JPH06334816A - Picture reader - Google Patents

Abstract

PURPOSE:To enhance the accuracy for gradation reproduction and color reproduction by devising the reader such that a cut filter is used so as not to transmit a wavelength region not required for picture reading but so as to transmit surely only a required wavelength. CONSTITUTION:A thermal ray cut filter 2 is used for a light from a illuminating lamp 1 to eliminate the heat, the resulting light passes through a color resolving filter controlled by a stepping motor such as a blue filter 3, and the resulting light to pass an undesired light component such as a blue component and a near infrared ray component emitting it to a film original 8 and recording the image. The transmitted light is made incident in an infrared ray cut filter 4, where the near infrared ray component is excluded and the image of the resulting light is formed on a CCD sensor 7 by a lens 6 and photoelectric- conversion is made. Similarly, the same processing is applied to the red and green components and the result is outputted to a monitor and a printer. A cut filter transmitting a wavelength light near 670nm whose transmission rate is 0.5% or below and whose transmission region and cut region are made steep is adopted for the color decomposition filter 3.

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 which converts a transparent original into an electric signal and reads the electric signal, and is used, for example, in a film scanner, a film direct transfer machine, a color copying machine, a color facsimile machine and the like. .

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. Figure 1
Reference numeral 4 shows a general optical system of a conventional image reading apparatus. 14, in the image reading apparatus, after the light emitted from the illumination lamp 1 passes through the heat ray cut filter 2 and the color separation filter 3, the light enters the film original 8 and the light transmitted through the film original 8 passes through the lens 6. An image is formed on the CCD sensor by passing the light through the medium, and the film original 8 is read.

The illumination lamp 1 is a light source for irradiating the film original 8, and a halogen lamp or the like is used.
The heat ray cut filter 2 is a heat ray reflection type optical filter, and is for preventing thermal damage to the film original or optical parts even when a halogen lamp having a strong output in the infrared region is used as an illumination lamp. Is.

The color separation filter 3 is a red color filter,
It is composed of three color filters, a green filter and a blue filter, and separates light from the illumination lamp 1 into three colors. The film original 8 is a film (negative,
Positive). The lens 5 is for forming an image of the light passing through the film original 8 on the CCD sensor 6 described later.

The CCD sensor 6 is a sensor having a photoelectric conversion element and is for converting an optical signal into an electric signal. After reading the image recorded on the film original 4 by these members, image processing is performed by an image processing circuit (not shown) or the like, and the image can be displayed on a monitor or the like.

[0006]

The CCD sensor used in the image reading apparatus has sensitivity up to a wavelength of 1000 nm or more. Therefore, in addition to the wavelength light in the visible light range which is originally necessary for reading the image of the film original,
It reacts even with near-infrared (near 700 nm) wavelength light, which is harmful light.

Using the experimental data of FIGS. 15 to 20, the wavelengths of light in the near infrared range (harmful light) are generated by the original density of the film, the color separation filter and the heat ray cut filter, respectively, and , Its effect will be explained. FIG. 15 shows a spectral characteristic of transmitting a low density portion a of a film original on which a Macbeth chart is photographed. Figure 1
Reference numeral 6 shows a spectral characteristic of transmitting a portion of the film original having a Macbeth chart having an intermediate density b. FIG. 17 shows a spectral characteristic of transmitting a portion of high density c of a film original obtained by photographing a Macbeth chart. FIG. 18 shows the luminance with respect to the wavelength transmitted through a film original having a transmission density of 3.07 through a color separation filter (blue filter). FIG. 19
Shows the spectral characteristics of the heat ray cut filter. Figure 20
Shows the output value converted from the density of the film original of the conventional apparatus.

First, the influence of the original density of the film will be described. The spectral characteristics shown by the density of the film original will be examined with reference to FIGS. Figure 1
5, FIG. 16 and FIG. 17 show spectral characteristics of film originals having densities a, b and c, respectively. Concentration is a, b, c
It becomes higher in that order. As is clear from the comparison of these figures, the higher the density of the film original, the lower the transmittance in the visible light range, which is supposed to be obtained, but the near-infrared light range (after 700 nm) ) Has a transmittance of 8
It can be seen that it is 0 to 90%, which does not change depending on the density of the film original. This indicates that the higher the density of the film original, the less the required light and the more the harmful light influences.

