by the sheet-like member 6, the current of a light source such as a light emitting diode for obtaining the required tilt detection accuracy can be reduced, and the power consumption can be reduced. Further, by making the incident surface 22 of the level 2 rough, it is possible to further increase the divergence angle of light incident on the incident surface 22 of the level 2, so that the light quantity distribution characteristics that are clearer and have higher light receiving sensitivity. Thus, the light receiving unit 3 can be made smaller.

  Next, a horizontal sensor according to a third embodiment of the present invention will be described with reference to FIGS. The horizontal sensor includes four light emitting diodes 1 as light sources, a level 2 having a cylindrical container 2a in which a substantially transparent liquid 2w is encapsulated so that bubbles 21 remain, and a light receiving area smaller than the projection light by the parallel light of the bubbles 21. The light-receiving part 3 which consists of the four light-receiving elements 31-34 having are provided. The four light emitting diodes 1 are arranged so as to be substantially rotationally symmetric with respect to the central axis of the level 2.

  The level 2 is disposed so that the central axis of the level 2 and the optical axis of the light receiving unit 3 are substantially in a straight line, and is disposed between the light emitting diode 1 and the light receiving unit 3. The cylindrical container 2a of the level 2 has an upper bottom portion 2b having a cavity on the inside and a curved surface shape in which one of the inner surfaces is substantially rotationally symmetric and having an emission surface 23 facing the light receiving portion 3. In addition, a lower bottom portion 2c having a light incident surface 22 and an output surface 26 and a side wall portion 2d are provided on both surfaces of the bottom thickness.

  In the above configuration, each light 11 emitted from the four light emitting diodes 1 uses a plurality of light emitting diodes 1 as light sources, thereby further increasing the spread angle of light incident on the incident surface 22 of the level 2 as a whole. Can form diffuse light. The diffused light 12 is incident on the incident surface 22 of the level 2, hits the interface between the liquid 2 w and the bubble 21 in the level 2, is refracted or totally reflected at the interface, and is emitted from the exit surface 23 of the level 2. , Enters the light receiving elements 31 to 34. Thereby, the projection light of the bubble 21 is projected on the light receiving elements 31 to 34, and the amount of received light is detected.

  At this time, since the light irradiated by the bubbles 21 is diffused light from the plurality of light emitting diodes 1, the light amount distribution characteristics similar to those shown in FIGS. 3A and 3B in the light receiving unit 3. Is obtained. Accordingly, when the level 2 is tilted and the bubbles 21 in the level 2 are slightly moved, the change amount can be read and the tilt angle can be detected as described above.

  As described above, the horizontal sensor of the present embodiment can increase the amount of incident light and increase the light divergence angle by using the plurality of light emitting diodes 1. Therefore, among the electronic components of the horizontal sensor while ensuring the above detection characteristics. Since the light receiving portion 3 that requires a large mounting area can be further reduced, it is possible to contribute to high sensitivity and downsizing of the sensor. Further, since the area of the light source is substantially widened, the light source can be brought close to the level, and further contribute to reduction in thickness and size.

  Further, by arranging the sheet-like member 6 between the light emitting diode 1 and the level 2 or by making the incident surface 22 of the level 2 rough, the uniformity of the amount of light incident on the level 2 is improved, It is possible to further improve the inclination detection accuracy.

  Next, a horizontal sensor according to a fourth embodiment of the present invention will be described with reference to FIGS. 7A and 7B, the horizontal sensor 10 includes a light emitting diode 1 as a light source, a level 2 having a cylindrical container 2a in which a substantially transparent liquid 2w is sealed so that bubbles 21 remain, and a light emitting diode. A light guide 7 made of a transparent member that guides light from 1 to the level 2, the sheet-like member 6, and four light receiving elements 31 to 34 having a light receiving area smaller than the projection light by the parallel light of the bubbles 21. A light receiving unit 3 is provided.

  The light guide 7 has a light incident surface 74 on which light from the light emitting diode 1 is incident, reflection surfaces 71 and 72 that totally reflect the incident light, and a light output surface 73 that emits the reflected light. The light emitting diode 1 and the light receiving unit 3 are mounted on the same printed circuit board 5 and arranged on the same side with respect to the level 2.

  The level 2 is disposed so that the central axis thereof and the optical axis of the light receiving unit 3 are substantially aligned, and is disposed between the light receiving unit 3 and the light exit surface 73 of the light guide 7. Further, the sheet-like member 6 is disposed between the light exit surface 73 of the light guide 7 and the level 2. The cylindrical container 2a of the spirit level 2 is opposite to the light receiving unit 3 in that the cylindrical container 2a of the spirit level 2 has a hollow inside, and at least one of the inner faces has a substantially rotationally symmetric curved shape. The upper bottom portion 2b having the outgoing surface 23, the lower bottom portion 2c having the light incident surface 22 and the outgoing surface 26 on both sides of the bottom thickness, and the side wall portion 2d are provided.

