JP3421151B2 - Variable optical axis direction photodetector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector suitable for monitoring relatively large objects such as roads and airports.

[0002]

2. Description of the Related Art As a device of this type, a device in which a photodetector is rotated by a motor, or a device in which a large number of photodetector elements are arranged such that the optical axis direction of each element is relatively widened can be considered.

[0003]

However, the above-mentioned devices have a problem that the device is large, cannot operate at high speed, and is not practical in terms of cost. Further, the above-mentioned one has a problem that it is necessary to correct the variation in the characteristics of each element.

The present invention has been made under such circumstances, and it is small in size, can perform high-speed scanning, can reduce the cost by mass production, and does not need to correct the characteristic variation of each element. It is intended to provide.

[0005]

In order to achieve the above object, in the present invention, a photodetector is provided with the following (1) to ( 1 )
3 ) Configure as follows. (1) A movable plate integrally formed on a semiconductor substrate, a torsion bar that pivotally supports the movable plate with respect to the semiconductor substrate, a drive coil provided on a peripheral portion of the movable plate, and a drive coil a magnetic field generating means for applying a static magnetic field, e Bei and a light detecting element which is formed on the movable plate, before Symbol light of the light detecting element by driving the movable plate by a force generated by supplying a current to the driving coil the axial an optical axis variable optical detector you variable, to electromagnetically coupled to said drive coil
And a drive coil for the drive coil.
Optical axis direction variable type optical detection that superimposes on the dynamic current and sends detection current
Output device. ( 2 ) An outer movable plate integrally formed with the semiconductor substrate, a first torsion bar that pivotally supports the outer movable plate with respect to the semiconductor substrate, and an inner movable plate inside the outer movable body. If, the inner movable plate to swingably supported relative to the outer movable plate, and a second torsion bar by the first torsion bar and the axially orthogonal, also the peripheral edge of the outer movable plate A first drive coil provided in a portion, a second drive coil provided in a peripheral portion of the inner movable plate, a first magnetic field generating means for applying a static magnetic field to the first drive coil, and the second Second magnetic field generating means for applying a static magnetic field to the drive coil and a photodetector element formed on the inner movable plate, and is generated by applying a current to the first drive coil and the second drive coil. The outer movable plate by force,
The optical axis of the light detecting element by driving the inner movable plate to an optical axis variable optical detector you variable <br/>, driving the first
Moving coil, and a second driving coil that is electromagnetically coupled to the second driving coil, respectively.
In addition to providing the first detection coil and the second detection coil,
The drive current is superimposed on the first and second drive coils for detection.
Optical axis direction variable type photo-detector for supplying output current. (3) Movable plate and this movable plate integrally formed on a semiconductor substrate
For swingably supporting the semiconductor substrate with respect to the semiconductor substrate
And a bar, and a drive coil provided on the periphery of the movable plate, this
Magnetic field generating means for applying a static magnetic field to the drive coil of
And a photodetector formed on the moving plate,
The movable plate is driven by the force generated by passing an electric current.
Moving the optical axis direction of the photodetector to change the optical axis direction
A modified photodetection device, wherein the optical axis displacement angle of the photodetection element
And a displacement angle detecting means for detecting
Current fed back to the drive coil by feeding back the output of
Control and calculate the shaft position from the output of the displacement angle detection means.
The image frame address is calculated based on the calculation result.
And output the output of the photodetector to the image frame address.
Repeat the process of transferring and storing the
An optical axis direction variable type photodetector that obtains the required monitoring data . (4) The outer movable plate integrally formed on the semiconductor substrate, and
An outer movable plate is pivotably supported on the semiconductor substrate.
First torsion bar and inside the outer movable body
The inner movable plate and the inner movable plate with respect to the outer movable plate
The first torsion bar and the axial direction that pivotally support
A second torsion bar whose directions are orthogonal to each other, and
A first drive coil provided on a peripheral portion of the outer movable plate;
A second drive coil provided on the peripheral portion of the inner movable plate;
A first magnetic field generator that applies a static magnetic field to the first drive coil.
And a second magnet for applying a static magnetic field to the second drive coil.
Field generating means, and a photodetector element formed on the inner movable plate
And a power supply to the first drive coil and the second drive coil.
The outer movable plate is generated by the force generated by the flow.
The inner movable plate is driven to change the optical axis direction of the photo detector.
An optical axis direction variable type photodetector, comprising:
The first variable for detecting the optical axis displacement angle applied to the outer movable plate of the child.
Position angle detection means and the movable plate inside the light detection element
And a second displacement angle detection means for detecting the displacement angle of the optical axis,
The outputs of the first and second displacement angle detecting means are fed back to each other.
Click to control the current flowing through the first and second drive coils.
However, the first displacement angle detection means and the second displacement angle detection
Calculate the axis position from the output of the means, and based on the calculation result
Calculates the image frame address and outputs the photodetector
Transfer to the image frame address and store
Repeated with the monitored obtain the required monitoring data optical axis variable optical detector. (5) Movable plate and this movable plate integrally formed on a semiconductor substrate
For swingably supporting the semiconductor substrate with respect to the semiconductor substrate
A bar, a drive coil provided on the periphery of the movable plate, and
Magnetic field generating means for applying a static magnetic field to the drive coil of
A photodetector formed on the moving plate, and the semiconductor substrate
Light with a three-layer structure by bonding glass substrates to the top and bottom of the plate
An axially variable photodetector, comprising the magnetic field generating means.
Are provided on the upper and lower glass substrates.
Planar coil on the opposite side of the movable plate parallel to the axial direction of the motion bar
A pair of permanent magnets that exert a magnetic field on their parts.
Force generated by passing an electric current through the drive coil
The movable plate is driven by the optical axis direction of the photodetector.
Optical axis direction variable type photo-detecting device for changing the optical axis. (6) The outer movable plate integrally formed on the semiconductor substrate, and
An outer movable plate is pivotably supported on the semiconductor substrate.
First torsion bar and inside the outer movable body
The inner movable plate and the inner movable plate with respect to the outer movable plate
The first torsion bar and the axial direction that pivotally support
A second torsion bar whose directions are orthogonal to each other, and
A first drive coil provided on a peripheral portion of the outer movable plate;
A second drive coil provided on the peripheral portion of the inner movable plate;
A first magnetic field generator that applies a static magnetic field to the first drive coil.
And a second magnet for applying a static magnetic field to the second drive coil.
Field generating means, and a photodetector element formed on the inner movable plate
And glass substrates on the upper and lower surfaces of the semiconductor substrate.
An optical axis direction variable type photodetector having a three-layer structure by being joined.
Thus, the first magnetic field generating means is provided with the upper and lower rattles.
Axial direction of the first torsion bar provided on the substrate
The magnetic field is applied to the flat coil part on the opposite side of the outer movable plate parallel to the direction.
A pair of permanent magnets that act on each other, and
Magnetic field generating means are provided on the upper and lower glass substrates.
In addition, the inner side parallel to the axial direction of the second torsion bar
Applying magnetic fields to the flat coil parts on opposite sides of the moving plate
A pair of permanent magnets, the first drive coil, the second
Due to the force generated by passing an electric current through the drive coil of
The light detecting element is driven by driving the outer movable plate and the inner movable plate.
Optical axis variable optical detection device for varying the optical axis direction. ( 7 ) The optical axis according to any one of (1) to (6) above.
In the variable direction photodetection device, the semiconductor substrate is a variable optical axis direction photodetection device having a three-layer structure in which another semiconductor substrate is laminated on the upper and lower surfaces of an intermediate semiconductor substrate. ( 8 ) Optical axis direction variable type according to (5) or (6) above
In the photodetector, an optical axis direction variable photodetector having an opening provided at a position facing the photodetector on a glass substrate bonded to the upper surface of the semiconductor substrate. ( 9 ) Optical axis direction variable type as described in (5) or (6) above.
In the photodetector, an optical axis direction variable type photodetector in which a concave portion for securing a swing space of the movable plate is provided in a central portion of a glass substrate joined to upper and lower surfaces of the semiconductor substrate. ( 10 ) Variable optical axis direction according to the above (5) or (6)
Type photodetector, wherein the glass substrate bonded to the upper surface of the semiconductor substrate is coated with an antireflection film. ( 11 ) Variable optical axis direction according to (5) or (6) above.
In the type photodetector, the swinging space of the movable plate is hermetically sealed by the semiconductor substrate and a glass substrate bonded to the upper and lower surfaces of the movable plate, and the optical axis direction variable type photodetector is placed in a vacuum state. ( 12 ) Variable optical axis direction according to (5) or (6) above
Type photodetector, the swinging space of the movable plate is sealed by the semiconductor substrate and a glass substrate bonded to the upper and lower surfaces thereof, and an inert gas is sealed in the swinging space. Light detection device. ( 13 ) The method according to any one of (1) to (12) above.
In the optical axis direction variable type photodetector, the optical axis direction variable type photodetector is provided with a microlens for converging incident light on the front surface of the photodetector element.

