JP3203030B2 - Document reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus such as a copying machine or a facsimile, and more particularly to the prevention of malfunctions due to noise or dust on an optical path.

[0002]

2. Description of the Related Art In a document reading apparatus such as a facsimile, it is necessary to detect the presence of a document and the leading and trailing edges of the document when reading the document. For this reason, in the conventional document reading apparatus, a single dedicated photocoupler is used as a sensor for detecting the presence or absence of the document and the front and rear ends of the document, and directly projects light on the document to determine whether or not the document is reflected. The leading and trailing edges of the document are detected. Further, as disclosed in Japanese Utility Model Publication No. 63-29332, a detection lever or an actuator is moved by a manuscript, and the detection lever or the actuator is moved.
The presence or absence of a document and the leading and trailing edges of the document are detected by detecting the moving state of the document with a reflective photocoupler.

As disclosed in JP-A-59-37763, a photoelectric conversion element for detecting the presence or absence of a document is provided separately from a photoelectric conversion element for reading an image of the document, and the detection of the presence or absence of the document is performed. A device for reading a document is also used.

[0004]

As described above, when the presence or absence of a document and the detection of the trailing edge of the document are detected by a dedicated photocoupler or photoelectric conversion element, the noise of equipment, the presence or absence of the document, and the leading edge of the document are detected. There is a risk that the presence or absence of a document and the accuracy of detecting the front and rear ends of the document may be reduced due to dust or the like adhering to the optical path for detecting the rear end.

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate such a danger, and provides an original reading apparatus capable of accurately detecting the presence or absence of an original by removing the influence of dust or the like adhering on an optical path. The purpose is to do so.

[0006]

A document reading apparatus according to the present invention includes a light source for projecting light over a predetermined width in the main scanning direction onto a document conveyed to a document reading position through a document conveyance path, and a light source for projecting light over a predetermined width. A photoelectric conversion unit provided with a plurality of photoelectric conversion elements, and a reduction optical system for reducing light reflected by the original being conveyed to the original reading position and introducing the light to the photoelectric conversion unit. A light source for an image having a width sufficient to irradiate the largest size document with light; and a light source for document detection provided outside the light emitting element group for an image. Divided into element groups,
The optical path of the light emitted from the document detection light emitting element group
Near the document reading position, the document detection
On the outgoing light emitting element group side, there is provided a reflecting plate for reflecting light emitted from the document detecting light emitting element group and introducing the light to a part of the photoelectric conversion means through the reduction optical system. A document detecting actuator and a document leading and trailing edge detecting actuator are provided at different levels in an optical path through which the reflected light passes. The document detecting actuator and the document leading and trailing edge detecting actuator have one end. Portion protrudes into the document conveyance path, and the protruding tip portion is pressed down by the conveyed document and rotated, and partially blocks the light in the optical path through which the reflected light from the reflection plate passes. The photoelectric conversion means is arranged so that the width in the main scanning direction is wider by a certain width than the width irradiated with the light reflected by the document pressing plate wider than the maximum document width, and emits light from the image light emitting element group. a plurality of reading an image of a document conveyed by the incident Hara are classified and the image reading area having a photoelectric conversion element, into the document detection region having a plurality of photoelectric conversion elements for detecting the reflected light from the reflecting plate is transported
When reading a document, the reflected light from the reflection plate guided to the document detection area is actuated for the document detection.
Conveyed depending on whether or not light is blocked by the rotation of the heater
The presence or absence of a document is detected, and the document is guided to the document detection area.
The reflected light from the reflector is used to detect the front and rear edges of the original.
-The leading edge and the trailing edge of the original
Is detected at regular intervals while the document is not being fed.
The document detection area for detecting reflected light from the reflection plate
Photoelectric conversion element whose light was blocked among a plurality of photoelectric conversion elements in the area
Check if there is a cell, and check if the photoelectric conversion element
In this case, the current information and the previous
Make sure that the information is the same,
The current information and the previous information of the element are the same
Is output when a predetermined number of times are repeated .

