JP2000286403A - Split photodiode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a split photodiode of a structure, wherein the optical response characteristics of the photodiode are enhanced, the generation of noise is reduced and is in a state in which incident light is received in the light-receiving surface of the photodiode can be detected with high accuracy. SOLUTION: Four quadrangular photodiodes are formed from a split photodiode 1 aggregate- constituted, in such a way that its sides are brought into contact opposingly to each other and the whole photodiode 1 is formed into a quadrangle, the vicinities of the outer peripheral edge sides of the phtodiode 1 are provided symmetrically to the sides coming into contact opposedly to each other of the photodiodes, the nonlight-receiving region of the light-receiving surface of the photodiode is cut off from light-receiving surface a triangular notch parts 5Aa, 5Ba, 5Ca and 5Da, photodiodes 1As to 1Da are respectively formed from the photodiodes, an incident laser beam into the light-receiving surface of the photodiode is not received at all, a reduction in the optical response characteristics of the photodiode due to a P-N junction capacitance of the photodiode at the region, where does not contribute to the photoelectric conversion of the photodiode, of the phtodiode and a reduction in the S/N ratio due to the generation of noise are reduced, the optical response characteristics are enhanced, the generation of the noise is reduced and detection of a state in which indident light is received in the light-receiving surface of the photodiode with high accuracy becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split type photodiode which comprises a plurality of photodiodes and detects and controls incident light based on a light receiving signal of each photodiode of the incident light.

[0002]

2. Description of the Related Art In an optical disk, particularly an optical disk formed of a plastic material substrate such as a PC, the disk is warped and undulated due to thermal strain during molding. , An error occurs in the roundness of the track. When the optical disk is placed on a turntable, the optical disk is bent by its own weight, and the optical disk is also eccentric corresponding to the processing accuracy of the center hole of the disk. As described above, some runout and track runout occur in the optical disc during the manufacturing process, and in the optical disc drive, there is also runout and track runout due to the tilt and swivel motion of the turntable. However, in order to record / reproduce information without being affected by these surface vibrations and track vibrations, a split-type photodiode is used as the light receiving element to detect the incident position of the laser beam on the photodiode. Then, focusing error detection or tracking error detection is performed, and focusing control of the laser beam or control of the incident position is performed based on the detection result.

[0003] The detection of a focusing error will be described.
Although a surface runout of about 2 mm to 0.3 mm occurs, the focal depth of the objective lens of the optical pickup is about ± 1 μm. Therefore, the objective lens is moved up and down so that the distance between the objective lens and the optical disc is reduced by the focal depth of the objective lens. It is necessary to detect the focusing error in order to keep it within. In this case, in the optical disk system, the knife edge method and the astigmatism method are mainly used for detecting a focusing error, but in general, a focusing error detection method using the astigmatism method is often used.

In the detection of a focusing error by the astigmatism method, as shown in FIG. 12, a reflected light of a laser beam incident on a disk 15 on an information recording surface 16 is converted into a parallel light beam by an objective lens 17. The light is converged by the detection lens 18 and is incident on the cylindrical lens 20. As shown in FIG. 13, the cylindrical lens 20 has a lens function only in the direction of the arrow X, and has an arrow Y perpendicular to the direction of the arrow X.
Since there is no lens action in the direction, the detection lens 18
When used together, the focal lengths are different in the X and Y directions, and the beam shape becomes astigmatic in the astigmatism area 21 between the combined focal point f1 of the detection lens 18 and the cylindrical lens 20 and the focal point f2 of the detection lens 18. Aberration occurs.

For this reason, the beam shape on the light receiving element 1A0 comprising a four-division type photodiode is as shown in FIG. 14, and at the position of the composite focal point f1, the beam 13a is vertical as shown in FIG. At the position of the focal point f2 of the detection lens 18, the beam 13e becomes a horizontal line as shown in (e), and at the combined focal point f1 side of the astigmatism area 21,
As shown in (b), the beam 13b has a vertically long elliptical shape,
On the focal point f2 side of the detection lens 18 in the astigmatism area 21,
As shown in (d), the beam 13d has a horizontally long elliptical shape,
Between the beam 13b and the beam 13d, there is a position where the beam 13c is circular as shown in FIG.