[0006]

[0007]

[0008]

[0009]

[0010]

[0011]

EXAMPLES The present invention will be described below based on examples.

(Embodiment 1) FIGS. 1 and 2 are views showing the configuration of an "optical axis direction variable photodetector" which is Embodiment 1. In FIG.
This embodiment operates on the same principle as a galvanometer like Embodiments 2 and 3 described later. Note that the size is exaggerated in FIGS. 1 and 2 for easy understanding. 3, FIG. 5, FIG. 6, FIG. 7, and FIG.
Is also the same.

In FIGS. 1 and 2, an optical axis direction variable type photodetector 1 includes flat plates as upper and lower insulating substrates made of, for example, borosilicate glass on upper and lower surfaces of a silicon substrate 2 which is a semiconductor substrate. It has a three-layer structure in which upper and lower glass substrates 3 and 4 are joined. The upper glass substrate 3 is laminated on the left and right ends (in FIG. 1) of the silicon substrate 2 so as to open the upper portion of the movable plate 5 described later.

On the silicon substrate 2, a flat plate-shaped movable plate 5 and a torsion bar 6 that pivotally supports the movable plate 5 at the center position of the movable plate 5 so as to be swingable in the vertical direction of the silicon substrate 2. And are integrally formed by anisotropic etching in the semiconductor manufacturing process. Therefore, the movable plate 5
The torsion bar 6 is also made of the same material as the silicon substrate 2. The movable plate 5 is provided on the peripheral portion of the upper surface of the movable plate 5.
A plane coil 7 made of a copper thin film for supplying a driving current for driving and a detecting current for detecting a displacement angle superimposed on the driving current is provided by being covered with an insulating film. The detection current is for detecting the displacement of the movable plate 5 based on the mutual inductance with the detection coils 12A and 12B provided on the lower glass substrate 4 as described later.

