JP2023125122A - Reflector element, light detection device, and optical scanner - Google Patents

Abstract

To provide a reflector element that, even if its attitude is changed, can prevent a change in the incident position and the quantity of beams in a light receiving element.SOLUTION: A reflector element has first to sixth reflecting surfaces. When the inner product of the unit normal vectors of the first and second reflecting surfaces is defined as S1, the inner product of the unit normal vectors of the first and third reflecting surfaces as T1, the inner product of the unit normal vectors of the second and third reflecting surfaces as U1, the inner product of the unit normal vectors of the fourth and fifth reflecting surfaces as S2, the inner product of the unit normal vectors of the fourth and sixth reflecting surfaces as T2, and the inner product of the unit normal vectors of the fifth and sixth reflecting surfaces as U2, the following conditions are satisfied.SELECTED DRAWING: Figure 2

Description

The present invention relates to a reflective element, and is particularly suitable for an optical scanning device.

In recent years, optical scanning devices have been made smaller by providing compact writing start position detection means.
Patent Document 1 discloses an optical scanning device that can detect a writing start position by a light receiving element provided in a light source receiving a light beam that is deflected by a deflector and then reflected back to the light source by a plane mirror. Disclosed.

Japanese Patent Application Publication No. 5-323221

In the optical scanning device disclosed in Patent Document 1, when the attitude of the plane mirror changes due to the occurrence of disturbance, the incident position of the light beam on the light receiving element changes, resulting in a decrease in the detection accuracy of the writing start position.
Furthermore, in the optical scanning device disclosed in Patent Document 1, the light beam reflected by the plane mirror passes through the light emitting element in the light source, so the amount of light incident on the light receiving element is reduced.
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a reflective element that can suppress changes in the incident position of a light beam and the amount of light on a light-receiving element even if the posture changes.

なる条件を満たすことを特徴とする。 The reflective element according to the present invention has first, second, third, fourth, fifth, and sixth reflective surfaces, and has a unit normal vector of the first reflective surface and a unit normal vector of the second reflective surface. The value of the inner product with the unit normal vector is S1, the value of the inner product between the unit normal vector of the first reflecting surface and the unit normal vector of the third reflecting surface is T1, and the unit normal of the second reflecting surface The value of the inner product of the vector and the unit normal vector of the third reflecting surface is U1, the value of the inner product of the unit normal vector of the fourth reflecting surface and the unit normal vector of the fifth reflecting surface is S2, and the value of the inner product of the unit normal vector of the fourth reflecting surface and the unit normal vector of the fifth reflecting surface is S2. The value of the inner product of the unit normal vector of the fourth reflective surface and the unit normal vector of the sixth reflective surface is T2, and the unit normal vector of the fifth reflective surface and the unit normal vector of the sixth reflective surface are T2. When the value of the inner product of is U2,

It is characterized by satisfying the following conditions.

According to the present invention, it is possible to provide a reflective element that can suppress changes in the incident position of the light beam and the amount of light on the light receiving element even if the posture changes.

FIG. 1 is a cross-sectional view of a photodetection device according to a first embodiment. A front view, a sectional view, and an enlarged front view of the reflective element according to the first embodiment. FIG. 7 is a main scanning sectional view, an enlarged main scanning sectional view, and a front view of an aperture means of an optical scanning device according to a second embodiment. A front view, a sectional view, and an enlarged front view of a reflective element according to a second embodiment. A main scanning sectional view and an enlarged main scanning sectional view of an optical scanning device according to a third embodiment. FIG. 7 is a diagram showing temporal changes in the output of light received by a light receiving element in the optical scanning device according to the third embodiment. FIG. 7 is a main scanning sectional view and a front view of an aperture means of an optical scanning device according to a fourth embodiment. FIG. 1 is a sub-scanning sectional view of main parts of an image forming apparatus according to an embodiment.

Below, the reflective element according to this embodiment will be described in detail based on the accompanying drawings. Note that the drawings shown below may be drawn on a scale different from the actual scale in order to facilitate understanding of the present embodiment.

[First embodiment]
FIG. 1 shows a cross-sectional view of a photodetection device 500 according to the first embodiment. Note that the arrows in FIG. 1 indicate the traveling direction of the luminous flux.

The photodetector 500 includes a light receiving element 100 (first light receiving element), a light source 101, imaging means 102, 104, 105, and a reflective element 106 according to this embodiment.

A photodiode or the like is used as the light receiving element 100, and receives the light beam reflected by the reflective element 106 as described later. As shown in FIG. 1, the light receiving element 100 is provided on the opposite side of the reflecting element 106 with respect to the light source 101 along the optical path of the light beam.
A semiconductor laser or the like is used as the light source 101, and emits a light beam toward the reflective element 106.

The imaging means 102 has a finite power (refractive power) within a predetermined cross section (hereinafter referred to as a first cross section) parallel to the plane of the paper, that is, parallel to the optical axis, and has a finite power (refractive power) that is focused within the first cross section.
In this way, the light beam emitted from the light source 101 is focused within the first cross section in the vicinity of the primary imaging point 103.

The imaging means 104 and 105 have finite power within the first cross section, and refocus the light beam that has passed through the primary imaging point 103 within the first cross section.

The reflective element 106 according to this embodiment reflects the light beam that has passed through the imaging means 104 and 105 toward the light receiving element 100. The detailed configuration of the reflective element 106 according to this embodiment will be described later.

In the photodetecting device 500, with the above configuration, as shown in FIG. , is guided to the light receiving element 100.

Next, a detailed configuration of the reflective element 106 according to this embodiment provided in the photodetecting device 500 will be described.

2(a), (b), and (c) are respectively a front view of the reflective element 106 according to the present embodiment, a cross-sectional view taken along line AA in FIG. 2(a), and FIG. 2(a). ) shows a cross-sectional view taken along line BB in ).
Moreover, FIG. 2(d) shows an enlarged front view of the reflection section 106p that constitutes the reflection element 106 according to this embodiment.

As shown in FIG. 2(a), the reflective element 106 according to this embodiment has a plurality of reflective parts 106p arranged two-dimensionally.
Here, two axes that are perpendicular to each other within the two-dimensional plane are the Y-axis and the Z-axis, and an axis perpendicular to the two-dimensional plane is the X-axis.
Furthermore, in FIGS. 2A and 2D, solid lines indicate peaks and dotted lines indicate valleys.

Specifically, as shown in FIG. 2(d), the reflecting section 106p includes a first reflecting surface 1061, a second reflecting surface 1062, a third reflecting surface 1063, and a fourth reflecting surface 1064. , a fifth reflective surface 1065 and a sixth reflective surface 1066.
The reflecting portion 106p has a parallelogram shape in the YZ cross section.

Moreover, as shown in FIG. 2(d), the first reflective surface 1061 and the second reflective surface 1062 are in contact with each other so as to form a ridgeline 106a (first ridgeline).
Further, the second reflective surface 1062 and the third reflective surface 1063 are in contact with each other so as to form a ridgeline 106b (second ridgeline).
Further, the third reflective surface 1063 and the first reflective surface 1061 are in contact with each other so as to form a ridgeline 106c (third ridgeline).