Therefore, in the focus error detecting optical system, the information recording surface 16 of the disk 15 is
When the astigmatic optical system is in the focal plane, the light receiving element 1A0 composed of a four-division photodiode is disposed at a position where the beam cross section of the astigmatism optical system is circular, and the light receiving state of the light receiving element 1A0 is detected. That is, as shown in FIG.
A0 is composed of square light receiving elements A to D in which a square photodiode original plate is divided symmetrically into four at the center, and the light receiving elements A and C are connected to the input terminal of the adder 10a. The element B and the light receiving element D are added to the adder 10b.
The output terminal of the adder 10a is connected to the non-inverting input terminal of the subtractor 11, and the output terminal of the adder 10b is connected to the inverting input terminal of the subtractor 11. And
Detection signal Fa of light receiving element A and detection signal Fc of light receiving element C
Are added by the adder 10a, the detection signal Fb of the light receiving element B and the detection signal Fd of the light receiving element D are added by the adder 10b, and the subtractor 11 outputs the output signal Fa + Fc of the adder 10a and the adder 10b. Subtraction with the output signal Fb + Fd of 10b is performed, and the error signal FE =
(Fa + Fd)-(Fb + Fd) is output.

In this case, as shown in FIG. 5A, if the beam 13c received by the light receiving element 1A0 is circular, the information recording surface 16 of the disk 15 is in the focal plane of the objective lens 17, and the focus error The signal FE becomes 0, and when the disk 15 is arranged closer to the objective lens 17 than the in-focus position, the focus error signal FE becomes FE> 0 as shown in FIG. If it is arranged farther from the objective lens 17 than the in-focus position, as shown in FIG.
E becomes FE <0, and an S-shaped characteristic as shown in FIG. 6 exists between the focus error signal FE and the focus shift (focus shift).

[0008]

As described above, by detecting the focus error signal FE, the objective lens 17 is moved up and down by the focusing drive circuit based on the detected focus error signal FE. Focusing control is performed so that the distance between the lens 17 and the disk 15 falls within the depth of focus of the objective lens 17. In this case, the shape of the beam incident on the light receiving element 1A0 becomes a vertical beam 12a at the position of the composite focal point f1, as shown in FIG.
Is a horizontal beam 13e at the position of the focal point f2, and the shape of the beam between these beams is a vertically long elliptical beam 13b, a horizontally long elliptical beam 13d, and a circular beam 13c.

However, in the light receiving element 1A0, a non-light receiving area in which none of these beams is received, for example, as shown in FIG.
The non-light receiving area 23 shown in FIG. Since the light receiving element 1A0 is formed of a photodiode, if there is a region on the light receiving surface of the photodiode that does not receive laser light and does not contribute to photoelectric conversion, the pn junction capacitance of the photodiode increases, Lowers the optical response characteristics,
S / N is reduced due to generation of noise.

The present invention has been made in view of the above-mentioned current situation of this type of split type photodiode,
It is an object of the present invention to provide a split type photodiode capable of detecting a light receiving state with high accuracy by improving light response characteristics and reducing generation of noise.

[0011]

In order to achieve the above object, according to the present invention, a plurality of photodiodes are collectively arranged around a combining center in a state of being in contact with each other, and the entirety is formed in a predetermined combining manner. A divided photodiode having a shape is configured, and based on a light receiving signal of the incident light on a light receiving surface of each photodiode, a light receiving state of the incident light is detected. The light receiving surface of the diode has a shape in which a part of the non-light receiving region is cut off as a cutout from the original light receiving surface in the non-light receiving region of the incident light.

Similarly, in order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the light receiving area of the incident light on the light receiving surface of the plurality of photodiodes is provided on the light receiving surface. It is characterized in that it occupies 1/2 or more of the entire area.

