JPH07336568A - Image input device - Google Patents

Abstract

PURPOSE:To display an original placing position at a uniform illuminance by providing an electrooptic element capable of controlling transmission of a desired luminous flux range and a filter varying continuously a light transmittivity to an optical path used for lighting an original. CONSTITUTION:An image pickup section 3 comprising a CCD or the like is provided with a zoom lens 5 and picks up the image of an original 15 on an original platen 15. An electrooptic element 9 transmits the light from a light source provided thereunder and emits the original 15 via a reflection mirror 7. The electrooptic element 9 is made of a liquid crystal or a photo chromic glass or the like and in which a light transmission range 11 from the light source is set to any of default patterns or an optional pattern by a command from a control switch 17. The light source lights up the original placing position 13 on the original platen 1 depending on the setting definitely. An ND filter whose density is changed continuously is arranged on the electrooptic element 9 to correct a partial difference from the illuminance on the original based on the difference from optical paths of the light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device for picking up an image of a document placed on a document table and generating an image signal thereof, and in particular, to provide appropriate illumination with less flare, abnormal reflection, and uneven illuminance. Regarding the technology to do.

[0002]

2. Description of the Related Art Recently, in place of an overhead projector (OHP), an image input device capable of displaying not only a transparent original but also an opaque original on a monitor television or a screen by an image pickup operation has been developed. An extremely large demand is expected because thick materials can be imaged and images can be stored and edited.

A general image input device is shown in FIG. The document placed on the document table 81 is illuminated by the illumination devices 83 and 85, and the document is imaged by the imaging device 87. The image signal generated by the image pickup is displayed on a television monitor or the like.
In such a device, when the document size changes, the illuminating device is also moved in the direction of the arrow in accordance with the change to adjust the position to an appropriate position. In particular, it is necessary to adjust the irradiation range to match the size of the original as much as possible to reduce reflection from outside the original size and adjust the angle of illumination so that abnormal reflection is not imaged.

In addition, the position of the image pickup device is generally fixed, and therefore the standardized document size (for example, A
(4, A3, etc.), the image pickup range is also determined in advance, and therefore, it is necessary to place the image pickup device at a position corresponding to the size of the document when the document is imaged. As one of the methods, as shown in FIG. 8, there is a method of displaying a placement place corresponding to the document size on the surface of the document table by silk-screen printing or the like, and placing the document in accordance therewith. If there is no indication of such a placement location on the surface of the platen, the document is placed at an appropriate position on the platen and then visually aligned while watching the screen of the monitor television. .

[0005]

However, in the conventional apparatus as described above, the illumination is generally adjusted by manually moving and changing the position or inclination of the illumination apparatus. On the other hand, it is difficult to optimally adjust the irradiation range and the irradiation light amount, and reflection and unevenness often occur. Especially, if the optimum irradiation range cannot be obtained, there is a problem that flare occurs due to the reflected light from the document table and the extra area of the input document and the image quality is deteriorated. In addition, if the optimum irradiation light amount is not obtained, when using a document with high reflectance such as a printed photograph or catalog or a document with a curled portion, abnormal reflection occurs and it is not possible to deal with it with only the diaphragm of the imaging unit. However, there was a problem that the image quality deteriorates.

Further, since the conventional illuminating device irradiates the document obliquely, there is a difference in the optical path, and the entire document is not irradiated with the same intensity and unevenness easily occurs, which is one of the causes of image quality deterioration.

Further, there is a problem that the shape of the entire apparatus becomes large due to the arrangement of the illumination and the securing of the adjustment movement area.

[0008] In addition, if the original table is of a type that also serves as a transparent original, or if a transparent original is used, if a position display for placing the original on the original table is provided, that display is imprinted at the same time. there were.

In view of the problems in the above-described conventional apparatus, an object of the present invention is to reduce flare, abnormal reflection, and illuminance unevenness when illuminating an input document in an image input apparatus for picking up an image of the document. The purpose is to enable proper image input by making it possible to easily identify the position to be placed.

