JPH09203872A - Lens for optical scanning, synchronous optical detecting device, and optical scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly increase the degree of freedom of design of the optical scanning device by making it possible to use a completely new layout for a synchronous optical detecting element of the optical scanning device. SOLUTION: This device deflects luminous flux by an optical deflector 5 and converges the deflected luminous flux as a light spot on a scanned surface 9 by a scanning image forming lens to optically scan the scanned surface 9. At this time, this device has an optical path bending part 6 which is a lens 8 for optical scanning that constitutes at least part of the scanning image forming lens and reflects synchronizing signal on the end part of the scanning start side of the deflected luminous flux in a horizontal scanning corresponding direction to bend the optical axis, and the optical path bending part 6 is constituted so as to bend the optical path so that the reflected synchronizing light passes through the lens in the main scanning corresponding direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning lens,
The present invention relates to a synchronous light detection device and an optical scanning device.

[0002]

2. Description of the Related Art An optical scanning device which collects a deflected light beam as a light spot on a surface to be scanned by a scanning imaging lens and optically scans the surface to be scanned is related to an optical printer, a digital copying machine, an optical printing machine or the like. It has been widely known since then.

Since a "mechanical optical deflector" such as a polygon mirror is generally used for "deflection of the light beam", the deflection cycle of the deflected light beam is not always constant, and the starting points of the optical scanning in the effective scanning area are aligned. Therefore, the deflected light flux that is deflected toward the effective scanning region is detected as synchronization light, and the start of optical scanning is synchronized based on this detection. Since the synchronized light detecting element for receiving the synchronized light receives the deflected light flux toward the effective scanning area as the synchronized light, its deployment position is limited to a narrow area, and conventionally, the deployment position of the synchronized light detection element is first determined. In addition, the layout of other members has been determined, and the synchronous photodetector has been a major limitation on the layout of the optical scanning device.

[0004]

In view of the above-mentioned circumstances, the present invention enables a completely new layout of the synchronous light detecting elements in the optical scanning device and greatly increases the degree of freedom in designing the optical scanning device. Is an issue.

[0005]

According to the "scanning / imaging lens" of the present invention, a light beam is deflected by an optical deflector, and the deflected light beam is condensed as a light spot on a surface to be scanned by the scanning / imaging lens. It is an optical scanning lens that "consists at least a part of a scanning imaging lens" in an optical scanning device that optically scans a surface to be scanned.

The optical scanning lens has an optical path bending portion for reflecting the synchronizing light and bending the optical path at the end of the deflected light beam on the scanning start side in the main scanning corresponding direction, and this optical path bending portion is reflected. It is formed to bend the optical path so that the synchronized light passes through the lens in the main scanning direction. ”
It is characterized by the following (claim 1).

The "main scanning corresponding direction" is a direction parallel to the main scanning direction on a virtual optical path in which the optical path from the light source to the surface to be scanned is linearly expanded along the optical axis, The direction corresponding to the sub-scanning direction in parallel on the virtual optical path is referred to as "sub-scanning corresponding direction".

"Synchronous light" is a light beam deflected by an optical deflector toward an effective scanning area, and is a light beam to be detected by a synchronous light detecting element.

The phrase "the reflected synchronizing light passes through the lens in the main scanning corresponding direction" means that the reflected synchronizing light is guided in the main scanning corresponding direction of the optical scanning lens so that the main scanning direction corresponds to the main scanning corresponding direction. It means that the light is emitted from the opposite side, that is, the end on the side opposite to the side on which the optical path bend is formed. As a form in which the synchronous light passes through the optical scanning lens in the main scanning corresponding direction, there is a case where the synchronous light simply "transmits" through the optical scanning lens in the main scanning corresponding direction, and the synchronous light is entirely transmitted by the lens surface. It also includes the case where the light passes through the lens in the direction corresponding to the main scanning while being reflected, and exits from the side opposite to the optical path bending portion.

The optical scanning lens "constitutes at least a part of the scanning and imaging lens" means that when the scanning and imaging lens is composed of a plurality of lenses, the scanning and imaging lens is "one of them. Is meant.