Further, the third reflective surface 1063 and the sixth reflective surface 1066 are in contact with each other so as to form a ridgeline 106d.
Further, the fourth reflective surface 1064 and the fifth reflective surface 1065 are in contact with each other so as to form a ridgeline 106e (fourth ridgeline).
Further, the fifth reflective surface 1065 and the sixth reflective surface 1066 are in contact with each other so as to form a ridgeline 106f (fifth ridgeline).
Further, the sixth reflective surface 1066 and the fourth reflective surface 1064 are in contact with each other so as to form a ridgeline 106g (sixth ridgeline).

As shown in FIGS. 2(a) and 2(d), the first reflective surface 1061, the second reflective surface 1062, and the third reflective surface 1063 of the reflective element 106 reflect the incident light beam. It forms a concave space.
Similarly, the fourth reflective surface 1064, the fifth reflective surface 1065, and the sixth reflective surface 1066 also form concave spaces that reflect the incident light flux.

Here, in the reflective element 106 according to this embodiment, the angle between the ridge line 106a and the ridge line 106b is different from 90 degrees, and the angle between the ridge line 106c and the ridge line 106b is different from 90 degrees. In other words, the edges 106a and 106b are non-perpendicular to each other, and the edges 106c and 106b are non-perpendicular to each other.
Further, the angle between the edge line 106e and the edge line 106f is different from 90 degrees, and the angle between the edge line 106g and the edge line 106f is different from 90 degrees. In other words, the edge 106e and the edge 106f are non-perpendicular to each other, and the edge 106g and the edge 106f are non-perpendicular to each other.

Specifically, the ridgeline 106a and the ridgeline 106c each make an angle of 89.2 degrees with respect to the ridgeline 106b, and the ridgeline 106e and the ridgeline 106g each make an angle of 90.8 degrees with respect to the ridgeline 106f.
On the other hand, the angle between the ridge line 106a and the ridge line 106c is 90.0 degrees, and the angle between the ridge line 106e and the ridge line 106g is 90.0 degrees. In other words, the ridge line 106a and the ridge line 106c are perpendicular to each other, and the ridge line 106e and the ridge line 106g are perpendicular to each other.

Further, as shown in FIG. 2(d), the angle between the perpendicular 1061d parallel to the first reflective surface 1061 on the hypotenuse of the vertical isosceles triangle forming the first reflective surface 1061 and the ridgeline 106b is It is 88.8 degrees.
Further, the angle between the perpendicular 1064h parallel to the fourth reflective surface 1064 on the hypotenuse of the perpendicular isosceles triangle forming the fourth reflective surface 1064 and the ridgeline 106f is 91.2 degrees.

Here, the unit vectors of the normals of the first reflective surface 1061, the second reflective surface 1062, and the third reflective surface 1063 (hereinafter referred to as unit normal vectors) are n ₁₀₆₁ , n ₁₀₆₂ , and n ₁₀₆₃ Expressed as
Further, unit normal vectors of the fourth reflective surface 1064, the fifth reflective surface 1065, and the sixth reflective surface 1066 are expressed as n ₁₀₆₄ , n ₁₀₆₅ , and n ₁₀₆₆ , respectively.
At this time, n ₁₀₆₁ , n ₁₀₆₂ , n ₁₀₆₃ , n ₁₀₆₄ , n ₁₀₆₅ and n ₁₀₆₆ in the reflective element 106 according to the present embodiment are each expressed as shown in Table 1 below.

Therefore, when the inner product of the unit normal vector n ₁₀₆₁ of the first reflective surface 1061 and the unit normal vector n ₁₀₆₂ of the second reflective surface 1062 is expressed as S1, the inner product S1 is calculated by the following equation (1). You are asked to do so.
S1=n ₁₀₆₁・n ₁₀₆₂ =0.01482...(1)
Furthermore, when the inner product of the unit normal vector n ₁₀₆₁ of the first reflective surface 1061 and the unit normal vector n 1063 of the third reflective surface ₁₀₆₃ is expressed as T1, the inner product T1 is calculated by the following equation (2). You are asked to do so.
T1=n ₁₀₆₁・n ₁₀₆₃ =0.01482...(2)
Further, when the inner product of the unit normal vector n ₁₀₆₂ of the second reflective surface 1062 and the unit normal vector n 1063 of the third reflective surface ₁₀₆₃ is expressed as U1, the inner product U1 is calculated by the following equation (3). You are asked to do so.
U1=n ₁₀₆₂・n ₁₀₆₃ =0...(3)

Similarly, when the inner product of the unit normal vector n ₁₀₆₄ of the fourth reflective surface 1064 and the unit normal vector n ₁₀₆₅ of the fifth reflective surface 1065 is expressed as S2, the inner product S2 is expressed by the following equation (4). It is required as follows.
S2=n ₁₀₆₄・n ₁₀₆₅ =-0.01480...(4)
Furthermore, when the inner product of the unit normal vector n ₁₀₆₄ of the fourth reflective surface 1064 and the unit normal vector n 1066 of the sixth reflective surface ₁₀₆₆ is expressed as T2, the inner product T2 is calculated by the following equation (5). You are asked to do so.
T2=n ₁₀₆₄・n ₁₀₆₆ =-0.01480...(5)
Further, when the inner product of the unit normal vector n ₁₀₆₅ of the fifth reflective surface 1065 and the unit normal vector n 1066 of the sixth reflective surface ₁₀₆₆ is expressed as U2, the inner product U2 is calculated by the following equation (6). You are asked to do so.
U2=n ₁₀₆₅・n ₁₀₆₆ =0...(6)

ここで、｜Ｓ１｜、｜Ｓ２｜、｜Ｔ１｜、｜Ｔ２｜、｜Ｕ１｜及び｜Ｕ２｜はそれぞれ、内積Ｓ１、内積Ｓ２、内積Ｔ１、内積Ｔ２、内積Ｕ１及び内積Ｕ２の絶対値である。 That is, in the reflective element 106 according to this embodiment, the following conditional expressions (7), (8), (9), and (10) are satisfied.

Here, |S1|, |S2|, |T1|, |T2|, |U1|, and |U2| are the absolute values of inner product S1, inner product S2, inner product T1, inner product T2, inner product U1, and inner product U2, respectively. be.

If at least one of conditional expressions (7), (8), (9), and (10) exceeds the upper limit, the light beam reflected by the reflective element 106 will be at a large angle with respect to the traveling direction of the incident light beam. Emits light in the wrong direction. Therefore, it becomes difficult to make the light beam enter the light receiving element 100 efficiently.
Furthermore, if at least one of conditional expressions (9) and (10) becomes equal to or less than the lower limit value, the light beam reflected by the reflective element 106 will be emitted in a direction whose angle is too small with respect to the traveling direction of the incident light beam, so that the light receiving element It becomes difficult to make the light incident on 100 efficiently. Note that, by definition, conditional expressions (7) and (8) never fall below the lower limit.

Also, the angle between the normal of the first reflective surface 1061 and the normal of the second reflective surface 1062 is θ1 (degree), and the angle between the normal of the second reflective surface 1062 and the normal of the third reflective surface 1063 is The angle between the two lines is expressed as θ2 (degrees).
Further, the angle between the normal of the third reflective surface 1063 and the normal of the first reflective surface 1061 is θ3 (degrees), and the angle between the normal of the fourth reflective surface 1064 and the normal of the fifth reflective surface 1065 is The angle between the two lines is expressed as θ4 (degrees).
Also, the angle between the normal line of the fifth reflective surface 1065 and the normal line of the sixth reflective surface 1066 is θ5 (degrees), and the angle between the normal line of the sixth reflective surface 1066 and the normal line of the fourth reflective surface 1064 is The angle between the line and the line is expressed as θ6 (degrees).
At this time, θ1, θ2, θ3, θ4, θ5, and θ6 in the reflective element 106 according to the present embodiment are each expressed as shown in Table 2 below.