[0007]

The original reading apparatus according to the present invention has the largest size.
Read a document that is wide enough to illuminate
Document detection light source provided outside the image light emitting element group
Near the original reading position in the optical path of the light emitted from the optical element group
At the document detecting light emitting element group side from the document conveying path.
The light emitted from the original detection light emitting element group is reflected to reflect the light.
Reflection introduced into a part of photoelectric conversion means through reduction optical system
With a plate. The light path through which the light reflected from this reflector passes
Manuscript detection actuator and original document trailing edge detection actuator
-Data is provided at different levels. This document detection actuator
The actuator and the actuator for detecting the leading and trailing edges of the original
Part protrudes into the document transport path, and the protruding tip
The document is fed down and turned, and the reflection plate
The light in the optical path through which the reflected light passes. The light
The conversion means is used for documents whose width in the main scanning direction is wider than the maximum document width.
The width is more constant than the width of the light reflected by the paper holding plate
Light from the image light emitting element group
Photoelectric conversion elements that read the image of the original conveyed
An image reading area having a mirror, and reflected light from the reflection plate.
And a document detection area having a plurality of photoelectric conversion elements to be detected.
It is classified.

Then, the conveyed document is read and
When the reflector is guided to the original detection area.
The reflected light is caused by the rotation of the original detecting actuator.
The presence or absence of a document being conveyed is detected based on whether
And, reflected from the reflector Ru guided to the document detection area
The light is turned by the rotation of the actuator for detecting the leading and trailing edges of the original.
The leading and trailing edges of the document are detected based on whether or not the light is shielded. Manuscript
While the paper is not conveyed, the reflection plate
A plurality of photoelectric sensors in the document detection area for detecting reflected light from
Whether there is a photoelectric conversion element whose light is blocked among the conversion elements
Check that if there is a photoelectric conversion element whose light is blocked,
The current and previous information of the photoelectric conversion element
Check if there is any
Repeat the information a certain number of times
When it is returned, it detects that dirt has adhered to the optical path.
Output abnormal alarm

[0009]

1 and 2 show a main part of an embodiment of the present invention. FIG. 1 is a perspective view and FIG. 2 is a sectional view. As shown in FIG. 1, the document reading apparatus separates a plurality of documents 14 set on a document guide plate 1 one by one by an ADF roller 2 and a separation pad 3, and presses a document with a document holding plate 15. The sheet is conveyed on the guide plate 1 and sent to the reading position P. The light source 5 illuminates the original 14 conveyed to the reading position P, and the light reflected by the original 14 is reflected by the mirrors 6, 7, 8 and then irradiates the photoelectric conversion means 10 through the lens 9. To read the image of the original 14. The original 14 whose image has been read at the reading position P is discharged outside by the discharge roller 4.

The light source 5 for irradiating the original 14 with light is LE
D, etc., each of which is provided with a plurality of independent light emitting elements in the width direction of the document is used, and these plurality of light emitting elements are sufficient for irradiating the largest size document 14 with light.
Image light emitting element group 5a having an appropriate width, and document detecting light emitting element group 5b provided outside image light emitting element group 5a
It is divided into and. The light emitting element group for image 5a and the light emitting element group for document detection 5b can be controlled independently of their lighting state. When the document 14 is conveyed, the image light emitting element group 5a The document reading light emitting element group 5b is turned on when the power of the document reading device is turned on, and is used for detecting the presence or absence of a document and for detecting the front and rear ends of the document.

[0011] near the position P reflector 11 reading that reflects the light from the document detecting light-emitting element group 5b, the document feed path
It is provided on the document detection light emitting element group 5b side . The reflected light from the reflection plate 11 is reflected by the mirrors 6, 7, 8 and passes through the lens 9 to enter the photoelectric conversion means 10.

