JP2914260B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus capable of reading a document or the like as image data.

[0002]

2. Description of the Related Art A document image is scanned by rotating a reflecting mirror.
As a conventional example of the image reading device 51 for reading with a one-dimensional image sensor, there is one disclosed in JP-A-6-133079. In this conventional example, as shown in FIG. 11, the entire original G is scanned simply by rotating the reflecting mirror 53, and the optical path length correction for keeping the optical path length between the one-dimensional image sensor 57 and the reading surface constant. There is no mechanism. For this reason, if no image processing is performed,
The optical path length is the longest distance (Lma) at both left and right ends as shown in FIG.
x), while it is the shortest (H) at the center (vertically below the reflector). When the document G is read by such an image reading device 51, for example, when a rectangular figure is read, as shown in FIG. 13, the outer diameter of the read image becomes slightly barrel-shaped, causing distortion.

In order to solve the above-mentioned problem, Japanese Patent Laid-Open No.
There is an image reading apparatus disclosed in Japanese Patent No. 73210/73. This image reading apparatus predicts barrel-shaped distortion in advance based on data relating to the arrangement of an optical system and an original to be read, which is fixed and installed in advance, and corrects the distortion by image conversion processing to correct the distortion. It is to convert to an image.

Another conventional image reading apparatus is disclosed in Japanese Patent Application Laid-Open No. 62-291259. That is, an image reading apparatus that scans the front surface of a document by rotating a reflecting mirror and reads the document with a one-dimensional image sensor includes an optical path length correction mechanism in order to improve the quality of a read image. In the conventional example, the parallel movement of the condensing lens and the one-dimensional image sensor required as the reflecting mirror rotates is realized by using a predetermined cam mechanism.

More specifically, a cam mechanism is disposed between a reflecting mirror mounted on a rotating shaft and a unit to which a condenser lens and a one-dimensional image sensor are fixed, and each component is constituted by a spring member. It is pressed against the sliding surface of the cam. The cam has a sliding surface for the reflector, a condenser lens and
The sliding surface for the unit to which the three-dimensional image sensor is fixed has a two-stage configuration. And the sliding surface of the cam is
It is designed so that the reflecting mirror can be rotated at a desired angle and the unit to which the condenser lens and the one-dimensional image sensor are fixed can be translated by a desired distance.

[0006] As a mechanism for driving the cam, for example, by rotating the cam by a driving mechanism such as a stepping motor, the unit to which the reflecting mirror, the condensing lens and the one-dimensional image sensor are fixed is simultaneously driven to reduce the optical path length. It is controlled to keep it constant.

Here, in the actual image reading process, as shown in FIG. 11, when the position of the reflecting mirror is substantially at the upper center of the read document, the optical path length when scanning the entire document is reduced. The fluctuation monotonically decreases from the start of reading, becomes the shortest vertically below the reflecting mirror, and thereafter monotonically increases.

[0008]

However, the above-mentioned prior art has the following disadvantages. That is,
The method of correcting the distortion of the barrel-shaped image by the image conversion processing has a disadvantage that a large amount of time is required for the conversion processing. Further, when a large number of thin vertical lines extending in the scanning direction are present in the original, there is also a disadvantage that lines that should be continuous in the original are interrupted by the image conversion processing. Further, it is necessary to provide the condensing lens with a depth of field corresponding to the optical path length variation, and this causes a problem that the so-called F number becomes large and the lens becomes dark.

In the optical path length correcting mechanism using a cam mechanism, a unit to which a reflecting mirror, a one-dimensional image sensor and a condenser lens are fixed is pressed against a sliding surface of a cam by a predetermined spring member. . For this reason, for example, a relatively high driving torque is required as a driving means such as a stepping motor. Further, as the rotation angle of the reflecting mirror and the amount of parallel movement for correcting the optical path length increase, the size of the cam itself increases, resulting in an inconvenience of increasing the size of the entire image reading apparatus. .