[0010]

To achieve the above object, according to the present invention, at least an image input device for capturing an image of a document placed on a document table and generating an image signal thereof is provided. Illuminating means having one light source for illuminating the original, and a part of the illuminating light installed on an optical path until the illuminating light from the illuminating means is transmitted to the original table by electrical control. Is installed on the optical path until the irradiation light from the illuminating means is transmitted to the original table, and the irradiation light adjusting means for limiting the irradiation range on the original table to the range of a desired original size by transmitting Filter means for continuously changing the transmittance of the irradiation light so that the amount of light on the original table becomes uniform within the irradiation range.

Instead of or in addition to the function of limiting the irradiation range of the irradiation light adjusting means to a range of a desired document size, a function of partially controlling the transmittance according to the intensity distribution of the image signal is provided. This makes it possible to prevent abnormal reflection.

Further, controlling the transmittance of the transmitting portion of the irradiation light adjusting means in a strip shape or a block shape is effective for emphasizing only an arbitrary portion of the original.

Further, at least one color for selectively irradiating the illuminating means with light of a plurality of colors and selectively transmitting a desired spectral portion of the illuminating light from the illuminating means. A special effect can be expected by further including filtering means.

It is effective for size reduction to transmit the irradiation light from the illumination means to the document table via at least one reflection mirror.

[0015]

In the above structure, the document placed on the document table is illuminated by the illumination light emitted from the illumination means through the illumination light adjusting means and the filter means. When the irradiation light adjusting means having the function of limiting the irradiation range is used, the transmission range of the irradiation light is electrically controlled by the irradiation light adjusting means, and the irradiation range on the platen is limited to the range of the desired document size. To be done. Furthermore, via filter means,
By increasing the transmittance in the region where the optical path length is long and the irradiation intensity is weak, and decreasing the transmittance in the region where the optical path length is short and the irradiation intensity is strong, the difference in the irradiation intensity on the platen due to the optical path difference is eliminated. A uniform intensity illumination is obtained over the entire document. With the above operation, the inconvenience that the image quality is deteriorated due to the reflected light from outside the original range and the uneven illumination can be eliminated. Further, since the irradiation range is limited to the range of the document size, it is possible to eliminate the inconvenience when printing the position display of the document and displaying the conventional position display.

Further, when the irradiation light adjusting means has a function of partially controlling the transmittance according to the intensity distribution of the image signal, the original is imaged once to generate the image signal, and then the intensity distribution of the image signal is obtained. Is analyzed and the presence or absence of abnormal reflection is recognized. When the occurrence of abnormal reflection is recognized, the transmittance of the irradiation light adjusting means is partially changed so as to reduce the intensity of the irradiation light for that portion. By the above action,
It is possible to reduce the influence of abnormal reflection and prevent deterioration of image quality.

The above-mentioned function of adjusting the transmission range of the irradiation light adjusting means and the function of controlling the transmittance according to the image signal are
It is also possible to act each independently or to use them together.

Further, when the irradiation light adjusting means is additionally provided with a function of controlling the transmittance of the transmissive portion in a strip shape or a block shape, after placing the original document and operating the above-mentioned function, the original document is watched. Only the transmittance of the portion corresponding to the desired portion is increased to provide spot-like illumination.

When an illuminating means capable of selectively irradiating light of a plurality of colors is used, the original can be effectively displayed by selecting the light of a desired color. This can also be realized by passing the irradiation light through the color filtering means.

