JP4095327B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus that scans a document and reads an image with an image sensor such as a CCD line sensor, and an image forming apparatus including the image reading apparatus.
[0002]
[Prior art]
Conventionally, as shown in Japanese Patent Laid-Open No. 6-308627, an image reading apparatus of this type has been proposed as shown in FIG.
[0003]
In FIG. 2, reflected image light is generated by the light irradiated by the light source 113 b provided on the first carriage 113 on the document 111 placed on the document table 112 on the image reading device 117. After being reflected by the reflecting members 113a, 114a, and 114b provided on the first carriage and the second carriage, a line image is formed on the CCD (imaging device) 116 via the imaging lens 115. Such an apparatus uses a reduction optical system.
[0004]
Then, by moving the first carriage and the second carriage in the direction perpendicular to the line direction (main scanning direction) (→ direction in the figure, sub-scanning direction), the image of the document is sequentially scanned. Go.
[0005]
Here, an inverter 110 that supplies power to the light source is mounted on the first carriage.
[0006]
In recent years, as shown in FIG. 3, a device is also proposed in which a contact image sensor 121 having a length equal to or greater than the document width is mounted on the carriage 120 and scanned to read a document image at an equal magnification. In this figure, the same reference numerals as those in FIG. 2 denote members that perform the same function. Such an apparatus uses a 1 × optical system.
[0007]
Further, the above-mentioned two apparatuses are generalized by an image reading apparatus that enables a continuous reading by moving a document on a reading position without driving a scanning optical system by using an automatic document feeder. Yes.
[0008]
In many cases, the driving means (motor) of the scanning means is arranged with the power supply means to prevent the cost increase when the apparatus main body is divided into two regions on a plane perpendicular to the main scanning direction of the scanning means. Generally, the length of the power line is shortened by arranging it on the side where the power line is located.
[0009]
In recent years, it is common to integrate a substrate for controlling an apparatus and a substrate for controlling the output of an image signal into a single control substrate.
[0010]
[Problems to be solved by the invention]
In recent years, the speed of reading time in an image reading apparatus has rapidly increased, and accordingly, in order to obtain a necessary exposure amount per unit time, it is indispensable to support a scanning light source with high luminance.
[0011]
Further, since it is necessary to increase the scale of a memory circuit or the like in order to improve the image quality, a signal processing circuit for outputting an image signal has been increased in size . However, the high luminance response of the light source is necessarily accompanied by an increase in the size and temperature of the inverter. Therefore, when the inverter is mounted on the first carriage as in the prior art, the following problems occur.
[0012]
Increasing the weight of the scanning table causes an increase in the size of driving means, an increase in cost, and an increase in power consumption.
[0013]
As shown in FIG. 4, the relationship between the longitudinal position of the first carriage and the light source temperature is that the temperature distribution in the longitudinal direction of the light source becomes extremely non-uniform due to the influence of inverter heat generation, and the amount of light in the same direction is also non-uniform. For this reason, partial fogging, overexposure, etc. occur in the image reading signal.
[0014]
As shown in FIGS. 3 and 5, in the apparatus using the contact image sensor 121, the contact image sensor 121 is mounted on the carriage 120 on which the inverter 110 is mounted. As shown in FIG. 3, the CCD line sensor 128 inside the contact image sensor causes an image defect or failure due to exceeding the guaranteed operating temperature.
[0015]
As shown in FIG. 5, the contact image sensor 121 includes a light source 126, a CCD line sensor 128, a Selfoc lens (registered trademark) 129, and the like that are mounted on and integrated with the housing 130. As the amount increases, the optical performance of a single component decreases, and the tolerance of positional deviation between components deviates from the optical design value, resulting in blurring, color misregistration, and the like. In particular, this is a serious problem in a 1 × optical system with a small depth of field.
[0016]
In order to mount an inverter in the apparatus housing in an image reading apparatus using a reduction optical system, the second carriage reaches the furthest distance from the home position during the moving scanning operation for the purpose of thinning the apparatus. In general, an inverter is mounted further away from the position to prevent interference with the second carriage. Therefore, the following problems occur.
[0017]
When using an automatic document feeder using a belt to perform scanning reading using a conveyance belt, the first carriage of the scanning table is fixed near the center of the document table and near the end of the document table to read the document. Therefore, when the inverter is arranged on the back side of the device casing and forced cooling is performed by the cooling means (blower device) 140, the hot air that has passed through the inverter 110 flows in the longitudinal direction of the light source as shown in FIG. The temperature distribution is made non-uniform, and as described above, partial fogging, overexposure, etc. occur in the image reading signal.
[0018]
When an inverter is placed on the back side of the document case at the end of the platen and forced cooling is performed, hot air hits the CCD and its drive circuit, etc., downstream of the inverter, as seen from the air source, causing malfunctions of the IC, etc. In addition, problems such as failures occur.