As shown in Table 2, in the reflective element 106 according to the present embodiment, θ1>θ2, θ3>θ2, θ4<θ5, and θ6<θ5 are satisfied.

In the photodetecting device 500, the light beam incident on the reflective element 106 according to the present embodiment is reflected once by each of the first to third reflective surfaces 1061 to 1063, or reflected once to the fourth to sixth reflective surfaces. It is reflected once by each of surfaces 1064-1066.
As shown in FIG. 1, the light beams reflected by the first to third reflecting surfaces 1061 to 1063 form an angle of +2.4° with respect to the incident light beam within the first cross section, and In the second cross section parallel to the optical axis and perpendicular to the first cross section, the light beam is emitted in the same direction but opposite to the incident light beam.
Furthermore, the light beams reflected by the fourth to sixth reflecting surfaces 1064 to 1066 form an angle of −2.4° with respect to the incident light beam within the first cross section, and the angle of -2.4° with respect to the incident light beam within the second cross section. It emits light in the same and opposite direction to the light beam.

That is, in the photodetecting device 500, the light flux incident on the reflective element 106 according to the present embodiment forms angles with substantially the same absolute value and different signs within the first cross section with respect to the traveling direction of the incident light flux. , are reflected in two opposite directions within the second cross section.
As a result, as shown in FIG. 1, the light beam reflected by the reflecting element 106 passes through the imaging means 105, 104, and 102 again, and is efficiently directed to the light receiving element 100 without entering the light source 101. Can be well guided.
In particular, even if the attitude of the reflective element 106 changes, at least one of the emitted light beams reflected by the reflective element 106 and traveling in two directions can be guided to the light receiving element 100.

As described above, in the photodetecting device 500, by using the reflective element 106 according to the present embodiment having the configuration shown above, even if the attitude of the reflective element 106 changes, the light flux can be directed to the light receiving element 100 with high precision. It can be returned.
As a result, the optical system in the photodetector 500 can be evaluated with high precision by measuring the amount of change in the light amount due to the light flux emitted from the light source 101 passing through the imaging means 102, 104, 105, etc. can.

Note that in the photodetecting device 500, in order to make the light beam reflected by the reflective element 106 enter the light receiving element 100 provided in a predetermined range close to the light source 101, the angle between the traveling directions of the incident light beam and the reflected light beam is is preferably 6 degrees or less.

[Second embodiment]
FIG. 3A shows a main scanning cross-sectional view of an optical scanning device 600 according to the second embodiment.
Further, FIG. 3(b) shows a front view of the aperture means 208 included in the optical scanning device 600 according to the second embodiment.
Further, FIG. 3(c) shows an enlarged main scanning cross-sectional view in the vicinity of the deflection element 210 of the optical scanning device 600 according to the second embodiment.
Note that the arrows in FIGS. 3(a) and 3(c) indicate the traveling direction of the light beam.

In the following description, the main scanning direction is a direction perpendicular to the rotation axis of the deflector and the optical axis of the optical system. The sub-scanning direction is a direction parallel to the rotation axis of the deflector. The main scanning section is a section perpendicular to the sub-scanning direction. The sub-scanning section is a section perpendicular to the main scanning direction.
Therefore, in the following description, it should be noted that the main scanning direction and the sub-scanning cross section are different between the incident optical system and the scanning optical system.

The optical scanning device 600 includes a light source 201, a first aperture stop 202, an anamorphic collimator lens 203, and a second aperture stop 204.
The optical scanning device 600 also includes a deflector 205, a first fθ lens 206, a second fθ lens 207, and an aperture means 208.
The optical scanning device 600 also includes a reflection element 209, a deflection element 210, an imaging means 211, and a light receiving element 212 (first light receiving element) according to this embodiment.

A semiconductor laser or the like is used as the light source 201, and emits a light beam toward the deflector 205.
The first aperture stop 202 limits the diameter of the light beam emitted from the light source 201 within the sub-scanning cross section.

The anamorphic collimator lens 203 converts the light beam that has passed through the first aperture stop 202 into a parallel light beam within the main scanning section. Note that the term "parallel light beam" as used herein includes not only strictly parallel light beams but also substantially parallel light beams such as weakly diverging light beams and weakly converging light beams.
Further, the anamorphic collimator lens 203 has a finite power (refracting power) within the sub-scanning cross section, and condenses the light beam that has passed through the first aperture stop 202 in the sub-scanning direction.

The second aperture stop 204 limits the diameter of the light beam that has passed through the anamorphic collimator lens 203 within the main scanning cross section.

In this way, the light beam emitted from the light source 201 is focused only in the sub-scanning direction near the deflection surface 205a of the deflector 205, and is imaged as a long line image in the main-scanning direction.
Note that in the optical scanning device 600, an input optical system 75 is configured by the first aperture stop 202, the anamorphic collimator lens 203, and the second aperture stop 204.

The deflector 205 deflects and scans the incident light beam by being rotated by a drive means such as a motor (not shown). Note that the deflector 205 is composed of, for example, a polygon mirror.

The first fθ lens 206 (first imaging optical element) and the second fθ lens 207 are anamorphic imaging lenses that have different powers in the main scanning section and in the sub scanning section.
In the optical scanning device 600, the first fθ lens 206 and the second fθ lens 207 constitute a scanning optical system (imaging optical system) 85.
Note that the refractive power of the second fθ lens 207 within the sub-scanning section is stronger than the refractive power of the first fθ lens 206 within the sub-scanning section, that is, the strongest in the scanning optical system 85.

In this way, the light beam deflected by the deflector 205 is focused (guided) onto a surface to be scanned (not shown) and scanned by the scanning optical system 85.

The aperture means 208 detects the inside of the main scanning section and the sub-scanning section of the light beam that has been deflected in a predetermined direction (first direction) by the deflector 205 and has passed through the first fθ lens 206 and the second fθ lens 207. limits the diameter of the luminous flux within.
Specifically, as shown in FIG. 3(b), the aperture means 208 has a first aperture 2081 through which the light flux that has passed through the first fθ lens 206 and the second fθ lens 207 passes. has been done.
Note that, as shown in FIG. 3(b), the aperture means 208 allows the light beam reflected by the reflective element 209 according to this embodiment to pass therethrough, thereby changing the diameter of the light beam in the main scanning section and the sub-scanning section. A second opening 2082 is also formed that is configured to limit the.

The reflective element 209 according to this embodiment reflects the light beam that has passed through the aperture means 208 toward the deflector 205 . The detailed configuration of the reflective element 209 according to this embodiment will be described later.

As shown in FIG. 3C, the deflection element 210 changes the traveling direction of the light beam that has passed through the second fθ lens 207 again after being reflected by the reflection element 209 according to the present embodiment (deflection). ) means.
The deflection element 210 is constituted by an optical element having, for example, a wedge shape, in other words, the incident surface and the exit surface are non-parallel to each other in the main scanning cross section.
Further, the deflection element 210 is provided between the deflector 205 and the surface to be scanned in the optical axis direction of the scanning optical system 85. Note that the apex angle of the deflection element 210 is set to 10°.

