JP2002135534A - Image reader and image forming device provided with the image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can read an image clearly even when using a light source with a low luminous quantity or the like. SOLUTION: A control means 75 changes a period of a horizontal synchronizing signal to change an electric charge storage quantity of a CCD 67 with respect to the same incident luminous quantity, which is different from the way of a conventional image reader that changes an incident luminous quantity. The image reader of this invention can use a light source with less incident luminous quantity such as a light source without a luminous quantity adjustment device, a light source with a low luminous quantity or a light source whose luminous quantity is decreased because of the use for a long time. Furthermore, the image reader can prevent deterioration in the S/N and occurrence of blooming even when using the light source as above.

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 an image forming apparatus including the same, such as a copier, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art In an image reading apparatus used in combination with an image forming apparatus such as a copying machine, a CCD is used as an image sensor (image sensor) for converting an image into an electric signal.
(Charge Coupled Device) is often used.

This CCD uses incident light as light reflected from the image surface when the light source is moved relative to the image surface while irradiating the image surface of the document with the light source, and converts the incident light into electric charges. And accumulates the electric charge, and converts the accumulated electric charge into an electric signal. This electric signal is used as an image signal
For example, a laser scanner unit (exposure device) for a copier
Is input to The laser scanner unit controls ON / OFF of a laser beam according to the image signal, and forms an electrostatic latent image by exposing the uniformly charged surface of the photosensitive drum with the laser beam. The electrostatic latent image is then developed with a toner attached thereto as a toner image.

In the CCD, generally, the smaller the incident light amount, the smaller the accumulated charge amount, and the larger the incident light amount, the larger the accumulated charge amount.
Any of these causes a defect. That is, when the amount of incident light is small and the amplitude of the image signal converted into an electric signal is small, the S / N ratio is reduced, and a defect occurs that the image quality of the toner image is reduced. On the other hand, if the amount of light is too large, a charge overflow called "blooming" occurs, causing a defect that normal image reading cannot be performed. In general, the light source deteriorates as the use time (lighting time) elapses, the amount of emitted light decreases, and the S / N ratio decreases.

Therefore, conventionally, the amount of incident light has been adjusted to prevent the above-mentioned defects. That is, the light source is provided with a light amount adjusting function and the light amount of the light emitted from the light source is adjusted so that the incident light amount falls within an appropriate range.

[0006]

However, according to the above-mentioned conventional example, there is a problem that the light source has a light amount adjusting function (a light amount adjusting circuit) and thus becomes expensive.

Further, a light source having a light amount adjusting function that does not match the CCD, for example, a light source that cannot secure a sufficient light amount for the CCD even if the light amount is adjusted to the maximum, or a light source that has a light amount adjustment range that is too narrow. There is also a problem that it cannot be used.

Therefore, the present invention can use an inexpensive light source having a low light quantity without a light quantity adjustment function for a long period of time, and even when such a light source is used, the S / N ratio is reduced.
It is an object of the present invention to provide an image reading apparatus capable of preventing a reduction in the ratio and preventing occurrence of blooming, and an image forming apparatus including the same.

[0009]

An image reading apparatus according to a first aspect of the present invention incorporates a light source for illuminating the image surface while moving relative to the image surface of the original, and a light reflected on the image surface. A CCD that converts the light into electric charges and accumulates the electric charges, and outputs the accumulated electric charges as a voltage signal; and a control unit that controls the operation of these light sources and the CCD. The control means compares the reference value of the light amount of the light source with the actual light amount of the light source based on the output signal of the CCD, and changes the cycle of the horizontal synchronization signal input to the CCD based on the comparison value. Thus, the amount of charge stored in the CCD is changed, and the speed at which the light source is relatively moved with respect to the image plane is changed.

According to the present invention having such a configuration, the period of the horizontal synchronizing signal is changed by the control means to change the charge accumulation amount, unlike the conventional method in which the incident light amount is changed. As the light source, a light source without a light amount adjusting mechanism, a light source with a low light amount, a light source with a reduced light amount over a long period of use, or the like can be used. Moreover, even when such a light source is used, it is possible to prevent a reduction in the S / N ratio and the occurrence of blooming.