Here, the coil has a Joule heat loss due to the resistance component, and a thin film coil having a large resistance is used as the plane coil 7.
Since the driving force is limited due to heat generation when mounted in high density, the plane coil 7 is formed by the known electroformed coil method by electrolytic plating in this embodiment.
In the electroformed coil method, a thin nickel layer is formed on a substrate by sputtering, copper electroplating is performed on the nickel layer to form a copper layer, and the copper layer and the nickel layer are removed except for the portion corresponding to the coil. By removing it, a thin-film planar coil consisting of a copper layer and a nickel layer is formed. It has the characteristic that the thin-film coil can be mounted with low resistance and high density, and it is effective for downsizing and thinning of micro magnetic devices. .

A pn photodiode 8, which is a photodetector, is formed by a known method in the central portion of the upper surface of the movable plate 5 surrounded by the plane coil 7. Further, a pair of electrode terminals 9, 9 electrically connected to the planar coil 7 via the portion of the torsion bar 6 are provided on the lateral upper surface of the torsion bar 6 of the silicon substrate 2. ，
9 is formed on the silicon substrate 2 at the same time as the plane coil 7 formed by the electroforming coil method.

Magnetic fields are applied to the left and right sides (in FIG. 1) of the upper and lower glass substrates 3 and 4 (in FIG. 1) on the flat coil 7 portion on the opposite side of the movable plate 5 parallel to the axial direction of the torsion bar 6. Paired circular permanent magnets 10A, 1
0B, 11A, and 11B are provided. The upper and lower permanent magnets 10A and 10B, which are paired with each other, are provided so that the upper and lower polarities are the same, for example, as shown in FIG. 2, the lower side is the N pole and the upper side is the S pole. There is. In addition, the other three permanent magnets 11A and 11B each have the same upper and lower polarities, for example, as shown in FIG.
The lower side is an S pole and the upper side is an N pole. The permanent magnets 10A and 11A on the upper glass substrate 3 side and the permanent magnets 10B and 11B on the lower glass substrate 4 side are provided so that the upper and lower polarities thereof are opposite to each other.

Further, as described above, the lower glass substrate 4
A pair of coils 12A and 12B, which are arranged so as to be electromagnetically coupled to the planar coil 7 and whose ends are electrically connected to the paired electrode terminals 13 and 14, respectively, are provided on the lower surface of (1) by patterning ( In addition, in FIG. 1, although it is schematically shown by one broken line, it is actually wound plural times). The detection coils 12A and 12B are arranged at symmetrical positions with respect to the torsion bar 6 to detect the displacement angle of the movable plate 5, and the flat coil 7 based on the detection current passed through the flat coil 7 in a manner superimposed on the drive current. Since the mutual inductance between the detecting coil 12A and the detecting coil 12A and 12B changes so that one of them approaches and increases and the other of them separates and decreases due to the angular displacement of the movable plate 5,
For example, the displacement angle of the movable plate 5 can be detected by differentially detecting the change in the voltage signal output based on the mutual inductance.

Next, the operation will be described.

For example, one electrode terminal 9 is used as a + pole and the other electrode terminal 9 is used as a pole, and a current is passed through the planar coil 7. A magnetic field is formed on both sides of the movable plate 5 by the permanent magnets 10A and 10B and the permanent magnets 11A and 11B in a direction crossing the plane coil 7 along the plane of the movable plate 5 as shown by the arrow B in FIG. Therefore, when a current flows through the plane coil 7 in the magnetic field, the plane coil 7, in other words, both ends of the movable plate 5, are moved in accordance with the current density and the magnetic flux density of the plane coil 7.
A force F acts in a direction (indicated by an arrow F in FIG. 3) according to the Fleming's left-hand rule of current, magnetic flux density, and force, and this force is obtained from the Lorentz force.

This force F is obtained by the following equation (1), where i is the current density flowing in the planar coil 7 and B is the magnetic flux density of the upper and lower permanent magnets.

F = i × B (i) Actually, it depends on the number of turns n of the plane coil 7 and the coil length w (shown in FIG. 3) on which the force F acts. Like

F = nw (i × B) (2) On the other hand, the rotation of the movable plate 5 causes the torsion bar 6 to rotate.
Is twisted, and the relation between the spring reaction force F ′ of the torsion bar 6 and the displacement angle φ of the movable plate 5 generated by this is as shown in the following expression (3).

Θ = (Mx / GIp) = F′L / 8.5 × 10 ⁹ r ⁴ ) × 1 ₁ (3) where Mx is the torsional moment, G is the lateral elastic coefficient, and Ip
Is the polar moment of inertia. Further, L, l ₁ , and r are the distance from the central axis of the torsion bar to the force point, the length of the torsion bar, and the radius of the torsion bar, respectively, which are shown in FIG.

Then, the movable plate 5 is rotated to a position where the force F and the spring reaction force F'balance. Therefore, by substituting the F in the equation (2) into the F ′ in the equation (3), it is understood that the displacement angle φ of the movable plate 5 is proportional to the current i flowing in the plane coil 7.