Next, the influence of the color separation filter will be described. The spectral characteristics when the color separation filter 3 is arranged between the illumination lamp 1 and the film original 8 will be described with reference to FIG. This time, the color separation filter 3 red,
Of the green and blue filters, the case of the blue filter in which harmful light appears remarkably is listed as data. In the vicinity of 400 to 500 nm in FIG. 18, a blue light component that originally passes through the film original 8 and is to be obtained appears. Then, in the vicinity of 700 nm or less, harmful light which has been originally unnecessary and has passed through the film original 8 appears. Therefore, 70
It can be seen that harmful light in the vicinity of 0 nm cannot be removed even through the color separation filter.

Next, the influence of the heat ray cut filter will be described. Consider a case where the heat ray cut filter 2 is arranged between the illumination lamp 1 and the film original 8 with reference to FIG. The heat ray cut filter 2 used in the conventional apparatus is sufficient if it cuts the heat component that deforms the film original, and it is not required to strictly cut the light in the near-infrared light region, which is costly. The balance determines the filter performance. Therefore,
FIG. 19 shows the heat ray cut filter 2 used in the conventional device.
3 shows the spectral transmittance characteristics of Looking at the spectral transmittance of the heat ray cut filter 2 in FIG. 19, it can be seen that the transmittance of harmful light in the vicinity of 700 nm and below is removed to 5% or less.

However, for example, when a quantizing ability of 1024 levels (10-bit resolution) or higher is required, FIG.
The spectral transmittance of the heat ray cut filter 2 of No. 9 has a remarkable effect on the image. Next, FIG. 20 shows the reproduction characteristics of the image obtained through the heat ray cut filter 2 and the color separation filter 3 as shown in the image reading apparatus of FIG. Diagram R in FIG. 20 shows the case where a red filter is used, diagram G shows the case where a green filter is used, and diagram B shows the case where a blue filter is used. . Especially in Diagram B,
As is clear from the density-converted output value with respect to the film original density, the linearity is worse on the high density side.

Then, how the harmful light effect shown in FIG. 20 appears in an actual image will be described below. 1. The tone changes when the density range of the film original changes. 2. When reading a film original recorded with high density, the CCD sensor outputs higher than it should be due to the influence of harmful light, so if the film original is negative, it will be crushed white, and if it is positive, it will be crushed black. Will end up. 3. When a document film recorded in a very narrow density range is read, gradation skipping occurs. 4. Color separation error occurs due to harmful light. 5. Due to the variation in the spectral distribution of the light source, the color between the units,
Difference in gradation occurs.

Further, in the conventional apparatus, in consideration of cost and the like, it is only necessary to dispose a heat ray cut filter which is not very excellent in the removal characteristics of light of wavelengths in the near infrared and beyond. However, in recent years, with the improvement of film quality, it has become possible to record with a higher maximum density, so that the above-mentioned influence becomes more remarkable.

It is an object of the present invention to provide an image reading apparatus which solves the above problems and accurately reproduces gradation and color.

[0015]

In order to solve the above problems, an image reading device that irradiates a transmissive original with light emitted from a light source and reads light passing through the transmissive original with a sensor is used in the vicinity of 670 nm or later. A cut filter having a transmittance of 0.5% or less for transmitting light having a wavelength of 5% and a steep cutoff region is provided.

[0016]

In the present invention, since the image reading device is constructed as described above, the wavelength range unnecessary for image reading is not transmitted, but the necessary wavelength range can be surely transmitted.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An image reading apparatus according to a first embodiment of the present invention will be described with reference to FIGS. Figure 1
FIG. 3 is a diagram schematically showing an optical system of an image reading device. FIG. 2 is a diagram illustrating the apparatus of FIG. 1 in detail. FIG. 3 is a diagram showing the spectral transmittance of the infrared cut filter used in the apparatus of FIG.

In FIG. 1, the image reading apparatus cuts off the illumination lamp 1, a quartz rod (not shown) for guiding the light of the illumination lamp 1 to the transparent original 8 and unnecessary components of the illumination lamp 1. A heat ray cut filter 2 that transmits illumination light, a color separation filter 3 for color separation of the light flux from this filter 2, and an unnecessary light component (near infrared light component) of the light flux from the color separation filter 3 is cut. The infrared cut filter 4 and the CCD sensor 7 that reads the light transmitted through the transparent original 8 through the mirror 5 and the imaging lens 6 based on the light flux from the filter 4.