According to a second aspect of the present invention, there is provided an image forming apparatus, an image carrier, a charging unit for charging the surface of the image carrier, an image reader for reading image information on an image surface of a document, and the image reader. Exposure means for exposing the charged image carrier surface based on image information sent from to form an electrostatic latent image, and developing means for developing the electrostatic latent image as a toner image,
Transfer means for transferring the toner image on the image carrier to a transfer material,
Wherein the image reading device is the image reading device according to claim 1.

According to the present invention having such a configuration, the operation and effects of the above-described image reading apparatus can be received as a whole by the image forming apparatus, and further, the image forming apparatus can perform the S / S operation.
Since it is possible to appropriately read an image by preventing the reduction of the N ratio and the occurrence of blooming, a good electrostatic latent image can be formed by the exposure unit, and a good toner image can be formed. As a result, High quality image formation becomes possible.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Image Forming Apparatus) FIGS. 1 and 2 show an example of an image forming apparatus according to the present invention. here,
FIG. 1 is a schematic view of the internal configuration of a copying machine 10 as an image forming apparatus as viewed from the front side. FIG. 2 shows a copying machine 1
FIG. 2 is a perspective view showing an outer appearance of the copying machine, that is, a shape viewed from the outside of the copying machine main body 11.

First, an outline of the configuration of the copier 10 will be described mainly with reference to FIG. 1 and, where appropriate, with reference to FIG. 2, followed by a detailed description of the configuration.

The copying machine 10 includes a copying machine body 11 formed in a substantially rectangular parallelepiped shape. The copying machine body 11 includes three parts in the vertical direction, that is, a lower housing 12 and a connecting housing 13 and an upper housing 14. And, inside the lower housing 12,
From the bottom, in order from the bottom, the sheet feeding unit 15, the image forming unit 16, and the fixing unit 17
Is provided. The connection housing 13 is provided with a paper discharge unit 18 and a post-processing unit 20. From the paper supply unit 15 to the post-processing unit 20, the transfer material (for example, paper) P as an image formation target is arranged from bottom to top in order corresponding to being transported from below to above. An image reading section 21 is provided inside the upper housing 14.
The connection housing 13 described above has a paper discharge space S between the lower housing 12 and the upper housing 14 on the right side of the paper discharge unit 18.

Next, details of the configuration of each unit will be described in order from the paper supply unit 15.

The paper supply unit 15 includes a paper supply cassette 23 in which a plurality of transfer materials P are stored in a stacked state, and a paper supply cassette 23.
Paper feed roller 24 for feeding the transfer material P therein one by one, a manual feed tray 25 for the user to manually feed the transfer material, and a paper feed for feeding the transfer material set in the manual feed tray 25 A roller 26 and a registration roller 27 for temporarily stopping the transfer material P supplied from the paper feed rollers 24 and 26 and supplying the transfer material P in synchronization with the image forming unit 16
And As shown in FIG. 2, the paper feed cassette 23 is located at the front side (arrow a) of the user.
The transfer material P can be replenished or replaced with a transfer material P of a different size in the pulled-out state. As shown in FIG. 1, the manual feed tray 25 is swingably supported by the lower housing 12 via a shaft 25a on the base end side.
1 and a retracted position substantially upright along the left side surface of the copying machine main body 11.

The image forming section 16 includes a photosensitive drum 28 as an image carrier, a primary charger 30 (charging means) for uniformly charging the surface of the photosensitive drum 28, and exposing the surface of the photosensitive drum 28 after charging. (Exposure unit, for example, a laser scanner unit) 31 for forming an electrostatic latent image by applying the toner, a developing unit (developing unit) 32 for applying toner to the electrostatic latent image for development, and a photosensitive drum 28 A transfer charger (transfer roller) 33 for transferring the upper toner image onto the transfer material P supplied from the above-described registration roller 27, and a cleaner 34 for removing residual toner remaining on the surface of the photosensitive drum 28 after the transfer of the toner image. And The exposure unit 31 scans the surface of the photoconductor drum 28 with a laser beam that is turned on / off based on image information read by an image reading unit 21 described later.