Therefore, when the scanning and imaging lens is composed of one lens, the optical scanning lens itself constitutes the scanning and imaging lens (claim 2). The optical scanning lens can of course be made of optical glass, but it can also be made of "optical plastic" (claim 3).

The optical path bending of the synchronizing light by the optical path bending portion can be performed "only by reflection".
The optical path may be bent by "refraction upon incidence on the bent portion of the optical path and internal reflection on the reflecting portion of the bent portion of the optical path" (claim 4), and in this case, the synchronous light incident on the bent portion of the optical path. The incident surface that refracts light and the reflecting surface that constitutes the reflecting portion can be made to be "a wedge shape that points toward the scanning start side in the main scanning corresponding direction" (claim 5), and "the reflecting portion at the bent portion of the optical path". It is also possible to form the reflecting surface constituting the above so that the synchronous light is totally reflected ”(claim 6).

In addition, it is possible to "have an element holding portion for holding the synchronous light detecting element integrally with the lens portion" at an end portion (a portion where the synchronous light whose optical path is bent is emitted from the synchronous light) on the scanning end side in the optical scanning lens. Yes (Claim 7). In this case, the element holding portion may be made of a material different from the lens portion, and the element holding portion and the lens portion may be integrated by a means such as adhesion. In the case of (1), the optical path bending portion, the lens portion, and the element holding portion can be molded by optical plastic as a whole.

The reflecting portion of the bent portion of the optical path can be formed as a curved surface so as to have "power for condensing the reflected synchronous light toward the synchronous light detecting element" (claim 8). Further, the synchronization light, which is bent in the optical path by the optical path bending portion, passes through the optical scanning lens in the main scanning corresponding direction and is emitted from the optical scanning lens. A refracting surface for converging light may be formed (claim 9). In the case of claim 9, it is possible to form a mask having a "diaphragm effect" for the synchronizing light on the refracting surface portion formed at the end portion on the scanning end side of the optical scanning lens (claim 10).

An eleventh aspect of the synchronous light detecting device includes the optical scanning lens according to any one of the first to ninth aspects, a synchronous light detecting element, a correction lens, and a diaphragm member.
The “synchronous light detecting element” is a light receiving element, and receives the synchronous light emitted from the optical scanning lens after passing through the optical scanning lens in the main scanning corresponding direction. The “correction lens” focuses the synchronization light emitted from the optical scanning lens on the synchronization light detection element.

The "diaphragm member" is provided between the correction lens and the synchronous light detecting element, and limits the luminous flux portion of the synchronous light incident on the synchronous light detecting element and its incident position.

When the optical scanning lens has a reflecting portion and / or a refracting surface having a "function of condensing the synchronous light toward the synchronous light detecting element" as in the eighth and ninth aspects, The power of the correction lens is determined so that the deflected light beam is well focused on the synchronous light detecting element in combination with the power of the reflecting portion and / or the refracting surface.

According to a twelfth aspect of the present invention, there is provided a synchronous light detecting device including the optical scanning lens according to the eighth or ninth aspect, a synchronous light detecting element, and a diaphragm member. The "synchronous light detecting element" receives the synchronous light that has passed through the optical scanning lens in the main scanning corresponding direction and emitted from the optical scanning lens. "Throttle member" is
It is provided between the optical scanning lens and the synchronous light detecting element, and limits the luminous flux portion of the synchronous light incident on the synchronous light detecting element and its incident position.

Since the optical scanning lens according to claim 8 has a reflecting portion and / or a refracting surface having a function of condensing the synchronous light toward the synchronous light detecting element, it is incident on the synchronous light detecting element. The "correction lens" in the synchronous light detecting device according to claim 11 is omitted so that the light flux is effectively condensed on the synchronous light detecting element by the reflecting portion and / or the refracting surface.

According to a thirteenth aspect of the present invention, there is provided the synchronous light detecting device, wherein the optical scanning lens of the tenth aspect and the synchronous light emitted from the optical scanning lens after passing through the optical scanning lens in the main scanning corresponding direction. And a synchronous light detecting element for receiving light.