In FIG. 1, an infrared cut filter 4 is provided.
May be arranged anywhere in the optical path from the color separation filter 3 to the CCD sensor 7, for example, may be arranged at the position shown by the dotted line. In FIG. 2, an illumination lamp 1 is a light source for irradiating the film original 8 and a halogen lamp or the like is used. The heat ray cut filter 2 is provided immediately before the illumination lamp 1,
This is a heat ray reflection type optical filter for preventing thermal damage to the transparent original (for example, film original) 8 and optical parts even when a halogen lamp or the like having a high infrared power is used as an illumination lamp. . The color separation filter 3 is three filters composed of three colors of red (R), green (G), and blue (B), and separates the light from the illumination lamp 1 into three colors.

The filter mounting box 10 holding the color separation filter 3 is formed in a cylindrical shape, and a quartz rod for guiding the light flux from the illumination lamp 1 is arranged inside the filter mounting box 10. The light flux passing through this quartz rod becomes a linear irradiation light through a slit-shaped opening, and this irradiation light is irradiated onto the film original 8 through the color separation filter 3 and the infrared cut filter 4. Heat ray cut filter 2
Are arranged between the quartz rod and the illumination lamp 1.

The infrared cut filter 4 is an interference type filter and has a characteristic of cutting light having a wavelength of around 700 nm or later, as described in detail below. Mirror 5
It is a reflection mirror for bending the optical path of the light flux that has passed through the film original 8 and is used due to restrictions such as the space of the device. The lens 6 is for forming an image of the light passing through the film original 8 on the CCD sensor 7. The CCD sensor 7 uses a known charge storage type photoelectric conversion element. The film original 8 is a transparent original such as a color negative or a positive film. The stepping motor 11 is a motor for rotating and controlling the filter mounting box 10. The film holding frame 9 is used to hold the film original 8.

The image reading operation of the apparatus shown in FIG. 2 will be briefly described. Light emitted from the illumination lamp 1 removes heat through the heat ray cut filter 2, and then passes through a predetermined color filter (for example, a blue filter) of the color separation filter 3 controlled by the stepping motor 11. The light passing through the blue filter is applied to the film original 8 and the blue component and the unnecessary light component (near infrared component) of the image recorded on the film original 8 pass through.

The light passing through the film original 8 enters the infrared cut filter 4. The light from which the near infrared component has been removed by the infrared cut filter 4 is imaged on the CCD sensor 7 by the lens 6 and photoelectrically converted by the CCD sensor 7. Similarly, since the red and green components of the film original 8 are read, the red and green filters of the color separation filter 3 are also performed. Then, the near-infrared light component that has passed through the color separation filter 3 (red and green filters) is removed by the infrared cut filter 4. The signal photoelectrically converted by the CCD sensor 7 is appropriately analog-processed and digital-processed by a processing circuit (not shown) and converted into a video signal which can be output by a printer or the like on a monitor.

Therefore, the infrared cut filter 4 for removing the unnecessary light component (near infrared light component) which has passed through the color separation filter 3 will be described. According to the experiment, it was found that the light component in the vicinity of 700 nm has a great influence on the image processing, and the infrared cut filter 4 is provided to remove the unnecessary light component.

The spectral transmittance of the infrared cut filter 4 is shown in FIG. As shown in FIG. 3, the feature of the infrared cut filter 4 used this time is 700 nm which is a cut region.
Transmittance in the wavelength range around and below is 0.5% or less,
In addition, the range from the transmission region (670 nm) to the cut region (700 nm) is as steep as 20 to 30 nm. Further, the infrared cut filter 4 used this time needs to have an error of ± 5 nm in wavelength between the transmission region and the cut region due to manufacturing error. With such an error, a clear image can be obtained without affecting the image processed image.

Therefore, the infrared cut filter 4 has a transmittance of 0.5 in the wavelength range around 700 nm which is the cut region.
% Or less, it is possible to completely suppress unnecessary light components around 700 nm that are not removed by the heat ray cut filter 2 and the color separation filter 3. By using the infrared cut filter 4 having such characteristics, the amount of light in this harmful light region becomes extremely small, and the CCD
Harmful light in the vicinity of 700 nm does not reach the sensor 7.
Therefore, even if the film original 8 has a gradation on the high density side, it can be accurately reproduced. For example, in order to accurately reproduce a high density of 3.0, a resolution up to a light intensity difference of 1/1000 is required, but if the infrared cut filter 4 of this time is used, as shown in FIG. It can be reproduced without losing the linearity of the output value and density. In FIG. 12, the blue light component is explained (the reason is that the blue light component is most affected by the unnecessary light component, and therefore the most improved when the infrared cut filter 4 is included). It goes without saying that the linearity is also improved for the green light component.