The fixing unit 17 includes a fixing roller 36 having a built-in heater 35 and a pressure roller 3 pressed by the fixing roller 36 to form a fixing nip between the fixing roller 36 and the fixing roller 36.
7 is provided. In the above-described image forming unit 16, the transfer material P on which the toner image has been transferred to the surface thereof is
In the above, when the toner image passes through the fixing nip portion, the toner image is fixed on the surface by being heated and pressed.

The paper discharge unit 18 is provided with a transfer material P after the toner image is fixed.
The flapper 38 switches the transport path between the upper post-processing unit 20 side and the right discharge space S side, and the discharge paper that discharges the transfer material P from the flapper 38 toward the right discharge space S A roller 40 and a flat discharge plate 41 forming the bottom of the discharge space S are provided. The transfer material P discharged from the discharge roller 40 is stacked on the discharge plate 41 in a so-called face-down manner with the image surface (the surface on which the toner image is fixed) facing downward.

The post-processing unit 20 includes a feeding / conveying unit 42,
An alignment unit 43, a paper discharge tray 44, and a stapler 45 (see FIG. 2) as a post-processing device are provided.

The entire feeding / conveying unit 42 is disposed above the above-described paper discharge unit 18. The feeding / conveying unit 42
As shown in FIGS. 3 and 4, which are enlarged views, first and second switchable first flapper 46 and second flapper 47 for guiding the transfer material P conveyed from the paper discharge unit 18, An upper discharge roller 48, a lower discharge roller 50 for discharging the transfer material P guided by the second flapper 46, 47 toward the right alignment unit 43, and the alignment unit 43.
A retractable stopper 51 that regulates the position of the rear end of the transfer material P that has been discharged, and a transport roller 52 that transports the transfer material P on the alignment unit 43 toward the left discharge tray 44
And

Of these, the first and second flappers 46, 47
Can be switched to the positions shown in FIGS. When the position shown in FIG. 3 is taken, the transfer material P conveyed from the lower paper discharge unit 18 is guided to the upper and lower paper discharge rollers 48, 50. Further, when the position shown in FIG.
Thus, the transfer material P nipped and conveyed from the right is guided to the left discharge tray 44 side. In addition, the stopper 51 has an upright position protruding upward from the reference surface 59 shown in FIG. 3 and a retracted position retracting below the reference surface 59 shown in FIG. Further, the transport roller 52 has a retracted position shown in FIG. 3 retracted downward from the reference surface 59 and an operating position shown in FIG. 4 projected upward from the reference surface 59. When the transport roller 52 is in the retracted position, a gap is formed between the transport roller 52 and the upper lower discharge roller 50 so that the rear ends of the plurality of transfer materials P can enter. In addition, the lower discharge roller 50 also serves as a discharge roller and a transport roller. That is, in the state shown in FIG. 3, the lower discharge roller 50 discharges the transfer material P onto the intermediate tray 53 (described later) together with the upper discharge roller 48, while in the state shown in FIG. The transfer material P is sandwiched together with the rollers 52 and transported to the left.

As described above, the feeding / conveying unit 42 discharges the transfer material P conveyed from the lower paper discharge unit 18 to the right alignment unit 43, and also discharges the transfer material P discharged onto the alignment unit 43. P is carried out onto the left discharge tray 44.