A document detecting actuator 12 and a document leading and trailing edge detecting actuator 13 are provided at different levels in an optical path through which the reflected light from the reflecting plate 11 passes. Both the original detecting actuator 12 and the original leading and trailing end detecting actuator 13 project into the path of the original 14 to which one end is conveyed , and the leading ends of the actuators 12 and 13 are conveyed. When it is pushed down and rotated by the document 14, the light on the optical path through which the reflected light from the reflection plate 11 passes is partially blocked. The position of the blocked light is detected by the photoelectric conversion means 10 to detect the presence or absence of the conveyed document 14 and the front and rear edges.

The photoelectric conversion means 10 has a plurality of photoelectric conversion elements such as CCDs arranged in rows. The photoelectric conversion means 10 has a width in the main scanning direction which is wider by a certain width than a width irradiated with the light reflected by the document pressing plate 15 which is wider than the maximum document width, and is shown in the arrangement diagram of FIG. As described above, the light from the image light emitting element group 5a is incident and conveyed.
An image reading area 10a for reading an image of the original 14 to be read and an original detection area 10b for detecting the reflected light from the reflector 11 are divided.

There are provided a plurality of N effective elements (the number of bits) as photoelectric conversion elements which are turned on and off in order to detect the original in the original detection area 10b. And the original detection area 1
As shown in the block diagram of FIG. 4, the control unit that processes the information detected at 0b includes the CPU 21 and the document detection area 10b.
RAM 22 for temporarily storing information detected by an effective element
And the RAM 23 for temporarily storing the previous information detected by the effective elements in the document detection area 10b, and the number of effective elements among the effective elements is blocked from the information stored in the RAM 22 and turned on. A sensor counter 24 that counts whether the information has been read, and a timer counter 25 that counts the difference between the previous information stored in the RAM 23 and the information stored in the RAM 22.

The operation of detecting the presence or absence of the document 14 and the leading and trailing edges of the document 14 by the document reading apparatus having the above-described configuration will be described with reference to the flowchart of FIG.

When the manuscript 14 is conveyed and the manuscript detecting actuator 12 and the manuscript front and rear end detecting actuator 13 are pushed down by the manuscript 14 and a part of the light reflected from the reflecting plate 11 is cut off, the CPU 21 Is the document detection area 10b
Is read and temporarily stored in the RAM 22 (step S1). Next, the CPU 21 sets the count value of the sensor counter 24 to zero (step S2),
The first bit information of the effective element of the document detection area 10b is read from the RAM 22, and the reflected light from the reflector 11 incident on the first bit of the effective element is reflected on the document detection actuator 12 and the document front and rear end detection actuator. And the effective element of the first bit is turned on, ie, “1”.
(Steps S3 and S3)
4). If the effective element of the first bit is "1", the count value of the sensor counter 24 is set to "+1" (step S5).

Subsequently, the CPU 21 reads the information of the effective element of the second bit, and the effective element of the second bit is "1".
It is confirmed whether or not (steps S6, S7). When the effective element of the second bit is "1", "+1" is added to the count value of the sensor counter 24 (step S8). Thereafter, similarly, it is confirmed whether the information of the N effective elements stored in the RAM 22 is “1” or “0” (Steps S9, S6, S6).
S7) If the information of the effective element is “1”, “+1” is sequentially added to the count value of the sensor counter 24 (step S8). When the CPU 21 confirms all the information of the N effective elements, the CPU 21 confirms whether or not the count value of the sensor counter 24 is a number set in advance according to the number N of the effective elements, for example, N / 2 or more. (Step S
10) When the count value of the sensor counter 24 is equal to or more than N / 2, it is determined that the original detecting actuator 12 and the original leading and trailing end detecting actuator 13 are operating to detect the original 14 (step). S11). When the count value of the sensor counter 24 is N / 2 or less, the document detecting actuator 12 and the document leading and trailing edge detecting actuator 13 do not operate, and it is determined that the document 14 is not detected. (Step S12).