[0019]
When an inverter is arranged on the back side of the device casing, if the substrate is arranged with the size of the conventional device due to the increase in size of the inverter, a control circuit board that performs image signal processing and device control as shown in FIG. 161 and the communication means 162 that outputs image data to another device are connected at the shortest distance, the signal line 163 can only pass through the vicinity of the inverter 110 that is a noise source. Prone to problems.
[0020]
When the inverter is arranged on the back side of the apparatus housing, as shown in FIG. 7, heat source such as the device driving power source 164, the scanning means driving motor 166 and its driver circuit 165 are concentrated on the back side of the apparatus housing. Therefore, the air heated by the heat from these members is blown to the inverter by the cooling means, and the heat dissipated directly to the heat radiation source of the inverter for the heat transferred from these members to the device housing When the member 110a is connected to the apparatus housing, the time required for saturation of the inverter temperature is shortened or the equilibrium temperature is increased.
[0021]
Here, as shown in FIG. 7, a cover 167 is provided to prevent external light from entering the CCD unit as much as possible and to prevent noise emission from the CCD drive circuit 160. A cover 168 is provided to prevent jumping in and noise emission.
[0022]
The present invention has been made in order to solve the above-described problems of the prior art, and the object of the present invention is to bring the temperature to an equilibrium with the increase in size and temperature of the inverter that supplies power to the lighting means. In addition to preventing the time required to become short and the equilibrium temperature from becoming high, and preventing adverse effects on each member such as a CCD in the apparatus, it is possible to improve the image quality of the image reading apparatus and the image forming apparatus. It is to increase the speed.
[0025]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides:
An original table on which an original is placed;
A casing in which the document table is provided at the top;
An imaging means provided in the housing for capturing an image of a document;
Scanning means provided in the housing, having illumination means for illuminating the original and forming an image of the original on the imaging means;
An inverter for supplying power to the illumination means;
Driving means for driving the scanning means;
Power supply means for supplying power to each drive source in the image reading apparatus;
Cooling means for circulating the air to cool the inside of the image reading apparatus;
In an image reading apparatus comprising:
The driving means and the power supply means are disposed in the vicinity of the first side surface of the casing parallel to a surface perpendicular to the main scanning direction of the scanning means ,
The inverter is disposed along a second side surface opposite to the first side surface of the housing, parallel to a surface perpendicular to the main scanning direction of the scanning means ,
The cooling means is disposed in the vicinity of the first side surface;
The inverter is provided so as to face an air blowing direction by the cooling means .
[0026]
Comprising communication means for outputting image data to another device;
The communication means is arranged on the first side surface.
[0027]
A heat sink that dissipates heat from the inverter;
The heat radiating plate is provided in the vicinity of the second side surface.
[0029]
In the above invention, the scanning unit has at least one of a function of scanning an image of a document by moving in the sub-scanning direction or a function of scanning by moving the document while stopped. Features.
[0030]
In the invention described above, the imaging unit and the scanning unit may be formed by a reduction optical system or an equal magnification optical system.
[0031]
Furthermore, in the reduction optical system, the present invention is implemented by using a xenon tube with a very small drop in the amount of light at both ends and a small sensitivity to fluctuations in the amount of light with respect to variations in the temperature distribution in the main scanning direction. It is characterized in that a luminance light source can be provided in a minimum space.
[0032]
Further, the image forming apparatus includes the image reading apparatus according to the invention described above and an image forming unit that forms an image of a document imaged by the image reading apparatus on a sheet.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0034]
In FIG. 1, reflected image light is generated by light emitted from a light source (illuminating means) 3 b provided on the first carriage 3 and supplied with electric power from the inverter 1, and this reflected light is generated by the first carriage. Then, after being reflected by a reflecting member (not shown) provided on the second carriage (not shown), a line image is formed on a CCD (imaging means) (not shown) via the imaging lens 13.
[0035]
Then, by moving the first carriage and the second carriage in the direction perpendicular to the line direction (main scanning direction) (→ direction, sub-scanning direction in the figure), the document image is scanned sequentially or By using the automatic feeding device, the image is scanned by moving the document and scanning it without moving the first carriage and the second carriage.
[0036]
A device that illuminates the original with such illumination means and scans the image of the original and forms an image of the original on the imaging means via the imaging means corresponds to the scanning means. The system is used.
[0037]
In such a configuration, when the main body of the image reading apparatus is divided into two regions on a plane perpendicular to the main scanning direction of the scanning means, the power supply means 9 supplies power to the drive source in the image reading apparatus. In a region on the side where the heat sources such as the drive motor 11 that drives the scanning means and the driver circuit 10 of the drive motor are not concentrated (front side of the device housing) (along the second side surface of the device housing 4). ) since the arrangement Te, it is possible to influence of heat transferred from these means to the device housing 4 is almost no casing wall, to connect the heat radiating member 1a which is directly connected to the radiation source of the inverter, the inverter Therefore, it is possible to efficiently dissipate heat without shortening the time required for saturation of the temperature or increasing the equilibrium temperature.