[0013] Similarly, in order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the predetermined combined shape is a quadrangle, and the light receiving surface is provided on the outer periphery of the plurality of photodiodes. The vicinity of the edge portion has a shape cut off as the notch.

[0014] Similarly, in order to achieve the above object, according to a fourth aspect of the present invention, in the first aspect of the present invention, the predetermined combined shape is a triangle, and the light-receiving surface is formed of a plurality of photodiodes. The vicinity of the edge portion has a shape cut off as the notch.

Similarly, in order to achieve the above object, according to a fifth aspect of the present invention, in the first aspect of the present invention, the predetermined combined shape is an elliptical shape, and the light receiving surface is formed of the plurality of photodiodes. The vicinity of the outer peripheral edge portion has a shape cut off as the cutout portion.

[0016] Similarly, in order to achieve the above object, according to a sixth aspect of the present invention, in the first aspect of the present invention, the predetermined combined shape is a circle, and the light receiving surface is formed on the outer periphery of the plurality of photodiodes. The vicinity of the edge portion has a shape cut off as the notch.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory diagram showing a configuration of the present embodiment, and FIG. 7 is an explanatory diagram showing a first configuration of a conventional split type photodiode.

In the first example of this embodiment, as shown in FIG. 7, four rectangular photodiodes 1A to 1A are respectively provided.
D is formed of a divided photodiode 1 which is disposed with its sides in contact with each other around the center of the set, and which is entirely formed in a quadrangular shape. A part of the non-light receiving area is cut off as a notch from the non-light receiving area of the surface.

That is, from the photodiode 1A, FIG.
As shown in (a), the vicinity of the outer peripheral edge of the photodiode 1A is formed as a triangular cutout 5Aa, which is cut off from the original light receiving surface, symmetrically with respect to the tangent sides with the photodiodes 1B and 1D. A photodiode 1Aa having a light receiving surface is formed. In addition, the photodiode 1
From B, the vicinity of the outer peripheral edge of the photodiode 1B has a light receiving surface cut off from the original light receiving surface as a triangular cutout 5Ba, respectively, symmetrically to the tangent sides with the photodiodes 1A and 1C. The photodiode 1Bb is formed.

Further, from the photodiode 1C, the vicinity of the outer peripheral edge of the photodiode 1C is cut off from the original light receiving surface as triangular cutouts 5Ca, symmetrically with respect to the tangent sides with the photodiodes 1B and 1D. A photodiode 1Ca having a light receiving surface having a curved shape is formed. Then, from the photodiode 1D, the vicinity of the outer peripheral edge of the photodiode 1D is cut out from the original light receiving surface as a triangular cutout 5Da, symmetrically with respect to the tangent sides with the photodiodes 1A and 1C. A photodiode 1Da having a light receiving surface is formed.

In the second example of this embodiment, similarly to the first example, as shown in FIG. 7, four rectangular photodiodes 1A to 1D are arranged so that the sides thereof are in contact with each other around the center of the set. The divided light-receiving surface of the present embodiment is formed from a non-light-receiving area of the light-receiving surface of the split-type photodiode 1 and a part of the non-light-receiving area. Is cut off as a notch.

That is, from the photodiode 1A, FIG.
As shown in (b), the vicinity of the outer peripheral edge of the photodiode 1A is cut off from the original light receiving surface as a half crescent-shaped notch 5Ab, respectively, symmetrically with respect to the tangent sides with the photodiodes 1B and 1D. A photodiode 1Ab having a light receiving surface having a shape is formed. Further, from the photodiode 1B, the vicinity of the outer peripheral edge of the photodiode 1B was cut off from the original light receiving surface as a half crescent-shaped notch 5Bb, respectively, symmetrically with respect to the tangent sides with the photodiodes 1A and 1C. A photodiode 1Bb having a light receiving surface having a shape is formed.

