JPH08248529A - Image input device and image input method - Google Patents

Abstract

PURPOSE: To make it possible to lessen the influence of external light without using a cap member, etc., in particular by correcting line data by using line sensor (CCD) storage data when a light source is put out at the time of image reading. CONSTITUTION: An image reading mechanism section 51 is provided with an illuminating section, projecting section, carriage, etc. The mechanism section has a memory section 52 for temporarily storing the line data after reading the data and is so formed that the respective data of R, G, B can be stored therein. The influence of external light is removed by executing signal processing of respective pieces of the data in a signal processing section 53 after the data of R, G, B are read and thereafter, the data are transferred to a host computer 55 via an I/F section 54 after removing the influence of external light. In such a case, the light source is put out and the data reading is executed with a CCD by the prescribed storage time after reading of R, G, B. At this time, only the signal components by the external light appear in the CCD output if the external light enters. The components by the intrinsic illumination light are obtd. by subtracting the components by the external light from the line data of the respective colors.

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 reading image information on a transparent or reflective original. In particular, the present invention relates to an image input device capable of reducing the influence of external light on a read image.

[0002]

2. Description of the Related Art FIGS. 4 to 8 show the structure of an example of a conventional image input device. In FIGS. 4 and 5, the image input device includes an illumination unit 3 that guides illumination light emitted from the light source 1 onto the document 2.
And a carriage 4 that holds and moves the original 2 and the original 2
The transmitted light that passes through the line sensor (CC
D) a projection unit 6 for forming an image on the image.

The illumination unit 3 has a plate-shaped base member 7 and a light source 1 which emits light in a radial direction, and a first mirror 8 and a second mirror 8 which change the direction of the light so as to be linear on the original surface. A mirror 9 is attached. Furthermore, while being arranged so as to cover the light source 1, the first mirror 8, and the second mirror 9,
Illumination unit cover member 1 having slits 10 through which illumination light passes
1 is fixed to the base member 7 by a claw-shaped hooking portion 11a. The light emitted from the light source 1 is condensed by the first mirror 8 so as to be linear on the document surface, and is bent by the second mirror 9 in the document direction, that is, in the vertical direction.

Therefore, the light from the second mirror 9 has an elongated rectangular shape in the vicinity of passing through the slit 10 of the lid member 11. Slit 10 provided in lid member 11
Has a rectangular shape that is slightly larger than the shape of the light, as long as it has a size necessary for the illumination light to pass through. Further, a part of the slit 10 has a plate 11b bent inward, and prevents external light from the opening 12 provided in the front surface of the base member 7 from reaching the light source 1 through the slit 10. I'm out.

A toric mirror is used as the first mirror 8. As shown in FIG. 6, the toric mirror 8 has a curved surface R1 having a first curvature parallel to the original surface 2a and a curved surface R2 having a second curvature perpendicular to the original surface 2a. It is formed by being compounded. The curved surface R1 reads the light 1a emitted from the light source 1 at the position of the original surface 2a and illuminates the width of one line, and the curved surface R2 forms the light source image of the light source 1 on the original surface 2a. I'm making you image.

An upper carriage 4a for holding the original 2 in between.
And the lower carriage 4b are guided by two guide bars 13 arranged in parallel, and are movable in the left-right direction.
A rack portion (not shown) is provided in a part of the upper carriage 4a, and the carriage 4 moves left and right by a pinion driven by this and a stepping motor (not shown).

The projection unit 6 includes a third mirror 14 and a lens 1.
5, a CCD 5 and a projection cover member 17 provided with a slit 16 which covers the entire surface and at the same time allows the light transmitted through the document to pass therethrough. In addition, the slit 16 of the projection unit cover member 17
Also, similarly to the illumination unit cover member 11, the plate 17a is bent inward to prevent outside light from the opening 12 from directly entering the inside of the projection unit 6 through the slit 16.
Further, both the illumination unit cover member 11 and the projection unit cover member 17 have a black surface and have a matte treatment so as not to reflect external light. The image information of the document 2 illuminated by the illumination unit 3 is reflected by the third mirror 14 and is reflected by the lens 1
5 forms an image on the CCD 5.