The optical scanning lens according to claim 10 has a reflecting portion and / or a refracting surface having a function of condensing the synchronous light toward the synchronous light detecting element, and the end of the optical scanning lens on the scanning end side. Since there is a "mask having a diaphragm effect" in the refraction surface portion formed in the portion, the synchronization light incident on the synchronization light detection element is effectively condensed by the reflection portion and / or the refraction surface on the synchronization light detection element. Therefore, the "correction lens" in the synchronous light detecting device of the eleventh aspect is omitted, and by having the mask, the "diaphragm member" in the synchronous light detecting device of the eleventh and the twelfth aspects is omitted.

The optical scanning device of the present invention has a light source, a coupling lens, an optical deflector, a scanning image forming lens, and a synchronous light detecting device (claim 14). The “light source” emits a light beam for optical scanning. The "coupling lens" couples the light flux emitted from the light source into a parallel light flux, a weakly convergent light flux, or a weakly divergent light flux. The "light deflector" deflects the coupled light flux. The "scan imaging lens" is a lens that condenses the deflected light flux as a light spot on the surface to be scanned. The "synchronized light detection device" detects the deflected light beam deflected by the optical deflector and headed for the effective scanning region as synchronized light by the synchronized light detection element in order to synchronize the optical scanning. This synchronous light detecting device is the synchronous light detecting device according to claim 11 or 12 or 13. Therefore, at least a part of the scanning imaging lens is composed of the optical scanning lens.

In the optical scanning device according to the fourteenth aspect, the optical deflector has a deflecting / reflecting surface, has a function of deflecting the light flux reflected by the deflecting / reflecting surface at a constant angular velocity, and comprises a coupling lens and an optical deflector. In between, there is a line image forming optical system for forming a "line image long in the main scanning corresponding direction" in the vicinity of the deflecting reflection surface, and the scanning image forming lens is arranged in the main scanning corresponding direction. In addition to having the "function of making the scanning speed of the light spot uniform", it is possible to have the "function of making the deflection reflection surface position and the scanned surface position a substantially conjugate relationship" in the sub-scanning corresponding direction ( Claim 15). The optical deflector in this case is a polygon mirror or the like, but the optical scanning device according to the fifteenth aspect has a function of correcting so-called "face tilt" of the deflective reflection surface.

In the optical scanning device according to claim 14 or 15, the optical scanning start side is the side opposite to the light source with respect to the optical axis of the scanning imaging lens, and the synchronous light detection element in the synchronous light detection device is for optical scanning. It can be provided on the same control board as the light source, separately from the lens (claim 16).

[0025]

Embodiments of the present invention will be described below. FIG. 1 schematically shows only an essential part of an embodiment of an optical scanning device according to a fifteenth aspect. The light source 1 is a semiconductor laser, and the divergent light beam emitted from the light source 1 is coupled by the coupling lens 2 to be a parallel light beam or a weak converging or weak divergent light beam.

The coupled light flux passes through the beam shaping aperture 3 to remove the peripheral portion of the light flux, and then enters the line image imaging optical system 4. The line image forming optical system 4 is a cylinder lens having a positive power only in the sub-scanning corresponding direction (direction orthogonal to the drawing), converges the light beam only in the sub-scanning corresponding direction, and makes the optical deflector 5 a polygon mirror. An image is formed in the very vicinity of the deflective reflection surface 5A as a "long line image in the main scanning corresponding direction".

The light beam reflected by the deflecting / reflecting surface 5A is incident on the optical scanning lens 8 and is condensed as a light spot on the surface to be scanned (the surface of the photoconductive drum-shaped photosensitive member 9) by the action of the lens 8. The reflected light beam is deflected at a constant angular velocity by the constant-speed rotation of the light deflector 5. The optical scanning lens 8 itself constitutes a "single-lens configuration scanning imaging lens", and has a function of making the scanning speed of the light spot uniform in the main scanning corresponding direction (coupling by the coupling lens 2). When the light flux is a parallel light flux, it has a so-called "fθ characteristic") and also has a function of making the position of the deflective reflection surface 5A and the position of the scanned surface substantially conjugate with each other in the sub-scanning corresponding direction. Therefore, this optical scanning device has a function of correcting the surface tilt of the deflective reflection surface of the optical deflector 5.