Therefore, since the displacement angle φ of the movable plate 5 can be controlled by controlling the current flowing through the plane coil 7, for example, the photodetector 8 in the plane perpendicular to the axis of the torsion bar 6. The optical axis direction of can be freely controlled, and if the displacement angle is changed continuously,
You can scan in dimensions.

When controlling the displacement angle φ of the optical axis of the photo-detecting element 8, the displacement angle is detected at a frequency at least 100 times higher than the driving current frequency by superimposing it on the plane coil 7 on the driving current. Apply the detection current. Then, based on this detection current, the induced voltage due to the mutual inductance between the plane coil 7 and the detection coils 12A and 12B provided on the lower glass substrate 5 is changed to the respective detection coils 12A and 12B.
It occurs in B. The induced voltages generated in the detection coils 12A and 12B are equal in distance between the detection coils 12A and 12B and the corresponding planar coil 7 when the movable plate 5, in other words, the photodetection element 8 is in the horizontal position. They are equal and the difference is zero. When the movable plate 5 is rotated about the torsion bar 6 by the driving force described above, the one detection coil 12A (or 12B) approaches and the induced voltage increases due to an increase in mutual inductance, and the other detection coil 1 moves.
In 2B (or 12A), the induced voltage is lowered due to the reduction of mutual inductance. Therefore, the detection coil 1
The induced voltage generated in 2A and 12B changes according to the displacement of the photodetecting element 8, and the optical axis displacement angle φ of the photodetecting element 8 can be detected by detecting this induced voltage.

Then, for example, as shown in FIG. 4, a power source is connected to a bridge circuit constituted by providing two resistors in addition to the detection coils 12A and 12B, and the middle point between the detection coil 12A and the detection coil 12B is connected to the bridge circuit. The output of the differential amplifier according to the voltage difference between the two midpoints is fed to the drive system of the movable plate 5 by using a circuit configured by providing a differential amplifier having a voltage between the midpoint of the two resistors as an input. By backing up and controlling the drive current, it is possible to accurately control the optical axis displacement angle φ of the photodetecting element 8.

As described above, in this embodiment, the movable portion including the photodetector can be made small and lightweight, so that the optical axis direction of the photodetector can be changed at high speed and the object to be monitored can be scanned at high speed. Further, since the movable plate, the torsion bar, and the photodiode, which are the main parts, can be formed from the same semiconductor substrate by utilizing the semiconductor element manufacturing process, cost reduction due to mass production can be expected. Further, since the monitoring target is scanned by one photodiode, it is not necessary to correct the characteristic variation of each element.

(Embodiment 2) FIG. 5 is a diagram showing the configuration of an "optical axis direction variable photodetector" which is Embodiment 2. In FIG.

In the first embodiment described above, the optical axis direction is shaken in one dimension, but in this embodiment, the torsion bars are orthogonal to each other so that they can be shaken in two dimensions.
It is an example of a two-axis photodetector provided. The same elements as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 5, an optical axis direction variable type photodetector 21 of the present embodiment has an upper side and a lower side made of borosilicate glass or the like on the upper and lower surfaces of a silicon substrate 2 which is a semiconductor substrate. And lower glass substrates 3 and 4
Has a three-layer structure in which they are stacked and joined as shown by the arrow.
As shown in the figure, the upper and lower glass substrates 3 and 4 each have a structure in which rectangular recesses 3A and 4A formed by, for example, ultrasonic processing are provided in the central portions, and when bonded to the silicon substrate 2, In the upper glass substrate 3, the recessed portion 3A is located on the silicon substrate 2 side with the recessed portion on the lower side, and in the lower glass substrate 4, the recessed portion 4A is located on the silicon substrate 2 side in the same manner. To join. Thereby, the swinging space of the movable plate 5 on which the photo-detecting element 8 described later is provided is secured and hermetically sealed.

The silicon substrate 2 is provided with a flat movable plate 5 composed of an outer movable plate 5A formed in a frame shape and an inner movable plate 5B axially supported inside the outer movable plate 5A. ing. The outer movable plate 5A is pivotally supported on the silicon substrate 2 by the first torsion bars 6A and 6A,
The inner movable plate 5B includes the first torsion bar 6
The second torsion bar 6 whose axial direction is orthogonal to A and 6A
B and 6B are pivotally supported inside the outer movable plate 5A. Movable plates 5A, 5B and first and second torsion bars 6
A and 6B are integrally formed on the silicon substrate 2 by anisotropic etching, and are made of the same material as the silicon substrate 2.

On the upper surface of the outer movable plate 5A, a pair of outer electrode terminals 9A, 9A formed on the upper surface of the silicon substrate 2 are formed.
A flat coil 7A (both of which has a plurality of turns on the movable plate 5A is schematically shown by a single line in the drawing) whose both ends are electrically connected to each other through one of the first torsion bars 6A It is provided so as to be covered with an insulating layer. Further, on the upper surface of the inner movable plate 5B, a pair of inner electrode terminals 9B, 9B formed on the silicon substrate 2 is passed from the one second torsion bar 6B through the outer movable plate 5A portion to the first torsion bar. The flat coil 7B (which is schematically shown by a single line in the drawing, but has a plurality of turns on the inner movable plate 5B as well as the outer movable plate 5A) electrically connected to each other via the other side of 6A is insulated. It is provided covered with a layer. Similar to the first embodiment, the plane coils 7A and 7B are formed by the above-mentioned known electroplating coil method by electrolytic plating. The outer and inner electrode terminals 9
A and 9B are formed on the silicon substrate 2 at the same time as the plane coils 7A and 7B by the electroformed coil method. Plane coil 7
At the center of the inner movable plate 5B surrounded by B, a photodiode 8 which is a photodetecting element is formed by a known method.

