JP2002323724A - Structure for holding flexible circuit board for driving light source of image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange a flexible circuit board which connects an inverter circuit for driving a light source and a power supply via the space between a full rate carriage and a half rate carriage so that the flexible circuit board does not protrude upwards by bending in an image reader of the stationary document read type. SOLUTION: A circuit board holding member 20 is fixed in front of a half rate carriage 4 by taking the direction of a circuit board guide part 22 which orthogonally crosses the moving direction of the half rate carriage 4 as the longitudinal direction. The guide surface 22a of the circuit board guide part 22 is formed as a round smooth surface so that a flexible circuit board 16 can easily slide thereon. A tongue-shaped piece 23 for preventing bending is provided opposite to this guide surface 22a. A tongue-shaped piece 24 for preventing disengagement is provided at the front end of the circuit board guide part 22. The flexible circuit board 16 is guided by the circuit board guide part 22 from a floor plate 2c of a casing 2 to the inverter circuit of the full rate carriage 3.

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 which irradiates a document placed on a platen glass with light while moving a light source lamp, and reads data relating to an image formed on the document from the reflected light. More particularly, the present invention relates to a structure for holding a flexible circuit board connected to an inverter circuit of the light source lamp.

[0002]

2. Description of the Related Art An image reading apparatus, such as a copying machine or a scanner, which reads image data of a document shown on a paper surface and provides it to various processings, irradiates the document with light from a light source lamp such as a fluorescent lamp and the like. The reflected light is made to enter a light receiving section provided with a photoelectric conversion device such as a CCD. In an original reading type image reading apparatus, light from a light source lamp is applied to an original placed on a platen glass while moving the light source lamp. The light source lamp is mounted on a carriage so that the carriage moves. The carriage also has an inverter circuit for the light source lamp.

Since the light source lamp must irradiate the entire area of the original even with the maximum size of the original, the carriage moves from a position facing one end of the platen glass to a position facing the other end. That is, the carriage on which the light source lamp is mounted is a full rate carriage.

On the other hand, a reflecting mirror is used to guide the reflected light from the document to the light receiving portion, and the optical path length from the document to the light receiving portion needs to be kept constant even when the irradiation position on the document changes. There is. In order to keep the optical path length constant, a half-rate carriage that moves in the same direction at half the speed of the full-rate carriage in synchronization with the full-rate carriage is used. A second reflecting mirror and a third reflecting mirror are mounted on this half-rate carriage, and reflected light from the original is reflected by a first reflecting mirror mounted on the full-rate carriage, and sequentially reflected by a second reflecting mirror and a third reflecting mirror. The light is reflected and guided to the light receiving unit.

Incidentally, the inverter circuit and the power supply device are connected by a flexible circuit board having flexibility so as not to impair the smoothness of movement of the full rate carriage. The flexible circuit board has a bottom surface of a housing accommodating the carriage crawling from a position near a movement destination of the full-rate carriage during scanning, and reaches the inverter circuit via the half-rate carriage. Therefore, the half-rate carriage is appropriately curved and directed in the opposite direction, and passes through the air to reach the full-rate carriage.

Conventionally, this flexible circuit board holding structure is such that a guide pulley is supported on the opposite side of the half rate carriage from the full rate carriage, that is, on the back side, and the half pulley is inverted by passing through the guide pulley. It passes over and reaches the full rate carriage.

Further, for example, the image reading apparatus described in Japanese Patent Application Laid-Open No. 2000-78367 has a structure in which an elastic member for applying a tension to a power supply cable is provided.

[0008]

However, in the above-described conventional holding structure, since the guide pulley is provided on the back side of the half-rate carriage, it is in a standby position for waiting for scanning the image of the original. The guide pulley is located between the half-rate carriage and the side wall of the housing. For this reason, a space for the guide pulley is required between the half-rate carriage and the housing, and this space must be ensured, and the housing is made large, which hinders miniaturization of the image reading apparatus.

In the image reading apparatus described in Japanese Patent Application Laid-Open No. 2000-78367, since the power supply cable passes through the back side of the half-rate carriage, a space for passing the power supply cable is provided between the full-rate carriage and the wall surface of the housing. It is necessary to secure in between. Further, an elastic member for tensioning the power supply cable is required, and this elastic member becomes expensive, which may increase the cost of the image reading apparatus.