The infrared cut filter 4 has a range of 20 to 3 from the transmission range (670 nm) to the cut range (700 nm).
Since it is as steep as 0 nm, unnecessary light components that could not be removed by the heat ray cut filter 2 can be suppressed. Therefore, the infrared cut filter 4 can remove only the harmful light without losing the information of the magenta and yellow dyes (distributed from 680 to 690 nm) in the film original 8.

The infrared cut filter 4 is not limited to the interference type filter, and may be a reflection type as long as similar characteristics can be obtained. (Second Embodiment) An image reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a diagram schematically showing an optical system of the image reading apparatus. Figure 5
FIG. 3 is a cross-sectional view of FIG. 2 and is a diagram illustrating in detail the device of FIG. 4.

The second embodiment is different from the above-mentioned first embodiment in that the heat ray cut filter 2 and the infrared ray cut filter 4 are eliminated, and the infrared ray cut filter 40 is placed in the place where the heat ray cut filter 2 was arranged. I have placed it. In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals. In FIG. 4, the infrared cut filter 40 is arranged between the illumination lamp 1 and the color separation filter 3 and has characteristics similar to the spectral transmittance shown in FIG. 3 of the first embodiment.

In FIG. 5, the infrared cut filter 4 is arranged between the illumination lamp 1 and the quartz lot 12 and is made of a heat resistant material. The infrared cut filter 40 has the heat ray cut characteristic which is the characteristic of the heat ray cut filter 2 of the first embodiment, and
It has the characteristics of the infrared cut filter 4 described in the embodiment.

As described above, in the second embodiment, it is sufficient to provide one infrared cut filter 40, which is more effective than the first embodiment in terms of product assembly and cost. The infrared cut filter 40 of the second embodiment is the color separation filter 3
The present invention is not limited to this in the case where the component holding the filter or the like is resistant to heat, and may be arranged between the color separation filter 3 and the film original 8, for example.

In the first and second embodiments described above, the infrared cut filters 4 and 40 act particularly effectively when the illumination light from the illumination lamp 1 enters the film original as parallel light. Is. However, there are two types of illumination lamps of the image reading apparatus, one of which emits parallel light and the other of which emits diffused light. In the image reading device of the type that emits diffused light, the diffused light (angle incident light component) incident on the film original becomes a problem. Therefore, even such an image reading device sufficiently removes the unnecessary light component of the emitted light. A configuration for this will be described in the next third embodiment. (Third Embodiment) A third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a diagram schematically showing an optical system of the image reading apparatus. FIG. 7 is a cross-sectional view of FIG. 2 and is a diagram illustrating an optical path of irradiation light. 8 and 9
FIG. 4 is a diagram illustrating a spectral transmittance characteristic depending on an incident angle of a color separation filter. FIG. 10 is a diagram for explaining the spectral transmittance characteristic depending on the incident angle of the infrared cut filter 4. FIG. 11 is a diagram illustrating spectral transmittance characteristics when a color separation filter and an infrared cut filter are combined. FIG. 12 is a characteristic diagram of the output value and the document density when the color separation filter (blue filter) is used. Figure 1
3 is a characteristic diagram of the output value and the document density for each model when the color separation filter (red filter) is used.

The structure of the third embodiment is almost the same as that of the first embodiment. A different structure is an interference type color separation filter 30 having excellent spectral characteristics even if the color separation filter 3 is a diffused light source. The same reference numerals are given to the same configurations. In FIG. 7, the quartz rod 12 on which the illumination light of the illumination lamp (halogen lamp) 1 of FIG.
A cylindrical reflection cover 13 is provided around the, and a cylindrical filter mounting box 10 holding a color separation filter 30 is arranged around the reflection cover 13. Further, the quartz rod 12 is provided with a diffusion band 10 a extending in the same direction as the slit hole at a position facing the slit hole formed in the reflection cover 13.