Since the light deflector 5 rotates at a constant speed in the direction of the arrow, the deflection of the deflected light beam is clockwise in FIG. The optical path bending portion 6 that reflects the synchronization light D and bends the optical path thereof is reflected by the “end portion of the deflected light beam on the scanning start side (A portion in FIG. 1) in the main scanning corresponding direction” of the optical scanning lens 8. The optical path is formed so that the generated synchronizing light passes through the lens in the main scanning corresponding direction.

The deflected light beam has a deflection angle of θ before the start of optical scanning of the effective scanning area (the area indicated by the symbol W in FIG. 1).
_At the deflection position of D, it enters the optical path bending portion 6 as the synchronous light D,
When the optical path is bent, the light passes through the optical scanning lens 8 in the main scanning corresponding direction, and exits from the opposite end portion (B portion in FIG. 1), it enters the correction lens 10 and is given a converging tendency.
It is incident on the synchronous light detecting element 7 via 1. When the synchronous light detecting element 7 receives the synchronous light, it emits a light receiving signal, and based on the light receiving signal, a synchronizing signal for determining the starting point of the optical scanning of the effective scanning area is generated.

In the embodiment shown in FIG. 1, the optical scanning lens 8 is used.
A synchronous light detecting element 7 for receiving the deflected light flux, which has passed through the same lens 8 in the main scanning corresponding direction and is emitted, as synchronous light;
Correction lens 10 for focusing the synchronized light on the synchronized light detecting element 7
And the diaphragm member 11 provided between the correction lens 10 and the synchronous light detecting element 7, the embodiment is also one embodiment of the synchronous light detecting device according to claim 11.

FIG. 2 shows a specific example of the form of the bent portion of the optical path.
An example is shown. In the form shown in (a), a hook-shaped portion 6a is formed at the end of the optical scanning lens 8 in the main scanning corresponding direction, and a reflective film 6b is formed at the sloped portion at the tip thereof. The synchronous light traveling to the effective scanning area is bent in the optical path by being reflected by the reflection film 6b forming the reflecting portion, enters from the end portion of the optical scanning lens 8, and passes through the lens 8 in the main scanning corresponding direction. .

In the configuration shown in FIG. 3B, the optical path bending portion 6c is provided so as to project from the end portion of the optical scanning lens, has an incident surface 6i and an inclined surface portion, and a reflection film 6d is formed on the inclined surface portion. Prior to the optical scanning, the synchronous light heading for the effective scanning area is incident from the incident surface 6i, is reflected by the reflection film 6d forming the reflection portion, has its optical path bent in the main scanning corresponding direction, and is main-scanned in the optical scanning lens 8. Transparent in the corresponding direction.

In the form shown in FIG. 3C, the surface portion forming the reflection film 6f forming the reflection portion of the optical path bending portion 6e is a curved surface serving as a concave reflection surface, and the reflected synchronization light is not shown. It has a function of condensing light toward the detection element (claim 8).

In the embodiment shown in FIGS. 2B and 2C, the synchronizing light is first refracted when entering the bent portion of the optical path from the entrance surface 6i, and then reflected by the reflecting portion. Therefore, the optical path is bent by refraction when entering the optical path bending portion and by internal reflection in the reflecting portion (claim 4).

FIG. 3 is a diagram for explaining a characteristic portion of the optical scanning lens according to the fifth and sixth aspects. The optical path bend is
An incident surface (a for refracting the synchronous light incident on the bent portion of the optical path)
The surface) and the reflection surface (surface b) forming the reflection portion form a wedge shape that is pointed toward the scanning start side (upper side in the drawing) in the main scanning corresponding direction.

Deflection angles of the synchronous light to be received by the synchronous light detecting element: θ _D , incident angles and refraction angles on the a-plane are θ _A and θ _A ', and incident angles and reflection angles on the b-plane are θ.
_The angles formed by the _R , a, and b surfaces with the main scanning corresponding direction are θ _a and θ _b . At this time, the angle formed by the a-plane and the b-plane: θ _p = θ _a + θ _b , and the incident angle: θ _A = θ _D + θ _a , the optical path bending portion (the same material as the material for the optical scanning lens is used. Is assumed)
If the refractive index of N is N, then “sin (θ _D + θ _a ) = N · si
n θ _A '”holds.