The matching unit 43 is, as shown in FIG.
It is arranged so as to be adjacent to the right side of the feeding / conveying unit 42,
It is located above the above-mentioned paper discharge plate 41, that is, above the discharge space S. The alignment unit 43 includes the feeding / conveying unit 4
And an upper surface of the intermediate tray 53 (transfer material loading surface) supporting the transfer material P discharged from the second tray 53 from below.
A front shift member 54 movable substantially in the left-right direction along
Width shifting members 55 and 56 are provided that can move substantially in the front-rear direction along the upper surface of the intermediate tray 53. Front shifting member 5
4 reciprocates in the left and right direction each time the transfer material P is discharged onto the intermediate tray 53, and when the transfer material P moves to the left,
Is pressed to bring the rear end of the transfer material P into contact with the stopper 51, thereby aligning the position of the transfer material P on the intermediate tray 53 in the transport direction. On the other hand, each time the transfer material P is discharged onto the intermediate tray 53, the width shifting members 55 and 56 repeatedly approach and separate from each other, and press the edge of the transfer material P when approaching, whereby the intermediate tray 53 is pressed. The position of the transfer material P in the direction perpendicular to the transport direction of the transfer material P (hereinafter referred to as “width direction”) is aligned. In addition to the above-described alignment operation, the above-described width shifting members 55 and 56 move the transfer material P on the intermediate tray 53 to the front side (front side) and discharge the transfer material P onto the discharge tray 44. And the transfer material P on the intermediate tray 53 is similarly moved to a position corresponding to the stapler 45 on the front side, and the stapled transfer material P is moved.
Can be moved backward to return to the original position.

The paper discharge tray 44 is disposed on the left side of the paper supply / conveyance unit 42 and has paper discharge rollers 57 for discharging the transfer material P conveyed from the paper supply / conveyance unit 42 to the left side;
And a stacking portion 58 for supporting the discharged transfer material P from below.

The stapler 45 is for stapling a plurality of transfer materials P, and is arranged on the front side of the above-mentioned feeding / conveying unit 42 as shown in FIG.

The image reading section (image reading device) 21
A light-transmissive platen 60 on which the document D is placed with its image surface (image information) directed downward, an openable document pressing plate 61 for pressing the document D against the platen 60, and a platen 60 A scanning unit 62 that moves from left to right while irradiating the image surface G of the upper document D with light, mirrors 63, 64, and 65 that further reflect light reflected from the image surface G, and CC that reflects the reflected light.
A lens unit 66 that forms an image on the D67 and a CCD 67 that performs photoelectric conversion are provided. The document reading unit 21 performs so-called fixed reading in which the document D is fixed and the scanning unit 62 is moved. The image information read by the image reading section 21 is sent to the above-described exposure device 31. Such an image reading unit 2
On the front side of the upper housing 14 in which 1 is disposed,
An operation panel 68 operated by a user is provided.

In the copying machine 10 configured as described above, the document D placed on the document table 60 is scanned by the scanning unit 62 or the like, whereby the image surface (image information) G is read. The read image information is sent to the exposure device 31 of the image forming section 16.

On the other hand, in the image forming section 16, the photosensitive drum 28 is driven to rotate in the direction of the arrow, and the surface thereof is uniformly charged to a predetermined polarity and a predetermined potential by the primary charger 34. The surface of the photosensitive drum 28 after the charging is
Exposure based on the image information is performed by 1 to form an electrostatic latent image. The electrostatic latent image is developed as a toner image by attaching toner to the developing unit 32. The toner image thus formed on the photosensitive drum 28 is transferred to the surface of the transfer material P by the transfer charger 33.

The transfer material P is fed from a paper feed cassette 23 or a manual tray 25 of the paper feed unit 15 by a paper feed roller 24 or a paper feed roller 26,
, And is supplied to a transfer section between the photosensitive drum 28 and the transfer charger 33 in synchronization with the toner image on the photosensitive drum 28.

After the transfer of the toner image, the residual toner remaining on the surface of the photosensitive drum 28 is removed by the cleaner 34, and the photosensitive drum 28 is subjected to the next image formation.

On the other hand, the transfer material P after the transfer of the toner image is conveyed to the fixing unit 17, where it is heated and pressed by the fixing roller 36 and the pressing roller 37, and the toner image is fixed on the surface.

The transfer material P on which the toner image is fixed in this way
Differs depending on the presence or absence of post-processing as follows.