Further, from the photodiode 1C, the vicinity of the outer peripheral edge of the photodiode 1C is symmetrically formed with the photodiodes 1B and 1D in the form of a half-crescent cutout 5Cb from the original light receiving surface. A photodiode 1Cb having a cut-off light receiving surface is formed. Then, from the photodiode 1D, the vicinity of the outer peripheral edge portion of the photodiode 1D is cut off from the original light receiving surface as a half crescent shaped notch 5Db, respectively, symmetrically with respect to the tangent sides with the photodiodes 1A and 1C. A photodiode 1Db having a light receiving surface having a shape is formed.

In the third example of this embodiment, similarly to the first example, as shown in FIG. 7, four rectangular photodiodes 1A to 1D are arranged so that their sides are in contact with each other around the center of the set. The divided light-receiving surface of the present embodiment is formed from a non-light-receiving area of the light-receiving surface of the split-type photodiode 1 and a part of the non-light-receiving area. Is cut off as a notch.

That is, as shown in FIG.
As shown in (c), the vicinity of the outer peripheral edge of the photodiode 1A is cut off from the original light receiving surface as a half crescent-shaped notch 5Ac, respectively, symmetrically with respect to the tangent sides with the photodiodes 1B and 1D. A photodiode 1Ac having a light receiving surface cut off from the original light receiving surface is formed as a notch 5Ac1 near the intersection of both outer peripheral edges of the photodiode 1A. In addition, the photodiode 1
From B, the vicinity of the outer peripheral edge portion of the photodiode 1B is cut off from the original light receiving surface as half-crescent cutouts 5Bc, respectively, symmetrically with the tangent sides with the photodiodes 1A and 1C. A photodiode 1Bc having a light receiving surface of a shape cut off from the original light receiving surface as a notch 5Bc1 in the vicinity of the intersection of both outer peripheral edges of
Are formed.

Further, from the photodiode 1C, the vicinity of the outer peripheral edge of the photodiode 1C is cut off from the original light receiving surface as a half crescent-shaped notch 5Cc, symmetrically with respect to the opposing sides to the photodiodes 1B and 1D. Further, a photodiode 1Cc having a light receiving surface cut off from the original light receiving surface is formed as a notch 5Cc1 in the vicinity of the intersection of both outer peripheral edges of the photodiode 1C. Then, from the photodiode 1D, the vicinity of the outer peripheral edge portion of the photodiode 1D is cut off from the original light receiving surface as a half-crescent-shaped notch 5Dc, respectively, symmetrically with the tangent sides with the photodiodes 1A and 1C. A photodiode 1Dc having a light receiving surface cut off from the original light receiving surface is formed as a notch 5Dc1 in the vicinity of the intersection between the two outer peripheral edges of the photodiode 1D.

In the embodiment described above,
In any of the examples, the notch is cut so that the light receiving area of the light receiving surface on the light receiving surface occupies 1/2 or more of the entire area of the light receiving surface.

As described above, in the present embodiment, the square 4
The photodiodes 1 </ b> A to 1 </ b> D are formed from a basic divided photodiode 1 that is formed by assembling the sides of the divided photodiodes 1 A to 1 D so that their combined shape is a quadrangle. In the vicinity of the outer peripheral edge, the non-light-receiving area of the light-receiving surface is cut off from the light-receiving surface as a triangular or crescent-shaped notch, symmetrically with the sides of the photodiodes 1A to 1D that are opposed to each other. In the vicinity of the intersection of both outer peripheral edges of the diode 1, the non-light receiving area of the light receiving surface is cut off from the light receiving surface as a triangular cutout, and the light receiving area of the incident light on the light receiving surface is one of the entire area of the light receiving surface. / 2 or more. For this reason, according to the present embodiment, the laser light on the light receiving surface of the photodiode is not received at all, and the pn junction capacitance of the photodiode in the region that does not contribute to the photoelectric conversion lowers the optical response characteristic and generates noise. The reduction in S / N is reduced, the optical response characteristics are enhanced, and the occurrence of noise is reduced, so that the light receiving state of the incident light can be detected with high accuracy.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is an explanatory diagram showing the configuration of the present embodiment, and FIG. 8 is an explanatory diagram showing a second configuration of a conventional split-type photodiode.