[0038]
This effect can be realized without the cooling unit 8, but when the image reading apparatus main body is divided into two regions on a plane perpendicular to the main scanning direction of the scanning unit, the power supply unit 9 and the drive motor 11 are provided. Further, the inverter can be more effectively cooled by disposing the cooling means 8 in the region on the side where the driver circuit 10 and the like are disposed (in the vicinity of the first side surface of the device housing 4) .
[0039]
Further, when the automatic document feeder using a belt is used for scanning using a conveyor belt, the first carriage of the scanning table is fixed near the center of the document table and near the end of the document table, and the document is scanned. Even if the flow is read, the inverter is arranged so that the illumination means is located in a region excluding the downstream side of the inverter with respect to the air flow path formed by the cooling means and passing through the inverter. Since it is not directed to the illumination means, it is possible to prevent non-uniformity in the amount of light accompanying non-uniform temperature distribution of the light source.
[0040]
Similarly, by arranging the inverter as in the present embodiment, the CCD is located in a region excluding the downstream side of the inverter with respect to the air flow path formed by the cooling means and passing through the inverter. Since the hot air that has passed through is not directed to the CCD, the CCD does not reach a high temperature and a good image quality is guaranteed.
[0041]
Further, when the image reading apparatus main body is divided into two areas on a plane perpendicular to the main scanning direction of the scanning means, the image reading apparatus main body is arranged in an area on the side where the communication means 6 for outputting image data to another apparatus is not disposed (apparatus Since the inverter is arranged ( along the second side surface of the housing 4) , the signal line 7 that connects the communication circuit 6 and the control circuit board 2 that performs image signal processing and device control is the noise source. Therefore, it is possible to mount a large-sized inverter with the same image reading apparatus size as the conventional one.
[0042]
Also, a cover 14 is provided to prevent external light from entering the CCD unit as much as possible and to prevent noise emission from the CCD drive circuit.
[0043]
The same configuration may be adopted when the scanning unit has both a function of scanning an image of a document by moving in the sub-scanning direction and a function of scanning by moving the document while stopped. it can.
[0044]
Further, by implementing the present invention using a xenon tube having a small sensitivity to fluctuations in the amount of light as illumination means, a high-intensity light source can be realized in a minimum space.
[0045]
The embodiment shown in FIG. 1 is a component arrangement / configuration in the case where the scanning unit and the imaging unit are reduction optical systems, but the same component arrangement / configuration may be used even in the case of an equal-magnification optical system. it can.
[0046]
In this equal-magnification optical system, a contact image sensor is mounted directly on the carriage (3). The contact image sensor includes a light source (illumination means), a CCD line sensor (imaging means), and a SELFOC lens (registered trademark). ) (Imaging means) and the like are mounted on the housing and integrated (see FIG. 5).
[0047]
Then, the illumination unit illuminates the original and scans the image of the original, and the portion corresponding to the scanning unit that forms an image of the original on the imaging unit via the imaging unit and the CCD line sensor that is the imaging unit Are integrated, and the carriage (3) on which they are mounted is moved in the sub-scanning direction (→ direction in the figure) to sequentially scan and capture the image of the document or use an automatic document feeder. Thus, the image is scanned and imaged by moving the document without moving the carriage, and by scanning the original.
[0048]
With this configuration, the contact image sensor housing is located in a region excluding the downstream side of the inverter with respect to the air flow path formed by the cooling means and passing through the inverter. The optical performance of a single component decreases due to an increase in the amount of each component in the contact image sensor due to thermal expansion, and the tolerance for positional deviation between components deviates from the optical design value. It is possible to prevent blurring or color misregistration caused by the above.
[0049]
Similarly, in the 1 × optical system, the scanning unit has either one of a function of scanning an image of a document by moving in the sub-scanning direction or a function of scanning by moving the document while stopped. In the case where both the function of scanning the image of the document by moving in the sub-scanning direction and the function of scanning by moving the document while stopped are provided, the same form can be obtained. .
[0050]
Furthermore, the image reading apparatus according to this embodiment can be applied to an image forming apparatus including an image forming unit that forms an image of a document imaged by the image reading apparatus on a sheet. Thereby, an image forming apparatus capable of forming a high-quality image at high speed can be realized.
[0051]
【The invention's effect】
As described above, according to the present invention, when the image reading apparatus main body is divided into two regions on a plane perpendicular to the main scanning direction of the scanning means, the communication means for outputting the image data to another apparatus is arranged. An inverter was placed in the area that was not used, and the size was increased to increase the amount of light while minimizing the effect of noise on the signal line between the control circuit board that performs image signal processing and device control and the communication means. Since an inverter can be arranged, a high-quality image can be obtained at high speed.