First, when there is no post-processing, the transfer material P on which the toner image has been fixed is guided to the right discharge roller 40 by the flapper 38 of the discharge section 18, and the right discharge roller 40 by the discharge roller 40. The sheets are discharged face-down on the discharge plate 41 with the image surface (the surface on which the toner image is formed) facing downward, and stacked one after another.

On the other hand, when there is post-processing, the transfer material P after fixing the toner image is conveyed to the upper feeding unit 20 by switching the flapper 38. The transferred transfer material P is moved upward and downward by the first and second flappers 46 and 47 disposed at the positions shown in FIG.
And discharged onto the intermediate tray 53. At this time,
The transport roller 52 is located at the retracted position, and the stopper 51 is located at the upright position. The leading end of the transfer material P discharged onto the intermediate tray 53 is pushed leftward by the forward moving member 54, and the rear end of the transfer material P is abutted against the stopper 51, whereby the position in the transport direction is aligned. Transferred transfer material P
At the same time, the left and right side ends are pressed by the width-shifting members 55 and 56, thereby aligning the positions in the width direction. Such an alignment operation is similarly performed on the transfer materials P that are successively discharged onto the intermediate tray 53.

When a predetermined number of transfer materials P to be stapled are stacked on the intermediate tray 53, the discharge of the transfer materials P is stopped. Thereafter, the width shifting members 55 and 56 in contact with the side edges of the transfer material P in the width direction move forward, and the front side of the rear end of the transfer material P is arranged at a position corresponding to the stapler 45. . The stapler 45 operates to bind a predetermined number of transfer materials P. Transfer material P after stapling
Is moved backward by the width shifting members 55 and 56 and returns to the original position. As shown in FIG. 4, the rear end of the returned transfer material P is sandwiched between the transfer roller 52 disposed at the operation position and the lower discharge roller 50. Then, the stopper 51 is moved to the retracted position shown in FIG.
The flappers 46 and 47 are disposed at the positions shown in FIG. 4, and the lower discharge roller 50 and the transport roller 52 rotate in the direction of the arrow, so that the stapled transfer material P is discharged to the left and discharged. The paper is discharged onto the stacking section 58 (see FIG. 1) by the paper discharge rollers 57 of the tray 44 and stacked.

(Image Reading Apparatus) Next, referring to FIGS. 5 and 6, an image reading section 21 (hereinafter, referred to as an image reading section) according to the present invention will be described.
This is referred to as “image reading device 21”. ) Will be described.
FIG. 5 is a schematic diagram showing a schematic configuration of the image reading device 21, and FIG. 6 is a control unit (control signal generation circuit).
It is a block diagram which shows control by 75.

The image reading device 21 according to the present invention includes a CCD 67, a light source (for example, a halogen lamp) 69, and a control unit 75 as main components shown in FIGS. The light source 69 is mounted on a moving frame (not shown) together with the above-mentioned mirror 63, and is mounted on the scanning unit 62.
The mirrors 64 and 65 are mounted on a moving frame (not shown) to form a mirror unit 71.

The image reading device 21 reads the image surface G of the document D as described above. As shown in FIG.
Is placed on the document table 60 with its image surface G facing downward. The image reading device 21 sequentially moves the scanning unit 62 and the mirror unit 71 to the right (sub-scanning direction) in FIG. 5 while irradiating the image plane G with a light source 69 as shown in FIG. To read.
Assuming that the moving speed of the scanning unit 62 at this time is V, the moving speed of the mirror unit 71 is V / 2.
Thereby, the optical path length during image reading, that is, the light source 69
And is reflected by the image surface G of the document D, further reflected by the mirrors 63, 64 and 65, and
The travel distance of the light passing through 6 and reaching the CCD 67 is
It is always the same during image reading. The CCD 67 will be described later in further detail.