7 and 8 show the structure of the light source 1. The light source 1 is a blue (B) LED 2 as six light emitting elements.
1, 4 green (G) LEDs 22 and 2 red (R)
LED 23, and each LED 21, 22, 23
Are mounted on the stem 24. Also, 6 blue L
The EDs 21 are arranged on a straight line, and the green LEDs 22 and the red LEDs 23 are arranged on a parallel straight line in the order of GRGGRG. Then, each LED 21, 22, 2
The optical axes of the light emitted from the light source 3 and reflected by both surfaces of the reflection mirror 25 provided in the light source 1 are located on the same plane.

The twelve LEDs 21, 22, 23 are mounted on a stem 24 formed of a conductive material in a plate shape, and one pole of each LED 21, 22, 23 is connected to the stem 24. The other poles of the LEDs 21, 22, 23 are connected to electrodes 27 mounted on the stem 24 via insulating members 26 via wires 28, respectively.
Further, the stem 24 around each of the LEDs 21, 22, 23 is formed with a conical reflector portion 24a that reflects light emitted in the lateral direction and emits it upward. The light reflected by each reflector portion 24a is reflected by the reflection mirror 25, emitted to the front, and further collected by the mirrors 8 and 9 so as to be linear on the original 2.

At this time, the light emitted from the blue LED 21 is reflected by the blue reflecting film 25 formed on the first surface of the reflecting mirror 25.
The light reflected by a and emitted from the green LED 22 and the red LED 23 is reflected by the total reflection film 25b formed on the second surface of the reflection mirror 25. As a result, when viewed from the front of the light source 1, the three colors appear to emit light from the same position. Further, the original 2 can be read at high speed by electrically controlling the switching of the three colors of blue, green and red. Reference numeral 29 shown in FIG. 10 is a 45 degree prism provided on the light emitting surface of the reflection mirror 25, and an infrared cut film 30 is formed on the light emitting surface of the 45 degree prism 29.

In the image input apparatus constructed as described above, first, the carriage 4 holding the original 2 is moved so that the first line of the original 2 comes to the reading position of the CCD 5. Next, the red (R) LED 23 of the light source 1 is turned on. The light transmitted through the original 2 is focused on the CCD 5 by the projection lens 15, and the R data is read. Similarly, the green (G) LED 22 is turned on, read, and blue (B).
The RGB data is read by turning on and reading the LED 21.

At this time, in general, the LEDs 21, 22, 23
Since the amount of light emitted from each is different, the time for accumulating the transmitted light of the CCD 5 is changed for each RGB. That is,
RGB can be balanced by shortening the accumulation time for a color with a large amount of light and increasing the accumulation time for a color with a small amount of light.

When the RGB reading of one line of the original 2 is completed, the carriage 4 is driven with the light source 1 turned off, the original 2 is moved by one line, and the above-described one-line reading sequence is repeated. By repeating this operation for a predetermined number of lines, the reading for one screen is completed.

[0014]

However, according to the conventional image input apparatus configured as described above, the opening 12 for inserting the original 2 to be read into the apparatus is provided. External light may enter the inside of the device through the opening 12. As shown in FIG. 4, the image input device is provided with plate members 11b and 17a that are bent in the slits 10 and 16 of the lid members 11 and 17, respectively, so that light from the outside can directly enter the projection system or the illumination system. It is designed not to enter. However, in the case where the mount itself holding the original 2 reflects external light and guides it to the projection unit 6, it is impossible to completely prevent external light.
It sometimes affected the CD output.

FIG. 9 shows an example of the CCD output when external light enters. For example, as shown in (a), when a document with a black square in the center is read at the position indicated by the dotted line, and when there is no influence of external light, the output signal is white as shown in (b). → Black → White uneven signal. However, when signals having a small mountain-shaped convex portion in the central portion are overlapped by external light as shown in (c), a convex component appears in the central portion of the read line data as shown in (d). When this appears steadily in one screen, a streak appears in the sub-scanning direction in the output image, as shown in (e). That is, only the portion where the external light overlaps becomes brighter than it should be, and that portion is colored whitish.

On the other hand, if the lid member for completely blocking the external light is provided after the document 2 is inserted into the apparatus, the influence of the external light can be prevented, but the number of parts increases and the cost increases. Not only that, but the operability for the user is also reduced.

