JPH08331336A - Original reading unit - Google Patents

Abstract

PURPOSE: To provide a compact original reading unit easy in mirror angel adjustment without deterioration in read performance. CONSTITUTION: At least one of plural mirrors 51-54 reflecting a light from an original S to lead the reflected light to an optical lens 61 is formed as a plural-reflection mirror 53 whose reflection order numbers of plural-reflection are all odd or even numbers and an angle adjustment mechanism 80 is provided for the plural-reflection mirror 53. The mechanism 80 is provided with a lever whose tip is press contact with one end of the mirror 53, a circular-arc using a length from a turning center of the lever to the tip as a radius of curvature and using a point on the extension of the lever in the axial line of the turning center as a center, and formed to the frame 30 in press contact with the other end of the mirror 53, and a mount metallic fixture energizing the mirror 53 toward the tip of the lever and the circular-arc part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading unit.

In particular, the present invention relates to a miniaturized reading unit. The present invention also relates to a document reading unit that facilitates adjustment of the mirror angle.

[0003]

2. Description of the Related Art Conventionally, a document reading unit has been used in a document reading device as shown in FIG.

In FIG. 1, reference numeral 1 is a main body of the document reading apparatus, and 2 is a lid attached to the main body 1 so as to be openable and closable by a shaft 2a.

The reading unit 4 is a case 3 of the main body 1.
Housed within.

An opening 3a is formed on the upper surface of the case 3, and the upper surface 5a of the glass plate 5 attached so as to close the opening 3a from the inside constitutes a document setting surface for setting the document S. are doing.

The reading unit 4 includes a frame 4a and
A lamp 6 for irradiating a document mounted on the frame 4a
, A mirror 7, an optical lens 8, and an image sensor (for example, CCD) 9 are included.

The reading unit 4 has its frame 4a.
Are supported by guide means such as guide shafts and guide rails (not shown), and are driven in the arrow X direction by drive means (not shown).

When reading the original S, the lid 2 is opened,
The document S is set on the document setting surface 5a of the main body 1 and the lid 2 is closed.

After that, when a document reading switch (not shown) is turned on, the lamp 6 of the reading unit 4 causes the document S to move.
At the same time when the irradiation of the light is started, the reading unit 4 starts traveling in the arrow X direction.

As described above, while the reading unit 4 is running, the light emitted from the lamp 6 and reflected by the document S is read by the image sensor 9 through the mirror 7 and the optical lens 8.

For example, such a reading unit is
There is a demand for downsizing, especially for reducing the length L.

The miniaturization of the reading unit can be achieved by increasing the number of mirrors and increasing the number of times of reflection of light (the number of times of return).

Further, for example, in Japanese Unexamined Patent Publication No. 2-21768, as shown in FIG. 9, two mirrors 11 and 12 are arranged, and one mirror 12 reflects light a plurality of times, thereby There is disclosed a reading device in which the number of mirrors is reduced without reducing the number of reflections, and the size is further reduced.

[0015]

[Problems to be Solved by the Invention]

<Problem 1> In the reading unit as shown in FIG. 8, because of the mounting tolerance of the mirror 7, the image forming point P ′ of the point P to be read on the document S on the image sensor 9 is in the arrow Y direction. May shift to.

Therefore, conventionally, with respect to such a deviation,
This has been dealt with by adjusting the mounting position of the image sensor 9 in the arrow Y direction.

However, when the number of mirrors is increased in order to reduce the size of the unit, the image sensor 9 at the point P to be read on the document S is accumulated due to the stacking of the mounting tolerances.
The image forming point P ′ above may be largely displaced in the direction of the arrow Y.

In such a case, if the image sensor 9 is moved to deal with the problem, the optical path is largely deviated from the central portion of the optical lens 8 and the reading performance is deteriorated.

<Problem 2> On the other hand, a structure for adjusting the angle of the mirror is also known as a structure for dealing with the displacement of the image forming point P ′ in the direction of the arrow Y.

As shown in FIG. 10, the structure is a structure in which three mirror screws 14a, 14b, 14c are brought into contact with the back surface of the mirror 13 and the mirror angles are adjusted by rotating these mirror screws.

However, in this structure, the mirror 13
The adjustment work of is complicated.

