JPH06164833A - Picture reader - Google Patents

Abstract

PURPOSE:To display presence of dust when dust is adhered to a loaded original in the case of reading an original. CONSTITUTION:A light from a light source 1 is converged by a condenser lens 2 onto an optical axis 3 and emitted to an original 4. The image of light transmitted through the original 4 is formed on an image sensor 6 by an image forming lens 5. Part of light is scattered in the transmission through the original and the image of the light going to the direction of optical axes 9, 12 is formed to line sensors 8,11 via image forming lenses 7, 10. When dust 13 is adhered to the original 4, the light of the optical axis 9 or 12 is interrupted by the dust as the original is carried as shown in the arrow A. The signal from the line sensors 8, 11 is judged by a control section 16 or the length of the interrupt time or the like is calculated by an arithmetic operation section 14 to judge the presence of the dust and displayed on a display section 15 via the control section 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, and more particularly to a device for detecting dust adhering to a document.

[0002]

2. Description of the Related Art In an image reading apparatus in which light transmitted through a document is read by an image reading element and an image signal is output, when dust or the like adheres to the document surface, the image light is blocked by the dust and the image reading element A normal image signal may not be obtained due to the fact that the light of the image does not enter or the light of the image is scattered due to dust. To prevent this, remove dust on the document surface in advance, and then load the document on the device.However, if minute dust remains on the document surface, it is difficult to distinguish it with the naked eye. In addition, it is troublesome, which may lead to a failure such as finding dust after the document reading operation and reading the document again.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, the present invention mounts a document on an image reading apparatus and performs a reading operation, and outputs a signal when dust is attached to the document surface, and the dust is removed. It is to provide something to let you know that there is adherence.

[0004]

In order to solve the above-mentioned problems, the present invention irradiates a document conveyed in a desired direction with light from a light source and reads the transmitted light of the document with a linear image reading element. In the image reading apparatus, a plurality of line image sensors are arranged in front of and behind the optical axis in order to read the light at the position where the optical axis from the light source to the image reading element intersects the document surface. The present invention provides an image reading apparatus that detects dust on the surface of a document based on output.

[0005]

With the above-described structure, in the image reading apparatus according to the present invention, when a document is mounted on the apparatus and a required reading operation is performed, the line image sensor for detecting dust emits light due to dust on the document surface. Detects and displays the presence or absence of dust.

[0006]

Embodiments of the image reading apparatus according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a principal block diagram including a conceptual configuration diagram of an embodiment of an image reading apparatus according to the present invention. In the figure, reference numeral 1 denotes a light source, which uses, for example, a white halogen lamp or the like, and outputs the light forward along with the light reflected by the reflector (upward in the drawing). Reference numeral 2 denotes a condenser lens, which is formed, for example, cylindrically in the front and back directions of the figure, and condenses the light from the light source 1 into linear light in the front and back directions of the figure.
3 is an optical axis. Reference numeral 4 denotes an original, on which an image or the like is formed on a medium such as a substantially transparent film. An image forming lens 5 is formed, for example, cylindrically in the front and back directions in the drawing, and forms an image of the line-shaped light on the optical axis 3 which has passed through the original 4 on the image sensor 6. The image sensor 6 is, for example, a CCD
An image reading device such as a (charge coupled device) is arranged in a line in the front and back directions in the figure, and the intensity of light is converted into an electric signal and output.

Imaging lenses 7 and 10 respectively image the light of the optical axis 9 or the optical axis 12 from the original 4 on the line sensor 8 or the line sensor 11, respectively. Line sensor 8 and line sensor 11 are dust detection sensors,
The image sensor 6 has the same structure. Reference numeral 13 denotes dust, which is attached to the original 4. Reference numeral 14 denotes a calculation unit, which calculates based on signals from the line sensor 8 and the line sensor 11. A display unit 15 displays based on a signal or the like from the calculation unit 14. Reference numeral 16 is a control unit, which is the arithmetic unit 14 and the display unit 15
To control.