In the present embodiment, as shown in FIG. 8, four photodiodes 2A to 2D each having a triangular shape are arranged so that their sides are in contact with each other around the center of the group, and the whole is formed in a quadrangle. The light receiving surface of the present embodiment is formed from the non-light receiving area of the light receiving surface of the split type photodiode 2 and a part of the non-light receiving area is cut out as a cutout. I have.

That is, from the photodiode 2A, FIG.
As shown in the figure, the light receiving surface of the shape cut off from the original light receiving surface is formed as a triangular cutout 6Aa in the vicinity of the outer peripheral edge of the photodiode 2A, symmetrically with the tangent sides with the photodiodes 2B and 2D. Having photodiode 2
Aa is formed. In addition, from the photodiode 2B, the vicinity of the outer peripheral edge of the photodiode 2B is cut off from the original light receiving surface as a triangular cutout 6Ba, symmetrically with respect to the tangent sides with the photodiodes 2A and 2C. A photodiode 2Bb having a light receiving surface is formed.

Further, from the photodiode 2C, the vicinity of the outer peripheral edge of the photodiode 2C is cut off from the original light receiving surface as triangular cutouts 6Ca, respectively, symmetrically with respect to the opposing sides to the photodiodes 2B and 2D. A photodiode 2Ca having a light receiving surface having a curved shape is formed. Then, from the photodiode 2D, the vicinity of the outer peripheral edge of the photodiode 2D is cut out from the original light receiving surface as a triangular cutout 6Da symmetrically with respect to the tangent sides with the photodiodes 2A and 2C. A photodiode 2Da having a light receiving surface is formed.

In the embodiment described above,
The light receiving area of the incident light on the light receiving surface is １ ／ of the entire area of the light receiving surface
Notches are cut out to account for the above.

As described above, in the present embodiment, the triangular 4
The photodiodes 2 </ b> A to 2 </ b> D are formed from the basic divided photodiodes 2 that are collectively configured so that the composite shape is quadrilateral with the sides in contact with each other. In the vicinity of the outer peripheral edge, a part of the non-light-receiving area of the light-receiving surface is symmetrical to the sides of the photodiodes 2A to 2D that are opposed to each other. The laser light on the light receiving surface of the photodiode is not received at all because the laser light is cut off so as to be １ ／ or more of the entire region of the light receiving surface, which is caused by the pn junction capacitance of the photodiode in a region that does not contribute to photoelectric conversion. The reduction of the optical response characteristics and the reduction of S / N due to the generation of noise are reduced, the optical response characteristics are improved, the generation of noise is reduced, and the light receiving state of incident light is detected with high accuracy. Rukoto becomes possible.

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is an explanatory diagram showing a configuration of the present embodiment, and FIG. 9 is an explanatory diagram showing a third configuration of a conventional split-type photodiode.

In the present embodiment, as shown in FIG. 9, four divided elliptical photodiodes 3A to 3D are provided.
Are arranged around the center of the set with their sides facing each other,
The light receiving surface of the present embodiment is formed from a non-light receiving region of the light receiving surface of the split type photodiode 3 and a part of the non-light receiving region is formed as a cutout portion. It has a resected configuration.

That is, from the photodiode 3A, FIG.
As shown in the figure, the light receiving portion 3A is cut off from the original light receiving surface in the vicinity of the outer peripheral edge portion of the photodiode 3A as a notched portion 7Aa in a symmetrical manner with respect to the tangent sides with the photodiodes 3B and 3D. A photodiode 3Aa having a surface is formed. Also, the photodiode 3
From B, the light receiving surface of the shape cut off from the original light receiving surface is formed in the vicinity of the outer peripheral edge of the photodiode 3B as a notch 7Ba of a split ellipse, respectively, symmetrically with the tangent sides with the photodiodes 3A and 3C. Photodiode 3B having
b is formed.

