JP4471348B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus for reading a transparent original having a plurality of transparent original areas.

  Conventionally, an image reading apparatus for reading a transparent original is equipped with a light source for reading a transparent original separately from that for a reflective original. When reading a transparent original, this image reading apparatus uses a light source for a transparent original installed separately from a light source for a reflective original, and sub-scans a contact image sensor mounted on an imaging device in the main body of the image reading apparatus. The transparent original is read by moving in the direction.

  The fluorescent tube that is often used as the light source for the above transparent document has a long time (hereinafter referred to as “warm-up time”) until the light amount of the light source is stabilized after lighting, and the document is read immediately after it is lit. Can't start.

  This warm-up time can be shortened by keeping the temperature by controlling the lighting of a fluorescent tube used as a light source for a transmissive document and keeping the light quantity of the light source constant (see, for example, Patent Document 1). As shown, a warm-up time is not required by using a light emitting diode instead of a fluorescent tube as a light source for a transparent original (see, for example, Patent Document 2).

The image reading apparatus shown in FIG. 6 places a read original, and contacts glass 16 in which a transparent original area 18 is set, and the read original placed on the contact glass 16 to illuminate the read original. And a transparent document illumination device 17 disposed above. The illuminating device for transmissive document 17 includes a planar light guide 20 and a light emitting diode 21 disposed on the side of the planar light guide 20 corresponding to the transmissive region.
JP-A-8-87075 JP 2003-315931 A

  However, in an image reading apparatus that can only use power limited by USB bus power (500 mA), when reading a plurality of frames of transparent originals by placing a single document without moving the light source for image reading, A light source must be installed. When a fluorescent tube is used as the light source of such an image reading apparatus, there is a problem that no matter how much control lighting is performed, sufficient heat cannot be kept due to power shortage and the warm-up time cannot be shortened.

  Further, when the point light source LED is used as the light source, the above problem does not occur because the warm-up time is unnecessary. However, when reading a color image, a plurality of point light sources installed in a plurality of frames are used. The LEDs are turned on at a time, and there is a problem that a sufficient amount of light cannot be secured due to insufficient power.

  An object of the present invention is to provide an image reading apparatus capable of reducing power consumption of a light source for reading a transparent original having a plurality of transparent original areas.

To achieve the above object, an image reading apparatus comprising: a platen glass in which a plurality of transparent original region while placing the transparent original is set, the light to the placing permeate document A plurality of light source units to be irradiated and an image reading that moves along the original platen glass, receives light transmitted through the transparent original by the plurality of light source units, and reads an image of the transparent original. And the plurality of light source units are arranged side by side in the direction of movement at positions corresponding to the plurality of transparent document regions, and the image reading unit has moved to the reading position. characterized in that it comprises a light source unit switching unit to switch a light source unit for lighting the plurality of light source units in accordance with the transmission document area that has been set to.

The image reading apparatus according to claim 2 is the image reading apparatus according to claim 1, wherein the plurality of light source units include a plurality of light sources having different emission colors, and the image reading apparatus sequentially applies the plurality of light sources. It has the lighting control means to switch, It is characterized by the above-mentioned.

According to a third aspect of the present invention, in the image reading device according to the second aspect, in reading each area of the transparent original area, the plurality of light sources of the corresponding plurality of light source units are sequentially turned on line by line. It is characterized by reading.

The image reading apparatus according to claim 4, wherein, in the image reading apparatus according to claim 2 or 3, wherein the plurality of light sources, characterized in that it consists of red, green, and blue color light-emitting diodes.

The image reading apparatus according to claim 5 is the image reading apparatus according to any one of claims 2 to 4, wherein the lighting control unit generates driving currents of the plurality of light sources according to the type of the transparent original. It is characterized by controlling.