The image information (image signal) read by the CCD 67 is transmitted to an A / D conversion circuit 7 as shown in FIG.
2, after being A / D converted, input to the image processing circuit 73, and various image processing such as black correction and shading correction is performed as digital data. The image data subjected to the image processing is temporarily stored in a memory 74 for an image editing function, and is stored in the image forming unit 16 at a necessary timing.
It is output to an exposure unit (LSU: laser scanner unit) 31 (see FIG. 1). Writing to the memory 74 is performed at a required speed on the image reading device 21 side, and reading from the memory 74 is performed at a required speed on the exposure device 31 side as an image writing unit. Since the image data is temporarily stored in the memory 74 as described above, the reading speed and the writing speed need not always be the same. The above-mentioned CCD 67, A / D conversion circuit 72, image processing circuit 7
3, memory 74, scan motor (drive means) 7 described later
The operation of each of the control units 6 is controlled by a control unit (control signal generation circuit) 75.

The above-mentioned CCD 67 is, for example, a one-chip photoelectric conversion element in which several thousands of light receiving elements of several microns square are arranged in a line. A photodiode is used as the light receiving element, and one photodiode corresponds to one pixel. When light is applied to the photodiode, the photodiode generates charges corresponding to the amount of light, and the generated charges are stored in the storage electrode of the photodiode. Then, the electric charge accumulated in the photodiode is converted into a voltage signal, and the voltage signal is output to the A / D conversion circuit based on the horizontal synchronization signal output from the control means to the CCD 67. Here, the cycle of the voltage signal output from the CCD is determined according to the cycle (speed) of the horizontal synchronization signal, and the resolution (sub-scanning line density) in the sub-scanning direction is determined accordingly. In other words,
By changing the period of the horizontal synchronizing signal, the resolution in the sub-scanning direction changes. Generally, the control unit controls the cycle of the horizontal synchronization signal so that the resolution in the sub-scanning direction has the same value as the resolution in the main scanning direction.

By changing the cycle of the horizontal synchronizing signal as described above, the charge accumulation time can be changed in addition to the resolution in the sub-scanning direction. For example, when the amount of incident light is the same, if the output of the voltage signal is delayed by lengthening the cycle of the horizontal synchronization signal, the charge accumulation time becomes longer, the charge accumulation amount increases, and the output signal increases. In this case, S /
The N ratio increases, and the image quality of the toner image increases. However, as described above, if the accumulation time is too long, the CCD 67
Causes blooming.

Here, the light amount of the light source 69 and the sensitivity of the CCD 67 vary from one individual to another. Therefore, by changing the cycle of the horizontal synchronizing signal according to the level of the output signal of the CCD 67, it is possible to read an image with incident light optimal for the CCD 67.

Therefore, the reference value of the cycle of the horizontal synchronizing signal is
An original (or a standard white plate) having a reference density is read in advance, and is determined in advance based on the output level of the CCD 67 at that time. The reading of the reference document is performed, for example, when the copier is shipped from the factory. Then, at the time of maintenance after shipment from the factory, a document (or a standard white plate) having a reference density is periodically read, and the CCD 67 at that time is read.
Is compared with a reference value, and the period of the horizontal synchronizing signal is changed based on the comparison value. This allows
Light amount change of light source 69 (for example, light amount decrease due to deterioration)
Can be supplemented.

That is, the image reading apparatus 2 according to the present invention
1, when the light amount of the light source 69 is small, the charge accumulation time of the CCD 67 can be lengthened by lengthening the cycle of the horizontal synchronization signal. As a result, the charge accumulation amount of the CCD 67 can be increased and the output signal (voltage signal) from the CCD 67 can be increased, so that the S / N ratio can be increased and the image quality of the toner image can be improved. Therefore, a light source without a light amount adjustment function, a light source with a low light amount, and a light source with a reduced light amount for a long period of use can be used satisfactorily, which is economical.

The image reading apparatus 21 according to the present invention
Does not require a light amount adjustment circuit for adjusting the light amount of the light source 69 as in the conventional example, and a stable voltage signal can be output from the CCD by the existing components, so that the product price can be reduced. be able to.

