JPH0662179A - Image input device - Google Patents

Abstract

PURPOSE:To exactly read color information without any color slurring by providing an illuminator for illuminating images and an optical system for picking up images, and installing an optical path changing means between the image and the image forming plane of the optical system. CONSTITUTION:Plural fluorescent lamps of different spectroscopic characteristics, namely, a blue fluorescent lamp 14, green fluorescent lamp 16 and red fluorescent lamp 18 are cyclically successively turned on, and an image 36 placed on a transparent glass platen is irradiated with light with a reading line S as a center. Reflected light L2 from the image 36 is reflected by a mirror 24, and the image is formed on a linear image sensor 28 by a lens 26. An optical path deflector 38 is arranged between the lens 26 and the linear image sensor 28, and all the beams from the lens 26 to the linear image sensor 28 are passed through this optical path deflector 38. The linear image sensor 28 outputs electric signals in proportion to the reflected light intensity of respective picture elements constituting the reading line S on the image 36, those signals are digitally converted, and the color information of the image 36 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to image input devices such as image scanners, digital copying machines, and facsimiles.

[0002]

2. Description of the Related Art As a method of reading color information of an image, there is a method of using a plurality of fluorescent lamps having different spectral characteristics,
An example thereof is disclosed in JP-A-54-81715. FIG. 6A shows an image input device according to a conventional example.
Further, FIG. 6B is a sectional view taken along the line AA ′ of FIG.

First, a blue fluorescent lamp (14), a green fluorescent lamp (16), and a red fluorescent lamp (18) are periodically turned on, and an image is placed on a glass table (20) made of a transparent glass plate.
Light is emitted centering on the reading line S1 of (36). image
The reflected light L1 from (36) is reflected by the mirror (24) and is imaged by the lens (26) which is an image forming system on the linear image sensor (28) which is a photoelectric conversion means.

The linear image sensor (28) outputs an electric signal proportional to the reflected light intensity of each pixel constituting the reading line S1 on the image (36) when sequentially illuminated by the illumination device. The output signal is digitally converted by an A / D converter (not shown) to obtain color information of the image (36).

Next, the carriage (30) is moved by a drive unit (34) through a timing belt (32) in a direction perpendicular to the one-dimensional array of the linear image sensor (28) by an amount corresponding to the reading resolution. To do. By repeating the above-mentioned reading operation, the two-dimensional array information of the image (36) is obtained.

A detailed reading procedure will be described below with reference to a timing chart. FIG. 7 is a read timing chart according to a conventional example. 300dpi as an example
The reading operation at (= 84.7 μm = 25.4 mm / 300) will be described. The symbol a) shown in FIG. 7 is
FIG. 7 is a partially enlarged view of a reading line S1 portion on the image (36) shown in FIG. 6 (b). Position coordinates of the reading point marked on the image (36), P1, P2, P3, P4, P5, P
The intervals of 6, P7 and P8 are 28 μm pitch, which is one-third of 300 dpi, and the points on the image formed in the center of the linear image sensor (28) at the time shown in i) are Show. Also, in image (36),
An image having a width of 170 μm and a black line drawn on a white background is shown.

B) is the change in reflectance at the image position shown in a). c) shows the amount of light incident on the light receiving surface of the linear image sensor (28) at each time, d) is a clock pulse that determines the light amount integration (accumulation) time of the linear image sensor (28), and e) is the linear image sensor. (28)
Output, f) is a lighting timing chart of the green fluorescent lamp (16), g) is a lighting timing chart of the blue fluorescent lamp (14),
h) is a lighting timing chart of the red fluorescent lamp (18).
i) shows a time axis scale.

When a reading start signal is sent by a host computer (not shown), the reading operation of the image input device is started. First, the carriage (30) is moved by the drive unit (34) through the timing belt (32) shown in FIG. 6, and moves to the reading position P1 on the image (36) shown in FIG. At this point, the image P is taken by the lens (26).
A linear image sensor (28) is formed on the linear image sensor (28) corresponding to a reading resolution of 300 dpi centered on 1.