  The light emitted from the light emitting diode 1 is incident on the light incident surface 74 of the light guide 7, and the light incident on the light incident surface 74 is totally reflected by the reflective surface 71 in the light guide 7 and proceeds rightward in the figure. The direction is changed, and the light is further totally reflected by the reflecting surface 72 and emitted from the light emitting surface 73. The light emitted from the light exit surface 73 is diffused by the sheet-like member 6 and becomes diffused light and enters the entrance surface 22 of the level 2. When this diffused light hits the interface between the liquid 2w and the bubble 21, it is refracted or totally reflected at the interface, exits from the exit surface 23 of the level 2, and enters the light receiving elements 31-34. Thereby, the shadow of the bubble 21 is projected onto the light receiving elements 31 to 34 by the light from the light emitting diode 1, and the amount of received light is detected.

  Thus, by providing the light guide 7 and disposing the sheet-like member 6 between the light exit surface 73 and the level 2, the spread angle of light incident on the incident surface 22 of the level 2 is increased. The same light quantity distribution characteristics as described above can be obtained. Therefore, when the level 2 is tilted and the bubble 21 in the level 2 is slightly moved by this light quantity distribution characteristic, the change amount can be read and the tilt angle can be detected as described above.

  As a result, the horizontal sensor of the present embodiment can reduce the size of the horizontal sensor because the light receiving unit 3 that requires a large mounting area among the electronic components used in the horizontal sensor can be reduced while ensuring the above detection characteristics. Can contribute. Further, since the incident light can be efficiently transmitted using the light guide 7, the ratio of the amount of light incident from the light incident surface 74 of the light guide 7 to the amount of light emitted from the light exit surface 73 can be increased, and a sheet-like member can be used. 6, diffused light can be efficiently formed. For this reason, the current of the light emitting diode 1 for obtaining the required tilt detection accuracy can be reduced, and the power consumption of the horizontal sensor can be reduced. In addition, the light output portion of the light guide 7 may be formed in a flat plate shape so as to be a so-called light guide plate. In this case, the same one as in the first embodiment is obtained.

  Next, a horizontal sensor according to a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 8, the horizontal sensor is smaller than the light emitted from the light emitting diode 1 as a light source, the level 2 having a cylindrical container 2 a in which a substantially transparent liquid 2 w is sealed so that the bubbles 21 remain, and the parallel light of the bubbles 21. A light receiving unit 3 including four light receiving elements 31 to 34 having a light receiving area is provided, and minute unevenness for diffusing light is formed on at least one surface other than the surface on which the bubble of the level 2 slides. The optical axis of the light emitting diode 1, the central axis of the level 2, and the optical axis of the light receiving unit 3 are arranged so as to be substantially in line with each other, and the level 2 is between the light emitting diode 1 and the light receiving unit 3. Is arranged.

  The level 2 has minute irregularities for diffusing light on a surface other than the surface on which the bubbles 21 slide, for example, at least one of the incident surface 22, the side wall inner surface 24, and the exit surface 26. . Therefore, now if it is assumed that minute irregularities are formed on the exit surface 26, the light emitted from the light emitting diode 1 enters the entrance surface 22 of the level 2 and is diffused by the exit surface 26 to diffuse. It becomes light and irradiates the bubble 21 in the level 2. Similarly, even if minute irregularities are formed on the incident surface 22 or the side wall inner surface 24, similar diffused light can be generated.

  In this way, the light irradiated on the bubble 21 is diffused in the level 2 and becomes diffused light, so that the same light quantity distribution characteristic as shown in FIGS. 3A and 3B is obtained. Can do. Therefore, when the level 2 is tilted and the bubble 21 in the level 2 is slightly moved, the light receiving unit 3 can read the amount of change and detect the tilt angle as described above.

  Thereby, the horizontal sensor of this embodiment has the effect of diffusing light by forming minute irregularities for diffusing light on at least one surface other than the surface on which the bubble 21 slides in the level 2. Can be formed by the level 2 itself. Therefore, the sheet-like member 6 and the like can be omitted, the number of parts can be reduced, and the thickness of the sensor can be reduced, thereby contributing to downsizing of the sensor.

  Next, a horizontal sensor according to a sixth embodiment of the present invention will be described with reference to FIGS. 9 (a) and 9 (b), the horizontal sensor includes a light emitting diode 1 serving as a light source, a level 2 having a cylindrical container 2a in which a substantially transparent liquid 2w is sealed so that the bubbles 21 remain, The light receiving unit 3 includes four light receiving elements 31 to 34 having a light receiving area smaller than that of the projected light by parallel light, and a light guide 7 that guides incident light from the light emitting diode 1 to the side surface of the level 2.

  The central axis of the level 2 and the optical axis of the light receiving unit 3 are arranged so as to be substantially in a straight line. The level 2 includes a light incident part 25 on which the light from the light guide 7 is incident on the side far from the light receiving part 3 of the side wall part 2d, and on the surface far from the light receiving part 3 in the bottom thickness of the lower bottom part 2c. The reflecting surface 22a having minute unevenness or groove shape for diffusing light is provided.