When transmitting the irradiation light from the illuminating means to the document table, it is possible to incorporate the illuminating means into the document table by using a reflecting mirror. The degree of freedom in selecting a place is increased, and it is possible to eliminate the inconvenience that the device becomes large in size to secure the adjustment movement area of the lighting device.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of an image input device according to an embodiment of the present invention, and FIG. 2A is a cross sectional view of the image input device of FIG. The image input device includes an original table 1, an image pickup unit 3, a zoom lens 5, a reflecting mirror 7, and an electro-optical element 9 that transmits light emitted from an illumination light source 19 in a limited manner. The original 15 is illuminated through the reflection mirror 7 by the illumination light that has passed through the electro-optical element 9,
The image is captured by the image pickup unit 3 (for example, solid-state CCD video camera).
Is imaged at. The illumination light source 19 is installed close to the electro-optical element 9 as shown in FIG. 2, and its irradiation light is condensed by the reflection plate 21 and is irradiated toward the electro-optical element 9 in a manner close to parallel rays. .

The electro-optical element 9 is made of a material such as liquid crystal or photochromic glass, and can electrically change the transmission range 11 (shaded area in FIG. 1) through which the irradiation light from the illumination light source 19 is transmitted. Since the irradiation light from the illumination light source 19 is in a form close to parallel rays, the irradiation range irradiated onto the document table 1 via the reflection mirror 7 is the irradiation range 13 (dotted line in FIG. 1) associated with the transmission range 11. It is limited to the shaded area surrounded by. Since the transmission range 11 can be electrically set freely, the irradiation range 13 can be limited to a desired range.

Further, in this image input apparatus, as shown in FIG. 2A, the ND filter 23 is provided between the electro-optical element 9 and the illumination light source 19. This is to correct the unevenness of the light amount caused by the different optical path lengths (a + b> c + d) in the irradiation range on the document table 1 so that the light amount becomes uniform on the document table. Therefore, as shown in FIG. 2B, the density distribution of the ND filter is continuously changed so that the density becomes higher in the region where the optical path length becomes shorter. The rate of this change is determined according to the rate of change of the optical path length.

Further, the color filter 25 is used for the illumination light source 1.
It is provided on the front surface of 9 so as to be slidable.
The color filter 25 shown in FIG. 2A has three primary colors (R,
Although a filter that transmits only G and B light is shown,
A filter that selectively transmits light of other colors can also be used.

In the above-mentioned image input apparatus, the control switch 17 is provided on the document table 1, and the designation of the input document size, the selection of the illumination mode, the designation of the color filter 25, the change of the transmittance and the like can be performed.

The operation of the image input device configured as described above will be described below.

First, when the input document size is designated by the control switch 17, the transmission range 1 of the electro-optical element 9 is set.
1 changes and switches to the specified input size. In this case, the control switch 17 can specify two types of modes: a mode in which the input size is preset as a default value, and a mode in which the size is designated (the size changes in the arrow direction). When the input size is switched, the irradiation light of the illumination light source 19 has its light path changed only by the reflection mirror 7 after passing through the transmission range 11 of the electro-optical element 9, and the irradiation range 13 equal to the input document size of the document table 1 is changed. Irradiate. The input document is placed on the document table 1 along the irradiation range 13, and the image thereof is picked up by the image pickup unit 2.

By the above operation, the original can be illuminated with an illumination size equal to the input original size and a uniform light quantity, so that flare due to reflected light from outside the input range and uneven illumination due to difference in optical path length are reduced. Image quality image input can be achieved. Furthermore, since the position on which the input document is placed is instructed by the illumination equal to the size of the input document, the input document can be placed easily and the operability can be improved. In particular, even when the document table is of a type that also serves as a transparent document, it becomes possible to easily indicate the position where the document is to be placed, and there is no inconvenience that the position indication marked on the document table is imprinted at the same time.

In addition, when the color filter 25 is designated by the control switch 17, the color filter 25 slides on the front surface of the illumination light source 19 and the color of the illumination light can be selectively changed to obtain a special effect.
In the present embodiment, the case where the color filter is used to change the color of the illumination light has been described.
It is also possible to change the color of the illumination light by using an illumination light source capable of selectively irradiating light of a plurality of colors on 9 itself. It can also consist of multiple color cathode ray tubes. Furthermore, in the color filter 25, a color is changed by using a filter that selectively transmits a spectrum of a desired color, but if a filter having the same center spectrum and different spectrum bandwidth is prepared, the color temperature is changed. It is also possible to get various special effects