On the upper and lower glass substrates 3 and 4, eight disk-shaped permanent magnets 1 each consisting of two pairs are provided.
0A to 13A and 10B to 13B are arranged as illustrated. The permanent magnets 10A and 11A facing each other on the upper glass substrate 3 are the permanent magnets 10 on the lower glass substrate 4.
B and 11B act on the plane coil 7A of the outer movable plate 5A by a magnetic field to drive the outer movable plate 5A by interaction with a drive current flowing in the plane coil 7A. The permanent magnets 12A and 13A facing each other on the substrate 3 are the permanent magnets 1 on the lower glass substrate 4.
2B and 13B are for rotating the inner movable plate 5B by interacting with a driving current flowing through the planar coil 7B by applying a magnetic field to the planar coil 7B of the inner movable plate 5B. The upper and lower polarities of the permanent magnets 10A and 11A facing each other are opposite to each other.
When the upper surface of A is the S pole, the upper surface of the permanent magnet 11A is provided so as to be the N pole, and the magnetic flux thereof is arranged so as to cross the plane coil portion of the movable plate 5 in parallel.
Other permanent magnets 12A and 13 facing each other
A, permanent magnets 10B and 11B and permanent magnets 12B and 13
The same applies to B. Furthermore, the corresponding permanent magnets 1 in the vertical direction
The relationship between 0A and 10B is such that the upper and lower polarities are the same, for example, when the upper surface of the permanent magnet 10A is the S pole, the upper surface of the permanent magnet 10B is also the S pole. Other upper and lower corresponding permanent magnets 11A and 11B, permanent magnets 12A and 12
The same applies to B and the permanent magnets 13A and 13B, whereby the forces act in opposite directions at both ends of the movable body 5.

Then, on the lower surface of the lower glass substrate 4, the detection coils 15A, 15B and 16A, 16B arranged so as to be electromagnetically coupled with the above-mentioned plane coils 7A, 7B, respectively.
Are patterned and provided. Detection coil 15
A and 15B are provided at symmetrical positions with respect to the first torsion bar 6A, and the detection coils 16A and 16B are provided at symmetrical positions with respect to the second torsion bar 6B and are paired with each other. Then, the pair of detection coils 15A, 1
Reference numeral 5B is for detecting the displacement angle of the outer movable plate 5A, and the mutual inductance between the flat coil 7A and the detection coils 15A and 15B based on the detection current which is superposed on the drive current in the flat coil 7A is detected by the outer movable plate. It is changed by the angular displacement of 5 A, and an electric signal corresponding to this change is output. The displacement angle of the outer movable plate 5A can be detected by this electric signal.
The pair of detection coils 16A and 16B similarly detect the displacement angle of the inner movable plate 5B.

Next, the operation will be described.

When a drive current is applied to the flat coil 7A of the outer movable plate 5A, the outer movable plate 5A rotates in accordance with the direction of the current with the first torsion bars 6A and 6A as fulcrums, and at this time, the inner movable plate 5B. Also rotates integrally with the outer movable plate 5A.
In this case, the photodiode 8 operates similarly to the first embodiment. On the other hand, when a drive current is applied to the plane coil 7B of the inner movable plate 5B, the inner movable plate 5B is moved to the second movable torsion bar 6B, 6B relative to the outer movable plate 5A in the direction perpendicular to the rotating direction of the outer movable plate 5A. Rotate around as a fulcrum.

Therefore, for example, after controlling the drive current of the plane coil 7A to rotate the outer movable plate 5A for one cycle,
By controlling the drive current of the plane coil 7B so as to displace the inner movable plate 5B by a certain angle, and repeating this operation periodically, the optical axis of the photodiode 8 can be swung two-dimensionally, and the monitored object is scanned two-dimensionally. it can.

When glass is present above the photodiode 8 as in this embodiment, it is advisable to coat the glass surface with an antireflection film or the like.

On the other hand, the plane coil 7A and the plane coil 7B
If the detection current is passed by superimposing it on each drive current flowing in
The outer movable plate 5A has the same principle as that of the first embodiment due to the mutual inductance between the detection coils 15A and 15B and the plane coil 7A and between the detection coils 16A and 16B and the plane coil 7B.
The displacement of the detection coil 1 is, for example, through a circuit similar to that of FIG.
It can be detected by the differential output of 5A and 15B,
This can be detected by the differential output of the displacement detection coils 16A and 16B of the inner movable plate 5B. If this differential output is fed back to each drive system of the outer movable plate 5A and the inner movable plate 5B, the outer movable plate 5A can be detected. Also, the displacement of the inner movable plate 5B can be controlled with high precision. Needless to say, in the case of the biaxial photodetector of this embodiment, two circuits similar to those shown in FIG. 4 are provided for detecting the outer movable plate displacement and for detecting the inner movable plate displacement.