  The light guide 7 is formed of a transparent member, and includes a light incident surface 74 on which incident light from a light source enters, a reflective surface 71 that totally reflects the incident light, and a light incident portion 25 on the side surface of the level 2 at the end surface of the light guide 7. And a light exit surface 73 for irradiating light. The light emitting diode 1 and the light receiving unit 3 are mounted on the same printed circuit board 5 and arranged on the same side with respect to the level 2.

  The light emitted from the light emitting diode 1 is incident on the light incident surface 74 of the light guide 7 and is totally reflected by the reflecting surface 71 in the light guide 7, and after changing the traveling direction to the right in the figure, the light emitting surface. The light is emitted from 73 and incident on the light incident part 25 of the level 2. The light incident on the light incident part 25 of the level 2 travels in the right direction in the figure while being repeatedly reflected by the reflecting surface 22a and the emitting surface 26.

  Here, since the reflecting surface 22a has a light diffusing shape due to minute unevenness or a groove shape, the light hitting the reflecting surface 22a is reflected and emitted in the direction determined by the scattering shape of the reflecting surface 22a. Irradiated from the surface 26, it proceeds toward the liquid 2 w and the bubbles 21 in the level 2. The concavo-convex shape or groove shape formed on the reflection surface 22a is formed so that a substantially uniform amount of light is emitted from the entire emission surface 26, and the light amount distribution of the emitted light is expanded. For this reason, the light emitted from the entire emission surface 26 becomes diffused light and can irradiate the bubble 21.

  Thus, since the light irradiated to the bubble 21 becomes diffused light by irradiation from the reflecting surface 22a having a scattering shape, the light receiving unit 3 is shown in FIGS. 3 (a) and 3 (b). It is possible to obtain the same light quantity distribution characteristic as that described above. Accordingly, when the level 2 is tilted and the bubbles 21 in the level 2 are slightly moved, the change amount can be read and the tilt angle can be detected as described above.

  As a result, the horizontal sensor according to the present embodiment can reduce the size of the horizontal sensor because the light receiving unit 3 that requires a large mounting area can be reduced among the electronic components of the horizontal sensor while ensuring the above-described detection characteristics. can do. In addition, light from the light guide 7 is incident from the side surface of the level 2, and a light diffusing component needs to be mounted outside the level 2 by forming an uneven shape or a groove shape on the reflection surface 22 a of the level 2. Therefore, the thickness of the horizontal sensor can be further reduced. Moreover, although the light emitting diode 1 and the light receiving part 3 are mounted on the same substrate, the same effect can be obtained even if they are mounted on different substrates.

  Next, a horizontal sensor according to a seventh embodiment of the present invention will be described with reference to FIGS. 10 (a) and 10 (b). 10 (a) and 10 (b), the horizontal sensor includes a light emitting diode 1 serving as a light source, a level 2 having a cylindrical container 2a in which a substantially transparent liquid 2w is sealed so that bubbles 21 remain, and four light receiving elements. A light receiving unit 3 including elements 31 to 34. Each of the light receiving elements 31 to 34 is arranged such that the vertex closest to the optical axis of the light receiving unit 3 is located farther from the emission surface 23 of the level 2 than the other vertexes. The area of the equivalent light receiving portion 3 viewed from the optical axes is equal to or smaller than the area of the projection light by the parallel light of the bubbles 21.

  The optical axis of the light emitting diode 1, the central axis of the level 2, and the optical axis of the light receiving unit 3 are arranged so as to be substantially in a straight line, and the level 2 is interposed between the light emitting diode 1 and the light receiving unit 3. Has been placed. The cylindrical container 2a of the level 2 has a hollow inside, and at least one of the inside surfaces has a substantially rotationally symmetric curved surface shape, and has an upper bottom 2b having an emission surface 23 facing the light receiving unit 3. And a lower bottom portion 2c having a light incident surface 22 and an output surface 26 on both sides of the bottom thickness, and a side wall portion 2d.

  The light emitted from the light emitting diode 1 enters the incident surface 22 of the level 2 and hits the interface between the liquid 2w and the bubble 21 and is refracted or totally reflected at the interface, and is emitted from the output surface 23 of the level 2. , Enters the light receiving elements 31 to 34. Thereby, the shadow of the bubble 21 is projected onto the light receiving elements 31 to 34 by the light from the light emitting diode 1.

  Here, the light receiving elements 31 to 34 of the light receiving unit 3 are arranged so that the vertex closest to the optical axis of the light receiving unit 3 is farther from the exit surface 23 of the level 2 than the other vertexes. Therefore, the light receiving surface of each of the light receiving elements 31 to 34 is equivalently shaped like a rhombus when viewed from the emission surface 23 of the level 2. Accordingly, the area is large at the center of each light receiving element 31 to 34, and the area decreases toward the top and bottom vertices. Thereby, the light quantity distribution received by the light receiving unit 3 can obtain the same light quantity distribution characteristics as in FIGS. 3 (a) and 3 (b). Therefore, with this light quantity distribution characteristic, it is possible to obtain a highly accurate detection characteristic capable of detecting a change in the light quantity of the light receiving elements 31 to 34 when the bubble 21 is slightly moved.