When the position of the reflecting mirror is located above the center of the document to be read, the optical path length from the reflecting mirror to the reading surface at the time of scanning monotonically decreases and then monotonically increases. For this reason, it is necessary to monotonically increase the distance between the reflecting mirror and the condenser lens, and then monotonously decrease the distance between the reflecting mirror and the condenser lens as the optical path length correction. Therefore, it is necessary to cause a reciprocating parallel movement in a single reading process as an optical path length correcting mechanism, and the mechanism becomes complicated and large in size to achieve simultaneous reflection mirror and optical path length correction by one driving unit. , Had the inconvenience.

Further, in an image reading apparatus in which the position of the reflecting mirror is located above the center of the document to be read, a method in which one scanning is completed, the scanning mechanism is returned to the scanning start state, and the next scanning is started again. In such a case, a waiting time is required until the next scanning starts, which is a serious problem particularly when a large number of originals are read. Further, in the case of a method of driving the image reading apparatus by a battery, extra power is required to return the scanning mechanism to the original position, resulting in a disadvantage that the operation efficiency is poor.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus which can improve the disadvantages of the prior art and, in particular, provides an image reading apparatus which can read a good quality image without image distortion using a reflecting mirror. Aim.

[0013]

According to the present invention, there is provided a light source for irradiating a document with predetermined light,
A reflecting mirror for reflecting the light emitted from the document by the light from the light source in different directions, a condensing lens for condensing the light reflected from the reflecting mirror, and a light transmitting through the condensing lens according to the image. and a light conversion means for converting into an electric signal
ing. In addition, the reflecting mirror is arranged at a predetermined position in the vicinity of the document, and is configured to be rotatable through a rotation axis parallel to the document, and the light converting means is disposed integrally with the condenser lens in the reflecting direction of the reflecting mirror. In addition, there is provided a light conversion means moving mechanism which makes the light conversion means relatively movable with respect to the reflecting mirror. Then, a driving mechanism is provided near the reflecting mirror to transmit the driving force to the rotation axis of the reflecting mirror and the driving force to the light conversion means moving mechanism, and the distance to the emission surface of the document accompanying the rotation of the reflecting mirror is provided. The distance between the reflecting mirror and the light converting means is adjusted in accordance with the change of the light source, and the optical path distance from the outgoing slope to the light converting means is maintained substantially constant.

With the above configuration, the image reading apparatus is activated and the original is irradiated with light from the light source. Then, predetermined light is emitted from the document, and a part of the light is incident on the reflecting mirror side. The light incident on the reflecting mirror becomes reflected light and is reflected toward the condenser lens. The reflected light that has entered the condenser lens enters a light conversion unit that converts the light into an electric signal corresponding to an image by the action of the condenser lens. Thus, a one-dimensional image on the reading line of the document is read.

Subsequently, the reflecting mirror is driven to rotate by the action of the driving mechanism provided in the image reading apparatus. As a result, the position of the reading line on the document changes, and another one-dimensional image is read. By repeating this,
An image is read for the entire document, and the image of the entire document is read by combining the one-dimensional images.

At this time, a predetermined relationship exists between the rotation angle of the reflecting mirror and the moving distance of the light conversion means support member. That is, when the reflecting mirror rotates, the instantaneous position of the reading line changes, and accordingly, the distance from the reflecting mirror to the reading line changes. For this reason, the light conversion means moving mechanism adjusts the mutual distance between the reflection mirror and the light conversion means according to the change from the reflection mirror to the reading line. Specifically, the light conversion means support member moves so that the optical path distance from the reading line to the light conversion means through the reflecting mirror and the condenser lens is substantially constant.

As a result, the disturbance and distortion of the image due to the change in the optical path distance are suppressed, and an image of good quality can be obtained.

Here, the light conversion means moving mechanism includes a rod-shaped screw member extending toward the reflecting mirror, a rod-shaped guide member extending parallel to the screw member and toward the reflecting mirror, and these screw members. it may be constructed from a to fit the light converting unit support member having a threaded member through-hole and the guide member and engaged by the guide member through hole is. Then, it disposed a predetermined pawl member to the inside of the threaded member through-hole, may I adopted a configuration that engages the pawl member to the screw groove of the screw member.

Further, while transmitting the driving force to the optical converting unit moving mechanism by driving kinematic mechanism, even I adopted the construction that transmits the driving force transmitted to the light conversion unit moving mechanism to the rotation axis of the reflection mirror Good .