The imaging means 211 is a means for condensing the light beam, which has passed through the deflection element 210 and the first fθ lens 206 and has been deflected again by the deflector 205, near the light receiving element 212, and is composed of, for example, a convex lens. .
The light-receiving element 212 is a light-receiving element that receives the light beam that has passed through the imaging means 211, and is composed of, for example, a photodiode.

That is, in the optical scanning device 600, the light beam reflected by the reflective element 209 according to this embodiment can be made to enter the light receiving element 212 via the deflector 205.
Further, in the optical scanning device 600, the light receiving element 212 is provided between the deflector 205 and the surface to be scanned in the optical axis direction of the scanning optical system 85.

4(a), (b), and (c) are respectively a front view of the reflective element 209 according to the present embodiment, a cross-sectional view taken along line AA in FIG. 4(a), and FIG. 4(a). ) shows a cross-sectional view taken along line BB in ).
Moreover, FIG. 4(d) shows an enlarged front view of the reflection section 209p that constitutes the reflection element 209 according to this embodiment.

As shown in FIG. 4(a), the reflective element 209 according to this embodiment has a plurality of reflective parts 209p arranged two-dimensionally.
Here, two axes that are perpendicular to each other within the two-dimensional plane are the Y-axis and the Z-axis, and an axis perpendicular to the two-dimensional plane is the X-axis.
In FIGS. 4A and 4D, solid lines indicate peaks and dotted lines indicate valleys.

Specifically, as shown in FIG. 4(d), the reflecting section 209p includes a first reflecting surface 2091, a second reflecting surface 2092, a third reflecting surface 2093, and a fourth reflecting surface 2094. , a fifth reflective surface 2095 and a sixth reflective surface 2096.
The reflecting portion 209p has a parallelogram shape in the YZ cross section.

Moreover, as shown in FIG. 4(d), the first reflective surface 2091 and the second reflective surface 2092 are in contact with each other so as to form a ridgeline 209a (first ridgeline).
Further, the second reflective surface 2092 and the third reflective surface 2093 are in contact with each other so as to form a ridgeline 209b (second ridgeline).
Further, the third reflective surface 2093 and the first reflective surface 2091 are in contact with each other so as to form a ridgeline 209c (third ridgeline).

Furthermore, the third reflective surface 2093 and the sixth reflective surface 2096 are in contact with each other so as to form a ridgeline 209d.
Further, the fourth reflective surface 2094 and the fifth reflective surface 2095 are in contact with each other so as to form a ridgeline 209e (fourth ridgeline).
Furthermore, the fifth reflective surface 2095 and the sixth reflective surface 2096 are in contact with each other so as to form a ridgeline 209f (fifth ridgeline).
Further, the sixth reflective surface 2096 and the fourth reflective surface 2094 are in contact with each other so as to form a ridgeline 209g (sixth ridgeline).

As shown in FIG. 4(d), the first reflective surface 2091, the second reflective surface 2092, and the third reflective surface 2093 form a concave space that reflects the incident light flux. There is.
Similarly, the fourth reflective surface 2094, the fifth reflective surface 2095, and the sixth reflective surface 2096 form a concave space that reflects the incident light flux.

Here, in the reflective element 209 according to this embodiment, the angle between the ridgeline 209a and the ridgeline 209c is different from 90 degrees, and the angle between the ridgeline 209e and the ridgeline 209g is different from 90 degrees.
Specifically, the angle between the ridgeline 209a and the ridgeline 209c is 91.7 degrees, and the angle between the ridgeline 209e and the ridgeline 209g is 88.3 degrees.
On the other hand, the ridgelines 209a and 209c are each at an angle of 90.0 degrees with respect to the ridgeline 209b, and the ridgelines 209e and 209g are each at an angle of 90.0 degrees with respect to the ridgeline 209f.

Further, as shown in FIG. 4(d), the angle between the perpendicular 2091d parallel to the first reflective surface 2091 on the hypotenuse of the isosceles triangle forming the first reflective surface 2091 and the ridgeline 209b is 90 .0 degrees.
Further, the angle between the perpendicular 2094h parallel to the fourth reflective surface 2094 on the hypotenuse of the isosceles triangle forming the fourth reflective surface 2094 and the ridgeline 209f is 90.0 degrees.

Here, the unit normal vectors of the first reflective surface 2091, the second reflective surface 2092, and the third reflective surface 2093 are expressed as _n2091 , _n2092 , and _n2093 , respectively.
Further, unit normal vectors of the fourth reflective surface 2094, the fifth reflective surface 2095, and the sixth reflective surface 2096 are expressed as _n2094 , _n2095 , and _n2096 , respectively.
At this time, n ₂₀₉₁ , n ₂₀₉₂ , n ₂₀₉₃ , n ₂₀₉₄ , n ₂₀₉₅ and n ₂₀₉₆ in the reflective element 209 according to the present embodiment are each expressed as shown in Table 3 below.

Therefore, when the inner product of the unit normal vector n ₂₀₉₁ of the first reflecting surface 2091 and the unit normal vector n ₂₀₉₂ of the second reflecting surface 2092 is expressed as S1, the inner product S1 is calculated by the following equation (11). You are asked to do so.
S1=n ₂₀₉₁・n ₂₀₉₂ =0...(11)
Furthermore, when the inner product of the unit normal vector n ₂₀₉₁ of the first reflecting surface 2091 and the unit normal vector n 2093 of the third reflecting surface ₂₀₉₃ is expressed as T1, the inner product T1 is calculated by the following equation (12). You are asked to do so.
T1=n ₂₀₉₁・n ₂₀₉₃ =0...(12)
Furthermore, when the inner product of the unit normal vector n ₂₀₉₂ of the second reflective surface 2092 and the unit normal vector n 2093 of the third reflective surface ₂₀₉₃ is expressed as U1, the inner product U1 is calculated by the following equation (13). You are asked to do so.
U1=n ₂₀₉₂・n ₂₀₉₃ =-0.02938...(13)

Similarly, when the inner product of the unit normal vector n ₂₀₉₄ of the fourth reflective surface 2094 and the unit normal vector n 2095 of the fifth reflective surface ₂₀₉₅ is expressed as S2, the inner product S2 is expressed by the following equation (14). It is required as follows.
S2=n ₂₀₉₄・n ₂₀₉₅ =0...(14)
Furthermore, when the inner product of the unit normal vector n ₂₀₉₄ of the fourth reflective surface 2094 and the unit normal vector n 2096 of the sixth reflective surface ₂₀₉₆ is expressed as T2, the inner product T2 is calculated by the following equation (15). You are asked to do so.
T2=n ₂₀₉₄・n ₂₀₉₆ =0...(15)
Furthermore, when the inner product of the unit normal vector n ₂₀₉₅ of the fifth reflective surface 2095 and the unit normal vector n 2096 of the sixth reflective surface ₂₀₉₆ is expressed as U2, the inner product U2 is calculated by the following equation (16). You are asked to do so.
U2=n ₂₀₉₅・n ₂₀₉₆ =0.02938...(16)

Therefore, in the reflective element 209 according to this embodiment, the above conditional expressions (7), (8), (9), and (10) are satisfied.

