JP2001094722A - Image reader and its signal correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that is free from deterioration in a black/ white correction performance due to the effect of dust and moisture or the like. SOLUTION: The image reader is provided with a light source 4, a one or two-dimensional image sensor element 1 with a photosensing section 10 forming a window through which a light from the light source passes, and a fiber array plate(FAP) 2 placed in contact with the face of the image sensor element 1. A black/white reference board 3 for correcting a black/white level is closely placed on an edge of the FAP 2.

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 and a signal correction method thereof, and more particularly to an image reading apparatus and a signal correction method capable of effectively performing black and white signal correction.

[0002]

2. Description of the Related Art In an image reading apparatus (image sensor) for inputting an image, such as a facsimile or a scanner, it is indispensable to perform black and white signal correction. This is because accurate reading cannot be performed unless corrections are made for the uneven illuminance of the light source, the change in temperature, the change with time, and the variation in characteristics of the image sensor element, the change in temperature, and the change with time.

In general, image signals in an image reading apparatus are corrected by storing data read using a white reference plate and a black reference plate in a memory in advance, and offsetting each pixel or block with reference to the data. And changing the amplification rate.

Various white reference plates and black reference plates have been proposed in terms of the device configuration. For example, there are a roller provided on a roller or a belt for feeding a document, and a roller provided at a position different from the document so that the position of an image sensor or a mirror is changed for each correction.

On the other hand, Japanese Patent Laying-Open No. 5-22515 discloses an image reading apparatus as shown in FIG. FIG.
2, a contact surface with a medium (hereinafter, referred to as an original) having an image (including characters) to be read is a glass plate 82.
The light emitted from the LED array 83 and reflected by the document is guided to the light receiving element 85 via the self-fox lens 84. A white paint is applied to the end surface of the glass plate 82 to form a white reference surface 86 for reading a constant white reference level.

[0006]

Many of the complaints from customers in the scanner section of a facsimile are caused by deterioration of the read image quality. The cause of this is that dust adheres to a light-turning mirror required for storing a large optical system in a narrow housing, thereby giving distortion and gradation fluctuation to an image. The problem due to the adhesion of dust also occurs on the surface of the black and white reference plate.

In most cases, image quality is restored by wiping off the dust on the mirror surface. However, the influence of dust on the black-and-white reference plate is much greater than that of the mirror. This is because the whole level goes out of order. In addition, the effects of moisture cannot be ignored. This is because even small water droplets greatly degrade optical characteristics. But that doesn't mean that users can disassemble the device to remove dust and moisture.

Therefore, the prior art in which the black-and-white reference plate is provided on a roller or a belt for feeding a document or is provided at a position different from the position of the document causes problems due to the adhesion of dust and moisture.

[0012] The same applies to the prior art shown in FIG. 12, in which the white reference surface 86 (the lower surface in the figure) that reflects light for correction is exposed, so that there is no protection against dust and moisture. It is.

That is, dust and moisture enter the housing,
This is caused by adhesion on the black-and-white reference level plate or the image sensor element. In mass-market products such as this type of device, it is difficult to take a completely sealed structure as a measure against dust. That alone adds considerable cost and is not feasible. Particularly in a small device such as a handy scanner, a fan with a filter or the like cannot be provided inside, and it is difficult to take effective dustproof measures. Even more so for moisture.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus capable of preventing deterioration of black-and-white correction performance due to the influence of dust, moisture and the like, and always enabling appropriate signal correction.

Another object of the present invention is to provide a signal correction method for performing correction with higher accuracy than in the past.

[0013]

SUMMARY OF THE INVENTION The present invention is characterized by a light source, a one-dimensional or two-dimensional image sensor element having a photosensitive portion having a window through which light from the light source passes,
In an image reading apparatus provided with a fiber array plate (hereinafter, referred to as FAP) provided in contact with a surface of the image sensor element, a black-and-white reference plate for correcting a black-and-white level is adhered to an end portion of the FAP. The image reading device provided as such.

