JP2001217993A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that attains a high-speed image reading operation and a sophisticated function or the like by variably controlling an emission luminous quantity in accordance with a corresponding read mode and reduces the energy. SOLUTION: The image reader is provided with a lighting means 12a that illuminates an original, which is a read object, an image read means 15 that reads an image drawn on the original on the basis of a light reflected from the original receiving the emission, and a luminous quantity control means 33 that variably controls the luminous quantity when the lighting means 12a illuminates the original. The luminous quantity control means 33 varies the emission luminous quantity by the lighting means 12a depending on a read mode set to the image reader.

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 for use in a copying machine, a facsimile apparatus, a scanner apparatus, etc., for optically reading an image drawn on the original from an original to be read. It is.

[0002]

2. Description of the Related Art Generally, in an image reading apparatus for optically reading an image, a charge coupled device (CCD) is used based on reflected light from a document obtained by irradiation of an illumination lamp.
An image drawn on the original is read by a solid-state imaging device such as the one described above. Therefore, if the amount of light received by the solid-state imaging device is insufficient, it becomes impossible to read an image satisfactorily. For this reason, in the image reading device, the irradiation light amount of the illumination lamp is usually set in advance to an amount that can obtain a necessary and sufficient light reception amount in the solid-state imaging device.

The image reading apparatus selects a plurality of different reading modes such as color reading / monochrome reading, multi-value reading / binary (low value) reading, high-resolution reading / low-resolution reading, high-speed reading / low-speed reading, and the like. It is known that these reading modes have different light amounts required by the solid-state imaging devices.

For example, when performing color reading, light reflected from a document is received through a filter for separating density signals of R (red), G (green), and B (blue). In this case, the color filter becomes unnecessary, and the loss of the light amount is eliminated, so that the required light amount can be reduced. Further, when detecting high gradations (smooth shades) by multi-valued reading, it is necessary to divide the difference between light and dark into a large number (to increase the entire width of lightness). Light intensity is required. Furthermore, in the case of high-resolution reading, the number of reading lines existing in one image area increases, so that if the low-speed reading is permitted, a small amount of light is not required. Therefore, a large amount of light is required to obtain the required amount of light in a short time.

[0005] As described above, since the required light amount differs depending on each reading mode, the conventional image reading apparatus can read an image well in any of the reading modes when supporting a plurality of different reading modes. In order to perform the reading, the irradiation light amount of the illumination lamp is set in accordance with the reading mode requiring the largest light amount among the reading modes. Then, in the case of a reading mode in which a small amount of light is required, the difference in required light amount is corrected by reducing the light amount via a filter or the like, or performing gain adjustment or the like during signal processing after image reading. It has become.

[0006] In addition, for example, Japanese Unexamined Patent Application Publication No. 10-3
As disclosed in Japanese Patent Application Laid-Open No. 008846, there is also a method in which a difference in required light amount is corrected by variably adjusting a distance between an illumination lamp and a document to be irradiated. Further, as disclosed in Japanese Patent Application Laid-Open No. H11-55461, for example, an auxiliary lamp is provided in addition to an illumination lamp, and the auxiliary lamp is used to make the luminance level of reflected light received by the solid-state imaging device uniform. In some cases, the correction is performed.

[0007]

However, in the above-described conventional image reading apparatus, the illumination light amount of the illumination lamp is set so as to correspond to various reading modes. This means that the light is radiated at a light amount more than necessary and sufficient. That is, in the reading mode in which a small amount of light is required, energy such as power consumption is wasted. Moreover, the energy that can be consumed by the entire image reading apparatus is limited, and the energy consumption is not limited to the illumination lamp. Therefore, if the illumination lamp is wasting energy, other effects may be caused by the effect. There is a possibility that an energy consuming portion (for example, a driving mechanism for scanning, a document feeding mechanism, etc.) is restricted, and as a result, there is a possibility that the image reading operation is hindered from being performed at a higher speed and with higher functionality.

Accordingly, the present invention provides an image reading apparatus capable of realizing high-speed and high-performance image reading operations and energy saving by controlling the amount of irradiation light variably in accordance with the corresponding reading mode. It is intended to provide a device.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to an image reading apparatus devised to achieve the above object, comprising: an illuminating means for irradiating a document to be read; An image reading unit that reads an image drawn on the original based on the reflected light from the original, and a light amount control unit that variably controls a light amount when the illumination unit irradiates the original. Things.