That is, when only the angle in the direction of the arrow a is to be adjusted, the adjusting screw is relatively easy because the set screw 14a may be rotated to move back and forth. I'm trying to adjust
When 4b or 14c is rotated and moved back and forth, the mirror 1
Since 3 always rotates in the direction of the arrow a, it is necessary to rotate the set screw 14a again for adjustment, and the work is complicated.

The object of the invention described in claim 1 is to solve the above-mentioned problem 1
It is to provide a document reading unit that can solve the above problem, can be downsized, and have no deterioration in reading performance.

The object of the invention described in claim 2 is to solve the above problem 2.
It is to provide a document reading unit in which the angle of the mirror can be easily adjusted.

The object of the invention as defined in claim 3 is to solve the above problem 1.
(2) and (2) can be solved at the same time to provide a document reading unit that can be downsized, the reading performance does not deteriorate, and the angle of the mirror can be easily adjusted.

[0026]

In order to achieve the above object, a document reading unit according to a first aspect of the present invention includes a plurality of mirrors for reflecting light from the document and guiding the light to an optical lens.
A reading unit including an optical lens that collects the light guided by these mirrors, and an image sensor that reads the light collected by the optical lens, wherein at least one of the plurality of mirrors is The light is reflected a plurality of times, and the order of the plurality of times of reflection is all odd-numbered or even-numbered multiple-reflection mirrors,
In addition, it is characterized by being provided with an angle adjusting mechanism capable of adjusting the angle of the reflecting mirror a plurality of times.

According to another aspect of the document reading unit of the present invention, a mirror that reflects the light from the document and guides it to an optical lens, an optical lens that condenses the light guided by the mirror, and a condensing optical lens. A reading unit including an image sensor for reading the reflected light and an angle adjusting mechanism capable of adjusting the angle of the mirror, wherein the angle adjusting mechanism includes a frame rotatably supporting both ends of the mirror, A lever rotatably attached to the frame, the tip of which comes into contact with one end of the mirror, and the length from the center of rotation of the lever to the tip is the radius of curvature, and is on the axial extension of the center of rotation of the lever. A circular arc portion centered on a point, which is formed on the frame and is in contact with the other end of the mirror, and a biasing member for biasing the mirror toward the tip of the lever and the circular arc portion. Characterized in that it comprises a means.

According to a third aspect of the present invention, in the document reading unit, the angle adjusting mechanism according to the first aspect is constituted by the angle adjusting mechanism according to the second aspect.

[0029]

According to the document reading unit of the first aspect, the light from the document is reflected by the plurality of mirrors and guided to the optical lens, condensed by the optical lens and read by the image sensor. That is, since the number of times light is reflected increases, it is possible to achieve compactness, and at least one of the plurality of mirrors is configured as a multiple-reflection mirror that reflects light multiple times.
The number of mirrors can be smaller than the number of times light is reflected, and the size can be further reduced.

If no measures are taken in such a unit, due to the stacking of mounting tolerances of a plurality of mirrors, the image forming point on the image sensor of the point to be read on the original is largely deviated. Sometimes.

On the other hand, in the document reading unit according to the first aspect of the present invention, the plural reflection mirrors are constructed such that the order of reflection is all odd or even. Since the angle adjusting mechanism capable of adjusting the angle of the reflecting mirror is provided, the angle of the reflecting mirror is adjusted plural times by this angle adjusting mechanism to correct the deviation of the image forming point without moving the image sensor. be able to.

Therefore, the optical path is not largely displaced from the central portion of the optical lens, and the reading performance is not deteriorated.

Moreover, since the angle of the multiple-reflection mirror is adjusted so that the order of reflection is all odd-numbered or even-numbered, as compared with the case where the angle of the single-reflection mirror is adjusted, the rotation of the mirror is adjusted. The angle can be made small, and it is possible to reliably deal with a large deviation.

According to the document reading unit of the second aspect, the light from the document is reflected by the mirror, guided to the optical lens, condensed by the optical lens, and read by the image sensor.

If no measures are taken in such a unit, the image forming point on the image sensor of the point to be read on the document may be displaced due to the mounting tolerance of the mirror.

On the other hand, the original reading unit according to the second aspect of the present invention is provided with an angle adjusting mechanism capable of adjusting the angle of the mirror. Therefore, by adjusting the angle of the mirror by this angle adjusting mechanism, the image is read. The shift of the image formation point can be corrected without moving the sensor.