Another feature of the present invention is that a light source, a one-dimensional or two-dimensional image sensor element having a photosensitive portion formed with a window through which light from the light source passes, and a surface in contact with the image sensor element. And an FAP provided with the FAP, the photosensitive portion of the image sensor element is wider than the FAP,
An image reading apparatus is provided in which a black-and-white reference plate for correcting a black-and-white level is provided in close contact with the photosensitive portion of the image sensor element located outside.

In these image reading apparatuses, the light source can be installed in close contact with the image sensor element.

In these image reading apparatuses, in the case of a one-dimensional image sensor element, the black and white reference plates are provided at both ends of the FAP or the image sensor element.
In the case of a two-dimensional image sensor element, it is preferable to provide the black-and-white reference plate at the four corners of the FAP or the image sensor element.

Further, these image reading devices are constituted by one-dimensional image sensor elements, and can be applied to a pen-type scanner.

Another feature of the present invention is to store a read signal obtained by reading a separately prepared white reference document and black and white reference plates at both ends as white correction data in a storage device, and to separately prepare a black reference document. Storing a read signal obtained by reading the original and the black and white reference plate portions at both ends in a storage device as black correction data, and when there is no change in the read signal of the black and white reference plate portion, Correcting the signal based on reading the white reference original and the black reference original,
If there is a change in reading of any of the black and white reference plates, a signal correction method of correcting data by modulating data read from the white reference document and the black reference document according to the change. is there. This signal correction method is preferably performed by the above-described image reading apparatus of the present invention.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing an image reading apparatus according to a first embodiment of the present invention. The image reading device (image sensor) includes a light source including a rod-shaped light emitting system and a lens system using an image sensor element 1, an FAP 2, a fluorescent lamp, an LED array, or an edge light type using a light guide plate and an LED. And a black-and-white reference plate 3 for black-and-white level correction is provided in close contact with the end of the FAP 2.

The black ink reference plate 3 is, for example, a white and black plastic plate. Alternatively, a glass plate coated with white and black paints can be used.

On the other hand, the surface 3A on the side on which light for correcting adhesion is incident is fixed to the FAP with an adhesive. This adhesive is, for example, an epoxy-based or silicon-based transparent and F
A resin having the same refractive index as the glass used for the fiber is used for the AP. This is because if it is not transparent, it will be colored and will not be the white reference, and if the refractive index is different, the interference color will appear depending on the thickness of the adhesive, or the reflectance will increase and black will not be regarded as black This is because there is a concern that inconveniences such as the above may occur.

As another concept, the adhesive is not applied to the above-mentioned surface 3A of the black-and-white reference plate, but the adhesive is applied to all the side surfaces, so that the surface 3A is in close contact with the main surface of the FAP2. The side of the black and white reference plate facing the side of the FAP
2 can be used. In this case, any material can be used for the adhesive. And this method also uses surface 3
Since A is in close contact with the FAP 2 and the entire peripheral edge of the surface 3A can be sealed with an adhesive, air and water do not enter, so that adverse effects due to dust, moisture, and the like do not occur.

In FIG. 1, which is a close-contact type image reading apparatus, the one-dimensional image sensor element 1 has a photosensitive portion 10 having a window provided on a glass plate and a thin film driving circuit (not shown) comprising a thin film transistor for driving the same. And a portion facing the FAP 2 is the photosensitive portion 10.
It has become.

The width over which the image of the document is read is W,
The image of the document is sequentially read by moving the image reading apparatus and the document below the FAP (lower in the drawing) in the direction perpendicular to the paper surface.

Next, an image reading apparatus according to the present invention will be described with reference to FIG. The basic principle of this configuration has already been described in JP-A-6-291935.

The photosensitive section 10 includes an opaque common electrode 11 and
It comprises a photosensitive layer 12 of a p-type amorphous silicon film and a number of individual electrodes 13 arranged. Individual photodiodes (photosensitive elements) are formed by the individual electrodes to form pixels. I have.

A window 1 penetrating through the common electrode 11, the photosensitive layer 12, and the individual electrode 13 for each individual electrode.
4 are formed respectively.