The condition that the direction of the synchronizing light reflected by the surface b is parallel to the main scanning corresponding direction is "sin (θ _D + θ _a )"
= N · sin ({π / 2} −2θ _R + θ _a ) ”. Optical scanning lens with optical plastic (PC,
When it is made of PMMA, polyolefin resin, etc.,
Since the oscillation wavelength of the light source 1 is 780 nm and the refractive index N of the optical plastic is about 1.48 to 1.6, in order to totally reflect the synchronous light on the b surface forming the reflecting portion of the optical path bending portion, b The inclination angle of the surface: θ _b may be 38.7 degrees or more.

As an example, when the reflection angle is θ _R = 45 degrees, the synchronization light deflection angle is θ _D = 50 degrees, and the refractive index is N = 1.6, the conditional expression “sin (θ _D + θ _a )” is given. = N.sin
({Π / 2} −2θ _R + θ _a ) ”is“ sin (50 + θ _a ) =
N · sin θ _a ”, and θ _a ≧ 0. Therefore, in this case, the incident surface (a surface) for refracting the deflected light beam incident on the bent portion of the optical path and the reflecting surface (b surface) forming the reflecting portion are “pointed toward the scanning start side in the main scanning corresponding direction. It has a "wedge shape" (claim 5).

FIG. 4 shows only a characteristic part of one embodiment of the optical scanning lens according to claim 9. Synchronous light, whose optical path is bent by the optical path bending portion, passes through the optical scanning lens 8 in the main scanning corresponding direction and exits from the lens 8 at the end of scanning, and the synchronous light is transmitted to the synchronous light detecting element 7. A refracting surface 13 is formed for converging light toward it. By making the power of this refracting surface appropriate, the correction lens 10 in the form of FIG. 1 can be omitted. Reference numeral 11 is a diaphragm member.

Further, as in the embodiment shown in FIG.
By forming a mask 14 having a "diaphragm effect" on the surface of the refracting surface 13 (claim 10), the diaphragm member 11 in the form of FIG. 4 can be omitted.

FIG. 6 shows only a characteristic part of one embodiment of the optical scanning lens according to claim 7. That is, the element holding portion 15 that holds the synchronous light detecting element 7 is integrally provided with the lens portion at the end portion of the optical scanning lens 8 on the scanning end side. FIG.
(A) is a view of the above-mentioned characteristic portion as viewed from a sub-scanning corresponding direction (direction orthogonal to the drawing of FIG. 1), and (b) is a view as seen from the optical axis direction of the optical scanning lens 8. The horizontal direction in FIG. 6B corresponds to the sub-scanning corresponding direction, and the element holding unit 15
Is formed so as to sandwich the synchronous light detecting element 7 from both sides in the sub-scanning corresponding direction at the end portion.

FIG. 7 shows a modified example, in which the element holding portion 16 is formed in the shape of a hook and the synchronous light detecting element 7 is fixedly adhered to the element holding portion 16 with a transparent adhesive. The left-right direction in the figure is the sub-scanning corresponding direction. The optical scanning lens has “optical axis symmetry in the sub-scanning corresponding direction”, and when the element holding portion is formed as shown in FIGS. 6 and 7, when the optical scanning lens and the element holding portion are molded by optical plastic. "Easy die cutting"
It is. In the embodiment shown in FIGS. 6 and 7, at the end of the optical scanning lens 8 on the synchronous light emission side, a refracting surface 13 for condensing the synchronous light toward the synchronous light detecting element and a mask 14 having a diaphragm effect. 2 is formed instead of the refracting surface.
The curved reflecting portion for collecting the synchronous light shown in (c) may be used, or the correction lens 10 of FIG. 1 may be held by a separate member between the optical scanning lens and the synchronous light detecting element 7. Alternatively, the mask 14 may be omitted, and the diaphragm member 11 or the “diaphragm member 11 and the correction lens 10” may be held by separate members.

FIG. 8 is a diagram for explaining one embodiment of the optical scanning device according to the sixteenth aspect. Only the features are schematically shown to simplify the drawing.