If the flexible circuit board is inverted on the front side of the half-rate carriage, no guide pulley or the like protrudes from the rear side, so that the half-rate carriage at the standby position can be brought as close as possible to the side wall of the housing. This is preferable for reducing the size of the image reading apparatus by reducing the size of the housing. Moreover, in the case of the structure passing through the rear side of the half-rate carriage, the length of the flexible circuit board is longer than that of the structure passing through the front side of the half-rate carriage. Via the front side of the vehicle.

However, the flexible circuit board is provided so as not to impair the smoothness and stability of the movement of the carriage.
Those having a length that allows some margin even when these move are used. In addition, both the rising angle when the flexible circuit board laid on the bottom of the housing reaches the front side of the half-rate carriage and the angle when the flexible circuit board reaches the full-rate carriage from the front side are compared with the state where the flexible circuit board passes through the rear side. growing. For this reason, in particular, the portion from the front side to the full rate carriage may be bent and bulged upward by the movement of the carriage. If it is swelled upward, the optical path from the first reflecting mirror of the full rate carriage to the second reflecting mirror of the half rate carriage may be blocked.

In the structure in which the flexible circuit board passes through the rear side of the half-rate carriage, if the guide pulley is urged to protrude, appropriate tension can be applied to the flexible circuit board, and the length of the extra length can be provided. Is not appropriately absorbed and is not carelessly bent. On the other hand, in the structure passing through the front side of the half-rate carriage, it is difficult to apply appropriate tension to the flexible circuit board, and the flexible circuit board may be inadvertently bent.

Therefore, the present invention provides a flexible circuit board that is not inadvertently moved even if the flexible circuit board is reversed by passing through the front side of the half-rate carriage. It is an object of the present invention to provide a structure for holding a flexible circuit board for driving a light source of an image reading apparatus, which is prevented from bending.

[0014]

As a technical means for achieving the above object, a holding structure of a flexible circuit board for driving a light source of an image reading apparatus according to the present invention includes a light source and a first reflecting mirror. Full rate carriage and the second
A half-rate carriage on which a reflecting mirror and a third reflecting mirror are mounted; and irradiating the original with light from the light source while moving these carriages along the original. A mounting plate portion mounted on the half-rate carriage in the holding structure for the light source driving flexible circuit board of the image reading device that sequentially reflects the image data with the second reflecting mirror and the third reflecting mirror and reads the image information; A board guide portion having a base end portion fixed to the plate portion and having a guide surface for guiding a curved portion of the flexible circuit board; and a side of the flexible circuit board curved and guided by the guide surface toward the full rate carriage. The board holding member consisting of a flexible tongue to prevent the flexible circuit board from bulging upward, It is characterized in that disposed in the portion facing the full rate carriage in the carriage.

The flexible circuit board crawled on the bottom surface of the housing of the image reading device is bent and bent by the board guide portion of the board holding member, and is connected to an inverter circuit mounted on a full rate carriage. When the flexible circuit board is bent from the board guide portion due to movement of the carriage or the like and is about to float, the flexible circuit board abuts on the bending preventing tongue piece to prevent the flexible circuit board from rising. Therefore, the flexible circuit board does not block the optical path from the first reflecting mirror to the second reflecting mirror.

According to a second aspect of the present invention, in the holding structure of the flexible light source driving circuit board of the image reading apparatus, the bending preventing tongue is provided so as to extend from the mounting plate to a position facing the flexible circuit board. It is characterized by that.

When connecting the flexible circuit board to the bending preventing tongue piece, the flexible circuit board is hooked on the board guide section from the front end side of the board guide section. Therefore, the flexible circuit board can be easily inserted into the board guide portion.

According to a third aspect of the present invention, in the structure for holding the flexible circuit board for driving the light source of the image reading apparatus, the bending preventing tongue is extended from the front end of the board guide to the position facing the flexible circuit board. It is characterized by being provided.

The flexible circuit board is passed over the mounting plate and hooked on the board guide. Since the bending prevention tongue is provided at the tip of the board guide, the flexible circuit board does not fall off from the tip of the board guide, nor does it fall from the mounting plate.