According to the configuration of the second embodiment, the first embodiment
In addition to the same effect as above, the scanning of the monitored object can be performed two-dimensionally, and the scanning area can be increased as compared with the case of the single axis of the first embodiment. Further, since the swinging space of the movable plate 5 is sealed by the upper and lower glass substrates 3 and 4 and the surrounding silicon substrate 2, the sealed space is brought into a vacuum state, so that the air with respect to the rotating operation of the movable plate 5 is closed. There is no resistance,
This has the effect of improving the responsiveness of the movable plates 5A and 5B.

Further, in the case where the displacement amount of the movable plates 5A and 5B is set to be large by increasing the drive current flowing through the plane coils 7A and 7B, the sealed movable plate swing space is not made to be a vacuum, but helium and argon are used. It is desirable to enclose an inert gas such as helium, and helium having particularly good thermal conductivity is preferable. This is because when the amount of current flowing through the planar coil 7 is increased, the amount of heat generated from the planar coil 7 increases, and heat radiation from the movable plate deteriorates when the movable plates 5A and 5B are in a vacuum state. As a result, the heat radiation from the movable plates 5A and 5B can be enhanced as compared with the vacuum state, and the heat effect can be reduced. By filling the inert gas, the responsiveness of the movable plates 5A and 5B will be slightly lower than that in the vacuum state.

It is needless to say that the upper and lower glass substrates of the first embodiment described above may have a structure similar to that of the second embodiment, in which the movable plate portions are hermetically sealed.

(Embodiment 3) FIG. 6, FIG. 7 and FIG. 8 are views showing the configuration of an “optical axis direction variable photodetector” which is Embodiment 3.

The present embodiment is a biaxial example similar to the second embodiment. The same elements as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

The biaxial optical axis direction variable type photodetector 31 of this embodiment has substantially the same structure as that of the above-mentioned Embodiment 2, but in this embodiment, as shown in FIGS. The upper and lower glass substrates 3 and 4 are different from those of the second embodiment in that
It has a flat plate shape without A and 4A. The upper glass substrate 3 is provided with a rectangular opening 3a in the upper portion of the movable plate 5 depending on the shape of the movable plate 5, and the detection light can directly enter the photodiode 8 with the portion above the photodiode 8 being in an open state. Is done. Since the upper and lower glass substrates 3 and 4 are flat, the intermediate silicon substrate 2
Another silicon substrate is laminated on the upper and lower sides to form a three-layer structure, and the movable plate 5 is formed in the intermediate layer so that a rotation space for the movable plate 5 is secured.

Further, as shown by a broken line in FIG. 6, on the lower surface of the lower glass substrate 4, the detection coils 15A and 15B for detecting the displacement of the outer movable plate 5A and the detection coil 16A for detecting the displacement of the inner movable plate 5B. , 16B is the corresponding planar coil 7
A and 7B are patterned and provided at positions where electromagnetic coupling is possible.

The operation and effect of this embodiment having such a configuration are the same as those of the second embodiment, and the description thereof will be omitted.

(Modification) In each of the above embodiments, the photodiode is formed as the light detecting element. However, the present invention is not limited to this, and a line sensor or an area sensor including a plurality of photodiodes is formed. Can be implemented in the form of Further, it can be implemented by using a phototransistor, a photoconductor, a CCD or the like as the photodetector. If necessary, a microlens for converging incident light is provided on the front surface of these photodetecting elements.

In the second embodiment, the scanning is performed linearly, but the scanning may be performed concentrically or spirally depending on the object.

In each of the embodiments, the central portion of the movable plate is pivotally supported by the torsion bar, but the present invention is not limited to this, and the end portion of the movable plate, for example, the right side portion of the movable plate 5 in FIG. 1 is pivotally supported. In this case, one detection coil is provided on the left side to detect the displacement angle.

In each embodiment, the drive current and the detection current are passed through the plane coil provided on the movable plate. However, when the frequency of the drive current is as high as several kilohertz, the drive current is also used as the detection current. , Can be implemented without superimposing detection currents.

Further, in each of the embodiments, the displacement angle is detected by the difference between the outputs of the two detection coils, but it can be implemented by providing one detection coil and detecting the displacement angle by its output. .

(Example of Use) An example of use of the optical axis direction variable type photodetector described above will be described with reference to FIGS.

FIG. 9 is a block diagram of an example in which a photodiode PD is used as a photodetector and biaxial driving is performed. This example is an example of using the apparatus of the second and third embodiments. The example using the apparatus of Example 1 corresponds to the one without one axis, eg the Y-axis, in this example.

The operation will be described with reference to FIG. S1
In (Step S1), X including the X-axis detection coil
The output of the shaft displacement angle detector 25 is converted into digital data by the A / D converter 26 and input to the microcomputer 23, and the X-axis table is searched based on the digital data in S2.
Based on the search result, the X-axis position is calculated in S3. S4
Then, the output of the Y-axis displacement angle detector 27 including the Y-axis detection coil is converted into digital data by the AD converter 26 and input to the microcomputer 23. At S2, the Y-axis table is obtained based on the Y-axis digital data. A search is performed, and the Y-axis position is calculated in S6 based on the search result. The image frame address is calculated in S7 based on the calculation results of S3 and S6. The output of the photodiode 20 is amplified in S8, converted into digital data by the AD converter 22, and input to the microcomputer 23. In S9, the digital data of the photodiode described above is
It is transferred to the image frame address in the memory 24 and stored. This operation is repeated for all image frame addresses to obtain the required monitoring data for the monitoring target.