Further, in the present image input device, the irradiation range can be formed into a bar code shape (bar code irradiation) or a block shape (block irradiation) as shown in FIGS. 3 and 4. This is performed by controlling the transmission range 11 of the electro-optical element 9 to have a barcode shape or a block shape. Bar code irradiation and block irradiation are
It can be designated by the control switch 17, and the width and position of irradiation can be selected. Such bar code irradiation and block irradiation are effective for illuminating a necessary row or column, especially for a document of a character string, and for not irradiating unnecessary rows or columns to emphasize the irradiated portion. .
Although FIG. 3 shows irradiation in the vertical direction, irradiation in the horizontal direction is also possible.

FIG. 5 is an explanatory view showing the operation of correcting abnormal reflection in the image input apparatus according to the second embodiment of the present invention. In addition to the respective functions of the image input device shown in FIG. 1, the present device is further provided with a function of partially controlling the transmittance of the electro-optical element 9 according to the intensity distribution of the image signal. This is effective in correcting abnormal reflection (including reflection) of an input document having a high reflectance such as a printed photograph or a catalog due to curl.

There are two types of correction operations, automatic correction and manual correction. First, the flow of automatic correction will be described. FIG. 6 is a block diagram of an automatic correction circuit for abnormal reflection. Incident light from the input document passes through the zoom lens 5 and the image pickup device 53 (composed of a CCD or the like).
Is photoelectrically converted by, and processed and output by the sample and hold circuit 55 and the signal processing circuit 57. The sample and hold circuit 55 samples and holds the output of the CCD and temporarily holds it as a CCD output waveform for each area of the document. FIG. 7 shows the sampled and held CCD output waveform. Note that the CCD output waveform in FIG. 7 shows the position in the original document in one dimension for convenience of description, but the data actually held in the sample and hold circuit 55 is represented in two dimensions in the original document. Has been done. In the figure, the part where the CCD output is particularly high is considered to be due to extraordinary reflection. This output waveform is sent to the comparison / detection circuit 59, compared / detected with a preset comparator voltage, and when the output is larger than the comparator voltage, it is recognized as abnormal reflection. When the abnormal reflection is recognized, the control circuit 61 reads the preset data from the memory 63, drives the driver 65, and sets the transmittance of the electro-optical element 9 and the diaphragm 51 so as to be optimized. . The data of the memory 63 is obtained by experimentally obtaining optimum data of the transmittance and the aperture value for various originals and stored in advance. As a memory, various ROMs (EPRO
M, E ² PROM, etc.) can be used.

As described above, the transmittance is automatically changed to reduce the total reflection level, thereby flattening the abnormal reflection light amount and compensating for the shortage of the light amount by opening the diaphragm to reduce the influence of the abnormal reflection. be able to. Conventionally, when there is a risk of abnormal reflection due to curl, non-reflective glass was placed on the original to remove the curl and diffuse the illumination light. It is possible to avoid trouble.

Further, the correction of abnormal reflection can be manually operated. In this case, the transmittance of the electro-optical element 9 is partially changed and corrected by using the function of bar code irradiation or block irradiation. Specifically, while watching the image displayed on the monitor television, the transmittance of the electro-optical element 9 corresponding to the portion corresponding to the abnormal reflection position of the input document is changed to reduce the abnormal reflection light amount to the same level as the whole. And correct it.

[0035]

As described above, according to the present invention, the irradiation range of the illumination can be selected and designated according to the size of the input document, and at the same time, the document placement position can be displayed. It is possible to prevent the deterioration of the image due to the above, and to easily realize the document placement position display.

Further, a special effect can be expected because the original document reflection is prevented by the transmittance control function of the electro-optical element, the barcode-shaped illumination function is provided, and the light source is provided with the color filter switching section so that the light primary colors can be converted.

Furthermore, the present invention has an advantage that it can be used for the function of automatically changing the transmittance of the electro-optical element according to the default value of the reflectance of the input document and the video signal from the image pickup section to perform optimum irradiation.