According to a fourth aspect of the present invention, in the image reading apparatus, the light source driving flexible circuit board holding structure is provided such that the distal end of the board guide extends to a position facing the curved portion of the flexible circuit board. It is characterized in that a tongue piece is provided.

When the flexible circuit board tries to come off from the board guide portion, the flexible circuit board is engaged with the come-off prevention tongue to prevent the flexible circuit board from coming off.

According to a fifth aspect of the present invention, in the image reading apparatus, the light source driving flexible circuit board holding structure is characterized in that the board holding member is integrally formed.

The mounting plate portion, the board guide portion, the bending prevention tongue piece and the like can be separated and assembled by screwing or the like. However, if they are integrally formed of synthetic resin or the like, the assembly time and the like can be reduced. The installation work becomes simpler.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a holding structure of a flexible circuit board for driving a light source of an image reading apparatus according to the present invention will be described in detail with reference to preferred embodiments shown in the drawings.

FIG. 10 is a perspective view for explaining a schematic structure of an image reading apparatus 1 suitable for mounting the image data correcting apparatus according to the present invention.

Two guide plates 2b and 2e are provided in the form of shelves on the inner surface of the longitudinal wall 2a of the housing 2 of the image reading apparatus 1, and these guide plates 2b and 2e are provided with a full-rate carriage 3 and a half-rate. Each of the carriages 4 is mounted thereon, and these carriages 3 and 4 are guided by guide plates 2b and 2e, respectively, and move in the longitudinal direction of the housing 2. A platen glass 15 (shown in FIG. 9) is attached to the upper surface of the housing 2, and a document is placed on the platen glass 15. A light source lamp 5 such as a fluorescent lamp is mounted on the full rate carriage 3, and the light source lamp 5 irradiates a document. An imaging lens 6 and a photoelectric conversion device 7 such as a CCD (charge imaging element) are provided at appropriate positions on the bottom plate 2c of the housing 2.

As shown in FIG. 9, the full-rate carriage 3 is provided with a first reflecting mirror 8, and the half-rate carriage 4 is provided with a second reflecting mirror 9 and a third reflecting mirror 10. The light emitted by the light source lamp 5 and reflected by the original is reflected by the first reflecting mirror 8, the second reflecting mirror 9, and the third reflecting mirror 1.
0, the light is sequentially reflected, passes through the imaging lens 6, and enters the photoelectric conversion device 7. The first reflecting mirror 8, the second reflecting mirror 9, and the third reflecting mirror 10 An optical path S reaching the photoelectric conversion device 7 is formed.
When the image information of the document is to be acquired, the entire area of the document must be irradiated. Due to the movement of the full rate carriage 3, the length of the optical path S reaching the photoelectric conversion device 7 must be constant. Therefore, the half-rate carriage 4 moves in synchronization with the full-rate carriage 3 by a movement amount of approximately の of the movement amount of the full-rate carriage 3 so that the optical path S has a constant length. . The driving of the full-rate carriage 3 and the half-rate carriage 4 is performed by pulleys 11 and 1 appropriately arranged.
A known mechanism including a wire 14 wound around 2, 13, and the like is used.

An inverter circuit (not shown) of the light source lamp 5 is mounted on the full rate carriage 3, and the inverter circuit includes a power supply device and a control device (not shown) arranged outside the housing 2 by the flexible circuit board 16. And so on. This flexible circuit board 16
Is introduced into the housing 2 from the vicinity of the photoelectric conversion device 7 at the movement destination of the full-rate carriage 3 during scanning, and passes through the front surface of the half-rate carriage 4 (the surface on the full-rate carriage 3 side). Carriage 3
Inverter circuit. A board holding member 20 is attached to the front surface of the half-rate carriage 4 and guides the flexible circuit board 16.

FIGS. 1 to 4 show the substrate holding member 20.
1 is a perspective view, FIG. 2 is a plan view, FIG. 3 is a side view, and FIG. 4 is a rear view, each showing a state in which a flexible circuit board 16 is connected. ing. The substrate holding member 20 is attached to a bracket plate (not shown) protruding from the front surface of the half-rate carriage 4 by a mounting plate 21 by screwing, bonding, or another method. It has a built structure. The substrate guide portion 22 is provided so as to project in a direction orthogonal to the moving directions P ₁ -P ₂ of the carriages 3 and 4. Note that indicates the scanning direction Yashirube P ₁ reads an image of a document, shows the return direction is Yashirube P _2. Surface of the returning direction P ₂ side of the board guide 22 has guide surfaces 22a is formed to the surface by a suitable shape smooth surface is slippery flexible circuit board 16.