[0020] Particularly, in the first aspect of the present invention, there it adopted <br/> the configuration of the exit surface of the vertically below the reflecting mirror and the reading start point.

[0021] Particularly, in the invention of claim 2, wherein, while maintaining the angle of the reflection mirror when the image reading is finished, when the next image reading, there I adopted the configuration that reversing the drive mechanism .

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, as shown in FIG. 1, an image reading apparatus 1 illuminates a document G with a light source (not shown).
A reflecting mirror 3 for reflecting outgoing light R emitted from the original G by the light from the light source in different directions;
And a light converting means 7 (one-dimensional image sensor) for converting light transmitted through the light collecting lens 5 into an electric signal corresponding to an image. The reflecting mirror 3 is arranged at a predetermined position near the document G and is rotatable via a rotation shaft 3a parallel to the document G. Further, a light converting means is provided integrally with the condenser lens 5 in the direction of reflection of the reflecting mirror 3 and the light converting means 7 is movable relative to the reflecting mirror 3. A moving mechanism 9 is provided.

In addition, a driving mechanism 11 is provided in the vicinity of the reflecting mirror 3 to transmit a driving force to the rotating shaft 3a of the reflecting mirror 3 and to transmit a driving force to the light conversion means moving mechanism 9 to thereby reflect the reflecting mirror The distance between the reflecting mirror 3 and the light converting means 7 is adjusted in accordance with the change in the distance of the original G to the reading line 13 (output surface) due to the rotation of the document 3, and the distance between the reading line 13 and the light converting means 7 is adjusted. The optical path distance is kept almost constant.

The above will be described in detail.
, The reflecting mirror 3 is formed of a rectangular mirror, and is carried on a rotating shaft 3a positioned parallel to the document G. Specifically, the document G is installed above one end in the longitudinal direction of the document G. Then, it has a role of reflecting the outgoing light R emitted from the document G to the light converting means 7 side. A predetermined reflecting mirror gear 3b is fixed to one end of a rotating shaft 3a that carries the reflecting mirror 3. The reflecting mirror gear 3b is for rotating the reflecting mirror 3 by receiving a driving force from a motor gear 11a described later. Here, since the reflecting mirror 3 rotates only slightly when reading an image, a gear having a large number of teeth is used for the reflecting mirror gear 3b with respect to the motor gear 11a.

In the vicinity of the reflecting mirror 3, a stepping motor 11 as a driving mechanism is provided. This stepping motor 11 is for driving the above-mentioned reflecting mirror 3 and a light conversion means moving mechanism 9 described later. The rotation of the stepping motor 11 is controlled according to a signal from a main control unit (not shown). A predetermined motor gear 11a is provided on a rotation shaft (not shown) of the stepping motor 11. This motor gear 11
As described above, a is for engaging with the reflecting mirror gear 3b and transmitting the driving force to the light conversion means moving mechanism 9 described later.

Further, a light converting means 7 is disposed in the direction of light reflection by the reflecting mirror 3. This light conversion means 7
Is for converting light emitted from the surface of the document G and reflected by the reflecting mirror 3 into an electric signal corresponding to an image. More specifically, an image on the surface of the document G is captured in one dimension, the entire document is scanned, and this is converted into a two-dimensional planar image to form an image.

A predetermined condenser lens 5 is provided between the light converting means 7 and the reflecting mirror 3. This condenser lens 5 is for forming an image of the light reflected from the reflecting mirror 3 on the above-mentioned light converting means 7. The condensing lens 5 is fixed on the flat light conversion means support member 15 so that the light conversion means 7 and the distance between the light conversion means 7 are fixed.

A predetermined screw member through hole 17a is formed on one of the lower surfaces of the light conversion means support member 15. The screw member through hole 17a is for fitting a screw member 17 described later, and is formed toward the reflecting mirror 3 direction. A predetermined claw member (not shown) is provided inside the screw member through hole 17a, and this claw member fits into the groove of the screw member 17. A predetermined guide member through-hole (not shown) is formed on the other of the lower surface of the light conversion means support member 15. The guide member through-hole is for fitting a rod-shaped guide member 19 described later, and is formed toward the reflecting mirror 3 side similarly to the screw member through-hole 17a. However, the fitting of the guide member 19 is not limited to the guide member through-hole, but may be a predetermined concave groove whose one side is open, and other shapes are irrelevant.