[Brief description of drawings]

FIG. 1 is an external view showing a schematic configuration of an image input device according to a first embodiment of the invention.

FIG. 2 is a schematic cross-sectional view (a) of the image input device of FIG.
FIG. 3B is an explanatory diagram (b) showing the density distribution of the ND filter used.

FIG. 3 is an explanatory diagram showing an irradiation range in a bar code irradiation mode in the image input device of FIG.

4 is an explanatory view showing an irradiation range in a block irradiation mode in the image input device of FIG.

FIG. 5 is an explanatory diagram showing an abnormal reflection correction operation of the image input apparatus according to the second embodiment of the present invention.

6 is a block diagram of an automatic correction circuit for abnormal reflection that can be used in the image input device of FIG.

FIG. 7 is a waveform diagram showing an output signal of a CCD image pickup device accompanied by abnormal reflection.

FIG. 8 is an external view of a conventional image input device.

[Explanation of symbols]

 1 Original Plate 3 Image Pickup Section 5 Zoom Lens 7 Reflection Mirror 9 Electro-Optical Element 11 Transmission Range of Electro-Optical Element 9 13 Irradiation Range on Original Plate 1 15 Input Original 17 Control Switch 19 Illumination Light Source 21 Reflector 23 ND Filter 25 Color Filter 51 diaphragm 53 image pickup device 55 sample and hold circuit 57 signal processing circuit 59 comparison / detection circuit 61 control circuit 63 memory 65 driver 81 document table 83,85 illumination device 87 image pickup device

Claims (7)

[Claims] 1. An image input device for picking up an image of a document placed on a document table and generating an image signal thereof, the lighting device having at least one light source for illuminating the document. And an irradiation range on the platen is desired by being installed on an optical path until the irradiation light from the illumination means is transmitted to the platen and transmitting a part of the irradiation light by electric control. Irradiation light adjusting means for limiting the size of the manuscript, and an irradiation light from the illuminating means installed on the optical path until it is transmitted to the manuscript table, and the amount of light on the manuscript table is uniform within the irradiation range. The image input device according to claim 1, further comprising: a filter unit that continuously changes the transmittance of the irradiation light. 2. An image input device for picking up an image of a document placed on a document table and generating an image signal thereof, the illumination means having at least one light source and illuminating the document. An irradiation light adjusting unit that is installed on an optical path until the irradiation light from the illumination unit is transmitted to the document table and partially controls the transmittance according to the intensity distribution of the image signal; Is installed on the optical path until the irradiation light from the platen is transmitted to the platen, and the transmittance of the irradiation light is continuously changed so that the amount of light on the platen becomes uniform within the irradiation range. The image input device, further comprising: 3. An image input device for picking up an image of a document placed on a document table and generating an image signal thereof, the lighting device having at least one light source for illuminating the document. And an irradiation range on the platen is desired by being installed on an optical path until the irradiation light from the illumination means is transmitted to the platen and transmitting a part of the irradiation light by electric control. Irradiation light adjusting means for limiting the range of the document size and further partially controlling the transmittance of the transmitting portion according to the intensity distribution of the image signal, and the irradiation light from the illuminating means is transmitted to the document table. A filter means which is installed on the optical path until the temperature of the original plate and continuously changes the transmittance of the irradiation light so that the amount of light on the original table becomes uniform within the irradiation range. Said image input device. 4. The image input device according to claim 1, wherein the transmittance of the transmitting portion of the irradiation light adjusting means is controlled in a strip shape or a block shape. 5. The image input device according to claim 1, wherein the illumination unit is capable of selectively emitting light of a plurality of colors. 6. At least one for selectively transmitting a desired spectral portion of the illumination light from the illumination means.
The image input device according to claim 1, further comprising one color filtering unit. 7. The image input device according to claim 1, wherein the irradiation light from the illumination means is transmitted to the document table via at least one reflection mirror.