As described above, it is known that, when the cycle of the horizontal synchronizing signal is changed, the resolution in the sub-scanning direction changes accordingly. Therefore, in the present invention,
By controlling a scan motor 76 (see FIG. 5) that drives the scanning unit 62 and the mirror unit 71, the moving speed of the scanning unit 62 and the mirror unit 71 is changed,
Thereby, the image reading speed is changed.
Specifically, when the period of the horizontal synchronization signal is increased,
Since the resolution in the sub-scanning direction is reduced, the speed of the scanning unit 62 and the like is reduced accordingly, and the image reading speed is reduced. This prevents a reduction in resolution. vice versa,
When the cycle of the horizontal synchronizing signal is shortened, the resolution in the sub-scanning direction increases, and accordingly, the speed of the scanning unit 62 and the like is increased to increase the image reading speed. This prevents an increase in resolution.

In the above description, the case where the image reading device 21 fixedly reads the image surface G of the original D has been described. However, the same applies to the case where the original reading mechanism is used to perform the flow reading using the original feeding mechanism (not shown). Actions and effects can be improved.

In the above description, the case where the image forming apparatus is an electrophotographic copying machine has been described. However, the present invention can be applied not only to the copying machine but also to a printer or a facsimile.

[0052]

As described above, according to the present invention, in order to change the charge storage amount, unlike the conventional method of operating the light source to change the amount of light incident on the CCD, the control means controls the horizontal synchronization signal. , The light source may be a light source without a light amount adjustment mechanism, a light source with a low light amount, or a light source with a reduced light amount due to long-term use. In addition, while such a light source can be used, a reduction in the S / N ratio and the occurrence of blooming are prevented, so that it is possible to effectively prevent the image quality of the toner image from deteriorating and the image reading from becoming impossible. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus (copier) according to the present invention.

FIG. 2 is a perspective view showing an external shape of the copying machine.

FIG. 3 is a diagram illustrating how a transfer material after a toner image is fixed is discharged to an intermediate tray.

FIG. 4 is a diagram for explaining how to discharge a transfer material after stapling.

FIG. 5 is a schematic configuration diagram of an image reading device.

FIG. 6 is a block diagram illustrating control of a CCD and a scan motor by a control signal generation circuit.

[Description of Signs] 10 ... copier (image forming apparatus), 16 ... image forming unit, 21 ... image reading device (image reading unit), 28 ...
.. Photosensitive drum (image carrier), 30 primary charger (charging unit), 31 exposure unit (exposure unit), 32 development unit (developing unit), 33 transfer charger (transfer unit) ), 6
7 ... CCD, 69 ... Halogen lamp (light source), 75
... Control means (control signal generation circuit), D ... Document, G ...
… Image surface, P …… Transfer material

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H076 AA07 AA35 AA58 BA68 BA95 2H108 AA01 CA01 CB01 5B047 AA01 BA02 BB02 BC11 CA08 CB04 5C072 AA01 BA11 CA02 EA05 FB19 MB02 RA13 XA01

Claims (2)

[Claims] 1. A light source for illuminating the image surface while moving relative to the image surface of a document, taking in light reflected on the image surface, converting the light into electric charge, accumulating the light, and accumulating the accumulated electric charge. And a control means for controlling the operation of the light source and the CCD, wherein the control means comprises: a reference value of the light amount of the light source, an actual light amount value of the light source, Are compared based on the output signal of the CCD, and based on the comparison value, the period of the horizontal synchronization signal input to the CCD is changed to change the charge accumulation amount of the CCD and the speed at which the light source is relatively moved to the image plane. An image reading device characterized by changing the following. 2. An image bearing member, a charging unit for charging the surface of the image bearing member, an image reading device for reading image information on an image surface of a document, and a charging device based on image information sent from the image reading device. Exposure means for exposing the surface of the image carrier to form an electrostatic latent image, developing means for developing the electrostatic latent image as a toner image, and transfer for transferring the toner image on the image carrier to a transfer material 2. An image forming apparatus comprising: an image reading apparatus according to claim 1, wherein the image reading apparatus is the image reading apparatus according to claim 1;