Generally, a stepping motor is used for the drive unit (34). The stepping motor can drive at high speed on the order of milliseconds, while the carriage (3
Due to the inertia of (0) and the vibration of the timing belt (32), it is impossible to stop in small increments. Therefore, once the reading operation is started, the carriage (30) runs at a substantially constant speed to the reading end point on the image (36). That is,
Stopping every read line is generally not done.

Next, at the timing t1 shown in i), the lighting signal f) of the green fluorescent lamp (16) is turned on. The light intensity value c) incident on the light receiving surface of the linear image sensor (28) is proportional to the average value of the reflectance b) of the area corresponding to the resolution centered on the reading position P1 on the image (36). Becomes Here, as mentioned above, the carriage (30)
Is operated at a constant speed, the reading position on the image (36) formed at the central position of the linear image sensor (28) moves every moment.

At the time point i) t2 when the read position on the image (36) comes to P2, the lighting signal g) of the green fluorescent lamp (16) is turned off, and a linear image sensor drive circuit (not shown) is used here. The clock pulse shown in d) is output, and the output from the linear image sensor 28 corresponding to the light of the green fluorescent lamp 16 is output as shown in e). (D1) Further, an analog signal is converted into a digital signal by an A / D converter (not shown) and transmitted to the host computer. At the timing t2, the next lighting color, that is, the lighting signal g) of the blue fluorescent lamp (14) is turned on.
At this time, the reading position on the image (36) has passed P2 because of the movement of the carriage 1 (30). Points P2 and P3 separated by 600 dpi, which is half the reading resolution
When the reading position reaches in the middle of, the incident light quantity value c) on the light receiving surface of the linear image sensor (28) is decreased due to the influence of the decrease of the reflected light from the black area starting from the reading position P4 on the image (36). Begins to decline.

At time i) t3 when the read position on the image (36) comes to P3, the lighting signal g) of the blue fluorescent lamp (14) is turned off, and the linear image sensor drive circuit (not shown) is used here. The clock pulse shown in d) is output, and the output from the linear image sensor 28 corresponding to the light of the blue fluorescent lamp 14 is output as shown in e). (D2) The output from the linear image sensor (28) accumulated during the time t2 and t3 corresponding to the light of the blue fluorescent lamp (14) is
As shown in e), the value becomes proportional to the integral value of the incident light amount of the polygon shown in c).
(16) The value is smaller than the output D1 from the linear image sensor (28) corresponding to light.

At timing t3, the next lighting color, that is, the lighting signal f) of the red fluorescent lamp (18) is turned on.
At the time point i) t4 when the read position on the image (36) reaches P4, the lighting signal h) of the red fluorescent lamp (18) is turned off. The output from the linear image sensor (28) accumulated during the time t3 and t4 corresponding to the red fluorescent lamp (18) light is the integrated value of the trapezoidal incident light amount shown in c) as shown in e). Since the values are proportional, the blue fluorescent lamp just before
(14) The value is smaller than the output D2 from the linear image sensor (28) corresponding to light. (D3) Similarly, at the timing t4, the next lighting color, that is, the lighting signal f of the green fluorescent lamp (16) is turned on. Image (36)
At the time when the upper reading position comes to P5, the lighting signal h) of the green fluorescent lamp (16) is turned off at i) t5. The output from the linear image sensor (28) accumulated during the time t4 and t5 corresponding to the light of the green fluorescent lamp (16) is e).
As shown in c), the value is proportional to the integrated value of the trapezoidal incident light amount shown in c), so it is a value smaller than the output from the linear image sensor (28) corresponding to the light of the immediately preceding blue fluorescent lamp (14). Becomes (D4) In this way, the color information for one line corresponding to the reading resolution of 300 dpi is output.

[0014]

However, when the above-mentioned reading operation is performed, the reading operation is performed while flowing the carriage (30), so that the output of the linear image sensor of e) shown in FIG. The respective data on the same reading line corresponding to (1) and (2) have different values because they are read at the positions shifted by 1/3 and 2/3 of the resolution. That is, when the color information of the points of 300 dpi from the points P1 to P4 on the image (36) is expressed by 256 gradations, the green light data D1 is 255 and the blue light data D is
2 is 200 and red light data D3 is 150, resulting in greenish color information.