At the upper end edge of the mounting plate portion 21, a support portion 23a which is appropriately protruded upward is extended, and the front end portion of the support portion 23a extends substantially parallel to the board guide portion 22. A bending prevention tongue piece 23 is provided in a state facing the surface 22. That is, the bending preventing tongue piece 23 faces the upper side of the flexible circuit board 16 whose direction has been changed by being guided by the board guide portion 22, and prevents the upper side portion from rising upward. It is.
Further, as shown in FIG. 2, the bending preventing tongue piece 23 is arranged so as to be deflected to the front side of the substrate guide portion 22.

A distal end of the substrate guide portion 22 is provided with a guide portion 24a extending in a rearward direction, and a distal end portion of the guide portion 24a is connected to the guide surface 22 of the substrate guide portion 22.
a tongue piece 2 formed by bending to a position facing a
4 are provided.

In the holding structure for the light source driving flexible circuit board of the image reading apparatus according to the first embodiment configured as described above, the mounting plate portion 21 is mounted at an appropriate position on the front surface of the half-rate carriage 4. At this time, the longitudinal direction of the substrate guide portion 22 is set to a direction substantially orthogonal to the moving direction of the half-rate carriage 4. The flexible circuit board 16 connected to an unillustrated power supply device or the like and creeping along the bottom plate 2c of the housing 2 and connected to an inverter circuit (not shown) mounted on the full rate carriage 3 is appropriately bent. The part is inserted from the front end side of the substrate guide part 22 and connected to the substrate guide part 22. At this time, the flexible circuit board 16 is
A state in which the board passes between the substrate guide portion 22 and the bending preventing tongue piece 23 is set.

When the flexible circuit board 16 is connected to the board holding member 20 as described above, as shown in FIG. 9, the flexible circuit board 16 is connected to a power supply (not shown) and drawn into the housing 2 from the bottom plate 2c of the housing 2. Circuit board 16
Are connected to an inverter circuit (not shown) mounted on the full rate carriage 3 via the substrate holding member 20. In this state, when the full-rate carriage 3 and the half-rate carriage 4 move for scanning, the flexible circuit board 16 is pulled by the movement of the full-rate carriage 3 and slides on the board guide surface 22 a of the board holding member 20. The flexible circuit board 16 is paid out toward the full rate carriage 3. At this time, when the flexible circuit board 16 is about to float, as shown by the imaginary line in FIG. 4, the flexible circuit board 16 comes into contact with the bending prevention tongue piece 23 and is prevented from further rising. Therefore, the flexible circuit board 16 is prevented from protruding upward and bulging. For example, in the state shown in FIG. 9, when the portion from the board holding member 20 of the flexible circuit board 15 to the inverter circuit of the full rate carriage 3 bulges upward, the optical path S from the first reflecting mirror 8 to the second reflecting mirror 9 is increased. However, since the flexible circuit board 16 is prevented from bending upward as described above, the optical path S is not blocked.

When the flexible circuit board 16 attempts to fall off, the flexible circuit board 16 engages with the detachment preventing tongue piece 24, thereby preventing the flexible circuit board 16 from accidentally falling off.

[0035] When the scanning is moved in the direction P ₂ the return carriage 3 and 4 completed, the flexible circuit board 1
6 is pushed in, and returns to a state where it is crawled along the bottom plate 2 c of the housing 2 from the board guide portion 22. At this time, the flexible circuit board 1 is in contact with the detachment preventing tongue piece 24 even if the flexible circuit board 1
6 does not come off the substrate guide portion 22.

Next, a description will be given of a second embodiment of the holding structure of the flexible circuit board for driving the light source of the image reading apparatus according to the present invention shown in FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, FIG. 5 is a perspective view, FIG. 6 is a plan view, FIG. 7 is a side view, and FIG. This shows a state in which the substrates 16 are linked.