Also, the angle between the normal line of the first reflective surface 2091 and the normal line of the second reflective surface 2092 is θ1 (degree), and the angle between the normal line of the second reflective surface 2092 and the normal line of the third reflective surface 2093 is The angle between the two lines is expressed as θ2 (degrees).
Also, the angle between the normal of the third reflective surface 2093 and the normal of the first reflective surface 2091 is θ3 (degrees), and the angle between the normal of the fourth reflective surface 2094 and the normal of the fifth reflective surface 2095 is The angle between the two lines is expressed as θ4 (degrees).
Also, the angle between the normal line of the fifth reflective surface 2095 and the normal line of the sixth reflective surface 2096 is θ5 (degrees), and the angle between the normal line of the sixth reflective surface 2096 and the normal line of the fourth reflective surface 2094 is The angle between the line and the line is expressed as θ6 (degrees).
At this time, θ1, θ2, θ3, θ4, θ5, and θ6 in the reflective element 209 according to the present embodiment are each expressed as shown in Table 4 below.

As shown in Table 4, in the reflective element 209 according to this embodiment, θ1>θ2, θ3>θ2, θ4<θ5, and θ6<θ5 are satisfied.

In the optical scanning device 600, the light beam incident on the reflective element 209 according to the present embodiment is reflected once by each of the first to third reflective surfaces 2091 to 2093, or reflected once to the fourth to sixth reflective surfaces. It is reflected once by each of surfaces 2094-2096.
The light beams reflected by the first to third reflecting surfaces 2091 to 2093 make an angle of +2.4° with respect to the incident light beam in the main scanning section, and with respect to the incident light beam in the sub-scanning section. and emit light in the opposite direction of the same direction.
Furthermore, the light beams reflected by the fourth to sixth reflecting surfaces 2094 to 2096 form an angle of -2.4° with respect to the incident light beam in the main scanning section, and form an angle of -2.4° with respect to the incident light beam in the sub-scanning section. The light is emitted in the same direction, but in the opposite direction.

That is, in the optical scanning device 600, the light beams incident on the reflective element 209 according to the present embodiment form angles with substantially the same absolute value and different signs in the main scanning cross section with respect to the traveling direction of the incident light beam. In the sub-scanning section, the light is reflected in two opposite directions.

In the optical scanning device 600, as described above, there is a first opening 2081 through which the light flux incident on the reflective element 209 passes, and a second opening through which one of the light fluxes reflected in two directions by the reflective element 209 passes. 2082 is provided.
That is, the other of the light beams reflected in two directions by the reflecting element 209 is blocked by the light blocking portion of the aperture means 208.

As a result, as shown in FIG. 3(a), one of the light beams reflected in two directions by the reflective element 209 according to the present embodiment is transmitted to the second fθ lens 207, the deflection element 210, and the first By passing through the fθ lens 206, the light enters the deflector 205 again.
The light beam deflected again by the deflector 205 passes through the imaging means 211 and enters the light receiving element 212 .

In this manner, in the optical scanning device 600, the light beam reflected by the reflective element 209 according to the present embodiment can be efficiently guided to the light receiving element 212 without entering the light source 201.
In particular, even if the posture of the reflective element 209 changes, the light beam reflected by the reflective element 209 can be guided to the light receiving element 212.

As described above, in the optical scanning device 600, by using the reflective element 209 according to this embodiment having the configuration shown above, even if the attitude of the reflective element 209 changes, the light beam can be directed to the light receiving element 212 with high precision. It can be returned.
As a result, the optical system in the optical scanning device 600 can be evaluated with high precision by measuring the amount of change in the light amount due to the light flux emitted from the light source 201 passing through the incident optical system 75 and the scanning optical system 85. can.

[Third embodiment]
FIGS. 5A and 5B show a main scanning sectional view of an optical scanning device 700 according to the third embodiment and an enlarged main scanning sectional view in the vicinity of the first fθ lens 306.
Further, FIG. 5C shows an enlarged main scanning cross-sectional view near the end of the first fθ lens 306 provided in the optical scanning device 700 according to the third embodiment.

Note that the optical scanning device 700 has the same configuration as the optical scanning device 600, except that the first fθ lens 306 is provided in place of the first fθ lens 206 and the deflection element 210, so the same components are used. are given the same reference numerals and the explanation will be omitted.
Moreover, the arrows in FIGS. 5(a) and 5(b) indicate the traveling direction of the luminous flux.

In the optical scanning device 700, the first fθ lens 306 (first imaging optical element) has the function of guiding the light beam deflected by the deflector 205 onto the scanned surface 313, and the function of guiding the light beam deflected by the deflector 205 onto the scanned surface 313. After that, it has a function of changing the traveling direction of the light beam that has passed through the second fθ lens 207 again.

Specifically, the first fθ lens 306 is an anamorphic imaging lens that has different power in the main scanning section and in the sub-scanning section in the region through which the light beam scanning the scanned surface 313 passes.
The light beam deflected by the deflector 205 is focused (guided) onto a scanned surface 313, which is a photosensitive drum, for example, and the scanned surface 313 is scanned in the main scanning direction by the deflector 205.

Further, the first fθ lens 306 has a deflection portion 3061 in a region different from the region through which the light beam scanning the scanned surface 313 passes, that is, at one end in the main scanning direction.
After being deflected by the reflection element 209, the light beam that passes through the second fθ lens 207 again is deflected by the deflection unit 3061.
That is, the first fθ lens 306 is an imaging optical element in which a deflection element that deflects the light beam from the reflection element 209 is integrated.

In the optical scanning device 700, a scanning optical system 85 is configured by the first fθ lens 306 and the second fθ lens 207.
The refractive power of the second f.theta. lens 207 within the sub-scanning section is stronger than the refractive power of the first f.theta. lens 306 within the sub-scanning section, that is, the strongest in the scanning optical system 85.
Further, the imaging means 211 and the light receiving element 212 constitute a synchronization detection optical system 95.

Further, in the optical scanning device 700, the deflection unit 3061 of the first fθ lens 306 converts the light flux from the reflection element 209 into the light beam of the scanning optical system 85 within the main scanning section. It has a shape that allows it to enter the deflector 205 by deflecting it toward the axis.
Thereby, the light beam can be guided to the light receiving element 212 arranged between the light source 201 and the reflective element 209 in the main scanning section.

Further, as shown in FIG. 5(c), the deflecting portion 3061 of the first fθ lens 306 has a shape in which the wall thickness becomes thinner from the inner end toward the outer end in the main scanning direction. There is.
Of the optical surface of the first fθ lens 306 on the deflector 205 side, the portion corresponding to the deflection section 3061 is divided into the remaining portion (i.e., the portion contributing to image formation) in the main scanning section including the optical axis. ) is inclined by an angle φ with respect to the inclination at the end on the deflecting portion 3061 side.
Note that in the optical scanning device 700, the angle φ is set to 17°.

Further, since the reflective element 209 is arranged between the deflector 205 and the scanned surface 313 in the optical axis direction, by giving a convex power to the deflecting part 3061, the light beam is directed to the light receiving element 212 with higher precision. It becomes possible to guide light.