In this embodiment, the polygon mirror 5, which is an optical deflector, rotates counterclockwise, contrary to the embodiment shown in FIG. Therefore, the optical scanning start side (bottom side of the figure)
Is on the side opposite to the light source 1 with respect to the optical axis of the optical scanning lens 8'which is a scanning imaging lens, and the synchronization light D whose optical path is bent by the optical path bending portion 6'is transmitted through the optical scanning lens 8 '. In the figure, it passes from the lower side to the upper side (in the main scanning corresponding direction). The synchronous light detecting element 7 in the synchronous light detecting device is provided separately from the optical scanning lens 8 ′ and provided on the same control board 17 as the light source 1.

[0045]

As described above, according to the present invention, a novel optical scanning lens / synchronous light detecting device and optical scanning device can be provided.

The optical scanning lens according to any one of claims 1 to 10 comprises:
Since the optical path of the synchronizing light is bent in the main scanning corresponding direction by the optical path bending part and passes through the lens in the main scanning corresponding direction, the position where the synchronous light detecting element is arranged is lateral to the optical scanning lens in the main scanning corresponding direction. , The degree of freedom of layout of other optical components and the like increases.

In the optical scanning lens according to the third aspect, the lens portion and the optical path bending portion and the like can be easily integrally formed by molding, and the optical scanning lens according to the fifth aspect is easy to perform die cutting. Therefore, it is easy to mold.

In the optical scanning lens according to the sixth aspect, since it is not necessary to provide a reflective film on the reflective portion of the bent portion of the optical path, the cost can be reduced accordingly.

The optical scanning lens according to the seventh aspect does not require a dedicated holding portion for holding the synchronous light detecting element, so that the optical scanning device can be made compact and low cost.

In the optical scanning lens according to the present invention, the cost of the correction lens can be reduced by reducing the power of the correction lens for condensing the synchronization light toward the synchronization light detection element, or the synchronization can be achieved by omitting the correction lens. The cost of the photodetector can be reduced, and the optical scanning lens according to claim 10 can reduce the cost and size of the synchronous photodetector by omitting a dedicated diaphragm member.

The synchronous light detecting device according to the eleventh to thirteenth aspects effectively increases the layout of the optical scanning device. Claim 14-
The optical scanning device described in 16 has a high degree of freedom in layout,
Can be realized compactly. Further, in the optical scanning device according to the sixteenth aspect, since the light source and the synchronous light detecting element are arranged on the control board at the same position, the electric circuit system can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical scanning device according to claim 15;

FIG. 2 is a diagram for explaining three specific examples of a bent portion of an optical path. .

FIG. 3 is a diagram for explaining an optical scanning lens according to claims 4, 5, and 6.

FIG. 4 is a diagram for explaining an embodiment of a characteristic part of the optical scanning lens according to claim 9;

FIG. 5 is a diagram for explaining an embodiment of a characteristic part of the optical scanning lens according to claim 10;

FIG. 6 is a diagram for explaining one embodiment of the optical scanning lens according to claim 6;

FIG. 7 is a diagram for explaining another embodiment of the optical scanning lens according to claim 6;

FIG. 8 is a diagram for explaining one embodiment of the optical scanning device according to claim 16;

[Explanation of reference numerals] 1 light source 2 coupling lens 4 line image forming optical system 5 optical deflector 5A deflection reflection surface 6 optical path bending portion 7 synchronous light detection element 8 optical scanning lens 10 correction lens 11 diaphragm member

Claims (16)