Therefore, the optical path is not largely displaced from the central portion of the optical lens, and the reading performance is not deteriorated.

The angle adjusting mechanism includes a frame that rotatably supports both ends of the mirror, a lever that is rotatably attached to the frame, and a tip of which is in contact with one end of the mirror, and this lever. The radius from the center of rotation to the tip is the radius of curvature, and the arc portion formed on the frame that abuts the other end of the mirror, centered on a point on the axial extension of the center of rotation of the lever, An urging means for urging the mirror toward the tip of the lever and the arc portion is provided, and thus the following operation is performed.

Since the biasing means biases the mirror toward the tip of the lever and the arc portion, the mirror is
Both ends thereof are supported while being pressed toward the tip of the lever and the arc portion.

When the lever is rotated in such a state,
Since one end of the mirror is pressed against the tip of the lever, the mirror rotates as the tip of the lever rotates.

On the other hand, the other end of the mirror is in a state of being pressed toward the circular arc portion, and this circular arc portion has a radius of curvature which is the length from the rotation center of the lever to the tip thereof, and the rotation of the lever. Since it is formed around a point on the axial extension of the center, the mirror rotates like the one end of the mirror.

That is, according to such an angle adjusting mechanism, the angle of the mirror can be adjusted by rotating the lever.

Moreover, since the arcuate portion has a radius of curvature which is the length from the center of rotation of the lever to the tip, and is formed around a point on the axial extension of the center of rotation of the lever, the mirror rotates. Even if it moves, the parallelism between the lever axis and the mirror is maintained.

Therefore, according to such an angle adjusting mechanism, it is possible to easily adjust the angle of the mirror simply by rotating the lever and without impairing the parallelism.

According to the document reading unit of the third aspect, the angle adjusting mechanism of the first aspect comprises the angle adjusting mechanism of the second aspect. The obtained action and the action obtained by the reading unit according to the second aspect can be obtained at the same time.

That is, it is possible to obtain a document reading unit which can be downsized and whose reading performance does not deteriorate and whose mirror angle can be easily adjusted.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a document reading unit according to the present invention.

The document reading unit 20 is used in place of the unit 4 in the document reading device shown in FIG. 8, for example.

As shown in FIG. 1, the document reading unit 20 of this embodiment includes a frame 30 and a frame 30.
A lamp unit 40 for irradiating an original, which is mounted on 0.
Mirrors 51, 52, 53, 54, an optical lens 61,
It has an image sensor (CCD) 62.

The frame 30 is made of sheet metal and has a bottom plate 31.
And a pair of side plates 32 and 33 which are parallel to each other (only one side plate 32 is shown in FIG. 1. For the other side plate 33, see FIG. 4).

Another relatively thin frame 41 is fixed to the upper portions of the side plates 32 and 33, and the lamp unit 40 is mounted in the frame 41.

The lamp unit 40 is for a color original and has cylindrical lamps 42R, 42G and 42B. The lamp 42R emits red light toward the original S, 42G emits green light, and 43B emits blue light.

The mirror 51 has a pair of mounting brackets 70 as shown in FIG.
It is attached to 33.

The mounting member 70 is made of a spring member bent into an approximately L shape as shown in the figure, and has a bottom plate 71, side plates 72, and a tongue piece 73 formed on the bottom plate 71. A locking hole 74 is formed in the tip portion of the tongue piece 73, and as a result, a neck portion 75 is formed.

On the other hand, the side plates 32 and 33 are provided with holes 32a and 33a for mounting mirrors, as shown in FIGS. Note that FIG. 4 shows the side plate 33 as viewed from the back side of the paper surface of FIG.

As shown in FIG. 3, in the hole 32a, a concave portion 32a1 into which the neck portion 75 of the mounting member 70 is fitted, engaging portions 32a2 and 32a2 on both shoulders of the concave portion, and the mirror 5 are formed.
The contact edge 32a3 which contacts the surface of 1 is formed.

As shown in FIG. 4, the hole 33a is basically similar to the hole 32a, and the neck portion 75 of the mounting bracket 70 is formed.
A concave portion 33a1 into which is fitted, engaging portions 33a2 and 33a2 on both shoulders of the concave portion, and an abutting edge 33a3 that abuts on the surface of the mirror 51 are formed. However, the contact edge 33a3 is formed in an arc shape.