FIG. 6 shows a temporal change in the output I of light received by the light receiving element 212 in the optical scanning device 700.

In the optical scanning device 700, the reference position of the rotational phase of the deflector 205 can be determined from the output 801 by synchronization detection by the synchronization detection optical system 95 composed of the imaging means 211 and the light receiving element 212. Time 0 (microsecond) can be determined.
Specifically, the light beam deflected by the deflector 205 in a predetermined direction (second direction), that is, toward the light receiving element 212, enters the light receiving element 212, so that the output 801 is detected at the light receiving element 212. .
By setting the threshold P as shown in FIG. 6, the reference time 0 (microsecond) can be determined from the time corresponding to the threshold P in the output 801.

Further, at a predetermined time, a light beam deflected by the deflector 205 in another predetermined direction (first direction), that is, toward the reflective element 209, enters the reflective element 209.
The light beam reflected by the reflective element 209 is deflected again by the deflector 205 as described above and returns to the light receiving element 212, whereby the output 802 is detected at the light receiving element 212.
At this time, t (microseconds) can be determined from the time corresponding to the threshold value P in the output 802.

Thereby, the position of the aperture means 208 can be determined from the determined time t (microseconds) and the scanning speed V (mm/s) by the deflector 205.

That is, in the optical scanning device 700, a control unit (not shown) operates based on the timing at which the synchronous detection optical system 95 receives the luminous flux (i.e., time 0) and the timing at which the light receiving element 212 receives the luminous flux (i.e., time t). can calculate the time between those light receptions.
This makes it possible to detect changes in the imaging position of the scanning optical system 85 caused by, for example, temperature rise.
The light emission timing of the light source 201 can then be adjusted based on the calculated time.

As described above, in the optical scanning device 700, by using the reflective element 209 according to this embodiment having the configuration shown above, even if the attitude of the reflective element 209 changes, the light beam can be directed to the light receiving element 212 with high precision. It can be returned.
Thereby, the scanning timing on the scanned surface 313 can be adjusted with high accuracy, and it becomes possible to perform highly accurate printing.

[Fourth embodiment]
FIG. 7A shows a main scanning cross-sectional view of an optical scanning device 800 according to the fourth embodiment.
Moreover, FIG. 7(b) shows a front view of the aperture means 308 included in the optical scanning device 800 according to the fourth embodiment.

Note that in the optical scanning device 800, the first fθ lens 206 provided in the optical scanning device 600 is provided in place of the first fθ lens 306 provided in the optical scanning device 700.
Further, in the optical scanning device 800, an aperture means 308 is provided in place of the aperture means 208 provided in the optical scanning device 700.
Further, in the optical scanning device 800, an imaging means 213 and a light receiving element 214 are newly provided, and the other configurations of the optical scanning device 800 are the same as the optical scanning device 700, so the same members have the same structure. Numbers are given and explanations are omitted.
Moreover, the arrow in FIG. 7(a) indicates the traveling direction of the luminous flux.

The imaging means 213 is a means for condensing the light beam, which has been reflected by the reflection element 209 and then deflected again by the deflector 205, near the light receiving element 214, and is composed of, for example, a convex lens.
The light-receiving element 214 (first light-receiving element) is a light-receiving element that receives the light beam that has passed through the imaging means 213, and is configured of, for example, a photodiode.

As shown in FIG. 7A, the light receiving element 212 is provided between the deflector 205 and the surface to be scanned 313 in the optical axis direction of the scanning optical system 85.
Further, as shown in FIG. 7A, the light receiving element 212 and the light receiving element 214 are provided on opposite sides to each other with respect to the sub-scanning section including the optical axis of the scanning optical system 85.

The aperture means 308 detects the inside of the main scanning section and the sub-scanning section of the light beam that has been deflected in a predetermined direction (first direction) by the deflector 205 and has passed through the first fθ lens 206 and the second fθ lens 207. limits the diameter of the luminous flux within.
Specifically, the aperture means 308 is formed with a first aperture 3081 through which the light flux that has passed through the first fθ lens 206 and the second fθ lens 207 passes, as shown in FIG. 7(b). has been done.
As shown in FIG. 7(b), the aperture means 308 allows the light beam reflected by the reflective element 209 according to the present embodiment to pass therethrough, thereby changing the diameter of the light beam in the main scanning section and the sub-scanning section. A second opening 3082 is also formed that is configured to limit the.

As shown in FIG. 6 in the third embodiment described above, the intensity of the output 801 and the intensity of the output 802 of the light received by the light receiving element 212 are different from each other.
Specifically, the intensity of the output 801 resulting from receiving the light beam deflected by the deflector 205 toward the light receiving element 212 is deflected by the deflector 205 toward the reflective element 209 and is reflected by the reflective element 209. The intensity of the output 802 is greater than the intensity of the output 802 resulting from receiving the light beam.

At this time, depending on the dynamic range of the light receiving element 212, it may be difficult to detect both the output 801 and the output 802, which have different intensities.
Therefore, in this embodiment, such a problem is solved by newly providing the light receiving element 214.

As described above, the light beams reflected by the first to third reflecting surfaces 2091 to 2093 of the reflective element 209 form an angle of +2.4° with respect to the incident light beam in the main scanning section, and in the sub-scanning section. Inside, the light beam is emitted in the same direction as the incident light beam, but in the opposite direction.
Furthermore, the light beams reflected by the fourth to sixth reflecting surfaces 2094 to 2096 of the reflecting element 209 form an angle of -2.4° with respect to the incident light beam in the main scanning section, and in the sub-scanning section. is emitted in the same and opposite direction to the incident light beam.

That is, in the optical scanning device 800, the light beams incident on the reflective element 209 according to the present embodiment form angles with substantially the same absolute value and different signs in the main scanning cross section with respect to the traveling direction of the incident light beam. Within the sub-scanning section, the light is reflected in two opposite directions.

In the optical scanning device 800, as described above, there is a first opening 3081 through which the light beam incident on the reflective element 209 passes, and a second opening through which one of the light beams reflected in two directions by the reflective element 209 passes. 3082 is provided.
That is, the other of the light beams reflected in two directions by the reflecting element 209 is blocked by the light blocking portion of the aperture means 308.

Here, in the opening means 208, as shown in FIG. 3(b), a second opening 2082 is formed on the left side of the first opening 2081 when viewed from the front.
On the other hand, in the opening means 308, as shown in FIG. 7(b), a second opening 3082 is formed on the right side of the first opening 3081 when viewed from the front.

That is, by using the aperture means 308 in the optical scanning device 800, among the light beams reflected in two directions by the reflecting element 209, the light beam blocked by the aperture means 208 passes through, while the light beam that has passed through the aperture means 208 passes through. is shielded from light.
This eliminates the need for the optical scanning device 800 to include the deflection element 210 that was provided in the optical scanning device 600.

In the optical scanning device 800, with the above-described configuration, the reference position of the rotational phase of the deflector 205 is determined from the output 801 by synchronization detection by the synchronization detection optical system 95 composed of the imaging means 211 and the light receiving element 212. It is possible to determine the reference time 0 (microsecond).
Specifically, a light beam deflected by a predetermined deflection surface 205a of the deflector 205 in a predetermined direction (second direction), that is, toward the light receiving element 212 (second light receiving element), enters the light receiving element 212. As a result, the output 801 is detected by the light receiving element 212.
By setting the threshold P as shown in FIG. 6, the reference time 0 (microsecond) can be determined from the time corresponding to the threshold P in the output 801.