[Claims] 1. An optical scanning device for deflecting a light beam by an optical deflector, condensing the deflected light beam as a light spot on a surface to be scanned by a scanning imaging lens, and optically scanning the surface to be scanned, scanning imaging An optical scanning lens that constitutes at least a part of the lens, wherein an optical path bending portion that reflects the synchronization light and bends the optical path is provided at an end portion on the scanning start side of the deflected light flux in the main scanning corresponding direction, The optical path bending portion is formed so as to bend the optical path so that the reflected synchronizing light passes through the lens in the main scanning corresponding direction. 2. The optical scanning lens according to claim 1, wherein the scanning imaging lens is composed of one optical scanning lens. 3. The optical scanning lens according to claim 1 or 2, wherein the optical scanning lens is formed of optical plastic. 4. The optical scanning lens according to claim 1, 2 or 3, wherein the bent portion of the optical path is refracted at the time of incidence on the bent portion of the optical path, and internal reflection occurs at a reflecting portion of the bent portion of the optical path, thereby synchronizing light is generated. An optical scanning lens having a curved optical path. 5. The optical scanning lens according to claim 4, wherein an incident surface for refracting the synchronous light incident on the optical path bending portion and a reflecting surface constituting the reflecting portion are provided on the scanning start side in the main scanning corresponding direction. An optical scanning lens characterized by forming a pointed wedge shape. 6. The optical scanning lens according to claim 4 or 5, wherein a reflecting surface forming a reflecting portion in the bent portion of the optical path is formed so as to totally reflect the synchronizing light. lens. 7. The optical scanning lens according to claim 1, 2 or 3 or 4 or 5 or 6, wherein an element holding portion for holding a synchronous light detecting element is integrally formed with the lens portion at the end portion on the scanning end side. An optical scanning lens having. 8. The optical scanning lens according to any one of claims 1 to 7, wherein the reflection portion of the optical path bending portion has a power for condensing the reflected synchronization light toward the synchronization light detection element. An optical scanning lens, which is formed into a curved surface as described above. 9. The optical scanning lens according to any one of claims 1 to 8, wherein the synchronization light whose optical path is bent by the optical path bending portion passes through the optical scanning lens in the main scanning corresponding direction and is emitted as light. An optical scanning lens, wherein a refracting surface for condensing the synchronous light toward the synchronous light detecting element is formed at an end portion on the scanning end side which is emitted from the scanning lens. 10. The optical scanning lens according to claim 9, wherein a mask having a diaphragm effect is formed on a refracting surface portion formed at an end portion on the scanning end side of the optical scanning lens. Optical scanning lens. 11. An optical scanning lens according to any one of claims 1 to 9, and the synchronizing light emitted from the optical scanning lens after passing through the optical scanning lens in a direction corresponding to main scanning. A synchronized light detecting device comprising: a synchronized light detecting element; a correction lens for focusing the synchronized light on the synchronized light detecting element; and a diaphragm member arranged between the correction lens and the synchronized light detecting element. . 12. The optical scanning lens according to claim 8 or 9, and a synchronous light detecting element for receiving the synchronous light emitted from the optical scanning lens after passing through the optical scanning lens in the main scanning corresponding direction. And a diaphragm member provided between the optical scanning lens and the synchronous light detecting element. 13. An optical scanning lens according to claim 10, and a synchronous light detecting element which receives the synchronous light emitted from the optical scanning lens by passing through the optical scanning lens in the main scanning corresponding direction. A synchronous light detection device having. 14. A light source, a coupling lens for coupling a light beam from the light source, an optical deflector for deflecting the coupled light beam, and a scanning connection for converging the deflected light beam as a light spot on a surface to be scanned. An image lens, and a synchronous light detection device for receiving and detecting, as synchronous light, a deflected light beam deflected by the optical deflector and directed toward an effective scanning area in order to synchronize optical scanning, The synchronous light detecting device according to claim 11 or 12 or 1.
3. The optical scanning device according to item 3, which is the synchronous light detection device. 15. The optical scanning device according to claim 14, wherein the optical deflector has a deflecting / reflecting surface, and has a function of deflecting a light beam reflected by the deflecting / reflecting surface at a constant angular velocity, a coupling lens and an optical deflector. And a line image forming optical system for forming a long line image in the main scanning corresponding direction in the vicinity of the deflection reflecting surface between the scanning image forming lens and the main scanning unit. It has a function of making the scanning speed of the light spot uniform in the corresponding direction, and a function of making the deflection reflection surface position and the scanned surface position substantially conjugate with each other in the sub-scanning corresponding direction. Optical scanning device. 16. The optical scanning device according to claim 14 or 15, wherein the optical scanning start side is on the side opposite to the light source with respect to the optical axis of the scanning imaging lens, and the synchronous light detecting element in the synchronous light detecting device optically scans. An optical scanning device characterized in that the optical scanning device is provided on the same control substrate as the light source, which is provided separately from the lens for use.