The light conversion means support member 15 and the reflecting mirror 3
A predetermined screw member 17 and a guide member 19 are provided between each other. First, the screw member 17 extends from the screw member through hole 17a toward one end of the reflecting mirror 3 and is parallel to the surface of the document G to be read. The screw portion of the screw member 17 fits into the screw member through hole 17a. Each screw groove constituting the screw portion of the screw member 17 has a different pitch between the grooves in each region as described later. On the other hand, the guide member 19 also extends from the above-described guide member through hole toward the other end of the reflecting mirror 3. That is, the screw member 17 and the guide member 1
Numerals 9 are parallel to each other and are arranged with one end thereof facing the reflecting mirror 3. The document G is also parallel to the original G, and the distance from the document G does not change even when the light conversion unit support member 15 is moved by the light conversion unit moving mechanism 9.

As shown in FIG. 2, a predetermined screw member gear 21 is provided at the tip of the screw member 17 described above. The screw member gear 21 is for receiving a driving force, and has a predetermined number of teeth. The screw member gear 21 and the motor gear 11a described above are used.
Are engaged with each other. This is because, as shown in FIG. 2, the center of the rotation shaft of the motor gear 11a and the center of the rotation shaft of the screw member 17 are substantially perpendicular to each other.

Here, in FIGS. 1 and 2, bearings and the like are not described for each rotating shaft and gear, but these are omitted for convenience in order to clarify the description of the positional relationship of each component. is there. Therefore, each rotating member is actually supported by a predetermined bearing or the like.

In the present embodiment, the screw member 17 and the guide member 19 which are parallel to each other are provided as described above. However, the present invention is not limited to this, and for example, two parallel guide members are provided. And a screw member is further provided in parallel with the light conversion means supporting member 15 for the screw member.
A predetermined claw member (not shown) is protruded from the device, and this is engaged with the screw portion of the screw member 17, and the light conversion means support member 15 is moved by the movement of the claw member accompanying the rotation of the screw member 17. May be. With the above configuration, the screw member 17 rotates, and the light conversion means support member 15 can be moved in parallel in the optical axis direction of the reflected light. here,
By appropriately selecting the number of teeth of the motor gear 11a and the screw member gear 21 and setting the reduction ratio, the light conversion means support member 15
Can be moved with high accuracy and at high speed.

Next, an optical arrangement and an image reading process according to this embodiment will be described with reference to FIG. As can be seen from FIG. 3, the reflecting mirror 3 is disposed above one end of the document G. The light converting means 7 is located on the right side of the reflecting mirror 3.
And a condenser lens 5. Further, the original G is positioned obliquely downward from vertically below the reflecting mirror 3, and its length in the scanning direction is represented by D in the figure.

First, the light reflected by the reflecting mirror 3 is imaged on the light converting means 7 by the condenser lens 5. The light conversion means 7 reads the formed reflected light as a partial image. The rotation of the stepping motor 11 is transmitted to the rotating shaft 3a of the reflecting mirror 3 by the motor gear 11a and the reflecting mirror gear 3b (see FIG. 2), whereby the reflecting mirror 3 is driven to rotate. Further, the reading line 13 on the emission surface moves on the original G with the rotation of the reflecting mirror 3. In synchronization with this, the light converting means 7 sequentially reads a plurality of partial images, and combines them to obtain a read original G.
Can be obtained.

On the other hand, the rotational driving force of the stepping motor 11 is applied to the screw member 17 by the motor gear 11a and the bevel gear 23.
The rotation is transmitted through a screw member gear 21 (see FIG. 2). As a result, the light conversion means support member 15 carrying the condenser lens 5 and the light conversion means 7 is moved in parallel in the direction of the optical axis reflected by the reflecting mirror 3.

In the image reading apparatus 1 according to this embodiment,
In order to scan vertically below the reflecting mirror 3 as a reading start point,
As shown in FIG. 3, an image is read with one end of the read original G positioned just below the center of the reflecting mirror 3. Therefore, assuming that the angle between the reflecting mirror 3 and the horizontal plane is θ, and the angle between the direction of the reading surface on the document G and the perpendicular surface is φ, the reflecting mirror 3 is in a range obtained by the following equation (1). It is driven to rotate. In addition, a relationship that satisfies the following equation (2) holds between θ and φ, as is clear from FIG.