The photosensitive section 10 is closely adhered to the upper glass substrate 7 and the lower FAP 2 by an adhesive layer 8. Also FA
The light absorption layer 17 is provided inside P2.

In FIG. 2, the light 5 from the light source 4 is
0, passes through the FAP2, enters the original 9, and passes through the window 14.
The light 6 reflected by the original 9 passes through the FAP 2 again,
The light enters the photosensitive section 10 of the image sensor element 1.

The features of this image reading apparatus (image sensor) are that the distance from the document to the image sensor element and the light source can be made extremely small, and that the light source can be placed directly above the image sensor element. Therefore, it is possible to reduce the size of the scanner using this.

The present embodiment is characterized in that a black and white reference plate 3 is provided in a part of the FAP 2. In this portion, the light from the light source 4 strikes not the original 9 but the black-and-white reference plate 3, and the reflected light enters the photosensitive section 10.

Therefore, a constant black-and-white signal is always obtained unless there is a change in the light amount or the characteristics of the photosensitive portion. Conversely, if there is a change in them, the output will change accordingly.

Then, the surface 3A of the black-and-white reference plate 3 from which the light incident through the FAP is reflected for signal correction (FIG. 1)
Is an adhesive surface, and the glass surface 7 (FIG. 2) is sealed above the adhesive surface, so that the black-and-white reference plate 3 of the present invention does not deteriorate in black-and-white correction ability due to the influence of dust and moisture on the reflection surface. .

FIG. 3 shows a circuit configuration example of the image sensor element 1. A portion surrounded by a dotted line is a thin film circuit formed on a glass substrate.

The shift register 24, the buffer 23, and the analog switch 22 are formed of, for example, polysilicon thin film transistors. The photodiode section 21 of each pixel formed in the photosensitive section 10, that is, the photosensitive element is made of amorphous silicon or the like, and is provided with the circular or striped window 14 shown in FIG.

As shown in FIG. 2, the size of the window 14 is FA
It is designed to be smaller than the diameter of the fiber used for P2. This image sensor element 1 has a shift register 2
4, a power supply, a clock, and a start pulse are externally applied by a power supply, a clock, and a start pulse line 25.
6 has been added externally.

Usually, the printed circuit board is connected to the glass substrate by wire bonding or the like. The output of the signal is guided to an external signal detection circuit 27. Behind this is a signal correction circuit. These configurations and structures are described in detail in the following references A and B.

A: H. Haga, et. al. , "C
impact Imaging Apparatus
for Pen-shaped Hand-held
Scanner. ", SPIE vol.3019,
pp. 168-173, Feb. , 1997. B: I. Fujieda, et. al. , "Colo
r Pen-shaped Scanner. ”, T
he fifth Color Imaging Co
nreference: Color Science, S
systems, and Applications,
p. 131, 1997. A circuit for correcting the signal is, for example, as shown in FIG. The signal output 33 from the signal detection circuit 27 shown in FIG. 3 is converted from an analog signal to a digital signal by the A / D converter 34.

The data for correction is stored in the white correction data storage device 32 and the black correction data storage device 31, respectively. Based on these data, the data output from the A / D converter 34 is corrected by the arithmetic unit 35. The corrected signal output 36 is output.

An embodiment of the signal correction method according to the present invention will be described below. This signal correction method can be used not only for the image reading apparatus of the first embodiment described above, but also for the image reading apparatus of the present invention including other embodiments described later. .

The signal correction is performed as follows. FIG. 5 shows the procedure. FIG. 5A shows the positional relationship between the intensity distribution 41 of the light source from the light source and the monochrome reference plate 3.

First, a separately prepared white reference original is read. The read signal 42 of the white reference original is as shown in FIG. Next, a signal of a separately prepared black reference original is read.
The read signal 43 of the black reference original is as shown in FIG.