As described above, the presence or absence of a document is determined based on the state in which N / 2 or more bits out of the N effective elements indicate, so that the reflection plate 11 to the mirrors 6, 7, 8, and lens 9 are determined. Even if dust or the like adheres on the optical path, the presence or absence of a document can be accurately detected without being affected by the dust. In this case, the number N of effective elements in the document detection area 10b
Is odd, and the true value is determined based on the value indicated by N / 2 or more bits, so that the determination is always one of them, and a vague determination in control can be eliminated.

FIG. 6 is a flow chart showing the operation of the document reading apparatus for checking whether dust or the like has adhered to the optical path from the reflector 11 to the mirrors 6, 7, 8, and the lens 9. This will be described with reference to a chart.

The CPU 21 reads information of N effective elements in the document detection area 10b by a timer interrupt at a predetermined period while the document is not being read, and reads the information from the RAM.
22 (step S21). Next CPU
In step S22, it is checked whether or not the N effective elements stored in the RAM 22 include an effective element that is set to "1" because the light reflected from the reflection plate 11 is blocked by dust or the like in the information. If there is an effective element that is "1", it is checked whether or not the information is the same as the information of the previous effective element stored in the RAM 23 (step S23). If there is an effective element that is "1" and the current information is the same as the previous information, "+1" is added to the count value of the timer counter 25 (step S24). Also,
When there is no valid element that is “1” or when the current information is different from the previous information, “0” is added to the count value of the timer counter 25 (step S25). Thereafter, the CPU 21 checks whether or not the count value of the timer counter 25 has exceeded a predetermined constant value (step S26). The information of the effective element is stored in the RAM 23 (step S27),
The above-described processing is repeated for each such timer interrupt at a fixed cycle. When the count value of the timer counter 25 exceeds a certain value by repeating this process, the CPU 21
It is determined that dust or the like is attached on the optical path from 1 to the mirrors 6, 7, 8, and the lens 9, and an abnormal display is displayed on the display unit or printed by a printing means to notify the operator. (Step S28). In this way, abnormal operation of the device can be prevented.

In the above embodiment, the information of the N effective elements in the document detection area 10b is stored in the RAM 22 via the CPU 21.
However, the direct memory access (DMA) for transferring the information of the N effective elements directly to the RAM 22 may be used. In this case, when the original 14 is not being read, the original detection area 10b
When the reading of the original 14 is started, the image reading area 10a
DMA for acquiring the data of the image reading area 10a
By applying the DMA to the main scanning side more widely, the DMA is also applied to the document detection area 10b. In this way, when the original 14 is being read, the dedicated D
There is no need to apply MA, and control when reading an image can be facilitated. At this time, it is not necessary to apply a dedicated DMA to the document detection area 10b, so that the reading speed can be improved.

[0022]

According to the present invention, as this invention has been described above, most large
Have a width large enough to illuminate a large document
The original provided outside the image light emitting element group for reading the original
Original reading position in the optical path of light emitted from the document detection light emitting element group
Near the printer, the document detecting light emitting element group from the document conveying path.
Side, reflects the light emitted from the document detection light emitting element group
And introduced into a part of the photoelectric conversion means through the reduction optical system
Optical path through which reflected light from this reflective plate passes
Has one end protruding into the document conveying path,
The leading edge is pushed down by the conveyed document and rotated
And the light in the optical path through which the reflected light from the reflector passes
A document detection actuator that blocks the document and a document front and rear edge detection
A rectifier is provided on a step, and the photoelectric
Image of the document conveyed by the incident light from the image light emitting element element group
Image reading area having a plurality of photoelectric conversion elements for reading an image
And a plurality of photoelectric conversions for detecting reflected light from the reflector
Documents conveyed divided into document detection areas with elements
When scanning is performed, scanning is performed to the original detection area.
The reflected light from the reflection plate is actuated for the original detection.
Conveyed depending on whether or not light is blocked by the rotation of the heater
The presence or absence of a document is detected, and the document is guided to the document detection area.
The reflected light from the reflector is used to detect the front and rear edges of the original.
-The leading edge and the trailing edge of the original
Is detected at regular intervals while the document is not being fed.
The document detection area for detecting reflected light from the reflection plate
Photoelectric conversion element whose light was blocked among a plurality of photoelectric conversion elements in the area
Check if there is a cell, and check if the photoelectric conversion element
In this case, the current information and the previous
Make sure that the information is the same,
The current information and the previous information of the element are the same
Is repeated a certain number of times, dust and dirt adhere on the optical path.
To detect equipment malfunctions.
Can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of the present invention.