Further, from the photodiode 3C, the vicinity of the outer peripheral edge of the photodiode 3C is symmetrically formed with the photodiode 3B, 3D in the vicinity of the outer peripheral edge thereof as a notch 7Ca of a divided elliptical shape from the original light receiving surface. A photodiode 3Ca having a cut-off light receiving surface is formed. Then, from the photodiode 3D, the vicinity of the outer peripheral edge of the photodiode 3D is cut off from the original light receiving surface as a divided elliptical cutout 7Da, symmetrically with respect to the tangent sides with the photodiodes 3A and 3C. A photodiode 3Da having a light receiving surface having a shape is formed.

In the embodiment described above,
The light receiving area of the incident light on the light receiving surface is １ ／ of the entire area of the light receiving surface
Notches are cut out to account for the above.

As described above, the present embodiment is based on a basic configuration in which four photodiodes 3A to 3D each having a divided elliptical shape are collectively configured such that the sides are in contact with each other and the composite shape is an elliptical shape. In the vicinity of the outer peripheral edge of the split type photodiode 3, a part of the non-light receiving area of the light receiving surface is symmetrical to the sides of the photodiodes 3A to 3D that are in contact with each other. Since the light receiving area of the incident light on the light receiving surface is cut off from the light receiving surface as a split elliptical notch so that the light receiving area is equal to or more than half of the entire area of the light receiving surface, the laser light on the light receiving surface of the photodiode is cut off. In a region that does not receive light at all and does not contribute to photoelectric conversion, a decrease in optical response characteristics due to a pn junction capacitance of the photodiode and a decrease in S / N due to generation of noise are reduced.
The optical response characteristics are enhanced, and the occurrence of noise can be reduced and the light receiving state of the incident light can be detected with high accuracy.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 4 is an explanatory diagram showing the configuration of the present embodiment, and FIG. 10 is an explanatory diagram showing a fourth configuration of a conventional split-type photodiode.

In this embodiment, as shown in FIG. 10, four photodiodes 4A to 4D each having a quadrant shape are used.
Are arranged around the center of the set with their sides facing each other,
The light receiving surface of the present embodiment is formed by cutting out a part of the non-light receiving region from the light receiving surface of the split type photodiode 4 as a cutout portion. It is the configuration that was done.

That is, from the photodiode 4A, FIG.
As shown in the figure, the light receiving surface of the shape cut off from the original light receiving surface in the vicinity of the outer peripheral edge portion of the photodiode 4A as a divided circular cutout 8Aa symmetrically with the tangent sides with the photodiodes 4B and 4D. Is formed. Also, the photodiode 4B
Therefore, in the vicinity of the outer peripheral edge of the photodiode 4B, the light-receiving surface of the shape cut off from the original light-receiving surface is formed in the vicinity of the outer peripheral edge of the photodiode 4B symmetrically with respect to the tangent sides with the photodiodes 4A and 4C. The photodiode 4Bb is formed.

Further, from the photodiode 4C, the vicinity of the outer peripheral edge of the photodiode 4C is cut out from the original light receiving surface as a divided circular notch 8Ca, respectively, symmetrically with respect to the tangent sides with the photodiodes 4B and 4D. A photodiode 4Ca having a light receiving surface having a shaped shape is formed. Then, from the photodiode 4D, the shape of the vicinity of the outer peripheral edge of the photodiode 4D is cut out from the original light receiving surface as a divided circular cutout 8Da, respectively, symmetrically with respect to the tangent sides with the photodiodes 4A and 4C. Is formed.

Also, in the present embodiment described above,
The light receiving area of the incident light on the light receiving surface is １ ／ of the entire area of the light receiving surface
Notches are cut out to account for the above.

As described above, the present embodiment is a basic structure in which four photodiodes 4A to 3D each having a four-part circular shape are collectively configured such that the sides are in contact with each other and the composite shape is circular. A part of the non-light receiving area of the light receiving surface is divided in the vicinity of the outer peripheral edge of the split type photodiode 4 symmetrically with the sides of each of the photodiodes 4A to 4D which are in contact with each other. Since the light receiving area of the incident light on the light receiving surface is cut off from the light receiving surface as a circular notch so as to be half or more of the entire area of the light receiving surface, the laser light on the light receiving surface of the photodiode is completely received. Therefore, a decrease in optical response characteristics due to the pn junction capacitance of the photodiode in a region that does not contribute to photoelectric conversion and a decrease in S / N due to generation of noise are reduced, and the optical response characteristics are enhanced. By reducing the occurrence of noise light receiving state of the incident light can be detected with high accuracy.