  As described above, the horizontal sensor according to the present embodiment can obtain the same light quantity distribution characteristic only by the light receiving unit 3, so that the diffused light is not necessarily required as the incident light, the configuration can be simplified, and the size of the sensor can be reduced. it can. In addition, since no diffused light is required, the light guide plate 4 having the reflection surface 42 for diffusion, the sheet-like member 6 and the like are not necessary, and the number of components can be reduced.

  Next, a horizontal sensor according to an eighth embodiment of the present invention will be described with reference to FIGS. The horizontal sensor of the present embodiment includes a member obtained by deforming the light guide plate 4 in the first embodiment shown in FIGS. 1 to 4, and this member will be referred to as a light guide and will be described below. Since the level sensor and the light receiving unit as the horizontal sensor are the same as those in the above-described embodiment, the illustration is omitted. The light guide 7 includes a cylindrical portion 75 having a convex shape so that the light L1 emitted from the light source is substantially parallel to the light incident surface 76 of the light guide. The cylindrical axis R1 is a plane normal line including the optical axis R2 of the light source and the axis R3 formed by reflecting the optical axis R2 of the light source with respect to the reflection surface 71 (total reflection surface) of the light guide. It is formed so that it may become parallel to.

  The cylindrical part 75 functions as a convex lens by having a convex cylindrical light incident surface 76. As a result, the light L1 incident on the light incident surface 76 of the light guide 7 from the light source is refracted in the direction along the optical axis of the convex lens by the convex lens action of the cylindrical portion 75, and this light axis in the light guide 7 It becomes the substantially parallel light L2. Thereby, the light L2 reflected by the reflecting surface 71 of the light guide 7 is easily totally reflected. On the other hand, as shown in FIG. 11 (c), when the light guide 7 has a flat light incident surface 74, the light incident surface 74 has no lens action, so that light incident from the light incident surface 74 is reflected by the reflective surface 71. The light Lx emitted from the reflecting surface 71 to the outside of the light guide increases, and the amount of light that guides the light from the light source toward the level 2 is reduced. Will end up.

  According to the present embodiment, the light guide 7 includes the cylindrical portion 75 having the convex cylindrical light incident surface 76, so that the reflection surface 71 of the light guide 7 can easily satisfy the condition of total reflection. Thus, the light emitted from the light guide 7 to the outside is suppressed, and the transmission efficiency of the light guide is increased. As a result, the intensity of the uniform light emitted from the surface light emitting unit is improved, so that the resolution of the horizontal sensor is improved, the power applied to the light emitting diode 1 of the light source can be reduced, and the current consumption of the horizontal sensor is reduced. realizable.

  Next, a horizontal sensor according to a ninth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the light guide 7 includes a light guide plate-like surface light emitting portion 77, and the reflection surface 71 of the light guide 7 is formed by reflecting the optical axis R 2 of the light source and the optical axis R 2 by the reflection surface 71. A cross-sectional shape in a plane including both axes with the axis R3 forms a paraboloid, and the focal point of the paraboloid is formed near the entrance of the surface light emitting portion 77 of the light guide 7.

  The light guide 7 includes a light guide plate-like surface light emitting portion 77 having a reflection surface 72 having irregularities and grooves for reflecting light and a light emission surface 73 (an emission surface) for emitting light from the plane. The reflecting surface 71 of the light source has a parabolic surface in a plane shape including both the optical axis R2 of the light source and the axis R3 formed by reflecting the optical axis R2 with the reflecting surface 71. The focal point of the surface is formed in the vicinity of the entrance of the surface light emitting portion 77 of the light guide 7.

  In the above-described configuration, the light L1 incident on the light incident surface 76 of the light guide 7 from the light emitting diode 1 of the light source is refracted in the direction along the optical axis R2 by the cylindrical portion 75 having a convex lens action, and is approximately aligned with the optical axis R2. The light becomes parallel light L2 and is reflected by the reflecting surface 71 that forms a paraboloid. When the parallel light L2 is reflected by this paraboloid, it is focused to the focal point (focal line) F1 of the paraboloid. The focal point F <b> 1 is positioned so as to be near the entrance of the surface light emitting unit 77 of the light guide 7. Further, the thickness of the surface light emitting portion 77 is the thinnest portion of the light guide 7 as compared with the light guide portion of the light guide 7 (the portion from the light incident surface 76 to the reflecting surface 71 and the surface light emitting portion 77). Thus, it is difficult for light to enter near the entrance of the surface light emitting portion 77. Accordingly, the light L2 in the light guide 7 is reflected by the reflecting surface 71 that forms the paraboloid of the light guide, and is condensed near the entrance of the surface light emitting portion 77 having the thinnest thickness. Is easier to enter.