Further, at a predetermined time, a light beam deflected by a predetermined deflection surface 205a of the deflector 205 in another predetermined direction (first direction), that is, toward the reflective element 209, enters the reflective element 209.
The light beam reflected by the reflection element 209 enters a deflection surface 205a of the deflector 205 that is different from the predetermined deflection surface 205a, is deflected again, and then enters the light receiving element 214, so that it is output from the light receiving element 214. 802 is detected.
At this time, t (microseconds) can be determined from the time corresponding to the threshold value P in the output 802.

Thereby, the position of the aperture means 308 can be determined from the determined time t (microseconds) and the scanning speed V (mm/s) by the deflector 205.

That is, in the optical scanning device 800, a control unit (not shown) controls the timing based on the timing at which the light receiving element 212 receives the light beam (i.e., time 0) and the timing at which the light receiving element 214 receives the light beam (i.e., time t). The time between light reception can be calculated.
This makes it possible to detect changes in the imaging position of the scanning optical system 85 caused by, for example, temperature rise.
The light emission timing of the light source 201 can then be adjusted based on the calculated time.

As described above, in the optical scanning device 800, by using the reflective element 209 according to this embodiment having the configuration shown above, even if the attitude of the reflective element 209 changes, the light beam can be directed to the light receiving element 214 with high precision. It can be returned.
Thereby, the scanning timing on the scanned surface 313 can be adjusted with high accuracy, and it becomes possible to perform highly accurate printing.

Although preferred embodiments have been described above, the invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof.

For example, in the apparatuses according to the first to fourth embodiments, a reflective element that reflects a luminous flux on the surface is used, but the same effect is obtained by using a reflective element that totally reflects the luminous flux on the inner surface. It will be done.
When such an internal reflection type element is used, the element may be made to protrude in a convex shape by the first to third reflective surfaces, and the element may be made to protrude in a convex shape by the fourth to sixth reflective surfaces. The same effect can be obtained.

Further, in the reflective element according to this embodiment, the shape and relative arrangement of each reflective surface are not limited as long as the above angular relationship is satisfied.
Further, although the optical scanning devices according to the second to fourth embodiments use an anamorphic collimator lens, the same effect is obtained by using an optical system that combines a collimator lens and a cylindrical lens. .

[Monochrome image forming device]
FIG. 8A shows a main part sub-scanning sectional view of an image forming apparatus 1204 including an optical scanning device according to any of the second to fourth embodiments.

As shown in FIG. 8A, code data Dc is input to the image forming apparatus 1204 from an external device 1217 such as a personal computer.
The input code data Dc is then converted into image data (dot data) Di by a printer controller 1211 within the apparatus.

Next, the converted image data Di is input to an optical scanning unit 1200, which is an optical scanning device according to any of the second to fourth embodiments.
A light beam 1203 modulated according to the image data Di is emitted from the optical scanning unit 1200, and the photosensitive surface of the photosensitive drum 1201 is scanned by the light beam 1203 in the main scanning direction.

A photosensitive drum 1201 serving as an electrostatic latent image carrier (photosensitive member) is rotated clockwise by a motor 1215 as shown in FIG. 8(a).
With this rotation, the photosensitive surface of the photosensitive drum 1201 moves with respect to the light beam 1203 in the sub-scanning direction orthogonal to the main scanning direction.

Further, above the photosensitive drum 1201, a charging roller 1202 that uniformly charges the surface of the photosensitive drum 1201 is provided so as to come into contact with the surface.
Then, the surface of the photosensitive drum 1201 charged by the charging roller 1202 is irradiated with a light beam 1203 scanned by the optical scanning unit 1200.

As described above, the light beam 1203 is modulated based on the image data Di, and by irradiating the light beam 1203, an electrostatic latent image is formed on the surface of the photosensitive drum 1201.
The formed electrostatic latent image is developed as a toner image by a developing device 1207 that is disposed so as to come into contact with the photosensitive drum 1201 further downstream in the rotational direction than the irradiation position of the light beam 1203 on the photosensitive drum 1201. be done.

Next, the toner image developed by the developing device 1207 is transferred onto a paper 1212 as a transfer material by a transfer roller 1208 disposed below the photosensitive drum 1201 so as to face the photosensitive drum 1201.
Although the paper 1212 is stored in a paper cassette 1209 in front of the photosensitive drum 1201 (on the right side in FIG. 8A), it can also be fed manually.
A paper feed roller 1210 is disposed at the end of the paper cassette 1209, and the paper 1212 in the paper cassette 1209 is fed into the conveyance path.

The paper 1212 onto which the unfixed toner image has been transferred as described above is conveyed to a fixing device located behind the photosensitive drum 1201 (on the left side in FIG. 8A).
The fixing device includes a fixing roller 1213 having an internal fixing heater (not shown) and a pressure roller 1214 disposed so as to be in pressure contact with the fixing roller 1213.
Then, the unfixed toner image on the paper 1212 is fixed by heating the paper 1212 conveyed from the transfer roller 1208 while being pressed by the pressure contact portion of the fixing roller 1213 and the pressure roller 1214.

Further, a paper discharge roller 1216 is disposed behind the fixing roller 1213, and the fixed paper 1212 is discharged to the outside of the image forming apparatus 1204.

Although not shown in FIG. 8A, in addition to the data conversion described above, the printer controller 1211 also controls each member in the image forming apparatus 1204 such as the motor 1215, the polygon motor in the optical scanning unit 1200, etc. It also controls.

[Color image forming device]
FIG. 8B shows a main part sub-scanning sectional view of an image forming apparatus 90 including an optical scanning device according to any of the second to fourth embodiments.

The image forming apparatus 90 is a tandem type color image forming apparatus in which four optical scanning devices record image information on the surface of a photosensitive drum, which is an image carrier, in parallel.
The image forming apparatus 90 includes optical scanning devices 11, 12, 13, and 14 having the same configuration as the optical scanning device according to any of the second to fourth embodiments, and photosensitive drums 23, 24, 25 as image carriers. and 26.
The image forming apparatus 90 also includes developing devices 15, 16, 17, and 18, a conveyor belt 91, a printer controller 93, and a fixing device 94.

As shown in FIG. 8B, each color signal of R (red), G (green), and B (blue) is input to the image forming apparatus 90 from an external device 92 such as a personal computer.
The input color signals are then converted into image data (dot data) of C (cyan), M (magenta), Y (yellow), and K (black) by a printer controller 93 within the apparatus.

Next, the converted image data is input to optical scanning devices 11, 12, 13 and 14, respectively.
Light beams 19, 20, 21 and 22 modulated according to each image data are emitted from the optical scanning devices 11, 12, 13 and 14. , 24, 25 and 26 are scanned in the main scanning direction.

A charging roller (not shown) that uniformly charges the surface of each of the photosensitive drums 23, 24, 25, and 26 is provided so as to come into contact with the surface.
The surfaces of the photosensitive drums 23, 24, 25 and 26 charged by the charging roller are irradiated with light beams 19, 20, 21 and 22 by the optical scanning devices 11, 12, 13 and 14. .