[0037]

(Equation 1)

Assuming that the entire optical path distance from the reading surface (exit surface) of the document G to the light converting means 7 is L, the optical path distance L can be expressed by the following equation (3). here,
Each symbol is L ₀ : the distance between the condenser lens and the light conversion means, L ₁ :
The distance between the reflecting mirror and the condenser lens, L ₂ : the distance from the reflecting mirror to the reading line, and H: the vertical downward distance from the reflecting mirror to the document. Further, the range of the distance L ₂ from the reflecting mirror 3 described above to the reading line 13, as is clear from FIG. 3, the range as represented by the following formula (4). Therefore, in order to make the optical path distance L from the reading line 13 to the light converting means 7 constant, it is necessary that the distance of each part satisfies the following expression (5). Here, the symbol C means a constant. Therefore, from equation (3) and (5), so as to satisfy the following relation (6) may be adjusted to the reflecting mirror 3 and the condenser lens 5 mutual distance L _2.

[0039]

(Equation 2)

Here, the number of teeth of the motor gear 11a is N ₁ ,
If the number of teeth of the reflecting mirror gear 3b is N ₂ , the number of teeth of the bevel gear 23 is N ₃ , the number of teeth of the screw member gear 21 is N _4, and the rotation angle of the stepping motor 11 is ψ, ψ and the reflecting mirror 3 Between the angle θ and the angle φ to the read line has a relationship expressed by the following equation (7). Assuming that the rotation angle of the screw member 17 at this time is α, a relationship expressed by the following equation (8) occurs between α, the angle θ of the reflecting mirror 3, and the angle φ to the reading line 13. ing. From the above, the screw member 17 has the angle α [de expressed by the equation (8).
g], the angle to the reading line 13 changes by an angle represented by the following equation (9). Accordingly, thread pitch of the screw member 17 so as to satisfy the relationship between the rotation angle α and L ₁ of the screw member 17 which is obtained by substituting the equation (9) into equation (6) is set.

[0041]

(Equation 3)

In scanning an image, by appropriately setting N ₁ and N ₂ , the reflecting mirror 3 can be driven to rotate with higher accuracy with respect to the step angle of the stepping motor 11. For example, when the step angle of the stepping motor 11 and [psi _0, reflected as shown in FIG. 4 mirror 1
Can be driven with an angular resolution determined by the following equation (10). Further, as can be seen from FIG. 4, the moving amount x of the reading line 13 due to the rotation of the reflecting mirror 3 is expressed by the following equation (1).
From 1). Then, when this is differentiated, the following equation (1)
The relationship represented by 2) is derived. As can be seen from the equation (12), the angle to the reading line 13 is a small angle d.
When rotated by φ, the reading line 13 moves by dx. This dx means the width in the scanning direction when the light conversion means 7 drives for reading. Therefore, assuming that the reading resolution (the number of reading lines) in the scanning direction for obtaining a good image is M, it is necessary to perform the reading operation at every minute distance that satisfies the following expression (13). Thus, in FIG. 4, if the drive angle per minute scanning of the stepping motor 11 is dφ, the read line 13
When the angle to the direction is φ, the screw member 13 may be configured to move the light conversion means support member 15 so as to satisfy the relationship represented by the following equation (14).

[0043]

(Equation 4)

Next, FIG. 5 shows a state in which a plurality of images are successively read by the image reading apparatus 1 of this embodiment. First, in the first reading (refer to FIG. 5A), scanning is performed rightward in the figure as a reading start point 25 vertically below the reflecting mirror 3.
The reading ends at the right end of the document G. At this time, the stepping motor 11 maintains this state without returning the reflecting mirror 3 and the screw member 17 to the first reading start point 25 (vertically below the reflecting mirror). In the second reading operation, scanning is performed in the reverse direction (leftward) with the first reading end point 27 (right end of the document) as the reading start point, and the scanning is performed at the left end of the document as the first reading start point. The reading is terminated (see FIG. 5B).