According to the above-described image reading apparatus, the light amount control means variably controls the amount of light when the illuminating means irradiates the original. , The amount of irradiation by the illuminating means can be reduced in the reading mode in which only a small amount of light is required. Therefore, even in the case of supporting various reading modes, by variably controlling the irradiation light amount,
Energy such as power consumption is not wasted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image reading apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of an image reading apparatus according to the present invention.

The image reading apparatus according to the present embodiment is used in a copier, a scanner, a facsimile, and the like, and converts an image drawn on the original from a sheet-like original to be read into image data as image data. It is something to read. Therefore, in this image reading apparatus, FIG.
As shown in FIG. 1, a platen glass 11 which functions as a document table on which a document to be read is placed is provided.

Below the platen glass 11, a first carriage (hereinafter, the carriage is referred to as "CRG") 12 and a second C which function as a scanning unit are provided.
RG13 is provided. The first CRG 12 includes an illumination lamp 12a for irradiating a document to be read and a first mirror 12b for changing an optical axis direction of light reflected from the document obtained by the irradiation. The second CRG 13 is
The second mirror 13a and the third mirror 13b that further change the optical axis direction with respect to the reflected light from the first mirror 12b
It is equipped with.

The first and second CRGs 12, 13
Can move along the platen glass 11 in the sub-scanning direction (the direction of arrow A in the figure). However,
These move in the same direction in conjunction with each other. At this time, the second CRG 13 moves at half the speed of the first CRG 12 in order to always keep the distance between the original on the platen glass 11 and the solid-state imaging device 15 described later constant. Note that such first and second CRGs 12 and 13
Is performed by operating a drive source such as a pulse motor (not shown).

Below the platen glass 11, there is provided a lens 14 for condensing the reflected light from the original having passed through the first and second CRGs 12 and 13 at a predetermined focal position. And a solid-state imaging device 15 such as a CCD that receives the reflected light and converts it into an electric signal.

On the other hand, above the platen glass 11, an automatic document feeder (hereinafter, referred to as "ADF") 20 that covers the platen glass 11 so that it can be opened and closed is provided.

The ADF 20 sequentially feeds out a document set on the paper feed tray 21, a paper feed tray 21 on which a document to be read is stacked, a paper discharge tray 22 for discharging the read document, and a platen glass. 11 while passing it at a predetermined speed at a predetermined speed,
And a document transport mechanism 23 for discharging the document upward. Note that the ADF 20 may include a document reversing mechanism 24 for reversing the document to be conveyed.

The image reading apparatus has a user interface (User Interface) in addition to the above-described components.
e; hereinafter referred to as “UI”) unit 31 and mode determination unit 32
And a light amount control unit 33.

The UI unit 31 includes, for example, an operation panel operated by a user of the image reading apparatus, and is used by the user to instruct the start of a reading operation and to specify a reading mode at that time. The reading modes are roughly classified into a fixed document reading mode (hereinafter, referred to as a “platen reading mode”) for reading an image from a fixed document placed on the platen glass 11 and a document that is being moved by the ADF 20. There is a document constant speed reading mode for reading an image (hereinafter referred to as “CVT (Constant Velocity Transfer) reading mode”). For each mode, color reading / monochrome reading, multi-value reading / binary (low value) reading, high-resolution reading / low-resolution reading, and the like can be selected.

The mode determination section 32 is composed of, for example, a CPU (Central Processing Unit) for executing a predetermined program. When starting a reading operation, the mode determining section 32 determines which reading mode the reading operation is to be performed in, and determines the reading mode. The content is instructed to the light amount control unit 33. In addition,
The mode determination unit 32 determines the reading mode by the UI unit 3
This is performed on the basis of the specified content in step 1 or a preset default value.

The light amount control unit 33 variably controls the light amount when the illumination lamp 12a irradiates a document while following instructions from the mode determination unit 32. This light amount control unit 3
3 may be mounted on the first CRG 12 together with the illumination lamp 12a, or may be provided separately from the first CRG 12 on, for example, a control board in an image reading apparatus.