An image reading apparatus according to a sixth aspect is the image reading apparatus according to the first aspect, wherein the plurality of light source units include white light sources.
An image reading apparatus according to a seventh aspect is the image reading apparatus according to the first aspect, wherein at least one of the plurality of light source units corresponds to one transparent original region.
The image reading apparatus according to claim 8 is the image reading apparatus according to claim 1, wherein the plurality of light source units are light sources that illuminate the transparent original area corresponding to an image of at least one frame of the transparent original. Features.

According to the image reading apparatus according to claim 1, wherein, since the switch the light source unit turned to one of the plurality of light source units in accordance with the transmission document area is set to the moved reading position of the image reading means, the transparent original The power consumption of the reading light source can be reduced.

  Since the image reading apparatus according to the second aspect emits light only in the reading color at the time of reading, unnecessary light emission can be suppressed.

  In the image reading apparatus according to the third aspect, since the light is sequentially turned on line by line, a large color shift does not occur and power consumption can be suppressed.

The image reading apparatus according to claim 4 wherein, said plurality of light sources, red, green, since a blue light emitting diode, it is possible to eliminate the need for warm-up time, and reducing power consumption.

The image reading apparatus according to the fifth aspect controls the drive currents of the plurality of light sources in accordance with the type of the transparent original, so that the power consumption of the light source for reading the transparent original can be reliably reduced.

  Since the image reading apparatus according to the sixth aspect uses a white light source, there is no color misregistration and power consumption can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 1 (a) is a side view and FIG. 1 (b) is a plan view.

In FIG. 1, the image reading apparatus 100 illuminates a contact glass 106 on which a read original 105 as a transparent original composed of three frames is placed, and a read original 105 placed on the contact glass 106. A transparent original illumination device 107 disposed on the original 105, an electric substrate 109 of FIG. 2 connected to the transparent original illumination device 107, which will be described later, and an electric substrate 109 connected to the lower side of the contact glass 106 And a contact image sensor (CIS) 101 (image reading means) that moves in the sub-scanning (arrow) direction. The image reading area on the contact glass 106 is controlled as three transparent original areas 108a, 108b, and 108c.

  The illuminating device 107 for a transparent document includes a planar light guide 110 having a light diffusion sheet (not shown) installed on the surface on the document side, and a transparent document light emitting diode (LED) for each color of R, G, B. LED units 111, 112, and 113 disposed at three positions on the side of the planar light guide 110 corresponding to the three transparent original regions 108 a, 108 b, and 108 c, respectively. The light emitting diodes for R, G, and B of each of the R, G, and B colors provided in the LED unit 111 illuminate the transparent original region 108a substantially uniformly by the structure of the light guide 110 and a light diffusion sheet (not shown). Similarly, the other LED units 112 and 113 illuminate the corresponding transparent document areas 108b and 108c substantially uniformly.

  The image sensor 101 includes a lens array 103 that receives the transmitted light that has passed through the read document 105 via the contact glass 106, and a monochrome image sensor 104 that photoelectrically converts the received light. A reflective document illumination device (not shown) equipped with a light guide.

  The image reading apparatus 100 operates as follows when a transparent original is read.

  At the time of reading a transparent original, the read original 105 is irradiated with light from the transparent original LED units 111, 112, and 113 via the planar light guide 110. At this time, the image reading apparatus 100 first switches the R, G, and B colors of the LED unit 111 to light for each line while moving the contact image sensor 101 along the document in the sub-scanning (arrow) direction. Thus, the R, G, and B transmitted light from the read original 105 is received by the monochrome image sensor 104 and photoelectrically converted into an electrical image signal corresponding to the received light amount. Each image signal is subjected to image processing on the electric substrate 109 to obtain a two-dimensional color transmission original image.

  Further, the image reading apparatus 100 converts the lighting LED unit into the LED unit 111, corresponding to the transparent original regions 108a, 108b, 108c according to the position of the contact image sensor 101 in the sub-scanning direction during the transparent original reading operation. By switching the LED unit 112 and the LED unit 113 in this order and turning on the light, a plurality of frames of transparent original images are read.