The present invention has been made in view of such a situation, and an object thereof is to provide an image input apparatus capable of reducing the influence of external light without providing a lid member or the like.

[0018]

To achieve the above object, the present invention according to claim 1 illuminates one line in the main scanning direction of a document 2 (for example, the light source 1 in FIG. 4).
And a photoelectric conversion unit (for example, CCD 5 in FIG. 4) that converts light from the document 2 into an electric signal and a transport unit (for example, carriage 4 in FIG. 4) that moves the document 2 in the sub-scanning direction. In the image input device for obtaining information of one screen, a storage unit (for example, the memory unit 52 in FIG. 1) that stores and holds a plurality of line data read when the light source 1 is turned on and off, and when the stored light is turned on. And data processing means for reducing the influence of external light on the read image by performing a calculation between the line data when turning off the light (for example, FIG. 1).
And a signal processing unit 53).

According to a second aspect of the present invention, the light from the light source 1 irradiates one line in the main scanning direction of the original 2 and the light from the original 2 is converted into an electric signal to read the image of the original 2. In the image input method of obtaining information of one screen by moving the document 2 in the sub-scanning direction and repeating the reading operation, one line of read data of the document 2 is stored when the light source 1 is turned on and off. However, it is characterized in that the influence of external light on the read image is reduced by processing both data.

[0020]

In the image input device and the image input method described above, the read data of one line of the original 2 when the light source 1 is turned on and off is subtracted by the signal processing unit 53, so that the external light in the read data is used. It is possible to remove the component and obtain only the component due to the original illumination light.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image input device of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the image reading mechanism section 51 is provided with an illuminating section, a projecting section, a carriage, and the like, and the arrangement configuration thereof is almost the same as the conventional example shown in FIG. In this embodiment, after reading the line data, it has a memory unit 52 for temporarily storing them, so that each of the RGB data can be stored. After reading the RGB data, the signal processing unit 53 performs signal processing on each data to remove the influence of external light, and then transfers the data to the host computer 55 via the I / F unit 54.

Next, an embodiment of the image input method of the present invention will be described with reference to the drawings.

FIG. 2 shows an image input sequence in the first embodiment of the image input method of the present invention. In FIG.
In step S101, the document 2 is moved to a predetermined position together with the carriage 4, and steps S102, S103, S10 are performed.
4, LED (R) 23 lighting / reading, LE
D (G) 22 lighting / reading, LED (B) 21 lighting /
Read sequentially. The sequence so far is the same as the conventional one.

At this time, when the external light enters, the signal component (the external light itself or the external light transmitted by the external light) in addition to the original signal component of the illumination light is superimposed on each RGB data. There is. Since the external light component is also proportional to the accumulation time of each of RGB, the influence of external light is relatively large for a color having a long accumulation time (that is, a dark color), and relative to a color having a short accumulation time (that is, a bright color). The effect of external light appears small.

After reading RGB, in step S105, the light source 1 is turned off, and the CCD is stored for a predetermined storage time.
Data is read at 5. Since the light source 1 is turned off, essentially no line data should be output at this time (all zeros), but when external light enters, only the signal component due to external light appears in the CCD output.

Considering that the line data of each color is composed of "the original component of the illumination light" and "the component of the external light", the component of the external light is subtracted from the line data of each color,
Find the "original illumination component". At this time, since the intensity of the signal is proportional to the accumulation time, it is necessary to perform conversion by the accumulation time ratio when subtracting data having different accumulation times.

The read R data, G data,
The B data and the data when the light source is off are respectively stored in the memory unit 52.
It is stored and stored in. Next, in step S106, the signal processing unit 53 performs the following signal processing to calculate line data.

S _R : R line data T _R : Accumulation time when R line data is taken S _G : G line data T _G : Accumulation time when G line data is taken S _B : B Line data T _B : Accumulation time when line data of B is taken S _X : Line data when light source is off T _X : Accumulation time when line data when light source is off S _RC : Transfer to host computer R Line data of _SGC : G line data of G transferred to the host computer _SBC : B line data of B transferred to the host computer
Calculate the line data to be transferred to. S _RC = S _R -S _X * T _R / T _X S _GC = S _G -S _X * T _G / T _X S _BC = S _B -S _X * T _B / T _X

Next, in step S107, the line data calculated as described above is output to the host computer 55 via the I / F unit 54. Next, step S1
At 08, it is judged whether or not the reading of the predetermined number of lines of data is completed. If completed, the image input is completed. If not completed, the process returns to step S101 to repeat the following processes.