Next, the operation of the image reading apparatus according to the present invention will be described. The original 4 is mounted on the image reading device and a required reading operation is performed. The original 4 is transported at a required speed in the direction of arrow B (sub-scanning direction). Then, the light on the optical axis 3 which is line-shaped in the main scanning direction (front and back direction in the drawing) from the light source 1 condensed by the condenser lens 2 is transmitted according to the density of the original and the like, and the imaging lens An image is formed on the image sensor 6 by 5. The image sensor 6 responds to the movement of the original 4, reads the light of an image or the like line by line, and outputs the data.
The line sensor 8 and the line sensor 11 enter the light from the light source 1 scattered by the document 4. That is, the light on the optical axis 9 is imaged on the line sensor 8 by the imaging lens 7,
The light of 12 is imaged on the line sensor 11 by the imaging lens 10.

These line sensor 8 and line sensor
The state of the change of the incident light due to dust in 11 will be described with reference to FIG. The light from the light source 1 is transmitted according to the light and shade of the original 4, and most of the transmitted light goes straight on the optical axis 3 and enters the image sensor 6 for image reading. However, a part of the light is refracted / reflected and scattered by various particles or the like present in the original 4, and these lights enter the line sensor 8 or the line sensor 11. Since these lights are scattered lights, they are of a lower level than the lights entering the line sensor 6, but it is sufficient if the presence or absence of light can be detected.
It is possible to detect the sensitivity by appropriately setting the sensitivity.

Optical axes 9 and 12 of the two line sensors
Are at positions where they intersect on the surface of the original 4. In the example of FIG. 2, the optical axis 3 is aligned on the original 4. These line sensors 8
Alternatively, the light to the line sensor 11 is blocked when dust that blocks the light is attached to the document 4. The dust 13 advances with the document 4 in the direction of arrow a. First, in Figure (A), garbage 13
The tip of the optical axis approaches the optical axis 3, and at this moment, the light on the optical axis 9 is blocked by the dust 13 and the light on the optical axis 12 is not blocked yet. That is, the light incident on the line sensor 8 is blocked, and the light is incident on the line sensor 11. When the document 4 further advances in the direction of arrow B and reaches the position shown in FIG. 3B, the dust 13 blocks both the optical axis 9 and the optical axis 11, and the two line sensors block the light input. Then, the document further advances, and at the moment when the right end of the dust 13 comes on the optical axis 3 as shown in FIG. 6C, the light advances toward the optical axis 9 and the optical axis 12 is still blocked, so that The line sensor 8 has received light, and the line sensor 11 has not received light.

The line sensor 9 and the line sensor 11
Signal is input to the control unit 16 and, for example, the optical axis 9
Only blocked, then both optical axis 9 and optical axis 12 blocked,
Next, when only the optical axis 12 is blocked, it is determined that there is dust, and the display unit 15 displays it. In this way, the two line sensors are provided with an angle and are arranged so as to be positioned forward and backward with respect to the document transport direction, so that the amount of light to the dust detection line sensor during transport of the document 4 changes. Check for the presence of garbage. A signal from the line sensor is input to the calculation unit 14 via the control unit 16, and a calculation process is performed based on the transfer speed of the document 4 and the size of dust is calculated based on the cutoff time of the signal. For example, when the size of the dust is larger than the set size, it may be determined that the dust is present and displayed on the display unit 15. It should be noted that there is a case where a document has a high density portion and it is difficult for the apparatus to distinguish between a high density portion and dust. However, only in such a case, the document may be visually checked.

[0012]

As described above, according to the image reading apparatus of the present invention, when a document is mounted on the apparatus and a required document reading operation is performed, dust on the document surface is detected and a warning is displayed. Therefore, it is possible to prevent the failure such that the reading operation is ended without noticing the dust, the dust is found in the read data later, and the reading is performed again.

[Brief description of drawings]

FIG. 1 is a principal block diagram including a conceptual configuration diagram of an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a diagram for explaining a dust detection operation of the image reading apparatus according to the present invention.

[Explanation of symbols]

 1 Light source 2 Condensing lens 4 Original 5 Image forming lens 6 Image reading element (line image sensor) 7 Image forming lens 8 Line image sensor (for dust detection) 10 Image forming lens 11 Line image sensor (for dust detection) 13 Garbage 14 Computing section 15 Display section 16 Control section

Claims (1)

[Claims] 1. An image reading apparatus in which a document transported in a desired direction is irradiated with light from a light source and transmitted light of the document is read by a linear image reading element, and an optical axis from the light source to the image reading element is used. An image in which multiple line image sensors are arranged in front of and behind the optical axis in order to read the light at the position where the document surface intersects, and dust on the document surface is detected based on the output from each line image sensor. Reader.