  The electric signal photoelectrically converted by the monochrome image sensor 104 is sent to the electrically connected electric substrate 109.

  FIG. 2 is a block diagram of various processing circuits including the electric substrate 109 in the image reading apparatus 100 of FIG.

  In FIG. 2, an electric board 109 performs processing such as amplifier amplification, DC offset correction, and A / D conversion on the electric signal output from the contact image sensor (CIS) 101 in FIG. 1, and outputs digital image data. AFE 402 that is an analog front-end preprocessor, a shading correction circuit 403 that performs shading correction of digital image data output from the AFE 402, and gamma conversion processing and packing processing on the image data corrected by the shading correction circuit 403 And an interface circuit 405 that receives control signals and outputs image signals between an image processing circuit 404 that performs predetermined processing such as the above and an external device 406 that is a host device of the image reading apparatus 100.

  The shading correction circuit 403 performs shading correction based on the reference level data created by the contact image sensor 101 reading the irradiation light from the illuminating device 107 for a transparent document. This reference level data is recorded in advance in the external device 406, and the shading correction circuit 403 acquires from the external device 406 via the interface circuit 405 when reading a transparent original.

  The image processing circuit 404 acquires an image reading mode (binary, 24-bit multivalue, etc.) preset by the external device 406 via the interface circuit 405, and performs packing processing according to the acquired image reading mode.

  The external device 406 has a scanner driver for controlling the image reading device 100 and constitutes an image processing system together with the image reading device 100. This scanner driver is software executed on the computer of the external device 406, and has a user interface for specifying the above-described image reading mode, resolution, and reading range, and a control signal based on each specification. And a reading start command and the like are transmitted to the image reading apparatus 100 via the interface circuit 405. The scanner driver controls the image data read by the image reading apparatus 100 to be transmitted to the external device 406 via the interface circuit 405, and the control to display the transmitted image data on a display (not shown) of the external device 406. Also do.

  The light source switching circuit 407 switches between the reflective original LED in the CIS 101 and the transparent original LED units 111, 112, and 113 in the transparent original illumination device 107. A system controller 408 controls the entire image reading apparatus 100.

  FIG. 3 is a block diagram of the light source switching circuit 407 of the transparent document illumination device 107 in FIG.

  In FIG. 3, a light source lighting control circuit 508 controls lighting of LEDs of R, G, and B colors. The R-LED driving circuit 501 drives the R-LED during a period in which lighting of the red LED is instructed by the light source lighting control circuit 508. Similarly, the G-LED and the B-LED drive green and blue LEDs, respectively. When reading a transparent document, each LED is driven with a drive current set for reading a transparent document, and when reading a reflected document, each LED is driven with a drive current set for reading a reflected document. Further, in transparent original reading, the drive current is changed depending on whether the transparent original is negative or positive. In response to an instruction from the light source switching control circuit 510, the SW 502 determines whether to connect the drive current of the LED drive circuit 501 to any one of the transparent document LED units 111, 112, and 113 or to the reflective document LED 114. Switch. The SW 503 switches which of the three sets of transparent document LED units 111, 112, and 113 is connected to the SW 502 according to an instruction from the lighting position switching control circuit 509. For example, when the SW 502 is connected to the transparent original LED and the SW 503 is connected to the transparent original LED unit 111, the LED drive circuit 501 is connected to drive the three color LEDs of the transparent original LED unit 111. The Further, the light source lighting control circuit 508 performs control so that the R, G, and B LEDs are sequentially lit while reading one line in the main scanning direction of color image reading. The image reading apparatus 100 reads a signal of one line in the main scanning direction of each color during a period in which each color LED is lit. The read signal is sent to the external device 406. The external device 406 receives this signal and obtains a color image signal of three colors.

  FIG. 4 is a flowchart of the transparent original reading process executed by the image reading apparatus 100 of FIG. Whether the transparent original is read or the reflective original is read, and whether the transparent original is negative or positive can be switched by a setting from the user, or can be set by automatically detecting the original. Here, a transparent document is set, the light source switching control circuit 510 indicates a transparent document LED, and the output of the LED drive circuit 501 is connected to SW503 by SW502.