FIG. 5 shows the first and second readings. However, the third reading may be performed in the same manner as the first reading, and the fourth reading may be performed in the same manner as the second reading. The same is true for As described above, when an image is read by reciprocal scanning, as shown in FIG. 6, the obtained image is turned upside down depending on the reading direction. The reverse is possible.

Second Embodiment Next, a second embodiment is shown in FIG. The image reading device 31 according to this embodiment has the same basic components as those of the above-described embodiment. However, in the present embodiment, two stepping motors are used. One stepping motor 11 is engaged with the reflecting mirror gear 3b via the motor gear 11a, and the other stepping motor 12 is connected to one end of the screw member 17. Have been. Then, the screw member 17 is directly rotated. In the first embodiment described above, the screw member gear 21 disposed at the tip of the screw member 17 and the motor gear 11a are engaged via the bevel gear 21 (see FIG. 1). In the embodiment, the engagement between them is disconnected (see FIG. 7). That is, the reflecting mirror 3 and the screw member 17 can rotate independently of each other.

With the above configuration, the reflecting mirror 3 is rotated by the one stepping motor 11 through the reflecting mirror gear 3b, and the screw member 17 is rotated by the other stepping motor 12. Specifically, as shown in FIG. 8, the driving force of one stepping motor 11 and the other stepping motor 12 is transmitted to the reflecting mirror 3 and the screw member 17. Stepping motor 1
The method by which 1 rotates the reflecting mirror 3 is basically the same as that of the above embodiment.

Here, there are two methods for rotating the screw member 17 by the other stepping motor 12 to correct the optical path distance. One is that a predetermined screw groove is cut in the screw member 17 in accordance with the above-described equations (6) and (8) as in the first embodiment, and the one stepping motor 1
This is a method in which one and the other stepping motors 12 are synchronously rotated at a constant speed. The second method is a method in which grooves at regular intervals are formed in the screw member 17 and the other stepping motor 12 is driven to rotate according to Expression 6 to correct the optical path distance. In the second method, since the rotation speed of the stepping motor 12 can be changed by software, it is possible to relatively flexibly cope with a change in the positional relationship of the image reading device 31 with the read document G.

Third Embodiment Next, a second embodiment will be described with reference to FIG. First,
The stepping motor 12 directly drives the screw member 17 to move the light conversion means support member 15 in parallel. Also,
A so-called worm is formed at the tip of the screw member 17, and a worm gear is formed by combination with the reflecting mirror gear 3c. Thus, the reflecting mirror 3 is driven to rotate. FIG. 10 shows the stepping motor 12.
A state in which the rotational drive of (1) is transmitted to the screw member 17 and the reflecting mirror 3 is shown. The stepping motor 12 is driven according to the equation (14) shown in the first embodiment of the present invention, so that an image can be read with a constant scanning width. Thereby, the screw groove of the screw member 17 may be formed according to the equations (6) and (8) shown in the first embodiment.

With the above configuration, the number of components can be greatly reduced, and the rotation of the reflecting mirror 3 and the movement of the light conversion means support member 15 satisfy predetermined conditions as in the above embodiment. Can be controlled.

[0051]

The present invention is constructed and functions as described above,
Since the optical path length from the exit surface of the document to the condenser lens and the light conversion means is always kept substantially constant, fluctuations in the optical path distance from the reflecting mirror to the exit surface due to scanning by rotation of the reflecting mirror are absorbed, An excellent effect is obtained in that no distortion occurs in the read image even without performing special image conversion processing.

Further, since the positions of the condenser lens and the light converting means are moved, a condenser lens having a small depth of field can be used. For this reason, there is an excellent effect that a brighter lens can be used as the condenser lens.

Further, since the rod-shaped screw member and the guide member are used as a mechanism for correcting the optical path distance, the image reading apparatus can be made compact as a whole and the reading speed can be increased. Produces excellent effects.