To mount the mirror 51, the holes 32a,
After inserting the mirror into 33a, for example, first, from the outside of the side plate 32, the back surface 51b of the mirror 51 (see FIGS. 1 and 5).
The bottom plate 71 of the mounting bracket 70 is inserted between the hole 32a and the hole 32a. At this time, the tongue piece 73 is inserted in a state of being bent toward the bottom plate 71, and when the neck portion 75 reaches the recess 32a1 of the hole 32a, the neck portion 75 falls into the recess 32a1 and at the same time, the locking holes 74, 74 are closed. The mounting bracket 70 is prevented from coming off by engaging with the engaging portions 33a2 and 33a2. And
In this state, the surface 51a of the mirror 51 is pressed against the abutting edge 32a3 of the hole 32a by the elastic force of the tongue piece 73, and the mirror 51 is pulled out laterally by the side plate 72 of the mounting member 70. To be prevented.

Similarly, by inserting the bottom plate 71 of the mounting bracket 70 from the outside of the side plate 33 between the rear surface 51b of the mirror 51 (see FIGS. 1 and 5) and the hole 33a, the mirror 51 is moved to the side plate 32. , 33.

According to such a mounting structure, one hole 3
Since the contact edge 32a3 with the mirror 2a is formed in a straight line and the contact edge 33a3 with the mirror in the other hole 33a is formed in an arc shape, it is easy to ensure the mirror mounting accuracy. . That is, if both of the contact edges with the mirror are formed linearly, a stable mounting state of the mirror cannot be obtained unless the positional accuracy of both contact edges is strictly controlled. On the other hand, according to the mounting structure of the present embodiment, the contact edge 33a3 of the other hole 33a with the mirror is formed.
Is formed in an arc shape, the contact edge 33
The position of the mirror with respect to a3 follows the position of the mirror defined by the abutting edge 32a3 of the one hole 32a formed in a straight line. Therefore, it suffices to strictly control the formation position of the abutting edge 32a3 of the one hole 32a, and as a result, it becomes easy to ensure the mirror mounting accuracy.

The mirror 52 is similar to the mirror 51,
Using the pair of mounting brackets 70, the side plates 32, 33 of the frame
Attached to. In FIG. 3, reference numeral 32b denotes a hole for mounting the mirror 52, which has the same shape as the hole 32a. In FIG. 3, 33b is a hole for mounting the mirror 52, and has the same shape as the hole 33a.

As will be described later, the mirror 53 is configured as a multiple-reflection mirror that reflects light a plurality of times, and the order of the multiple reflections is all odd.

The mounting structure of the mirror 53 is basically the same as the mounting structure of the mirror 51 described above, except that an angle adjusting mechanism 80 for adjusting the mounting angle is provided.

The angle adjusting mechanism 80 includes side plates 32 and 33 of the frame which rotatably support both ends of the mirror 53, a lever 81 rotatably attached to the side plate 32, and a side plate 3.
3 is provided with an arc portion 33c3 and the fittings 70, 70 as a biasing means.

The lever 81 is made of a metal plate, and as shown in FIG. 6, a shaft portion 82 protruding toward the front side of the paper surface of the figure, and an abutting edge 83 formed at the tip end portion. It has a knob portion 84 and two screw holes 85 and 86.

The lever 81, as shown in FIG.
It is located inside 2 and is rotatably attached by fitting the shaft portion 82 into the bearing hole 32d of the side plate 32. The side plate 32 has a screw hole 8 for the lever 81.
Slots 32e and 32f extending substantially in the direction of rotation are formed at positions corresponding to 5 and 86, respectively.
The lever 81 is prevented from coming off by screwing a screw (not shown) from the outside of the side plate 32 through the screws e and 32f into the screw holes 85 and 86 to such an extent that the rotation of the lever 81 is not hindered.

3 and 4, reference numerals 32c and 33c are holes for mounting the mirror 53, and the mirror 53 is rotatable with respect to these holes, as will be described later. Note that FIG.
In the above, reference numeral 32c1 is a recess into which the neck portion 75 of the mounting member 70 fits, and 32c2 is an engaging portion that engages with the engaging hole 74 of the mounting member 70. Similarly, in FIG. 4, 33c1
Is a concave portion into which the neck portion 75 of the mounting bracket 70 fits, 33c2
Is an engaging portion that engages with the engaging hole 74 of the mounting bracket 70.