Therefore, in the conventional reading method,
When reading an image in which the reflectance on the image (36) changes abruptly, a value different from the original color information is read, causing a color shift in the read result. there were.

In view of the above points, it is an object of the present invention to provide an image reading apparatus capable of reading accurate color information without color shift.

[0017]

An image input device of the present invention is an image input device having an illuminating device for illuminating an image and an optical system for picking up the image, wherein the image is between the image and the image plane of the optical system. An image input device characterized in that an optical path changing means is provided in the.

[0018]

The reflected light from the image illuminated by the illumination device is deflected by the optical path changing means arranged between the image and the image plane of the optical system, and is imaged on the image plane.

[0019]

FIG. 1 is a sectional view of a carriage (60) portion which is a reading optical system element of an image input apparatus showing an embodiment according to the present invention.

First, a schematic operation for reading will be described. A glass stand made of a transparent glass plate that sequentially lights a plurality of fluorescent lamps with different spectral characteristics that are lighting devices, a blue fluorescent lamp (14), a green fluorescent lamp (16), and a red fluorescent lamp (18). ] Light is emitted centering on the reading line S of the image (36) placed on it. The reflected light L2 from the image (36) is reflected by the mirror (24) and imaged on the linear image sensor (28) which is a photoelectric conversion means by the lens (26) which is an imaging system. .

Lens (26) and linear image sensor (28)
Between the optical path deflector and the optical path deflector (3
8) and place the linear image sensor (2
All light rays reaching 8) pass through this optical path deflecting device (38).

The linear image sensor (28) outputs an electric signal proportional to the reflected light intensity of each pixel constituting the reading line S on the image (36) when sequentially illuminated by the illumination device. The output signal is digitally converted by an A / D converter (not shown) to obtain color information of the image (36).

Lens (26) and linear image sensor (28)
A perspective view of the optical path deflecting device (38) inserted between the two is shown in FIG. Further, FIG. 3A is a sectional view taken along the line BB ′ of FIG.

The optical path deflector (38) comprises a prism (40), a displacement device (42), and a displacement device drive section (44). The prism (40) further comprises a plate A (46), a plate B (48), a fluid optical member (50), and a bellows (52).

Plate A (46) and Plate B (48)
Consists of two parallel glass plates 20 mm square and 0.2 mm thick. The fluid optical member (50) is inserted into the space sandwiched by the plate A (46) and the plate B (48), and the end thereof has a bellows (52) to prevent the fluid optical member (50) from flowing out. ). Flowable Optical Components (50)
Is water having a refractive index of 1.53, for example. Plate A (46)
Is rotatable about a rotating shaft attached to the central portion, and a displacement device (42) is attached to the lower end portion.
The displacement device (42) is composed of a piezoelectric element which is displaced when an electric field is applied, one end of which is in contact with the plate A (46) and the other is fixed.

FIG. 3 (b) is a diagram for explaining the operation of the displacement device (42). FIG. 3A is a diagram showing a state at the time when electric charges are not injected into the displacement device (42), and the plate A (4
6) and plate B (48) are arranged in parallel. Therefore, the light ray L3 incident on the optical path deflecting device (38) is
After passing through (38), it becomes a parallel light beam L3 'and enters the linear image sensor (28).

Here, the displacement device drive section (44) displaces the displacement device (42) by a predetermined displacement amount ΔX. As a result, the plate A (46) is inclined by a predetermined angle φ determined by the following equation, as shown in FIG. 3 (b).

[0028]

[Table 1]

H indicates the distance between the rotary shaft (fulcrum) and the displacement device (42) (point of action).

Then, as shown in FIG. 3 (b), the light ray L3 incident on the optical path deflecting device (38) becomes a light ray L3 '' refracted after passing through the optical path deflecting device (38) to the linear image sensor (28). Does not enter. Here, in the case of the light ray L4 which is inclined by the incident angle θ1 with respect to the light ray L3, it is refracted by the optical path deflecting device (38) and is incident on the linear image sensor (28) after passing through the optical path deflecting device (38). Displacement device (42)
It is possible to change the angle of the plate A (46) of the prism (40), and as a result, to change the angle component of the light beam incident on the linear image sensor (28) by adjusting the displacement amount ΔX of the prism (40).