As described above, the light beams 19, 20, 21, and 22 are modulated based on the image data of each color, and the photosensitive drums 23, 24, 25, and 26 are irradiated with the light beams 19, 20, 21, and 22. An electrostatic latent image is formed on the surface.
The formed electrostatic latent image is then developed as a toner image by developing devices 15, 16, 17, and 18 disposed so as to be in contact with the photosensitive drums 23, 24, 25, and 26.

Next, the toner images developed by the developing devices 15, 16, 17, and 18 are transferred to a conveyor belt by transfer rollers (transfer devices) (not shown) disposed to face the photosensitive drums 23, 24, 25, and 26. The images are multiple-transferred onto a sheet (transfer material) (not shown) that is conveyed on a sheet 91 to form one full-color image.
Then, the paper onto which the unfixed toner image has been transferred is further conveyed to a fixing device 94 provided behind the photosensitive drums 23, 24, 25, and 26 (on the left side in FIG. 8(b)).

The fixing device 94 includes a fixing roller having an internal fixing heater (not shown) and a pressure roller disposed so as to be in pressure contact with the fixing roller.
Then, the paper conveyed from the transfer section is heated while being pressed by a pressure contact section between the fixing roller and the pressure roller, thereby fixing the unfixed toner image on the paper.
Furthermore, a paper discharge roller (not shown) is disposed behind the fixing device 94, and the paper discharge roller discharges the fixed paper to the outside of the image forming apparatus 90.

The image forming device 90 has four optical scanning devices 11, 12, 13, and 14 lined up, each corresponding to each color of C (cyan), M (magenta), Y (yellow), and K (black). .
In the image forming apparatus 90, each of the four optical scanning devices 11, 12, 13, and 14 records image signals (image information) on the photosensitive surfaces of the photosensitive drums 23, 24, 25, and 26 in parallel. You can print color images at high speed.

Note that as the external device 92, for example, a color image reading device equipped with a CCD sensor may be used.
In this case, the color image reading device and image forming device 90 constitute a color digital copying machine.

106 reflective element 1061 first reflective surface 1062 second reflective surface 1063 third reflective surface 1064 fourth reflective surface 1065 fifth reflective surface 1066 sixth reflective surface

Claims (20)

having first, second, third, fourth, fifth, and sixth reflective surfaces;
The value of the inner product of the unit normal vector of the first reflective surface and the unit normal vector of the second reflective surface is S1, and the value of the unit normal vector of the first reflective surface and the unit normal vector of the third reflective surface is S1. The value of the inner product with the unit normal vector is T1, the value of the inner product between the unit normal vector of the second reflecting surface and the unit normal vector of the third reflecting surface is U1, and the value of the inner product of the unit normal vector of the second reflecting surface and the unit normal vector of the third reflecting surface is T1. The value of the inner product of the unit normal vector and the unit normal vector of the fifth reflective surface is S2, and the inner product of the unit normal vector of the fourth reflective surface and the unit normal vector of the sixth reflective surface is S2. When the value of is T2, and the value of the inner product of the unit normal vector of the fifth reflective surface and the unit normal vector of the sixth reflective surface is U2,

A reflective element characterized by satisfying the following conditions. The angle between the normal to the first reflective surface and the normal to the second reflective surface is θ1,
The angle between the normal line of the second reflective surface and the normal line of the third reflective surface is θ2,
The angle between the normal to the third reflective surface and the normal to the first reflective surface is θ3,
The angle between the normal line of the fourth reflective surface and the normal line of the fifth reflective surface is θ4,
The angle between the normal line of the fifth reflective surface and the normal line of the sixth reflective surface is θ5,
When the angle between the normal line of the sixth reflective surface and the normal line of the fourth reflective surface is θ6,
θ1>θ2
θ3>θ2
θ4<θ5
θ6<θ5
The reflective element according to claim 1, wherein the reflective element satisfies the following conditions. The first and second reflective surfaces are in contact with each other so as to form a first ridgeline,
The second and third reflective surfaces are in contact with each other so as to form a second ridgeline,
The third and first reflective surfaces are in contact with each other so as to form a third ridgeline,
The fourth and fifth reflective surfaces are in contact with each other so as to form a fourth ridgeline,
The fifth and sixth reflective surfaces are in contact with each other so as to form a fifth ridgeline,
3. The reflective element according to claim 1, wherein the sixth and fourth reflective surfaces are in contact with each other so as to form a sixth ridgeline. the first and second ridgelines are non-perpendicular to each other;
the second and third ridgelines are non-perpendicular to each other;
the fourth and fifth ridge lines are non-perpendicular to each other;
4. The reflective element according to claim 3, wherein the fifth and sixth ridge lines are non-perpendicular to each other. the third and first ridge lines are perpendicular to each other;
5. The reflective element according to claim 3, wherein the sixth and fourth ridge lines are perpendicular to each other. The reflective element according to any one of claims 1 to 5,
and a first light-receiving element that receives the light beam from the light source reflected by the reflection element. 7. The photodetecting device according to claim 6, wherein the first light receiving element is provided on a side opposite to the reflecting element with respect to the light source along the optical path of the light beam. A photodetection device according to claim 6 or 7,
An optical scanning device comprising: a deflector that deflects a light beam from the light source to scan a surface to be scanned in a main scanning direction. The light beam deflected in the first direction by the deflector is reflected once by each of the first to third reflecting surfaces, or once by each of the fourth to sixth reflecting surfaces. 9. The optical scanning device according to claim 8, wherein the optical scanning device is configured to reflect the optical beam simultaneously. 10. The optical scanning device according to claim 8, wherein the light beam from the reflective element is incident on the first light receiving element after being deflected by the deflector. The optical scanning device according to any one of claims 8 to 10, further comprising a deflection element that deflects the light beam from the reflection element. 12. The optical scanning device according to claim 11, wherein an entrance surface and an exit surface of the deflection element are non-parallel to each other in a main scanning cross section. comprising an imaging optical system that guides the light beam from the deflector to the scanned surface,
13. The optical scanning device according to claim 11, wherein the deflection element is provided between the deflector and the scanned surface in the optical axis direction of the imaging optical system. 14. The optical scanning device according to claim 13, wherein the imaging optical system includes an imaging optical element integrated with the deflection element. The optical scanning device according to claim 13 or 14, wherein the first light receiving element is provided between the deflector and the scanned surface in the optical axis direction of the imaging optical system. . 16. The optical scanning device according to claim 8, further comprising a second light receiving element that receives the light beam deflected in the second direction by the deflector. comprising an imaging optical system that guides the light beam from the deflector to the scanned surface,
17. The optical scanning device according to claim 16, wherein the first and second light receiving elements are provided on opposite sides of a sub-scanning section including the optical axis of the imaging optical system. The optical scanning device according to claim 16 or 17, further comprising a control unit that adjusts the light emission timing of the light source based on the timing of light reception by the first and second light receiving elements. The optical scanning device according to any one of claims 8 to 18, a developing device that develops an electrostatic latent image formed on the scanned surface by the optical scanning device as a toner image, and the developed toner. An image forming apparatus comprising: a transfer device that transfers an image to a transfer material; and a fixing device that fixes the transferred toner image to the transfer material. An image comprising: the optical scanning device according to any one of claims 8 to 18; and a printer controller that converts a signal output from an external device into image data and inputs the image data to the optical scanning device. Forming device.

Images