The read signal of the portion of the black and white reference plate should be exactly the same between these two readings. These data are stored in the white correction data storage device and the black correction data storage device. The fluctuation of each read signal is due to the light source intensity, the variation of the photosensitive unit, and the like. By storing the data of the black-and-white reference original and the data of the black-and-white reference plate at the same time, the relative signal magnitude can be stored.

FIG. 5D shows the relationship between the actual document reading signal 44 and the black and white reference document reading signals (black and white levels) 42 and 43.

At the time of actual reading, the black level and the white level are corrected by using data within the effective reading width of the stored signals, that is, data obtained by reading a monochrome reference document. At this time, the data of the black-and-white reference plate portion is monitored at the same time, and if there is no change in the level, the correction is performed by the above method, and if there is a change, the correction data is further corrected according to the change. The case where there is a change is, for example, a case as shown in FIGS.

FIG. 6 shows a case where the signal level of the black-and-white reference plate rises in a DC manner. This occurs when the dark signal of the photosensitive section increases with temperature and the overall level rises.

In such a case, the signal levels of the black and white reference plates on both sides are also shifted in parallel by the level fluctuation 53 caused by the dark current. Therefore, if this is monitored, a level fluctuation can be detected, and a true signal output can be obtained by subtracting the fluctuation from the read signal.

That is, the initially stored white level 51
(Corresponding to 42 in FIG. 5) is a level change 5 due to the black and white reference plate.
The white level 52 is shifted by 3 to become the white level 52 calculated by the fluctuation of the black and white reference plate portion, and the black level 54 initially stored is obtained.
(Corresponding to 43 in FIG. 5) is a level change 5 due to the black and white reference plate.
The image is shifted by 3 to become the black level 55 calculated by the fluctuation of the black and white reference portion, and the original document read signal 56 becomes the read signal 57 changed by the dark current.

When the brightness of the light source is uniformly reduced, the overall level is lowered. In this case, the signal reading of the white reference plate and the black reference plate decreases in accordance with the rate of decrease in the amount of light. If this is monitored, a true signal output can be obtained by changing the ratio of the signal instead of the DC offset.

FIG. 7 shows a correction method when the distribution of light sources changes. For example, as shown in FIG. 7A, when the light source intensity distribution 61 in the normal state becomes a fluctuating light source intensity distribution 62 in which the light amount in the right side is reduced, FIG.
As shown in the figure, the signal of the portion of the black and white reference plate located on the right side is reduced by the level fluctuation 65 caused by the light source fluctuation.

In this example, there is no change in the left part. As a result, the initially stored white level 63 (42 in FIG. 5)
) Becomes the white level 64 calculated by the fluctuation of the black and white reference plate portion, and the black level 66 (corresponding to 43 in FIG. 5) stored initially becomes the black level 67 calculated by the fluctuation of the black and white reference plate portion. , The original document reading signal 68 becomes the reading signal 69 changed by the light source fluctuation.

Therefore, by monitoring the level fluctuation 65 caused by the light source fluctuation in the signal of the black-and-white reference plate portion, it is known that at least the right portion has deteriorated, and correction can be performed.

Such an example can occur in the case of an edge light type light source using a light guide plate described later. The light guide plate may be distorted due to a temperature change, or the radiation angle of light from the LED may change, so that the degree of the change differs between the right end and the left end of the light guide plate. The same can occur with the aging of the LED.

In particular, the present invention can be applied to a device capable of monitoring by a black and white reference plate on both sides as in the present invention. For more accurate correction, store the characteristic change due to temperature change in the white correction data storage device and black correction data storage device for each certain temperature, and correct based on the data of the black and white reference plate on both sides. Can also.

FIG. 8 is a side view showing an image reading apparatus according to a second embodiment of the present invention. The components are basically
Therefore, duplicate description will be omitted.

In FIG. 1, the black-and-white reference plate 3 provided at the end of the FAP 2 has a photosensitive portion 10 of the image sensor element 1 wider than the FAP 3, and the photosensitive portion 10 of the image sensor element 1 located outside the FAP 3. A black and white reference plate for black and white level correction is provided in close contact with the portion.