Next, the relationship between the reading timing and the driving timing of the displacement device (42) when actually reading an image will be described with reference to a timing chart.

FIG. 4 is a schematic sectional view for explaining the reading operation.

For the sake of explanation, the refraction angle of light rays is exaggerated. Further, FIG. 5 is a timing chart for explaining the reading operation.

The detailed reading procedure will be described below with reference to FIGS. 4 and 5. As an example, 300 dpi (= 84.
The reading operation at 7 μm = 25.4 mm / 300) will be described.

The symbol a) shown in FIG. 5 is a partially enlarged view of the read line S portion on the image (36) shown in FIG.
Position coordinates of the reading point marked on the image (36), P
The intervals of 1, P2, P3, P4, P5, P6, P7, and P8 are 28 μm pitches, which are one-third of 300 dpi, respectively, and are at the center of the linear image sensor (28) at the time shown in i). The point on the image currently formed is shown. Also, the image (36) has 170μ, which is twice the resolution.
With a width of m, a black line is drawn on a white background from points P4 to P10.

B) is the change in reflectance at each image position shown in a). c) shows the amount of light incident on the light receiving surface of the linear image sensor 28 at each time. d) is a clock pulse that determines the light quantity integration (accumulation) time of the linear image sensor (28), and e) is the linear image sensor (28)
Output, f) is a lighting timing chart of the green fluorescent lamp (16), g) is a lighting timing chart of the blue fluorescent lamp (14),
h) is a lighting timing chart of the red fluorescent lamp (18). i) shows a time axis scale.

First, at the timing t1 shown in i), the lighting signal f) of the green fluorescent lamp (16) is turned on.
The reflected light L5 from the image (36) shown in FIG.
Then, the light passes through the optical path deflecting device (38) to form an image on the linear image sensor (28). Since the plate A (46) and the plate B (48) which form the optical path deflecting device (38) are parallel to each other, the light beam L5 is not deflected. As a result, the light intensity value c that is incident on the light receiving surface of the linear image sensor (28) shown in FIG. 5)
Is a light amount value proportional to the average value of the reflectance b) of the area corresponding to the resolution centered on the reading position P1 on the image (36).

Since the carriage 60 is operated at a constant speed, the reading position on the image 36 formed at the central position of the linear image sensor 28 moves every moment.

At the time point i) t2 when the reading position on the image (36) comes to P2, the lighting signal f) of the green fluorescent lamp (16) is turned off, and a linear image sensor drive circuit (not shown) is used here. The clock pulse shown in d) is output and the output from the linear image sensor 28 corresponding to the light of the green fluorescent lamp 16 is output as shown in e) (D1).

Further, an analog signal is converted into a digital signal by an A / D converter (not shown) and transmitted to the host computer.

At the timing t2, the next lighting color, that is, the lighting signal g) of the blue fluorescent lamp (14) is turned on.
At this time, the angle φ of the plate 1 (46) of the prism (40) of the optical path deflecting device (38) shown in FIG. 3 (b) is changed. Then, the reflected light L6 from the image (36) shown in FIG. 4 is deflected after passing through the optical path deflector (38), and is imaged on the linear image sensor (28) by the lens (26).

Here, the angle of the plate 1 (46) constituting the optical path deflecting device (38) is −0.0458 degrees, and the displacement amount of the displacement device (42) is 8 μm. The variable H in the above equation corresponds to half the size of the plate 1 (46) and H = 1.
It is 0 mm.

Here, as shown in FIG. 4, the carriage (60)
The central axis of the inner lens (26) is the point P2 on the image (36).
An image (36) that is directed to the linear image sensor (28) due to the refraction effect of the optical path deflector (38)
The upper point is P1.

Further, the plate 1 (46) of the optical path deflector (38)
Move the carriage while keeping the angle of -0.0458 degree. At the time i) t2 when the read position on the image (36) comes to P2, the lighting signal g) of the blue fluorescent lamp (14) becomes O.
In addition to the FF, the linear image sensor drive circuit (not shown) outputs the clock pulse shown in e), and the output from the linear image sensor (28) corresponding to the light of the blue fluorescent lamp (14) is shown in d). Is output (D2).