[0047]

According to the first aspect of the present invention, a plurality of photodiodes are collectively arranged in contact with each other around the center of assembly to form a divided photodiode having a predetermined combined shape as a whole. The light receiving state of the incident light is detected based on the light receiving signal of the light receiving surface of each photodiode of the incident light. Has a shape in which a part of the non-light receiving region is cut off as a cutout portion, so that the incident light on the light receiving surface of the photodiode is not received at all, and the pn junction of the photodiode in a region that does not contribute to photoelectric conversion Since the reduction of the optical response characteristic due to the capacitance and the reduction of the S / N due to the generation of noise are reduced, the optical response characteristic is improved, the generation of noise is reduced, and the light receiving state of the incident light is detected with high accuracy. Door is possible.

According to the second aspect of the present invention, the plurality of photodiodes are collectively arranged in a state of being in contact with each other around the center of the assembly, and a divided photodiode having a predetermined combined shape as a whole is formed. The light receiving state of the incident light is detected based on the light receiving signal of the light receiving surface of each photodiode. However, the light receiving surfaces of the plurality of photodiodes are different from the original light receiving surface in the non-light receiving area of the incident light. The light receiving area has a shape in which a part of the light receiving area is cut off as a notch, and the light receiving area of the incident light on the light receiving surface occupies more than half of the entire area of the light receiving surface. Since a decrease in the optical response characteristic due to the pn junction capacitance of the photodiode and a decrease in S / N due to generation of noise in a region where no incident light is received and which does not contribute to photoelectric conversion are reduced,
The optical response characteristics are enhanced, and the occurrence of noise can be reduced and the light receiving state of the incident light can be detected with high accuracy.

According to the third aspect of the present invention, a plurality of photodiodes are collectively arranged around the center of collection in a state of being in contact with each other, thereby forming a quadrangular divided type photodiode as a whole. The light receiving state of the incident light is detected based on the light receiving signal on the light receiving surface of each photodiode. Has a shape cut off as a notch,
In a region where no incident light is received on the light receiving surface of the photodiode and does not contribute to photoelectric conversion, the pn junction capacitance of the photodiode degrades the optical response characteristic and causes S
Since the decrease in / N is reduced, the optical response characteristics are improved, and the occurrence of noise can be reduced, and the light receiving state of the incident light can be detected with high accuracy.

According to the fourth aspect of the present invention, the plurality of photodiodes are collectively arranged around the center of collection in a state of being in contact with each other, thereby forming a triangular split type photodiode as a whole. The light receiving state of the incident light is detected based on the light receiving signal on the light receiving surface of each photodiode. Has a shape cut off as a notch,
In a region where no incident light is received on the light receiving surface of the photodiode and does not contribute to photoelectric conversion, the pn junction capacitance of the photodiode degrades the optical response characteristic and causes S
Since the decrease in / N is reduced, the optical response characteristics are improved, and the occurrence of noise can be reduced, and the light receiving state of the incident light can be detected with high accuracy.

According to the fifth aspect of the present invention, the plurality of photodiodes are collectively arranged around the center of the group in a state of being in contact with each other, thereby forming an elliptical split type photodiode as a whole, and the incident light is formed. The light receiving state of the incident light is detected based on the light receiving signal on the light receiving surface of each of the photodiodes, but the light receiving surfaces of the plurality of photodiodes do not receive light from the original light receiving surface in the non-light receiving area of the incident light. Because part of the area has a shape cut off as a notch,
In a region where no incident light is received on the light receiving surface of the photodiode and does not contribute to photoelectric conversion, the pn junction capacitance of the photodiode degrades the optical response characteristic and causes S
Since the decrease in / N is reduced, the optical response characteristics are improved, and the occurrence of noise can be reduced, and the light receiving state of the incident light can be detected with high accuracy.