FIG. 11 shows an example of uniaxial driving using a CCD licensor as a photodetector. In this case, the line sensor 2
The optical axis 8 is swung to scan the monitoring target in the Y-axis direction, and the signals of each pixel of the line sensor 28 are sequentially taken out to scan the monitoring target in the X-axis direction.

FIG. 12 shows an example in which a CCD area sensor is used as a light detecting element and biaxial driving is performed. In this case, the optical axis of the area sensor 29 is swung to scan the monitoring target in both X-axis and Y-axis directions, and the signals of each pixel of the area sensor 29 are sequentially taken out to scan the monitoring target in more detail.

[0060]

As described above, according to the present invention,
Compact size, high-speed scanning, and cost reduction by mass production
It is possible to provide a an optical detector. Further claims
According to the inventions of 3 and 4, the required items for the monitoring target are
Monitoring data can be obtained.

Further, according to the invention of claim 3, two-dimensional scanning can be performed, and according to the invention of claims 2 and 4,
The displacement angle of the optical axis can be detected, and the displacement angle of the optical axis can be accurately controlled by using feedback.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

2 is a sectional view taken along line AA of FIG.

FIG. 3 is an operation explanatory diagram of the first embodiment.

FIG. 4 is an explanatory diagram for detecting a displacement angle of the movable plate according to the first embodiment.

FIG. 5 is a diagram showing a configuration of a second embodiment.

FIG. 6 is a diagram showing a configuration of a third embodiment.

7 is a sectional view taken along line BB of FIG.

FIG. 8 is a sectional view taken along line CC of FIG.

FIG. 9 is a block diagram of an example using a photodiode.

10 is a flowchart showing the operation of the apparatus of FIG.

FIG. 11 is a block diagram of an example using a line sensor.

FIG. 12 is a block diagram of an example using an area sensor.

[Explanation of symbols]

1 Optical axis direction variable type photodetector 2 Silicon substrate 5 movable plate 6 torsion bar 7 plane coil 10A, 10B, 11A, 11B Permanent magnet 12A, 12B detection coil

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01J 1/00-1/60 G02B 26/00-26/10

Claims (13)