Here, the light amount control section 33 will be described in more detail. FIG. 2 is a schematic configuration diagram illustrating an example of the light amount control unit. As shown in the example, the light amount control unit 33 is provided corresponding to the illumination lamp 12a, and includes a DC power supply 33a, a driving circuit 33b, and a switching element 33c.
And a transformer 33d.

In the light quantity control unit 33 having such a configuration, if the illumination lamp 12a is a discharge lamp (fluorescent lamp), for example, while following the instruction from the mode determination unit 32 (see the arrow B in the figure), By changing the frequency of the drive signal (see C in the figure) given by the drive circuit 33b to the switching element 33c and changing the voltage cycle (see D in the figure) applied to the illumination lamp 12a, without changing the DC power supply voltage The light amount of the illumination lamp 12a is variably controlled. However, instead of controlling the switching frequency of the inverter as described above, the mode determination unit 32
DC power supply 3 while following instructions (see arrow E in the figure)
The drive current / voltage 3a may be changed to change the DC power supply voltage applied to the illumination lamp 12a, thereby variably controlling the light amount of the illumination lamp 12a. Also, for example, even when the illumination lamp 12a is an incandescent lamp, the DC power supply 33a changes the driving current / voltage while variably controlling the light amount of the illumination lamp 12a while following the instruction from the mode determination unit 32. And

Next, a description will be given of a processing operation example in the case where the image reading apparatus configured as described above performs a reading operation.

In this image reading apparatus, prior to the start of the reading operation, the mode determining section 32 determines in which reading mode the operation is to be performed. This determination is made based on the specified content if the reading mode is specified in the UI unit 31, and based on a preset default value if not specified in the UI unit 31.

At this time, from the specified reading mode,
An irradiation light amount required for performing a reading operation can be uniquely derived in the reading mode. Therefore, the mode determination unit 32
Determines the reading mode, gives a variable light amount control instruction to the light amount control unit 33 so that the illumination lamp 12a irradiates with the light amount suitable for the reading mode. Then, while following this instruction, the light quantity control unit 33 variably controls the light quantity when the illumination lamp 12a irradiates the document.
With this variable control, when performing the reading operation, the illumination lamp 12a irradiates the document with a light amount necessary and sufficient (optimal) for the reading mode in which the reading operation is performed. Since the correspondence between the reading mode and the light amount is uniquely determined as described above, it is assumed that the reading mode and the light amount are stored in advance in a predetermined location in the image reading apparatus, for example, in a table format.

Here, the reading mode will be described in more detail with a specific example. For example, when the reading operation is performed in the CVT reading mode, the document to be read moves on the first CRG 12 at a constant speed with the first and second CRGs 12 and 13 fixed at predetermined positions. ADF2
The original position of the original and the solid-state imaging device 15 are changed by the original conveying mechanism 23 conveying the original. Such a CVT reading mode is applied to a high-speed facsimile of a text image and a high-speed scanner,
Usually, this is used when performing an image reading operation continuously from a plurality of documents, and therefore, the speed of the operation, that is, continuous high-speed reading is required. Therefore, the light amount control unit 3
No. 3 increases the light amount of the illumination lamp 12a in the CVT reading mode so as to prevent the reading image quality from deteriorating even when continuous high-speed reading is performed.

On the other hand, for example, when the reading operation is performed in the platen reading mode, the first and second CRGs 12 and 13 are attached to the platen glass 11 with the original to be read placed thereon. By moving the original at a constant speed in the scanning direction, the relative position between the original and the solid-state imaging device 15 is changed. Such a platen reading mode is C
Higher speed is not required compared to the VT reading mode. Therefore, the light amount control unit 33 reduces the light amount of the illumination lamp 12a in the platen reading mode, and reduces the power of the reduced light amount to a portion requiring other high power (for example, the first and second CRGs 12 and 13). Drive) and make effective use of limited power.

However, the increase / decrease of the light amount of the illumination lamp 12a is not limited to the above-described embodiment, but changes variously depending on the combination of the reading modes. Generally, factors that use a lot of power as an image reading apparatus include color reading, multi-value reading, high-resolution reading, and high-speed reading. Therefore, in order to effectively use the limited power, the correspondence between each reading mode and the light amount of the illumination lamp 12a may be determined while considering the balance between these reading modes.