  In FIG. 4, first, when initialization is completed after the power is turned on, the image reading apparatus 100 receives an instruction to start reading the read original 105 as a transparent original from the scanner driver stored in the external apparatus 406 via the interface circuit 405. When this is received (YES in step S600), the lighting position switching control circuit 509 connects the LED driving circuit 501 to the transparent document LED unit 111 first by the lighting position switching control SW 503. (Step S601).

  Next, when receiving a pre-scan start command from the scanner driver via the interface circuit 405 (YES in step S602), the image reading apparatus 100 performs pre-scan processing (step S603). Specifically, in this process, first, the lighting position switching control circuit 509 drives the LED driving circuit 501 to turn on the R-LED of the transparent original LED unit 111 and to supply one line of R-LED light to the transparent original. The transmitted light from the read original 105 is accumulated in the monochrome image sensor 104 as an R read signal. Next, the G-LED of the transparent document LED unit 111 is turned on, and the same processing as the R-LED is performed. During this time, the R read signal for one line in the main scanning direction of the R-LED color previously accumulated in the monochrome image sensor 104 is output as an output signal from the monochrome image sensor 104 to the AFE 402 in FIG.

  Similarly, the G reading signal is output to the AFE 402 while the B-LED of the transparent document LED unit 111 is lit. Thereafter, after the contact image sensor 101 has moved by one line along the document in the sub-scanning direction, the R-LED of the transparent document LED unit 111 is lit to read the next one-line transparent document image. In the meantime, the B reading signal of the transparent original LED unit 111 is output. In this way, read signals for each color of R, G, and B are output from the monochrome image sensor 104 to the AFE 402 as output signals line by line.

  When this pre-scan processing is performed up to the designated line in one transparent original area 108a, 108b, or 108c of the read original 105 acquired from the scanner driver via the interface circuit 405 (YES in step S604), the transparent original LED It is determined whether or not the pre-scan process by all of the units 111, 112, and 113 has been completed (step S605). If not completed, the lighting position switching control circuit 509 switches the LED lighting position (step S606). Then, the processing after step S603 is repeated. Specifically, as described above, when only the prescan process for the transparent document LED unit 111 is completed, the prescan process (step S603) for the transparent document LED unit 112 is performed on the read document 105. The process continues until the designated line in the next one transparent original area 108b is completed (YES in S604), and then the prescan process (step S603) for the transparent original LED unit 113 is performed for the last transparent original area 108c of the read original 105. Until the designated line is completed (YES in S604).

  On the other hand, as a result of the determination in step S 605, when the pre-scan processing by all of the transparent document LED units 111, 112, 113 is completed, the pre-scan result is transmitted to the external device 406. Thereby, the external device 406 can display the result of the pre-scan on a monitor (not shown), and the user can check whether the pre-scan is performed within a desired range.

  Next, when receiving a main scan start command from the scanner driver via the interface circuit 405 (YES in step S607), the image reading apparatus 100 performs a main scan process (step S608). This scan process is substantially the same as the above-described prescan process (step S603), and the setting received from the normal scanner driver is the same as the setting when the reading range is specified and the reading resolution setting is the prescan process. Higher than that.

  Also in the main scanning process, when the monochrome image sensor 104 finishes reading the designated line (YES in step S609), it is determined whether or not the main scanning process by all of the transparent document LED units 111, 112, and 113 is completed. If it is determined (step S610) and the process has not been completed, the lighting position switching control circuit 509 switches the LED lighting position (step S611) and repeats the processing from step S608 onward.

  On the other hand, as a result of the determination in step S610, when the main scan processing by all of the transparent document LED units 111, 112, and 113 is completed, the result of the main scan is transmitted to the external device 406, and the main processing is ended. .