In the method of correcting external light according to the above embodiment,
Since the influence of external light is corrected for each line, the influence can be completely canceled if the external light is constant during the reading of one line. Further, even if the outside light changes, the influence is small. Because generally R per line
The total storage time of GB is on the order of several ms to several tens ms, and it is considered that outside light does not change significantly during this time. Therefore, even if the external light is changed and cannot be completely corrected, the influence on the image can be canceled at a considerable rate. Therefore, it is possible to perform correction to the extent that the effect is not apparent on the image.

FIG. 3 shows an image input sequence in the second embodiment of the image input method of the present invention. In FIG.
In step S201, the original 2 is moved to a predetermined position together with the carriage 4, the LED (R) 23 is turned on / read in step S202, and the light source 1 is turned off in step S203 to read. Similarly, the LED (G) 22 is turned on / read in step S204, the light source is turned off / read in step S205, and the LED (B) is turned on in step S206.
21 turn on / read, and turn off / read light source in step S207. Steps S208, S209, S210
Are steps S106 and S in the first embodiment, respectively.
The process is the same as 107 and S108.

In this case, since "lighting-on reading → off-lighting reading" is performed for each of the RGB colors, more precise correction is possible. That is, in the first embodiment, since G and B are read between "reading R" and "reading when the light is off", when the outside light changes, R is stochastically corrected most. Although it tends to be insufficient, in the present embodiment, since the accumulated data at the time of extinguishing is obtained for each of the RGB colors, the difference between the colors is unlikely to appear.

In the above-mentioned embodiment, two correction methods are described. For example, the correction is made in the indoor use where the outside light is expected to be relatively steady and in the outside use where the outside light is likely to change. The method may be switchable and an appropriate one may be used.

In each of the above-described embodiments, the case where the original 2 is a transparent original has been described, but the same effect can be obtained by applying it to the case of inputting an image of a reflective original.

As described above, according to the image input device and the image input method of the present invention, the line data is corrected by using the CCD accumulated data when the light source is turned off during image reading. In particular, the influence of external light can be reduced and accurate image reading can be performed without using a cover member for shielding light.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an image input apparatus of the present invention.

FIG. 2 is a flowchart showing an image reading procedure according to the first embodiment of the image input method of the present invention.

FIG. 3 is a flowchart showing an image reading procedure according to a second embodiment of the image input method of the present invention.

FIG. 4 is a partially cutaway side view showing the configuration of an example of a conventional image input device.

5 is an exploded perspective view showing a configuration of an illumination unit and a projection unit of FIG.

6 is an explanatory diagram showing an optical system of an illumination unit in FIG.

7 is a partially cutaway plan view showing the configuration of the light source of FIG.

FIG. 8 is a vertical cross-sectional view of FIG.

FIG. 9 is an explanatory diagram showing an example of the influence of external light on the output image of the conventional image input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source (illuminating means) 2 original 4 carriage (conveying means) 5 CCD (photoelectric conversion means) 52 memory section (storage means) 53 signal processing section (data processing means)

Claims (2)

[Claims] 1. An illumination unit for irradiating one line of a document in the main scanning direction, a photoelectric conversion unit for converting light from the document into an electric signal, and a conveying unit for moving the document in the sub-scanning direction. In the image input device for obtaining information of one screen of the document, a storage unit that stores and holds a plurality of line data read when the lighting unit is turned on and off, and a storage unit that stores the stored line data when the lighting unit is turned off An image input device comprising: a data processing unit that performs an operation between line data and reduces an influence of external light on a read image. 2. A line from the original in the main scanning direction is irradiated with light from a light source, the light from the original is converted into an electric signal to read the image of the original, and the original is moved in the sub-scanning direction. By repeating the above reading operation,
In an image input method for obtaining screen information, read data of one line of the original when the light source is turned on and off is stored, and both data are arithmetically processed to reduce the influence of external light on the read image. An image input method characterized by the above.