According to the sixth aspect of the present invention, a plurality of photodiodes are collectively arranged around the center of collection in a state where they are in contact with each other, so that a divided photodiode having a circular shape as a whole is formed. The light receiving state of the incident light is detected based on the light receiving signal on the light receiving surface of each photodiode. Has a shape cut off as a notch, so that it does not receive any incident light on the light receiving surface of the photodiode and does not contribute to photoelectric conversion. S / S due to deterioration of characteristics and generation of noise
Since the decrease in N is reduced, the light response characteristics are enhanced,
The occurrence of noise can be reduced, and the light receiving state of the incident light can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a configuration of a third exemplary embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of focus error signal detection by a split photodiode.

FIG. 6 is a characteristic diagram of a focus error signal.

FIG. 7 is an explanatory diagram showing a first configuration of a conventional split-type photodiode.

FIG. 8 is an explanatory view showing a second configuration of a conventional split type photodiode.

FIG. 9 is an explanatory diagram showing a third configuration of a conventional split-type photodiode.

FIG. 10 is an explanatory diagram showing a fourth configuration of a conventional split-type photodiode.

FIG. 11 is an explanatory diagram of a non-light receiving area of a conventional split type photodiode.

FIG. 12 is an explanatory diagram of an optical system that uses an optical system that uses the astigmatism method.

FIG. 13 is an explanatory diagram of the operation of the astigmatism method.

14 is an explanatory diagram of a beam shape in an astigmatism region in FIG.

[Explanation of symbols]

 1Aa, 1Ba, 1Ca, 1Da photodiode 1Ab, 1Bb, 1Cb, 1Db photodiode 1Ac, 1Bc, 1Cc, 1Dc photodiode 2Aa, 2Ba, 2Ca, 2Da photodiode 3Aa, 3Ba, 3Ca, 3Ca photodiode 4Aa, 4Ba, 4Ca , 4Ca photodiode 5Aa, 5Ba, 5Ca, 5Da Notch 5Ab, 5Bb, 5Cb, 5Db Notch 5Ac, 5Bc, 5Cc, 5Dc Notch 6Aa, 6Ba, 6Ca, 6Da Notch 7Aa, 7Ba, 7Ca, 7Da Notch 8A , 8Ba, 8Ca, 8Da Notch

Claims (6)

[Claims] 1. A plurality of photodiodes are collectively arranged around a collection center in a state where they are in contact with each other to form a divided photodiode having a predetermined combined shape as a whole, and a light receiving surface of each of the photodiodes for incident light. Based on the received light signal, the split type photodiodes that detect the light receiving state of the incident light are performed, and the light receiving surfaces of the plurality of photodiodes are arranged in a non-light receiving area of the incident light from the original light receiving surface. A split type photodiode having a shape in which a part of a non-light receiving area is cut off as a notch. 2. The split type photodiode according to claim 1, wherein a light receiving area of said incident light on a light receiving surface of said plurality of photodiodes occupies at least 1/2 of an entire area of said light receiving surface. Characteristic split photodiode. 3. The split type photodiode according to claim 1, wherein the predetermined combined shape is a quadrangle, and the light receiving surface is cut off in the vicinity of an outer peripheral edge of the plurality of photodiodes as the cutout. A split-type photodiode having a shape. 4. The split type photodiode according to claim 1, wherein the predetermined combined shape is a triangle, and the light receiving surface is cut off in the vicinity of an outer peripheral edge of the plurality of photodiodes as the cutout. A split-type photodiode having a shape. 5. The split type photodiode according to claim 1, wherein the predetermined combined shape is an ellipse, and the light receiving surface is cut off in the vicinity of an outer peripheral edge of the plurality of photodiodes as the cutout. A split type photodiode having a bent shape. 6. The split type photodiode according to claim 1, wherein the predetermined combined shape is circular, and the light receiving surface is cut off as a notch near an outer peripheral edge of the plurality of photodiodes. A split-type photodiode having a shape.