As shown in FIG. 4, the circular arc portion 33c3 is formed as one edge of the hole 33c.

The radius of curvature of the arc portion 33c3 is R ₀ ,
Its center is O ₀ .

The radius of curvature R ₀ is the length L ′ from the rotation center O ₀ ′ of the lever 81 to the tip 83 (see FIG. 7).
The center O ₀ is located on the extension of the rotation center O ₀ 'of the lever 81 in the axial direction (see FIG. 1).

The mirror 53 has holes 32 in the side plates 32 and 33.
After being inserted through c and 33c, as in the case of the mirror 51, the metal fittings 70 and 70 are inserted from the outside to be attached to the frame.

One end of the attached mirror 53 is pressed against the contact edge 83 at the tip of the lever 81 by the mounting bracket 70, and the other end is pressed by the mounting bracket 70 against the arc portion 33c3 of the hole 33c. .

As shown in FIG. 1, the optical lens 61 and the image sensor 62 are formed of a single synthetic resin case 63.
And is configured as a unit and is fixed to the frame 30.

The mirror 54 is mounted on a mounting portion 63a formed on the case 63.

According to the reading unit 20 as described above, the following operational effects can be obtained.

(I) Three colors of light are emitted from the lamp unit 40 toward the original S.

The light from the document S is sequentially reflected by the mirrors 51, 5
2, 53, 54, and is reflected again by the mirror 53 and guided to the optical lens 61.
The image is collected by the image sensor 62 and read by the image sensor 62.
In addition, in FIG. 1, ~ indicates the order of reflection.

As described above, the light from the original S is guided to the optical lens 61 after being reflected five times by the four mirrors 51, 52, 53 and 54, and the number of times the light is reflected increases. The reading unit 20 can be made compact.

Moreover, since the mirror 53 is configured as a multiple-reflection mirror that reflects light twice, the number of mirrors can be smaller than the number of times light is reflected, and further compactness can be achieved. it can.

(Ii) In such a unit, if no measures are taken, by stacking the mounting tolerances of a plurality of mirrors, the image forming point on the image sensor of the point to be read on the document is read. May deviate significantly.

On the other hand, in the reading unit 20 of this embodiment, the multi-reflection mirror 53 has a structure in which the order of reflection is all odd (third and fifth in this embodiment). Moreover, since the angle adjusting mechanism 80 capable of adjusting the angle of the reflection mirror 53 is provided,
By adjusting the angle of the reflecting mirror 53 a plurality of times by the angle adjusting mechanism 80, it is possible to correct the deviation of the image forming point without moving the image sensor 62.

Therefore, the optical path is not largely displaced from the central portion of the optical lens 62, and the reading performance is not deteriorated.

Moreover, since the angle of the multiple-reflection mirror 53 is adjusted so that all the reflection orders are odd-numbered, compared with the case where the angle of the single-reflection mirror, for example, the mirror 51 is adjusted. The rotation angle can be reduced, and a large deviation can be reliably dealt with.

In the configuration in which the order of reflection of the multiple-reflection mirror 53 is an odd-numbered and even-numbered combination (for example, the second and fifth), the angle of the optical path that changes with the rotation of the mirror angle is offset. As a result, a good adjusting action cannot be obtained.

(Iii) Since the mounting member 70 urges the mirror 53 toward the tip 83 of the lever 81 and the arc portion 33c3, both ends of the mirror 53 are respectively the tip 83 of the lever 81 and the arc portion 33c3. It is supported while being pressed against.

The angle of the mirror 53 can be easily adjusted by rotating the lever 81 with the knob 84 by the following action.

When the lever 81 is rotated, one end of the mirror 53 is in a state of being pressed against the tip 83 of the lever 81, so that the mirror 53 is rotated in accordance with the rotation of the lever tip 83.