As a result, in the conventional example, the influence of the decrease in reflectance starting from the point P4 on the image (36) does not occur, and the reading results of the green data D1 and the blue data D2 read immediately before are as follows: The values are obtained by reading the same portion, and if the points P1 to P2 on the image (36) are white, the values are the same.

At the timing t3, the next lighting color, that is, the lighting signal h) of the red fluorescent lamp (18) is turned on.
At this point, the angle φ of the plate A (46) of the prism (40) of the optical path deflector (38) is changed from -0.0458 degrees to -0.91.
Change to 67 degrees. Then, the image (36) shown in FIG.
The reflected light L7 from the linear image sensor (2) is deflected after passing through the lens (26) and then the optical path deflecting device (38).
8) Imaged on top.

Further, the plate A (46) of the optical path deflector (38)
The carriage is moved while keeping the angle of -0.9167 degrees. At the time i) t4 when the read position on the image (36) comes to P4, the lighting signal h) of the red fluorescent lamp (18) becomes O.
In addition to FF, the linear image sensor drive circuit (not shown) outputs the clock pulse shown in d), and the output from the linear image sensor (28) corresponding to the red fluorescent lamp (18) light is shown in e). Is output (D3).

At this point, the prism (4
Return the angle φ of plate 1 (46) of 0) to −0 degrees. Then,
The reflected light L8 from the image (36) shown in FIG.
After passing through, the light passes through the optical path deflecting device (38) without being deflected, and an image is formed on the linear image sensor (28).

In this way, color data for one line centering on the point P1 on the image (36) is obtained. That is, the color information for one line corresponding to the reading resolution of 300 dpi is output. Similarly, at the timing t4, the next lighting color, that is, the lighting signal f) of the green fluorescent lamp (16) is turned on. When the read position on the image (36) reaches P5 i) t
At 5, the green fluorescent lamp (16) lighting signal f) is turned off. Time t4, t5 corresponding to the green fluorescent lamp (16) light
Since the output from the linear image sensor (28) accumulated during the period becomes a value proportional to the integral value of the trapezoidal incident light amount shown in c) as shown in e), the immediately preceding blue fluorescent lamp
(14) The value is smaller than the output from the linear image sensor (28) corresponding to light (D4).

In summary, in the present embodiment, one cycle (t) in which the lamps of three colors are sequentially turned on in spite of performing the reading operation while flowing the carriage (60).
From 1 to t4), by sequentially changing the optical path by the optical path deflecting device (38), the point on the image (36) formed at the center of the linear image sensor (28) always starts from P1 and ends at P2. It becomes the range to do.

By reading the same area on the image (36), it is possible to eliminate the color shift that has occurred in the conventional method. Therefore, it is possible to provide an image reading device capable of reading accurate color information.

The same effect can be obtained not only in the color separation system using the light source shown in this embodiment but also in the color separation system combining the white light source and the spectral filters of the three primary colors.

[0053]

[Effects of the Invention] Even when an image whose reflectance changes abruptly is read, it is possible to provide an image reading apparatus capable of reading accurate color information without color shift.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a carriage (60) portion which is a reading optical system element of an image input apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of an optical path deflecting device (38).

FIG. 3 is a sectional view taken along the line BB ′ of FIG. 2 and an operation explanatory view of the displacement device (42).

FIG. 4 is a schematic sectional view illustrating a reading operation.

FIG. 5 is a timing chart illustrating a reading operation.

FIG. 6 is a perspective view of an image input device according to a conventional example and FIG.
A'sectional view.

FIG. 7 is a reading timing chart according to a conventional example.

[Explanation of symbols]

 (14) Blue fluorescent lamp (16) Green fluorescent lamp (18) Red fluorescent lamp (20) Glass table (24) Mirror (26) Lens (28) Linear image sensor (36) Image (38) Optical path deflector (40) Prism (42) Displacement device (44) Displacement device driver (46) Plate A (48) Plate B (50) Flowable optical member

Claims (1)

[Claims] 1. An image input device having an illuminating device for illuminating an image and an optical system for capturing the image, wherein an optical path changing means is provided between the image and an image plane of the optical system. Image input device.