JP3186183B2 - Black reference plate for image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital copying machine, and more particularly to a black reference plate used for performing black level correction.

[0002]

2. Description of the Related Art For example, in a digital scanner for optically reading a document, a black level correction (a process for correcting nonuniformity of image data of each pixel due to a variation in a read output of a black reference plate) is performed. Regarding the technology, see, for example, JP-A-62-235871 and
There is 18763. In Japanese Patent Application Laid-Open No. Sho 62-235871, the black level is corrected by using a reference black plate provided on a document table on which a document is placed.
In No. 763, the black level is read before reading the original.

[0003]

However, in the above-described prior art, it is difficult to produce a uniform, low-density reference plate with very little variation, and there is a fear of fading over time.

The method of turning off the lamp is effective for reading black data, but cannot read the black data at the optimal timing for reading the black data (at the time after reading the white reference plate). This is because when the light source is a halogen lamp, there is afterglow even when the power is turned off. Further, in the case of a fluorescent lamp, the lamp is repeatedly blinked in a short cycle, so that the lamp life is shortened and the lamp is frequently replaced, which is uneconomical.

[0005] The present invention has been made in view of the above-mentioned circumstances of the prior art, and has as its object to provide a black reference plate which can be easily managed.

[0006]

In order to achieve the above object, the present invention relates to an image forming apparatus, wherein a light from a light source is specularly reflected on a black reference plate serving as a reference for black level correction.
The light is radiated to the plate, and this light is specularly reflected by the specular
The light is reflected at an angle equal to the angle and projected on the slit regulating member.
A specular reflection plate arranged so as to be absorbed,
In an image forming apparatus using a reflection plate as the black reference plate, a regular reflection plate is used as the black reference plate in a black reference plate serving as a reference for black level correction.

Further, in order to reduce the number of parts and the number of assembling steps, the specular reflection plate can be formed by vapor deposition on the light irradiation surface side of the member forming the scanner.

Further, in order to prevent the specular reflection plate from being stained and to protect the specular reflection plate from being cleaned, the specular reflection plate is vapor-deposited on the surface of the transparent member facing the light source via the transparent member. Can be.

[0009]

According to the above-mentioned means, the light from the light source is specularly reflected by the regular reflection plate, reflected at an angle equal to the incident angle, and does not enter the reading sensor. Therefore, the light from the light source is not projected onto the sensor, and the black level can be read without turning off the lamp.

The number of parts and the number of assembling steps can be reduced by forming a regular reflection plate on the light irradiation surface side of a member forming the scanner, for example, a vertical scale plate, a contact glass, or the like.

Further, by depositing a specular reflection plate on the surface of the transparent member facing the light source via the transparent member, for example, the original mounting surface of the contact glass, the specular reflection plate is shielded from the outside air to be contaminated. And the occurrence of scratches due to cleaning friction can be prevented.

[0012]

1 is a front sectional view showing an arrangement of a black reference plate according to the present invention, and FIG. 2 is a front sectional view showing a schematic configuration of a reading optical system.

As shown in FIG. 2, the lamp 1 is disposed below the contact glass 2 so as to be relatively movable. The output light of the lamp 1 is irradiated in the horizontal direction, and a reflector 3 is provided on the optical path. The reflection light path of the reflection plate 3 is directed to the contact glass 2. A document 4 is placed on a predetermined position on the contact glass 2.

In this case, the reading optical axis 5 is perpendicular to the original 4 and the reflecting plate 3
Is set at an angle θ. Reading optical axis 5
The light that is read through is light that has been irregularly reflected by the document 4. Therefore, when a specular reflection plate is read instead of a document, there is no diffused light, and the state is the same as when a black document is read. Therefore, in the present invention, a regular reflection plate is used as the black reference plate. In addition, when a regular reflection plate is used, in particular, unlike the conventional black reference plate, there is no need to lay out the regular reflection plate at the same height as the document surface, and in a position where the regular reflection component of the illumination light is not read. It is only necessary to arrange them.

As shown in FIG. 1, the black reference plate is formed below a vertical scale 6 (a scale for positioning a document in accordance with the size) provided at an end (a reading start side) of the contact glass 2. A reference white plate 7 is provided in the concave portion, and a regular reflection plate 8 as a black reference plate is provided adjacent to the reference white plate 7. Thus, the reference white plate 7 and the specular reflection plate 8
Is provided at a position where there is no contact glass 2, and its installation height is set to the same height level as the document 4.

The specular reflection plate 8 is attached near the home position using a high-luminance aluminum plate, aluminum foil, or the like as the material. Alternatively, the vertical scale 6 or the contact glass 2
Aluminum or the like may be directly deposited on the lower surface of the substrate. With vapor deposition, the number of parts and the number of assembling steps can be reduced as compared with the case where a high-brightness aluminum plate is attached.