  According to the present embodiment, the light guide 7 has a reflecting surface 71 that forms a paraboloid, and the parabolic surface reflects the parallel light L2 from the light incident surface 76 so that the light is focused on the paraboloid. The amount of light incident on the surface light emitting portion 77 is increased by setting the focal point near the entrance of the surface light emitting portion 77. Thereby, since the intensity | strength of the light inject | emitted from the surface emitting part 77 improves, the resolution | decomposability of a horizontal sensor improves, the electric power applied to a light source can be reduced, and low current consumption can be implement | achieved.

  Next, a horizontal sensor according to a tenth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the light guide 7 includes a plurality of diffusion grooves 76 a (grooves) having a triangular or trapezoidal cross-sectional shape along the cylinder of the light incident surface in the cylindrical portion 75. Further, each of the diffusion grooves 76a (grooves) is on a plane orthogonal to the cylindrical axis R1, and is disposed on substantially the entire cylindrical surface at substantially equal intervals in the direction of the cylindrical axis R1. . As shown in FIGS. 13E and 13F, when the light L1 emitted from the light source is incident on the light incident surface 76 where the plurality of diffusion grooves 76a (grooves) are formed, the light L1 As described above, the light is collimated in the direction of the optical axis R2 of the light source by the cylindrical light incident surface 76 and reflected by the grooves of the plurality of diffusion grooves 76a, so that the direction of the cylindrical axis R1 And is incident on the light guide 7. Accordingly, since the light L2 spreads in the direction of the cylindrical axis R1 in the light guide 7, the light L3 incident from the vicinity of the entrance of the surface light emitting portion 77 has the same direction as the cylindrical axis R1 in the surface light emitting portion 77. It is spread and guided. Thereby, the surface light emission part 77 can improve the surface emission uniformity in the axis | shaft R1 direction of a cylindrical surface.

  According to the present embodiment, the plurality of diffusion grooves 76 a having a triangular or trapezoidal cross-sectional shape are provided along the cylindrical surface of the light incident surface 76, whereby the surface light emitting unit 77 in the direction of the axis R <b> 1. The surface emission uniformity is improved, and the resolution of the horizontal sensor is improved when the bubble 21 moves in the direction of the axis R1 of the cylindrical surface.

  Next, a horizontal sensor according to an eleventh embodiment of the present invention will be described with reference to FIGS. In the light guide 7 of the present embodiment, a plurality of triangular grooves 72 a (grooves) having a triangular cross section are formed on the reflection surface 72 of the surface light emitting unit 77, and the light emitting surface 73 of the surface light emitting unit 77 of the light guide 7 Between the level 2 are provided sheet-like members 6a and 6b in which a triangular prism 6p having an apex angle of 90 ° is formed. The triangular groove 72a is disposed parallel to the cylindrical axis R1 of the cylindrical portion 75, and the base angle θ of the light incident side surface 72b of the reflecting plate 72 of the surface light emitting portion 77 forms 20 to 40 °. The triangular prism 6p and the triangular groove 72a are arranged so that the ridge line Q2 of the prism 6p is parallel to the ridge line Q1 of the triangular groove 72a of the light guide 7. An auxiliary reflecting plate 78 is provided outside the reflecting surface 72 in parallel with the reflecting surface 72.

  In the light guide 7 of the present embodiment, when the light L3 from the reflection surface 71 of the light guide 7 enters the surface light emitting unit 77, the incident light L4 emits surface light when passing through the surface light emitting unit 77. Since the reflection surface 72 of the portion 77 is reflected by the incident side surface 72b in which the base angle θ of the triangular groove 72a is 20 to 40 degrees, it is emitted at 20 ° to 40 ° with respect to the normal line of the light exit surface 73. . Further, the light that is not reflected by the incident side surface 72b and is emitted from the reflecting surface 72 in the direction opposite to the emitting surface 43 is substantially totally reflected by the auxiliary reflecting plate 78 provided below the reflecting surface 72, and again, the surface emitting unit. The light enters the reflection surface 72 of 77 and exits from the light exit surface 73. Thereby, the surface light emission efficiency of the surface light emission part 77 increases.

  Further, the light emitted from the emission surface 43 sequentially enters the sheet-like members 6a and 6b, and is first bent along the central axis direction of the cylinder of the level 2 by the triangular prism 6p of the sheet-like member 6a. Furthermore, since the sheet-like member 6b is bent again in the same manner, the light beam becomes more parallel to the central axis of the level 2. Thereby, the center of the distribution of the light that has passed through the triangular prism 6p of the sheet-like members 6a and 6b is substantially perpendicular to the light exit surface 73 of the surface light emitting unit 77, and the surface light emission distribution is the central axis of the level 2 Is substantially symmetric with respect to. The light L <b> 5 whose surface emission distribution is substantially symmetric is incident on the level 2, passes through the bubble 21 of the level 2, and is disposed symmetrically with respect to the central axis of the level 2 in the light receiving unit 3. The received light is received by the respective light receiving elements 31, 32, 33, and 34 of the four-divided photodiode (PD), and the amount of light is detected.