[0052]
In addition, when the scanning unit is a reduction optical system, the inverter is arranged so that the illumination unit and the imaging unit are located in a region excluding the downstream side of the inverter with respect to the air flow path passing through the inverter. Since the hot air that has passed through the inverter does not travel toward the illumination means or imaging means, the weight of the scanning table increases, the uneven temperature distribution in the longitudinal direction of the illumination means, and the increase in the temperature rise of the sensor unit This is effective in preventing image defects.
[0053]
Furthermore, even when the scanning means is an equal-magnification optical system using a contact image sensor, the hot air that has passed through the inverter does not go to the housing of the contact image sensor, so the CCD line sensor (imaging means) has a guaranteed operating temperature. Image defects and failures due to exceeding the range, degradation of the optical performance of a single component due to an increase in the amount that each component becomes larger due to thermal expansion, and tolerance of positional deviation between components deviate from the optical design value. There is an effect of preventing the occurrence of defocusing, color shift, and the like.
[0054]
Further, when the image reading apparatus main body is divided into two regions on a plane perpendicular to the main scanning direction of the scanning means, the drive unit, the power supply unit, etc. By arranging the inverter at a position where the heat dissipation member directly connected to the heat dissipation source can be connected to the device housing where the heat generation source is not arranged, the time until the inverter temperature equilibrates is shortened or the equilibrium temperature rises. There is an effect to prevent.
[0055]
Furthermore, in the reduction optical system, the present invention is implemented by using a xenon tube with a very small drop in the amount of light at both ends and a small sensitivity to fluctuations in the amount of light with respect to variations in the temperature distribution in the main scanning direction. There is an effect that a light source of luminance can be realized in a minimum space.
[0056]
Further, by applying this image reading apparatus to an image forming apparatus, a high quality image can be formed at high speed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram illustrating a first conventional example.
FIG. 3 is a diagram illustrating a second conventional example.
FIG. 4 is a drawing for explaining the relationship between the temperature around the light source and the luminance in the first conventional example.
FIG. 5 is a diagram illustrating the inside of a contact image sensor.
FIG. 6 is a diagram for explaining the relationship between the temperature around the light source and the luminance at the time of flow reading in the first conventional example.
FIG. 7 is a diagram illustrating a configuration of a first conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,110 Inverter 1a Heat radiation member 2,161 Control circuit board 3,113 First carriage 3b, 113b, 126 Light source 4,117 Device casing 6 Communication means 7 Signal line 8 Cooling means 9 Power supply means 10 Drive motor driver circuit 11 Scanning means drive motor 12 CCD drive circuit 13, 115 Imaging lens 14 Cover 116, 128 CCD
20, 120 Carriage 121 Contact image sensor 126 Light source 129 Selfoc lens 130 Housing

Claims (8)

An original table on which an original is placed;
A casing in which the document table is provided at the top;
An imaging means provided in the housing for capturing an image of a document;
Scanning means provided in the housing, having illumination means for illuminating the original and forming an image of the original on the imaging means;
An inverter for supplying power to the illumination means;
Driving means for driving the scanning means;
Power supply means for supplying power to each drive source in the image reading apparatus;
Cooling means for circulating the air to cool the inside of the image reading apparatus;
In an image reading apparatus comprising:
The driving means and the power supply means are disposed in the vicinity of the first side surface of the casing parallel to a surface perpendicular to the main scanning direction of the scanning means ,
The inverter is disposed along a second side surface opposite to the first side surface of the housing, parallel to a surface perpendicular to the main scanning direction of the scanning means ,
The cooling means is disposed in the vicinity of the first side surface;
An image reading apparatus , wherein the inverter is provided so as to oppose the air blowing direction by the cooling means . Comprising communication means for outputting image data to another device;
The image reading apparatus according to claim 1, wherein the communication unit is disposed in the vicinity of the first side surface. Having a heat sink that dissipates heat of the inverter;
The image reading apparatus according to claim 1, wherein the heat radiating plate is disposed in the vicinity of the second side surface. 2. The scanning unit according to claim 1, further comprising at least one of a function of scanning an image of a document by moving in the sub-scanning direction and a function of scanning by moving the document while stopped. 4. The image reading apparatus according to any one of items 3 . The image reading apparatus according to any one of claims 1 to 4, characterized by using the reduction optical system as the imaging means and the scanning means. The image reading apparatus according to claim 5 , wherein a xenon tube is used as the illumination unit. The image reading apparatus according to any one of claims 1 to 4, characterized in that using a magnification optical system as the imaging means and the scanning means. An image reading apparatus according to any one of claims 1 to 7, the image forming apparatus characterized by comprising a, an image forming portion for forming a sheet image of the document captured in the image reading apparatus .

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