(57) [Claims] 1. A movable plate integrally formed on a semiconductor substrate, a torsion bar that pivotally supports the movable plate with respect to the semiconductor substrate, a drive coil provided at a peripheral portion of the movable plate, and a drive coil for driving the movable plate. a magnetic field generating means for applying a static magnetic field to the coil, the example Bei a light-detecting device formed on the movable plate, before Symbol the light detecting element by driving the movable plate by a force generated by supplying a current to the driving coil It varies the direction of the optical axis
An optical axis direction variable type photodetector , wherein a detection coil electromagnetically coupled to the drive coil is provided.
In addition, the drive coil is superimposed on the drive current and the detection current is applied to the drive coil.
An optical axis direction variable type photodetector characterized by flowing a flow. 2. An outer movable plate integrally formed with a semiconductor substrate, a first torsion bar that pivotally supports the outer movable plate with respect to the semiconductor substrate, and an inner side inside the outer movable body. A movable plate; and a second torsion bar axially orthogonal to the first torsion bar, which pivotally supports the inner movable plate with respect to the outer movable plate , and the outer movable plate. A first drive coil provided on the peripheral edge of the first movable coil, a second drive coil provided on the peripheral edge of the inner movable plate, a first magnetic field generating means for applying a static magnetic field to the first drive coil, and A second magnetic field generating means for applying a static magnetic field to the second drive coil; and a photo-detecting element formed on the inner movable plate, wherein a current is passed through the first drive coil and the second drive coil. The outer movable plate, the inner movable by the force generated A the driving direction of the optical axis variable optical detector you vary the optical axis direction of the light detection element, the first drive coil, said second drive coil and each electrostatic
Providing a first detection coil and a second detection coil that are magnetically coupled
And a drive current is applied to the first and second drive coils.
The direction of the optical axis is characterized in that the current for detection is superposed on
Variable photodetector. 3. A movable plate integrally formed on a semiconductor substrate.
Of the movable plate of FIG.
Partition bar and a drive coil provided on the periphery of the movable plate.
And a magnetic field generating means for applying a static magnetic field to this drive coil.
And a photodetection element formed on the movable plate , the force generated by applying a current to the drive coil.
Drive the movable plate to change the direction of the optical axis of the photodetector.
A variable optical axis direction variable type photodetector, which is a displacement angle detection means for detecting an optical axis displacement angle of the photodetection element.
Is provided to feed back the output of the displacement angle detection means.
Control the current flowing through the drive coil, calculate the shaft position from the output of the displacement angle detection means, and
Calculate the image frame address based on the result,
Transfers the output of the photodetector to the image frame address
Repeat the process of storing the
An optical axis direction variable type photodetector characterized by obtaining visual data . 4. An outer movable plate integrally formed with a semiconductor substrate.
And this outer movable plate can swing freely with respect to the semiconductor substrate.
The first torsion bar that supports the shaft and the inside of the outer movable body.
The inner movable plate on the side and this inner movable plate can be moved outside.
The first torsion bar that pivotally supports the plate.
And a second torsion bar whose axial direction is orthogonal to each other, and a first drive coil provided on a peripheral portion of the outer movable plate.
And a second drive coil provided on the peripheral portion of the inner movable plate.
And a first magnet for applying a static magnetic field to the first drive coil.
A static magnetic field is applied to the field generating means and the second drive coil.
Second magnetic field generating means and an optical detector formed on the inner movable plate.
An output element, and a current is passed through the first drive coil and the second drive coil.
The outer movable plate, the inner movable by the force generated by
An optical axis that drives a plate to change the optical axis direction of the photodetector
A variable direction photodetector for detecting an optical axis displacement angle applied to an outer movable plate of the photodetector
The first displacement angle detecting means and the inner side of the light detecting element.
Second displacement angle detection hand for detecting the optical axis displacement angle applied to the moving plate
And a step, and outputs of the first and second displacement angle detection means
Feedback to the first and second drive coils
The current flowing is controlled to control the first displacement angle detecting means and the second displacement angle detecting means.
The axis position is calculated from the output, and the image frame is calculated based on the calculation result.
The frame address is calculated and the output of the photodetector is calculated as
Repeat the process of transferring to the image frame address and storing
An optical axis direction variable type photodetector characterized in that it obtains required monitoring data for a monitoring target . 5. A movable plate and a member integrally formed on a semiconductor substrate.
Of the movable plate of FIG.
Partition bar and a drive coil provided on the periphery of the movable plate.
And a magnetic field generating means for applying a static magnetic field to this drive coil.
And a light detection element formed on the movable plate, and
A glass substrate is bonded to the upper and lower surfaces of the semiconductor substrate to form a three-layer structure.
A variable optical axis direction type photodetector having a structure, wherein the magnetic field generating means is provided on the upper and lower glass substrates, and is a flat surface opposite to a movable plate parallel to the axial direction of the torsion bar. It is a pair of permanent magnets that exert a magnetic field on the coil part, and is made by a force generated by applying a current to the drive coil.
Drive the movable plate to change the direction of the optical axis of the photodetector.
An optical axis direction variable type photodetector characterized in that it changes . 6. An outer movable plate integrally formed with a semiconductor substrate.
And this outer movable plate can swing freely with respect to the semiconductor substrate.
The first torsion bar that supports the shaft and the inside of the outer movable body.
The inner movable plate on the side and this inner movable plate can be moved outside.
The first torsion bar that pivotally supports the plate.
And a second torsion bar whose axial direction is orthogonal to each other, and a first drive coil provided on a peripheral portion of the outer movable plate.
And a second drive coil provided on the peripheral portion of the inner movable plate.
And a first magnet for applying a static magnetic field to the first drive coil.
A static magnetic field is applied to the field generating means and the second drive coil.
Second magnetic field generating means and an optical detector formed on the inner movable plate.
And a glass substrate bonded to the upper and lower surfaces of the semiconductor substrate.
An optical axis direction variable type photodetector having a three-layer structure, wherein the first magnetic field generating means includes upper and lower glass substrates.
The axial direction of the first torsion bar provided on the
The magnetic field is applied to the flat coil part on the opposite side of the outer movable plate.
A pair of permanent magnets, which generate the second magnetic field.
Raw means are provided on the upper and lower glass substrates.
The inner movable plate parallel to the axial direction of the second torsion bar
Apply a magnetic field to the flat coil part on the opposite side to form a pair.
It is a permanent magnet, and a current is passed through the first drive coil and the second drive coil.
The outer movable plate, the inner movable by the force generated by
An optical axis direction variable type photodetector, characterized in that a plate is driven to change the optical axis direction of the photodetection element . 7. The light according to any one of claims 1 to 6.
Axially variable optical detection device, the semiconductor substrate on the intermediate semiconductor substrate, the optical axis variable light detection you being a substrate for 3-layer structure of another semiconductor substrate to the lower surface apparatus. 8. The optical axis direction variable according to claim 5 or 6.
Type photodetector, in the glass substrate bonded to the upper surface of the semiconductor substrate,
At a location opposite to the light detecting element, the optical axis variable optical detector you characterized in that an opening is provided. 9. The optical axis direction variable according to claim 5 or 6.
In type light detecting device, the top of the semiconductor substrate, in the central portion of the glass substrate joined to a lower surface, the optical axis variable characterized in that a recess for securing the swinging space of the movable plate Light detection device. 10. The optical axis direction according to claim 5 or 6
In a variant light detecting device, the semiconductor substrate optical axis variable optical detector you wherein the coated antireflection film on a glass substrate joined to the upper surface of the. 11. The optical axis direction according to claim 5 or 6
In a variant light detecting device, the swinging space for the movable plate, the semiconductor substrate and thereon, the optical axis variable light detection you characterized in that a vacuum state as well as sealed by a glass substrate joined to a lower surface apparatus. 12. The optical axis direction according to claim 5 or 6
In the modified photodetector, the swing space of the movable plate is sealed by the semiconductor substrate and a glass substrate bonded to the upper and lower surfaces thereof, and an inert gas is filled in the swing space. Optical axis direction variable type photo detector. 13. The method according to any one of claims 1 to 12.
Of the optical axis variable optical detection device, the optical axis variable optical detector you characterized in that a micro lens for converging incident light in front of the light detecting element.