  Here, the surface light emission distribution state before the improvement of the surface light emission in the light guide 7 and after the improvement according to the eleventh embodiment will be described with reference to FIGS. Before the improvement shown in FIG. 15A, the light guide 7 does not include the sheet-like member 6 having the triangular groove 72a of the surface light emitting portion 77 or the triangular prism 6p, so the direction of the light emitted from the light exit surface 73 Forms a surface emission distribution G1 on the light exit surface 73 in a direction that is inclined and shifted from the parallel direction with respect to the central axis of the level 2. Therefore, the direction of light hitting the bubble 21 of the level 2 is oblique with respect to the central axis of the level 2. As a result, the amount of light received through the spherical bubble 21 differs between the left and right sides of the light receiving elements 31 and 32 on the A side and the light receiving elements 33 and 34 on the B side. On the other hand, after the improvement shown in FIG. 15B, the direction of the light emitted from the light exit surface 73 is substantially parallel to the light exit surface 73 with respect to the central axis of the level 2 and the surface emission distribution G2 is substantially symmetrical. Since it is light, the amount of light that has passed through the bubble 21 of the level 2 is substantially the same and symmetrical on the left and right sides of the A side and B side.

  16 (a) and 16 (b) show the above surface light emission when the temperature changes due to the environmental temperature change in the horizontal state where the bubble 21 on the central axis of the level 2 is present, for example, when the temperature rises. The respective light quantity detection states of the light receiving elements 31, 32, 33, and 34 before the improvement of the distribution and after the improvement according to the eleventh embodiment are shown. When the temperature rises in the horizontal state, the position of the bubble 21 does not change on the central axis of the level 2 but the diameter of the bubble 21 becomes small. Before the improvement, the light receiving amount La of the light receiving elements 31 and 32 on the A side of the light passing through the bubble 21 is set as the light receiving amount Lb of the light receiving elements 33 and 34 on the B side, and the difference before and after the temperature change is Δp1. , Δp2, the surface emission distribution G1 is inclined before the improvement, and thus Δp1 and Δp2 are not zero. The differences Δp1 and Δp indicate the level of the level 2 (Δp1, Δp is zero and horizontal), and in this case, the level 2 does not indicate horizontal even though it is horizontal, and an error occurs. become. On the other hand, after the improvement, since the surface light emission distribution G2 is symmetrical with respect to the central axis of the level 2, even if the temperature changes, the difference between the light reception amount La on the A side and the light reception amount Lb on the B side of each light receiving element. Δq1 and Δq2 are both substantially zero. Thereby, even if the temperature changes, it is confirmed that the position of the bubble 21 does not change, and it is possible to accurately detect the horizontal state.

  As described above, according to the eleventh embodiment, the center of the distribution of light emitted from the surface light emitting portion 77 of the light guide 7 is 20 ° to 40 ° with respect to the normal line of the light emitting surface 73 of the surface light emitting portion 77. Further, the center of the distribution of light that has passed through the triangular prism having an apex angle of 90 ° is substantially perpendicular to the light emitting surface 73 of the surface light emitting portion. That is, since the surface emission distribution is symmetric with respect to the central axis of the level 2, in the horizontal state where the bubble 21 is at the center of the light receiving elements 31 to 34 of the 4-split PD, even if the bubble diameter increases or decreases, the difference of the 4-split PD The outputs Δq1 and Δq2 are kept substantially zero. As a result, even when the bubble diameter changes due to a temperature change, it is possible to reliably detect the level.

  Next, a horizontal sensor according to a twelfth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the thickness t of the surface light emitting portion 77 of the light guide 7 can be freely changed depending on the design of the light guide 7. Here, as shown in FIG. 17B, when t = 0.7 to 1.5 mm, the surface light emission distribution G3 of the amount of light emitted from the surface light emitting unit 77 has a small amplitude variation and is uniform. Becomes nearly flat and the size of t is appropriate. Further, as shown in FIG. 17C, when t is large, the surface light emission distribution G4 has a large amplitude variation, and a bright part and a dark part are generated in the amount of light emitted from the surface light emitting part 77, which is not appropriate. . In addition, in the surface light emitting unit 77, if the thickness t is too small, the amount of light incident on the surface light emitting unit 77 is decreased, and thus the amount of light emitted from the surface light emitting unit 77 is decreased. Normally, the condensing position (focal point F1 position) of the light guide 7 fluctuates due to tolerance of the light source position. The amount of light incident on the portion 77 is drastically reduced.

  According to the present embodiment, by setting the thickness t of the surface light emitting portion 77 to a value in the range of 0.7 to 1.5 mm, the surface light emission uniformity is improved while ensuring the amount of light incident on the surface light emitting portion 77. .