For example, when the reading operation is performed in the platen reading mode and the operation is performed in color reading,
Since high gradation and high resolution are required, the illumination lamp 1
It is necessary to increase the irradiation light amount of 2a. Therefore, in such a case, the light amount control unit 33 increases the light amount of the illumination lamp 12a even in the platen reading mode,
High-gradation, high-resolution image reading can be performed.

At this time, the first and second CRGs 12, 1
If the low friction of the movement of the light source 3 is realized,
Can reduce the power required to drive the first and second CRGs 12 and 13 even if the light amount of the illumination lamp 12a is increased, so that the limited power can be effectively used as a whole.

On the other hand, for example, when the reading operation is performed in the CVT reading mode and the operation is performed in black and white reading (such as facsimile or filing of text data), high speed is required as the most important item. Therefore, in such a case, the light amount control unit 33 suppresses the gradation and the resolution even in the CVT reading mode, so that the illumination lamp 12a
To reduce the amount of light. Then, the high-speed driving of the ADF 20 uses the power corresponding to the decrease in the amount of light to realize continuous high-speed reading without loss of the return time of the first and second CRGs 12 and 13.

In other words, in color reading, the use of multi-valued / high-resolution images tends to be stronger because they are more often used for reading images such as photographs than text images. Is often used to read at high speed. Therefore,
In consideration of the characteristics of each reading mode, required characteristics, and the like, the mode of increase / decrease of the irradiation light amount is determined in advance for each combination pattern of the reading modes to be supported, and for example, high-speed / low-resolution The light amount control unit 33 variably controls the light amount of the illumination lamp 12a so as to reduce the irradiation light amount during black / white reading, so that the image reading apparatus of the present embodiment can perform color high-resolution reading and monochrome high-speed reading with the same apparatus. It is possible to satisfy these two conflicting requirements.

Moreover, in the image reading apparatus of the present embodiment,
The surplus power generated due to the reduction in the irradiation light amount can be used for other parts requiring high power, so that even if the power energy that can be consumed is limited, it is easy to realize a high-speed image reading operation. At the same time, the achievable function variations can be enhanced. In other words, the power energy that can be consumed is not wasted, and the power energy that is more detailed can be effectively used. Further, when the surplus power is not used for other purposes, in addition to saving energy, heat generation from the inside of the device is suppressed because no extra power is consumed, and the occurrence of troubles due to the heat generation is avoided. You can also do things.

In this embodiment, the light amount control section 33 applies a voltage cycle or a drive current / voltage applied to the illumination lamp 12a.
Although the case where the light amount of the illumination lamp 12a is variably controlled by changing the voltage has been described as an example, the present invention is not limited to this. That is, the illumination lamp 12a
As long as the light amount itself can be varied, the light amount control unit 33 may use another method.

[0036]

As described above, in the image reading apparatus according to the present invention, the light quantity control means variably controls the light quantity when the illuminating means irradiates the original. In the required reading mode, the amount of irradiation by the illumination unit is increased, and in the reading mode in which a small amount of light is required, the amount of irradiation by the illumination unit can be reduced. Therefore, even in a case where various reading modes are supported, energy such as power consumption is not wasted by variably controlling the irradiation light amount. For this reason, even if the energy that can be consumed is limited, it is possible to achieve the effect of realizing high-speed and high-performance image reading operation and energy saving.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an image reading apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a light amount control unit included in the image reading apparatus of FIG.

[Explanation of symbols]

11: platen glass, 12: first CRG, 12a: illumination lamp, 13: second CRG, 15: solid-state imaging device, 2
0: ADF, 31: UI unit, 32: Mode determination unit, 33
... Light intensity control unit

Claims (3)

[Claims] An illumination unit configured to irradiate an original to be read; an image reading unit configured to read an image drawn on the original based on reflected light from the original obtained by irradiation of the illumination unit; An image reading apparatus comprising: a light amount control unit that variably controls a light amount when the illumination unit irradiates the document. 2. The image reading apparatus according to claim 1, wherein the light amount control unit changes a light amount of the illumination unit according to an image reading mode corresponding to the image reading unit. 3. The light amount control means decreases the light amount of the illuminating means in a document constant speed reading mode for reading an image from a moving document, and in the document fixed reading mode for reading an image from a fixed document. 3. The image reading apparatus according to claim 2, wherein the light amount of the illumination means is increased.