As described above, in this embodiment, the image sensor element 1 is provided directly on a part of the photosensitive section 10. Since the signal does not pass through the fiber, the signal becomes large. Although signals cannot be read in principle if they are in close contact, the adhesive layer is usually about 10 microns and can sufficiently reflect reflected light.

FIG. 9 is a side view showing an image reading apparatus according to a third embodiment of the present invention. This is one in which an edge light type light source 4 using an LED 4A and a light guide plate 4B is directly attached to the image sensor element 1.

In the case of color reading, L of three colors of blue, red and green
ED is used. In the embodiment of FIG. 1 and FIG. 8, dust or dust adheres to the glass substrate on the image sensor element,
There was the possibility of condensation due to moisture. However, even in this case, since the influence is reduced because it is separated from the photosensitive portion by the thickness of the glass substrate, it is superior to the conventional example, but the embodiment of FIG. 9 can also eliminate this influence.

In this example, all the paths from the light source to the black-and-white reference plate and the photosensitive portion of the image sensor element are solidified, and there is no gap for air to enter. Therefore, the effects of dust, dust, and moisture, which are problems in the conventional example, can be completely eliminated.

FIG. 9 shows the black-and-white reference plate 3 bonded to the end of the FAP 3, but the black-and-white reference plate for black-and-white level correction is provided on the photosensitive portion 10 of the image sensor element 1 as shown in FIG. Such a light source structure may be used on a substrate to which is adhered.

FIG. 10 shows an example in which a fourth embodiment of the present invention is applied to a pen-type scanner. FIG. 10A is a perspective perspective view, and FIG.
It is sectional drawing of the BB part of (A).

For a pen-type scanner, see JP-A-8-21.
This is described in 1991 or in the above-mentioned documents A and B.

This pen-type image reading apparatus has a light source 4, an image sensor element 1 having a photosensitive portion 10 having a window, and a FAP 2, and a roller 7 for stabilizing the running.
2. An encoder 71 for detecting the position from the rotation of the roller 72, a circuit board 73 on which a circuit for reading the signal by driving the image sensor element 1 is formed, a housing for holding the circuit, a cable 74 for connecting to the outside, and the like. I have it. As shown in the figure, black and white reference plates 3 are provided at both ends of the FAP 2 by bonding.

FIG. 10 shows the monochrome reference plate 3 adhered to the end of the FAP 3. However, as shown in FIG. 8, a monochrome reference plate for black and white level correction is provided on the photosensitive portion 10 of the image sensor element 1. Can be used as such a pen-type image reading device.

FIG. 11 is a perspective perspective view showing a fifth embodiment of the present invention, showing an application example of the present invention to a two-dimensional image sensor. The light source 4 includes a fluorescent lamp 4C and a light guide plate 4B. The image sensor element 1 includes a photosensitive section 10 having an analog switch formed in a matrix and a photodiode with a window, and a drive circuit (not shown) for driving these. FAP under the photosensitive section 10 (below in the drawing)
2 are provided, and key-shaped black and white reference plates 3 are provided at four corners (four corners) of the photosensitive portion 10 outside the FAP 2.

Since the black-and-white reference plates 3 are present at the four corners, the correction can follow the two-dimensional change in the light amount. These black and white reference plates are not only square
It is also possible to provide at an arbitrary position on the side.

FIG. 11 shows an example of application to a two-dimensional image sensor in which the black-and-white reference plate 3 is adhered to the portion of the photosensitive section 10 outside the FAP 2.
It is also possible to adopt a structure in which the black and white reference plates 3 are bonded to the corners (four corners).

[0070]

As described above, the image reading apparatus of the present invention is not affected by dust and moisture in the air, and can perform a stable correction operation for a long period of time.

The reason is that since the black and white reference plate is adhered to the surface of the image sensor element or a part of the FAP, the black and white reference plate does not come into contact with air, and the deterioration of the black and white reference plate due to the adhesion of dust and the rubbing with the original document. This is because the correction function does not deteriorate.