  Next, a horizontal sensor according to a thirteenth embodiment of the present invention will be described with reference to FIGS. In the figure, only the reflection surface 72 of the surface light emitting portion 77 of the light guide 7 in the horizontal sensor is illustrated. A plane 72 c parallel to the reflection surface 72 is provided between the grooves of the plurality of triangular grooves 72 a of the reflection surface 72 of the surface light emitting unit 77. As described above, in the present embodiment, by providing the flat surface 72c, the light L4 incident on the surface light emitting unit 77 is totally reflected by hitting the flat surface 72c and travels from the vicinity of the entrance of the surface light emitting unit 77 to the back. . Accordingly, since the same amount of light reaches the entrance side and the back side in the surface light emitting unit 77, the light emission uniformity of the surface light emitting unit 77 is further improved.

  As mentioned above, although this invention is implement | achieved by various embodiment, it can change arbitrarily in the range which is not restricted to these but does not deviate from the meaning of invention.

The block diagram of the horizontal sensor by the 1st Embodiment of this invention. The external view of the said horizontal sensor. (A) is a figure which shows light quantity distribution by the light-receiving surface of the said horizontal sensor, (b) is a graph of light quantity distribution. (A) is a figure which shows the positional relationship on the plane of the bubble of the said horizontal sensor, and a light receiving element, (b) is a figure which shows the light reception level change of the light receiving element before and behind the movement of a bubble. (A) is a block diagram of the horizontal sensor by the 2nd Embodiment of this invention, (b) is the external view. (A) is a block diagram of the horizontal sensor by the 3rd Embodiment of this invention, (b) is the external view. (A) is a block diagram of the horizontal sensor by the 4th Embodiment of this invention, (b) is the external view. The block diagram of the horizontal sensor in the 5th Embodiment of this invention. (A) is a block diagram of the horizontal sensor by the 6th Embodiment of this invention, (b) is the external view. (A) is a block diagram of the horizontal sensor by the 7th Embodiment of this invention, (b) is a figure which shows the arrangement | positioning relationship of four light receiving elements and a level. (A) is a block diagram of the horizontal sensor by the 8th Embodiment of this invention, (b) is a figure explaining reflection of the light in a light guide, (c) is a figure for demonstrating reflection of light. The block diagram of the horizontal sensor by the 9th Embodiment of this invention. (A) is the block diagram of the horizontal sensor by the 10th Embodiment of this invention, (b) is a front view of the said horizontal sensor, (c) is an enlarged view of the A section of (a), (d) is (b) (B) is an enlarged view of part B, and (e) and (f) are diagrams for explaining light diffusion in a front view and a partial perspective view of the horizontal sensor. (A) is the block diagram of the horizontal sensor by the 11th Embodiment of this invention, (b) is an enlarged view of the C section of (a), (c) demonstrates the reflection of the light in the light guide of the said horizontal sensor. The figure, (d) is an enlarged view of the D part of (c), (e) is an enlarged view of the E part of (d). (A), (b) is a figure explaining the surface-emission distribution before and after the improvement of the light guide of the said sensor, respectively. (A), (b) is a figure explaining the influence by the temperature of the light quantity detection of the light receiving element before and after improvement of the light guide of the said sensor, respectively. (A) is the block diagram of the horizontal sensor by the 12th Embodiment of this invention, (b), (c) is each surface emission distribution in the case where the thickness of the surface emitting part in the said sensor is appropriate, and when it is large. Illustration to explain. (A) is a block diagram of the horizontal sensor by the 13th Embodiment of this invention, (b) is an enlarged view of F section of (a). (A) is a figure which shows the positional relationship of the bubble and light receiving element of the conventional horizontal sensor, (b) is a figure which shows the change of the light reception amount by the movement of the said bubble. (A) is a figure which shows the positional relationship of the bubble and light receiving element of the state which made the conventional light receiving element small, (b) is a figure which shows the light receiving state before and behind the movement of the said bubble.

Explanation of symbols

1 Light-emitting diode (light source)
2 Level 2w Liquid 3 Light receiving part 4 Light guide plate 4a Surface light emitting part (light guide plate)
DESCRIPTION OF SYMBOLS 5 Printed circuit board 6, 6a, 6b Sheet-like member 6p Triangular prism 7 Light guide 21 Bubble 31-34 Light receiving element 41 Reflecting plate 42 Light guide plate 71 Reflecting plate (total reflection plate)
72 Reflecting surface 72a Groove 72b Input side surface 72c Plane 75 Cylindrical portion 76 Light incident surface 76a Diffusion groove (groove)
77 Surface emitting portion F1 Focus R1, R2, R3 Optical axis Q1, Q2 Ridge line t Thickness

Claims (14)