FIG. 3 is a front sectional view showing a second embodiment of the black reference plate according to the present invention.

In this embodiment, an example is shown in which the specular reflection plate is formed by vapor deposition of aluminum, and a specular reflection plate 8 and a reference white plate 7 are provided at an overlapping portion of the contact glass 2 and the vertical scale 6. Therefore, in this configuration, the contact glass 2
The illumination and the reading of the black reference are carried out. Also in this embodiment, the reference white plate 7 and the specular reflection plate 8 are at the same height as the document 4.

The feature of this embodiment is that the contact glass 2
Since the specular reflection plate 8 is formed by aluminum vapor deposition between the vertical scale 6 and the vertical scale 6, the reading surface does not contact the outside air, the specular reflection plate 8 is hardly contaminated, and the opposite side to the vapor deposition surface is wiped during cleaning. Therefore, there is no possibility that the specular reflection plate 8 is damaged.

FIG. 4 is a front sectional view showing a third embodiment of the black reference plate according to the present invention.

This embodiment shows an example in which a regular reflection plate 8 is formed on the lower surface of the end portion (on the vertical scale 6 side) of the contact glass 2, and the reference white plate 7 is provided on the vertical scale 6. In this embodiment, the document 4 and the reference white plate 7 have the same height,
The regular reflection plate 8 is different in height from the document 4.

Here, the operation of the above embodiment will be described with reference to the image forming apparatus of FIG. 5 to which the embodiment of FIG. 4 is applied.

Light emitted from the lamp 1 toward the specular reflection plate 8 through the slit 9 is specularly reflected by the specular reflection plate 8 and is reflected at an angle equal to the incident angle β. Then, the reflected light is projected onto the slit regulating member 10 (which also forms the outer case of the scanner), which has been subjected to the matting process, and is absorbed. For this reason, no light from the lamp 1 is projected onto the unit-size sensor 11 using a light receiving element such as a CCD, and black level correction can be performed.

In FIG. 5, reference numeral 12 denotes an image reading device for converting an analog signal from the unit-size sensor 11 into a digital signal, and reference numeral 13 denotes an operation unit for inputting a processing method to be performed in the next stage. Reference numeral 14 denotes an image processing device that performs shading correction and MTF correction on digital signal data from the image reading device 12, and further performs masking, trimming, negative-positive inversion, and the like.

[0025]

Since the present invention is constituted as described above, the following effects can be obtained.

In the black reference plate of the image forming apparatus according to the first aspect, light from a light source is applied to a specular reflection plate, and this light is applied to the front.
The light is specularly reflected by the specular reflector and reflected at an angle equal to the incident angle.
So that it is projected onto the slit regulating member and absorbed.
A specular reflection plate placed, wherein the specular reflection plate and the black reference plate
Because to use, the black level read in without turning off the lamp becomes possible, furthermore, it arranged without restrictions, and is not affected by the illuminance distribution.

In the black reference plate of the image forming apparatus according to the present invention, since the specular reflection plate is formed by vapor deposition on the light irradiation surface side of the member forming the scanner, the number of parts and the number of assembling steps can be reduced. Can be planned.

In the black reference plate of the image forming apparatus according to the third aspect, the specular reflection plate is deposited on the surface of the transparent member facing the light source via the transparent member, so that the black reference plate is shielded from outside air. As a result, the specular reflection plate can be prevented from being stained, and the occurrence of scratches due to friction caused by cleaning can be prevented.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an arrangement state of a black reference plate according to the present invention.

FIG. 2 is a front sectional view showing a schematic configuration of a reading optical system.

FIG. 3 is a front sectional view showing a second embodiment of the black reference plate according to the present invention.

FIG. 4 is a front sectional view showing a third embodiment of the black reference plate according to the present invention.

FIG. 5 is a configuration diagram illustrating a schematic configuration of an image forming apparatus to which the embodiment of FIG. 4 is applied;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lamp 2 contact glass 3 reflection plate 4 document 5 reading optical axis 6 vertical scale 7 reference white plate 8 regular reflection plate 9 slit 10 slit regulating member 11 1: 1 sensor 12 image reading device 13 operation unit 14 image processing device

Claims (3)

(57) [Claims] A light from a light source is applied to a specular reflection plate on a black reference plate serving as a reference for black level correction in the image forming apparatus.
Specularly reflected by the firing plate, reflected at an angle equal to the incident angle,
The correct position is set so that it is projected and absorbed by the
Comprising a reflector, using the specular reflector as the black reference plate
Black reference plate of the image forming apparatus characterized by that. 2. The black reference plate of an image forming apparatus according to claim 1, wherein said specular reflection plate is formed by vapor deposition on a light irradiation surface side of a member forming a scanner. 3. The black reference plate of an image forming apparatus according to claim 1, wherein the specular reflection plate is deposited on a surface of the transparent member facing a light source via a transparent member.