The mounting plate 31 of the substrate holding member 30
Is the moving direction P of the carriages 3 and 4.₁ −P₂Orthogonal to
The substrate guide portion 32 is protruded in the direction shown in FIG. The arrow
Mark P ₁ Indicates the scanning direction. The board guide section
32 return directions P₂ The side surface is a smooth surface and the guide surface 32
a is formed.

At the upper edge of the tip of the substrate guide 32,
A support portion 33a appropriately protruding upward is extended, and a bending preventing tongue piece 33 is provided at a distal end of the support portion 33a so as to face the substrate guide portion 32 substantially in parallel with the substrate guide portion 32. . The bending tongue piece 33 prevents the flexible circuit board 16 from floating, similarly to the bending prevention tongue piece 23 according to the first embodiment.

Further, a tongue piece 34 is provided at the tip end of the board guide section 32 via a guide section 34a, similarly to the board holding member 20 according to the first embodiment.

Also in the flexible circuit board holding structure according to the second embodiment, the flexible circuit board 16 crawled along the bottom plate 2c of the housing 2
At 0, the direction is changed and guided to the inverter circuit mounted on the full rate carriage 3. The flexible circuit board 16 includes a board guide portion 32 and a tongue piece 33 for preventing deflection.
Between the two.

Even if the portion of the flexible circuit board 16 between the board holding member 30 and the full-rate carriage 3 tends to rise when the full-rate carriage 3 and the half-rate carriage 4 are moved, the tongue piece for preventing deflection is provided. 33, and it is prevented that it bulges upward by protruding. Therefore, the flexible circuit board 16 does not block the optical path S.

When the flexible circuit board 16 attempts to fall off, the flexible circuit board 16 is engaged with the detachment preventing tongue piece 34, thereby preventing the flexible circuit board 16 from accidentally falling off.

In the structure for holding a flexible circuit board according to the second embodiment, when the mounting plate 31 is mounted on the front surface of the half-rate carriage 4, the flexible circuit board 16 is mounted on the board guide 32. Attachment to the 32 from the tip side becomes complicated. For this reason, the flexible circuit board 16 is
Are attached to the bracket plate (not shown) protruding from the front surface of the half-rate carriage 4.

On the other hand, in the flexible circuit board holding structure according to the second embodiment, as compared with the structure according to the first embodiment, the flexible circuit board 16 has a board holding member 30.
Can be reliably prevented from dropping off. For this reason, in the holding structure according to the second embodiment, a structure without the detachment preventing tongue piece 34 may be used.

[0045]

As described above, according to the structure for holding the flexible circuit board for driving the light source of the image reading apparatus according to the present invention, the flexible circuit board crawled along the bottom plate of the housing can be mounted on the half-rate carriage. Even when the flexible circuit board is led to the inverter circuit mounted on the full rate carriage via the front surface, the flexible circuit board does not bend inadvertently, and the optical path of the reflected light from the document to the photoelectric conversion device may be blocked. Absent. For this reason, the flexible circuit board can pass through the front side of the half-rate carriage, and there is no need to provide a pulley or the like for guiding the flexible circuit board on the back side of the half-rate carriage. Therefore, the half-rate carriage at the standby position can be brought as close as possible to the side wall of the housing, and the size of the housing can be reduced, and the size of the image reading apparatus can be reduced.

According to the structure for holding the flexible circuit board for driving the light source of the image reading apparatus according to the second aspect of the present invention, the flexible circuit board is mounted on the half-rate carriage and the flexible circuit board is moved from the tip of the board guide section. Since the substrate can be attached to the substrate guide portion and linked, the operation of attaching the flexible circuit board to the substrate holding member is simplified.

According to the third aspect of the present invention, even if the flexible circuit board tries to fall off from the board guide portion, the flexible circuit board is engaged with the bending preventing tongue. Therefore, falling off is prevented.

According to the structure for holding the flexible circuit board for driving the light source of the image reading apparatus according to the fourth aspect of the present invention, even if the flexible circuit board tries to drop from the board guide portion due to inadvertent bending, etc. Since it is engaged with the prevention tongue, it is prevented from falling off. In particular, in the case where the bending prevention tongue is provided on the side of the mounting plate portion, the flexible circuit board is engaged with the separation prevention tongue at the distal end portion of the board guide portion and falls off from the board guide portion. Is reliably prevented.