The signal correction method of the present invention can perform signal correction with high accuracy.

The reason is that since the data of the black-and-white reference original and the data of the black-and-white reference plate are stored and stored at the same time, it is possible to correct the looseness caused by the light source intensity, the variation of the photosensitive portion, and the like. This is because the data of the stable black and white reference plate can be used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an image reading device according to a first embodiment of the present invention.

FIG. 2 is a diagram mainly showing an image sensor element in an image reading apparatus targeted by the present invention.

FIG. 3 is a diagram illustrating a circuit configuration example of an image sensor element.

FIG. 4 is a diagram illustrating a configuration example of a signal correction circuit.

FIG. 5 is a diagram illustrating an example of signal correction.

FIG. 6 is a diagram illustrating an example of signal correction.

FIG. 7 is a diagram illustrating an example of signal correction.

FIG. 8 is a diagram illustrating an image reading device according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an image reading apparatus according to a third embodiment of the present invention.

FIG. 10 is a diagram illustrating an image reading apparatus according to a fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating an image reading apparatus according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image sensor element 2 FAP 3 Black-and-white reference plate 3A Reflection surface of black-and-white reference plate 4 Light source 4A LED 4B Light guide plate 4C Fluorescent lamp 5 Incident light 6 Reflected light 7 Glass substrate 8 Adhesive layer 9 Document 10 Photosensitive section 11 Common electrode 12 Photosensitive layer DESCRIPTION OF SYMBOLS 13 Individual electrode 14 Window 17 Light absorption layer 21 Photodiode 22 Analog switch 23 Buffer 24 Shift register 25 Wiring 26 Bias power supply 27 Signal detection circuit 31 Black correction data storage device 32 White correction data storage device 33 Signal output 34 A / D converter 35 Arithmetic unit 36 Signal output after correction 41, 42, 43, 44, 51, 52, 53, 54, 5
5,56,57,61,62,63,64,65,6
6, 67, 68, 69 Light intensity waveform 71 Encoder 72 Roller 73 Circuit board 74 Cable 82 Glass plate 83 LED array 84 Selfox lens 85 Light receiving element 86 White reference surface

Claims (7)

[Claims] 1. A one-dimensional or two-dimensional image sensor element having a light source, a photosensitive portion having a window through which light from the light source passes, and a fiber array plate provided in contact with a surface of the image sensor element And a black-and-white reference plate for correcting a black-and-white level is provided in close contact with an end portion of the fiber array plate. 2. A one-dimensional or two-dimensional image sensor element having a light source, a photosensitive portion having a window through which light from the light source passes, and a fiber array plate provided in contact with a surface of the image sensor element. In the image reading device comprising: the photosensitive portion of the image sensor element is wider than the fiber array plate,
An image reading apparatus, wherein a black-and-white reference plate for correcting a black-and-white level is provided in close contact with the photosensitive portion of the image sensor element located outside the fiber array plate. 3. The image reading apparatus according to claim 1, wherein the light source is provided in close contact with the image sensor element. 4. In the case of a one-dimensional image sensor element, the black and white reference plates are provided at both ends of the fiber array plate or the image sensor element. In the case of a two-dimensional image sensor element, the fiber array plate or the image sensor element is used. 4. The image reading device according to claim 1, wherein the black and white reference plates are provided at four corners. 5. The image reading device according to claim 1, wherein the image reading device is a device used for a pen-type scanner.
An image reading device according to any one of the above. 6. A step of storing, as white correction data, a read signal obtained by reading a separately prepared white reference document and portions of the black and white reference plates at both ends in a storage device; Storing a read signal obtained by reading the plate portion as black correction data in a storage device, and when there is no change in the read signal of the monochrome reference plate portion, the white reference document and the black The signal is corrected based on the reading of the reference document, and if there is a change in reading of any of the black and white reference plates, the data read from the white reference document and the black reference document according to the change. And correcting the signal by modulating the signal. 7. The signal correction method according to claim 6, wherein the signal is corrected in the image reading device according to any one of claims 1 to 5.