In FIG. 7, the illumination light from the illumination lamp (halogen lamp) 1 of FIG.
Light emitted from the quartz rod 12 is reflected by a cylindrical reflecting cover 13 around the quartz rod 12, and the reflecting cover 1
It is ejected toward the film original 8 from the slit hole provided in 3. Illumination light from the quartz rod 12 includes specular reflection light A reflected by the diffusion band 10 a and angle incident light B reflected by the reflection cover 13.

The color separation filter 30 is an interference type color separation filter like the interference type infrared bracket and filter 4. The interference-type color separation filter 30 exhibits different spectral characteristics depending on the incident angle of incident light. Figure 8
Shows the spectral transmittance characteristics when the specular reflection light A is incident on the color separation filter 30 (blue filter). As can be seen from FIG. 8, since the interference type color separation filter 30 is used, the blue light component is almost completely transmitted, and the light components other than the blue light component are almost completely cut. However, when the angle incident light B enters the color separation filter 30 (blue filter) as shown in FIG. 9, the cut characteristic of light components other than the blue light component (light components after 600 nm) deteriorates and the unnecessary light components pass through. . In particular, it can be seen that the light of wavelengths around 650 nm, which was not transmitted in the case of 90 ° incidence in FIG. 8, is transmitted in the case of 45 ° incidence in FIG. 9. Obviously, if a blue filter that transmits only the blue component transmits the red wavelength range, it adversely affects the read image.

However, when combined with the infrared cut filter 4, unnecessary light components that have passed through the color separation filter 30 can be removed, as will be described below. Since the infrared cut filter 4 is also an interference filter like the color separation filter 13, it exhibits different spectral characteristics depending on the incident angle of incident light. What spectral characteristics are shown by the difference in the incident angle of the incident light on the infrared cut filter 4 will be described with reference to FIG. (Figure 3 already described
Shows the spectral characteristics when the incident angle is 90 degrees. ) FIG. 10 shows the spectral characteristics when the infrared cut filter 4 receives incident light of 45 degrees. Compared with the spectral characteristics in FIG. 3, it can be seen that the transmittance sharply decreases especially after 600 nm.

FIG. 11 shows the spectral transmittance characteristics when the angle incident light (45 degrees incident) on the film original 8 passes through the color separation filter 30 and the infrared cut filter 4, that is, the characteristics of FIG. 10 shows a case in which the characteristics of FIG. Therefore, as can be seen from FIG. 11, the wavelength light near 650 nm, which is harmful light by the blue filter, is hardly transmitted, and the light amount in the blue region is reduced, so that the influence of diffused light can be suppressed. On the other hand, since the specular reflection light passing through the blue filter is combined with the characteristic of FIG. 3 (the characteristic of the infrared cut filter 4) and the characteristic of FIG. 8 (the characteristic of the color separation filter), the light amount in the blue region is almost the same. Does not decrease.

Therefore, even if an interference type color separation filter, which has been unfavorable to use, is used in the diffused light source so far, the diffused light source has a remarkable angle dependency, the structure of the third embodiment, that is, the infrared cut filter 4 also interferes. By using a type filter, the effect of harmful light can be suppressed. Although the blue filter has been described, the red and green filters hardly generate harmful light depending on the incident angle, and thus the description thereof is omitted, but it can be understood from the spectral transmittance characteristics of the infrared cut filter 4 in FIG. As described above, the light amounts in the red and green regions can also be reduced. Therefore, similarly to the case of the blue filter, the influence of diffused light can be suppressed and the color reproduction is improved. In addition, the color separation filter 30
Instead of the above, the same effect can be obtained even when an interference type filter is used as a monochrome correction filter provided for obtaining a spectral characteristic suitable for monochrome reproduction of a color film original or a monochrome film original.

FIG. 12 shows the output characteristics (solid line diagram) of the image reading apparatus using the interference type color separation filter 30 and the interference type infrared cut filter 4 as described above. As can be seen from the results of this experiment, the case where the interference type infrared cut filter is used (the solid line is shown) is more than the case where the interference type infrared cut filter is not used (the dotted line diagram) like the conventional image reading apparatus. It can be seen that (Fig.) Has significantly better linearity and better image reproducibility. As described above, according to the embodiment of the present invention, the harmful light component at the time of reading the gradation of the film original is removed, and the linearity between the original density and the output of the apparatus can be maintained up to the high density range. A dynamic range more than double can be secured.