According to the structure for holding the flexible circuit board for driving the light source of the image reading apparatus according to the fifth aspect of the present invention, the board holding member can be formed by a synthetic resin or the like. The resin can easily provide the substrate guide portion of the substrate holding member with smoothness.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a board holding member of a holding structure of a flexible circuit board for driving a light source of an image reading apparatus according to the present invention, and also shows a flexible printed board.

FIG. 2 is a plan view of the substrate holding member shown in FIG. 1 and also shows a flexible circuit board.

FIG. 3 is a side view of the board holding member shown in FIG. 1 and also shows a flexible circuit board.

FIG. 4 is a rear view of the substrate holding member shown in FIG. 1 and also shows a flexible circuit board.

FIG. 5 is a perspective view showing another embodiment of the board holding member of the holding structure of the flexible light board for driving the light source of the image reading apparatus according to the present invention, which also shows the flexible circuit board.

FIG. 6 is a plan view of the substrate holding member shown in FIG. 5 and also shows a flexible circuit board.

FIG. 7 is a side view of the board holding member shown in FIG. 5, and also shows a flexible circuit board.

FIG. 8 is a rear view of the board holding member shown in FIG. 5 and also shows a flexible circuit board.

FIG. 9 is a side view schematically showing an image reading device provided with a holding structure of a light source driving flexible circuit board of the image reading device according to the present invention.

FIG. 10 is a perspective view schematically showing an image reading apparatus provided with a holding structure of a light source driving flexible circuit board of the image reading apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Housing 2c Bottom plate 3 Full rate carriage 4 Half rate carriage 5 Light source lamp 6 Imaging lens 7 Photoelectric conversion device 8 First reflecting mirror 9 Second reflecting mirror 10 Third reflecting mirror 16 Flexible circuit board 20 Board holding member 21 Mounting plate portion 22 Board guide portion 22a Guide surface 23 Deflection prevention tongue 23a Supporting portion 24 Detachment prevention tongue 24a Guide portion 30 Substrate holding member 31 Mounting plate 32 Substrate guide 33 Deflection prevention tongue 33a Support portion 34 Detachment prevention tongue Piece 34a guide part

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) H04N 1/107 F term (Reference) 2H108 AA01 CA01 CB01 5B047 AA01 BA02 BB02 BC05 BC09 BC11 BC20 BC30 5C062 AA05 AB33 AD06 BA01 5C072 AA01 BA01 CA02 CA20 DA02 DA04 EA05 LA02 XA01

Claims (5)

[Claims] 1. A full-rate carriage on which a light source and a first reflecting mirror are mounted, and a half-rate carriage on which a second reflecting mirror and a third reflecting mirror are mounted, and these carriages are moved along a document. Irradiating the original with light from the light source, and reflecting the reflected light on the first reflector and the second reflector;
In a holding structure for the light source driving flexible circuit board of an image reading device that sequentially reads and reflects image information with a third reflecting mirror, a mounting plate portion mounted on the half-rate carriage; A fixed portion, a board guide portion having a guide surface for guiding a curved portion of the flexible circuit board, and a flexible circuit board curved and guided by the guide surface, at a position facing the side facing the full rate carriage, A light source driving apparatus for an image reading apparatus, wherein a substrate holding member comprising a bending preventing tongue for preventing the flexible circuit board from bulging upward is disposed at a portion of the half rate carriage facing the full rate carriage. Flexible circuit board holding structure. 2. The flexible circuit board for driving a light source of an image reading apparatus according to claim 1, wherein the bending preventing tongue piece is provided so as to extend from the mounting plate to a position facing the flexible circuit board. Holding structure. 3. The light source driving apparatus according to claim 1, wherein the bending prevention tongue is provided so as to extend from a front end portion of the board guide portion to a position facing a flexible circuit board. Flexible circuit board holding structure. 4. A detachable tongue piece extending to a position facing a curved portion of a flexible circuit board is provided at a distal end portion of the board guide section. A holding structure of a flexible circuit board for driving a light source of the image reading apparatus according to the above. 5. The holding structure of a flexible circuit board for driving a light source of an image reading apparatus according to claim 1, wherein said board holding member is integrally formed.