A level that encloses liquid so that bubbles remain, a light source, and four or more light receiving elements that convert received light into an electrical signal, and irradiates light from the light source toward the level In a horizontal sensor that detects the degree of horizontality and inclination by projecting shadows of bubbles on the light-receiving element and detecting the position of projection light on the light-receiving element with the light-receiving element,
A surface light emitting unit having a light emitting area larger than the area of the projected light formed when projecting the bubble by parallel light, irradiating light diffused from the surface light emitting unit toward the level,
The light quantity distribution of the projection light on the light receiving element has a minimum point near the central axis of the bubble, and has a characteristic of increasing monotonously as the distance from the central axis of the bubble is approximately the same as the radius of the bubble. A horizontal sensor characterized by that. The light quantity distribution of the projection light on the light receiving element has a minimum point in the vicinity of the central axis of the bubble, and has a characteristic of increasing linearly as the distance from the central axis is approximately the same as the radius of the bubble by electrical correction. The horizontal sensor according to claim 1, wherein So as to be substantially uniformly surface radiation is reflected and refracted light incident from the light source, a light guide plate having an uneven or grooved shape transparent member according to claim 1, characterized in that disposed as the surface-emitting portion Horizontal sensor. A light source and a light receiving element are opposed to the level, and the optical axis of the light source, the central axis of the level and the optical axis of the light receiving element are arranged in a substantially straight line,
The horizontal sensor according to claim 1 or 3 , wherein a sheet-like member having irregularities formed so as to have a diffusion effect is disposed between the light source and the level. Two or more light sources are provided, the light sources are arranged in a rotationally symmetrical position with respect to the central axis of the level, and the light source and the light receiving element are opposed to the level. central axis becomes an optical axis on a substantially straight line of the light receiving element, according to claim 1, characterized in that the optical axis of the light receiving element and the optical axis of the light source is arranged substantially in parallel or claim 3 or The horizontal sensor according to claim 4 . A light guide made of a transparent member is disposed so that the light source and the light receiving element are disposed on the same side with respect to the level, and the light from the light source is incident and guided to a position where the light is irradiated toward the level. The light guide has a total reflection surface that totally reflects light from the light source ,
The total reflection surface is in a state of being inclined with respect to the horizontal direction, the horizontal sensor according to any one of claims 1 to 3, characterized in that it is arranged so as to face the light source. The horizontal sensor according to any one of claims 1 to 6 , wherein minute unevenness for diffusing light is formed on a surface of at least one level of an incident surface, an inner surface of a side wall, and an output surface. . A light incident portion where light from a light source is incident on a side far from the light receiving element on the side surface of the level is provided, and the light incident from the light incident portion is reflected and refracted so as to irradiate the surface substantially uniformly. The surface on the opposite side of the side with the light receiving element is provided with minute irregularities or groove shapes ,
The light incident portion, a horizontal according to any one of claims 1 or claim 2 or claim 6 or claim 7, wherein the lateral end is formed so as to be recessed close to the light source Sensor. The light guide has a convex cylindrical portion so that light emitted from the light source is substantially parallel to the light incident surface of the light guide, and the axis of the cylindrical portion is the axis of the light source. and the optical axis, Ri parallel der the normal of the plane containing the axes optical axis of the light source can be reflected on the total reflection surface of the light guide,
The horizontal sensor according to claim 6 , wherein the cylindrical portion has a convex cylindrical light incident surface to function as a convex lens . The light guide includes a light guide plate-like surface light emitting unit,
The total reflection surface of the light guide has a parabolic surface formed by a cross-sectional shape in a plane including the optical axis of the light source and an axis formed by reflecting the optical axis of the light source with respect to the total reflection surface. Formed so that the focal point of the object surface is near the entrance of the surface light emitting part ,
The horizontal sensor according to claim 9 , wherein the surface light-emitting unit has a reflective surface having irregularities and grooves for reflecting light, and a light emitting surface for emitting light from the plane . The light guide is formed with a plurality of grooves for diffusing light in the axial direction of the cylindrical portion along the cylindrical surface of the cylindrical portion ,
Each groove of the plurality of grooves is on a plane orthogonal to the axis of the cylindrical portion, and is disposed on substantially the entire cylindrical surface at substantially equal intervals in the axial direction of the cylindrical portion. The horizontal sensor according to claim 9 or 10 . In the light guide, a plurality of grooves having a triangular cross-sectional shape are formed on the reflecting surface of the surface light emitting portion in parallel to the axis of the cylinder of the cylindrical portion, and the light incident side surface of the groove is The base angle is 20-40 °,
A sheet-like member in which a triangular prism having an apex angle of 90 ° is formed between the exit surface of the surface light emitting portion of the light guide and the level, and the ridge line of the prism is parallel to the ridge line of the groove of the light guide. placed,
The horizontal sensor according to any one of claims 9 to 11 , wherein an auxiliary reflecting plate is provided outside the reflecting surface in parallel to the reflecting surface . The surface light emitting portion of the light guide has a configuration that can be freely changed in size by the design of the light guide,
The horizontal sensor according to any one of claims 10 to 12 , wherein a thickness of the surface light emitting portion is 0.7 to 1.5 mm. Between the triangular grooves formed on the reflection surface of the surface light emitting portion of the light guide, the light incident on the surface light emitting portion is totally reflected, and this light is near the entrance of the surface light emitting portion. horizontal sensor according to claim 12 or claim 13 from advancing to the back, characterized in that to form a plane parallel to said surface light emitting portion.