  As described above, according to the present embodiment, the monochrome image sensor 104 reads the designated line by irradiating one frame of the read original 105 by sequentially switching the three RGB light beams of the LED unit 111 for the transparent original. After completion (YES in step S604), the lighting position switching control circuit 509 switches the LED lighting position until the pre-scan processing by all of the transparent document LED units 111, 112, 113 is completed (YES in step S605). Thus, the same processing is performed for the transparent document LED units 112 and 113 (step S611), so that the lighting of the transparent document LED units 111, 112, and 113 is sequentially switched according to the image reading position by the monochrome image sensor 104. Of this switched lighting light source You can sequentially switch the Tsuniokeru plurality of light sources, power consumption of the light source for reading the transparent original can be reduced.

  In the present embodiment, the transparent document LED units 111, 112, and 113 are arranged at the center position on one side of each transparent document area 108 as shown in FIG. 1B. As shown in FIG. 5, it may be arranged at the center position on both sides of each transparent document area 108, and may be at the corner positions on both sides of each transparent document area 108 as shown in FIG. Accordingly, it is possible to read the read original 105 including a plurality of frames with higher accuracy. In the description of FIGS. 1 and 5, three transparent original areas 108 are set for the transparent original 105 having three frames, and the three lighting positions are switched. For example, three transparent original areas are set as a single transparent original area for two frames, and the three originals are switched for illumination and read by switching the positions of three LEDs for six frames. You can also. Further, the transparent document LED units 111, 112, and 113 can be configured by white LEDs, and CIS reading can be performed by an image sensor having three color filters instead of the monochrome image sensor 104.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the image reading apparatus which concerns on embodiment of this invention, (a) is a side view, (b) is a top view. It is a block diagram of various circuits with which the electric board 109 in FIG. 1 is provided. FIG. 2 is a block diagram of a light source switching circuit of the transparent document illumination device 107 in FIG. 1. 3 is a flowchart of a transparent document reading process executed by the image reading apparatus 100 of FIG. (A) is a top view of the modification of the image reading apparatus of FIG. 1, (b) is a top view of the other modification of the image reading apparatus of FIG. It is a top view of the conventional image reading apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image reader 104 Monochrome image sensor 105 Reading original 107 Illuminating device 108 for transparent originals Transparent original area 109 Electric substrate 110 Planar light guides 111, 112, 113 LED unit for transparent originals

Claims (8)

A platen glass having a plurality of transmissive original area while placing a transparent original is set, a plurality of light source units for irradiating light to the placing permeate document moves along the platen glass An image reading apparatus comprising: an image reading unit configured to receive light transmitted to the transparent original by the plurality of light source units and transmitted through the transparent original, and to read an image of the transparent original;
The plurality of light source units are arranged side by side in the movement direction at positions corresponding to the plurality of transparent document regions,
Read image, characterized in that it comprises a light source unit switching unit to switch the lighting to the light source unit of the plurality of light source units in accordance with the transmission document area that has been set to the moved reading position of said image reading means apparatus. The image reading apparatus according to claim 1, wherein the plurality of light source units includes a plurality of light sources having different emission colors, and the image reading apparatus includes a lighting control unit that sequentially switches the plurality of light sources. The image reading apparatus according to claim 2, wherein each of the transparent document areas is read by sequentially turning on the plurality of light sources of the corresponding plurality of light source units for each line.   4. The image reading apparatus according to claim 2, wherein the plurality of light sources are red, green, and blue light emitting diodes.   5. The image reading apparatus according to claim 2, wherein the lighting control unit controls drive currents of the plurality of light sources in accordance with a type of the transparent original. 6. The image reading apparatus according to claim 1, wherein the plurality of light source units include white light sources. The image reading apparatus according to claim 1, wherein at least one of the plurality of light source units corresponds to one transparent document area. The image reading apparatus according to claim 1, wherein the plurality of light source units are light sources that illuminate the transparent original area corresponding to at least one frame image of the transparent original.

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