In the conventional image reading device, the density-output characteristics differ from device to device, but as shown in FIG. 13, the image reading device of the third embodiment improves the color separation accuracy. It is possible to obtain a highly reliable and stable quality reading device in which pure color information is obtained and differences in tone and color reproduction between units are significantly reduced.

[0041]

As described above, according to the present invention, the image reading apparatus is provided with the cut filter having a transmittance of 0.5% or less for transmitting light having a wavelength of about 670 nm or later and a steep cut-off area. With this configuration, the wavelength light unnecessary for image reading can be cut, and the necessary light can be reliably transmitted, and the read image can be accurately reproduced.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an optical system of an image reading apparatus.

FIG. 2 is a detailed illustration of the device of FIG.

3 is a diagram showing a spectral transmittance of an infrared cut filter used in the apparatus of FIG.

FIG. 4 is a diagram schematically showing an optical system of an image reading apparatus which is a second embodiment of the present invention.

5 is a cross-sectional view of FIG. 2 and is a detailed description of the device of FIG.

FIG. 6 is a diagram schematically showing an optical system of an image reading apparatus which is a third embodiment of the present invention.

FIG. 7 is a cross-sectional view of FIG. 2 and is a diagram illustrating an optical path of irradiation light.

FIG. 8 is a diagram illustrating a spectral transmittance characteristic depending on an incident angle of a color separation filter.

FIG. 9 is a diagram illustrating a spectral transmittance characteristic depending on an incident angle of a color separation filter.

FIG. 10 is a diagram for explaining the spectral transmittance characteristic depending on the incident angle of the infrared cut filter 4.

FIG. 11 is a diagram illustrating a spectral transmittance characteristic when a color separation filter and an infrared cut filter are combined.

FIG. 12 is a characteristic diagram of an output value and a document density when a color separation filter (blue filter) is used.

FIG. 13 is a characteristic diagram of an output value and a document density of each model when a color separation filter (red filter) is used.

FIG. 14 is a diagram showing a general optical system of a conventional image reading apparatus.

FIG. 15 is a diagram showing a spectral characteristic of transmitting a low density portion a of a film original on which a Macbeth chart is photographed.

FIG. 16 is a diagram showing a spectral characteristic of transmitting a portion of an original density of a film original on which a Macbeth chart is photographed at an intermediate density b.

FIG. 17 is a diagram showing a spectral characteristic of transmitting a portion of high density c of a film original on which a Macbeth chart is photographed.

FIG. 18 is a diagram showing luminance with respect to a wavelength of light transmitted through a film original having a transmission density of 3.07 through a color separation filter (blue filter).

FIG. 19 is a diagram showing a spectral characteristic of a heat ray cut filter.

FIG. 20 is a diagram showing a density-converted output value with respect to a film original density of a conventional apparatus.

[Explanation of symbols]

 1 ... Illumination lamp 2 ... Heat ray cut filter 3 ... Color separation filter 4 ... Infrared cut filter 5 ... Mirror 6 ... Lens 7 ... CCD sensor

Claims (7)

[Claims] 1. An image reading apparatus which irradiates a transparent original with light emitted from a light source and reads light passing through the transparent original with a sensor, has a transmittance of 0.5 at wavelengths near 670 nm and below. %
An image reading apparatus including a cut filter having a steep transmission region and a cut region. 2. The image reading apparatus according to claim 1, wherein the cut filter has a cut wavelength of 670 nm to 70 nm.
An image reading device characterized by being 0 nm. 3. The image reading apparatus according to claim 1, wherein the cut filter has a cut wavelength of 670 nm to 70 nm.
An image reading apparatus, which has a tolerance of 0 nm and a cut wavelength tolerance of ± 5 nm. 4. The image reading device according to claim 1, wherein the cut filter is an interference filter. 5. The image reading apparatus according to claim 1, wherein the cut filter is arranged between the light source for illuminating the transparent original and the transparent original. 6. An image reading device for irradiating a transparent original with light emitted from a light source and reading light passing through the transparent original with a sensor, which is arranged immediately before the light source and cuts a heat ray. And a color separation filter which is arranged in the latter stage of the heat ray cut filter and separates the light source, and a transmittance which is arranged in the latter stage of the color separation filter and which transmits light having a wavelength of around 670 nm or less of 0.5% or less An image reading apparatus comprising a cut filter having a sharp transmission region and a sharp cutting region. 7. The image reading apparatus according to claim 6, wherein the cut filter is arranged in a subsequent stage of the transparent original.