FIG. 2 is a sectional view of the embodiment.

FIG. 3 is a layout diagram of a photoelectric conversion element array.

FIG. 4 is a block diagram showing a control unit of the embodiment.

FIG. 5 is a flowchart showing the operation of the embodiment.

FIG. 6 is a flowchart showing another operation of the embodiment.

[Explanation of symbols]

 Reference Signs List 5 light source 6, 7, 8 mirror 9 lens 10 photoelectric conversion means 10a image reading area 10b document detection area 11 reflector 12 document detection actuator 13 document front / rear end detection actuator 21 CPU 22 RAM 23 RAM 24 sensor Counter 25 Timer counter

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04N 1/19 G03G 15/04 113 // G03G 15/04 113 H04N 1/04 102 (58) Investigated field (Int.Cl. ⁷ , DB name) H04N 1/04-1/207 G03B 27/50 G03G 15/00 107 G03G 15/04-15/04 115 G03G 21/00 370-386 H04N 1/00-1/00 108

Claims (1)

(57) [Claims] A light source for projecting light over a predetermined width in a main scanning direction onto a document conveyed to a document reading position through a document conveyance path; and a photoelectric conversion unit provided with a plurality of photoelectric conversion elements over a predetermined width. Conveyed to the document reading position
And a reduction optical system for reducing the light reflected by the original and introducing the light to the photoelectric conversion unit, wherein the light source is sufficient to irradiate the largest size original with light. Light-emitting element group having an appropriate width and a document detection light-emitting element group provided outside the image light-emitting element group, and the optical path of light emitted from the document detection light-emitting element group is
Near the document reading position, the document detection
On the output light emitting element group side, there is provided a reflector for reflecting light emitted from the document detection light emitting element group and introducing the reflected light to a part of the photoelectric conversion means through the reduction optical system. A document detecting actuator and a document leading and trailing edge detecting actuator are provided at different levels in an optical path through which the reflected light passes. The document detecting actuator and the document leading and trailing edge detecting actuator have one end. Is the original carrying
Projecting sending passage, and the protruding depressed by pivoting from <br/> the original tip is conveyed, intercept portionwise light of the optical path through which light reflected from the reflection plate, the photoelectric conversion The means is arranged so that the width in the main scanning direction is wider by a certain width than the width irradiated with the light reflected by the document holding plate wider than the maximum document width, and the light from the image light emitting element group is incident and conveyed. An original reading area having a plurality of photoelectric conversion elements for reading an image of an original to be read and an original detection area having a plurality of photoelectric conversion elements for detecting reflected light from the reflection plate, for reading an original to be conveyed ; when performing the document reflected light from the reflecting plate to be guided to the document detection area
Depending on whether or not light is blocked by the rotation of the detection actuator
To detect the presence or absence of the original being conveyed, and
The reflected light from the reflection plate is used to detect the leading and trailing edges of the original.
Use actuator - Hara by Luke not be shielded by the rotation of the motor
Detects the leading and trailing edges of the manuscript, and while the manuscript is not
Before detecting reflected light from the reflector at regular intervals
Light is blocked among the photoelectric conversion elements in the original detection area.
Check if there is a photoelectric conversion element that has
If there is a conversion element, this time of the photoelectric conversion element where light was blocked
Make sure that the information in the
The current information and the previous information of the photoelectric conversion element whose
An alarm is issued when the same condition is repeated a certain number of times.
Document reading apparatus and outputting.