Further, since the reading start point or the reading end point is immediately below the reflecting mirror, the change in the optical path length from the one-dimensional image sensor to the reading surface monotonically increases or monotonically decreases. Therefore, the optical path length can be corrected by the parallel movement in only one direction. Further, since the reading end point of the previous scan is the reading start point, there is no need to return the reflecting mirror to the original state at the end of scanning, and the next scanning can be started immediately. In addition, since the driving time of the light conversion means moving mechanism and the reflecting mirror can be suppressed, there is an excellent effect that power saving can be achieved as a whole device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a plan view of the image reading apparatus disclosed in FIG.

FIG. 3 is an explanatory diagram illustrating an optical arrangement of the image reading apparatus disclosed in FIG. 1;

FIG. 4 is an explanatory diagram showing a change in the position of an emission surface to be read due to a change in the angle of a reflecting mirror when reading an image.

FIG. 5 is an explanatory diagram showing a state in which an image is read, and FIG.
FIG. 5A shows a case where the reflector goes obliquely downward from vertically below, and FIG. 5B shows a case where it goes vertically downward from diagonally below.

FIG. 6 is an explanatory diagram showing a read image, and FIG.
6A shows a case where the reading start point is set vertically below the reflecting mirror, and FIG. 6B shows a case where the reading start point is set diagonally below.

FIG. 7 is a perspective view showing a second embodiment of the present invention.

FIG. 8 is a plan view of the image reading apparatus disclosed in FIG. 7;

FIG. 9 is a perspective view showing a third embodiment of the present invention.

FIG. 10 is a plan view of the image reading apparatus disclosed in FIG. 9;

FIG. 11 is an explanatory diagram showing an optical arrangement of a conventional image reading apparatus.

12 is an explanatory diagram showing a relationship between an angle formed between emitted light and a vertical direction and a change in an optical path distance when reading is performed by the image reading apparatus disclosed in FIG. 11;

FIG. 13 is an explanatory diagram showing barrel distortion generated in an image read without correcting the optical path distance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading device 3 Reflecting mirror 3a Rotation axis 5 Condensing lens 7 Light conversion means 9 Light conversion means moving mechanism 11 Drive mechanism (stepping motor) 13 Reading line (outgoing surface) 15 Light conversion means support member 17 Screw member 19 Guide member G manuscript

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 1/04-1/207

Claims (2)

(57) [Claims] 1. A light source for irradiating a document with predetermined light, a reflecting mirror for reflecting light emitted from the document by light emitted from the light source in different directions, and condensing light reflected from the reflecting mirror. a condenser lens, includes a light conversion means for converting the light transmitted through the condenser lens into an electric signal corresponding to an image, via a rotation axis parallel with the document as well as arranging the reflecting mirror at a predetermined position near the document A light conversion means which is rotatable, and the light conversion means is disposed integrally with the condenser lens in the reflection direction of the reflection mirror, and the light conversion means is movable relative to the reflection mirror. A driving mechanism is provided in the vicinity of the reflecting mirror to transmit a driving force to a rotation axis of the reflecting mirror and to transmit a driving force to the light converting means moving mechanism; Responds to changes in the distance to the document exit surface. Te, by adjusting the mutual distance of the reflector and the light converting means, the images reader that maintain a substantially constant optical path length from the exit slope to the light converting means, the exit surface of the vertically downward of said reflector Reading start point
An image reading apparatus, comprising: A light source for irradiating the original with predetermined light;
The light emitted from the document differs depending on the light from the light source.
Reflector that reflects light in the direction, and light reflected from this reflector
Lens that collects light and the light that has passed through the lens.
A light conversion means for converting the reflection mirror into an electric signal corresponding to an image;
Rotatable through a rotating shaft parallel to the
Replacement means with the condenser lens in the direction of reflection of the reflecting mirror.
And the light conversion means is
A light conversion means moving mechanism for allowing the mirror to move in the opposite direction, and a driving mechanism provided near the reflecting mirror to rotate the reflecting mirror.
To transmit the driving force to the shaft and to the light conversion means moving mechanism.
Transmits the driving force and changes the distance to the document exit surface due to the rotation of the reflector.
Adjust the distance between the reflecting mirror and the light converting means according to
And make the optical path distance from the exit slope to the light conversion means almost constant.
In the maintaining image reading device, maintain the angle of the reflecting mirror when the image reading is completed.
At the same time, when reading the next image, the drive mechanism is reversed.
An image reading apparatus characterized in that the reading is performed.