On the other hand, the other end of the mirror 53 has an arc portion 33c.
3, the circular arc portion 33c3 is located at the tip 8 from the rotation center O ₀ 'of the lever 81.
The length L'up to 3 is the radius of curvature R ₀ , and the lever 81
Since it is formed with a point on the axial extension of the rotation center O ₀ ′ of the center of the mirror 53 as the center O ₀ , it rotates in the same manner as the one end of the mirror 53.

That is, according to such an angle adjusting mechanism 80, the mirror 53 is rotated by rotating the lever 81.
The angle of can be adjusted.

Further, the arcuate portion 33c3 has a length L'from the center of rotation O ₀ 'of the lever 81 to the tip 83 as its radius of curvature R _0, and extends in the axial direction of the center of rotation O ₀ ' of the lever 81. Since it is formed with a certain point as the center O ₀ , even if the mirror 53 rotates, the axis line of the lever 81 and the mirror 53
The parallelism with is maintained.

Therefore, such an angle adjusting mechanism 80
According to this, the angle of the mirror 53 can be adjusted easily by simply rotating the lever 81 and without impairing the parallelism.

After the adjustment, the position of the lever 81, that is, the mirror 53 can be fixed by tightening the screws screwed into the screw holes 85 and 86 of the lever 81.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be appropriately made within the scope of the present invention.

For example, in the above embodiment, the multi-reflection mirror 53 has a configuration in which the order of reflection is all odd-numbered, but the same action and effect can be obtained even if all the reflections are even-numbered. .

In the above embodiment, the unit for reading the reflected light from the manuscript has been described, but the present invention is also applicable to the unit for reading the transmitted light from the manuscript.

[0097]

According to the document reading unit of the first aspect of the present invention, it is possible to achieve the effect that the size can be reduced and the reading performance is not deteriorated.

According to the document reading unit of the second aspect, it is possible to obtain the effect of facilitating the angle adjustment of the mirror.

According to the document reading unit of the third aspect, the size can be reduced, the reading performance is not deteriorated, and the angle adjustment of the mirror can be facilitated.

[0100]

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a document reading unit according to the present invention.

2A and 2B are views showing a mounting bracket, in which FIG. 2A is a front view and FIG.
Is a side view and (c) is a bottom view.

FIG. 3 is a front view of the frame.

FIG. 4 is a partially omitted rear view of the frame.

FIG. 5 is a diagram showing a relationship between a mirror and a mounting bracket.

FIG. 6 is a front view of a lever.

FIG. 7 is a front view mainly showing a mounting state of a lever.

FIG. 8 is an explanatory diagram of a conventional technique.

FIG. 9 is an explanatory diagram of a conventional technique.

FIG. 10 is an explanatory view of a conventional technique, (a) is a plan view,
(B) is a front view and (c) is a side view.

[Explanation of symbols]

 S document 20 document reading unit 30 frame 33c3 arc portion 51 mirror 52 mirror 53 multiple reflection mirror 54 mirror 61 optical lens 62 image sensor 70 mounting bracket (biasing member) 80 angle adjusting mechanism 81 lever 81 lever tip

Claims (3)

[Claims] 1. A plurality of mirrors for reflecting light from an original to guide it to an optical lens, an optical lens for condensing the light guided by these mirrors, and an image for reading the light condensed by the optical lens. A reading unit including a sensor, wherein at least one of the plurality of mirrors reflects light a plurality of times, and the order of the plurality of times of reflection is all odd-numbered or even-numbered multiple reflections. An original reading unit, which is configured as a mirror and is provided with an angle adjusting mechanism capable of adjusting the angle of the reflecting mirror a plurality of times. 2. A mirror that reflects light from a document and guides it to an optical lens, an optical lens that collects the light guided by the mirror, and an image sensor that reads the light collected by the optical lens. A reading unit having an angle adjusting mechanism capable of adjusting the angle of the mirror, wherein the angle adjusting mechanism is a frame that rotatably supports both ends of the mirror, and is rotatably attached to the frame, A lever whose tip is in contact with one end of the mirror, and a radius of curvature that is the length from the center of rotation of the lever to the tip of the mirror, which is centered on a point on the axial extension of the center of rotation of the lever. An arc portion formed on the frame that abuts an end portion, and a biasing unit that biases the mirror toward the tip of the lever and the arc portion. Original reading unit that. 3. A document reading unit, wherein the angle adjusting mechanism according to claim 1 comprises the angle adjusting mechanism according to claim 2.