JP3129835B2 - Image 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 an image reading apparatus used for a facsimile machine or the like.

[0002]

2. Description of the Related Art FIG. 6 is a system diagram showing a structure of a conventional image reading apparatus 1, and FIG. 7 is a block diagram showing an electric configuration of the image reading apparatus 1.

[0005] The image reading apparatus 1 is provided with an original 12
Are transported one by one by a document separating roller 13 and a rubber separating plate 14 pressed against the outer peripheral surface thereof, and further transported to a reading position 18 along a transport path 17 by a transport pinch roller 15 and a transport roller 16. The image is read, and the read document is discharged by the transport pinch roller 19 and the transport roller 20.

At the reading position 18, light from a light source 21 irradiates an image surface, and reflected light 22 from the image surface is reflected by a first mirror 23, a second mirror 24, a third mirror 25, and a lens 2
The light is incident on the reading means 9 through 6. The reading means 9 is C
It is realized by a CD (Charge Coupled Device) or the like, and converts incident light into an electric signal and outputs it. On the back side of the light source 21 at the reading position 18, a white back plate 27 is installed. The optical sensor 10 is disposed near the downstream side of the transport pinch roller 15 in the transport direction.

The image reading apparatus 1 includes a central control circuit (CPU) 2 for controlling the entire apparatus. The central control circuit 2 includes a read signal processing circuit 3, a binary determination circuit 4, an input / output port 5,
The light source control circuit 6, the ROM 7, and the document conveyance control circuit 8 are connected to each other.

The read signal processing circuit 3 amplifies and shapes the output signal from the reading means 9 realized by a CCD (Charge Coupled Device) or the like, and supplies the output signal to the binary decision circuit 4. The binary determination circuit 4 converts the read signal from the read signal processing circuit 3 into a binary signal based on a predetermined threshold level, and provides the binary signal to the central control circuit 2.

The input / output port 5 is connected to an optical sensor 10 realized by a reflection type photo interrupter or the like.
The optical sensor 10 reflects light, for example, by the supplied original, and the central control circuit 2 determines whether the original is supplied to the image reading apparatus 1 by turning on / off the optical sensor 10. The light source control circuit 6 includes the central control circuit 2
On / off of the light source is controlled based on the control signal from the controller. The document conveyance control circuit 8 detects the number of drive pulses input based on a control signal from the central control circuit 2 and conveys the document by driving the pulse motor 11 as the number of motor conveyance steps. The ROM 7 stores a preset number of drive pulses of the pulse motor 11.

[0008]

In the image reading apparatus 1,
When the optical sensor 10 detects that a document to be read has been supplied, the transport pinch roller 15 is driven.
For example, the pulse motor 11 is driven by a predetermined number of drive pulses, that is, a distance d1 from the detection position of the optical sensor 10 to the reading position 18 and a predetermined length from the downstream end of the document to be read in the transport direction A1. Only when the reading start position reaches the reading position 18, the image reading is started when the reading start position reaches the reading position 18. Subsequently, when the optical sensor 10 detects that the supply of the document has been completed, the transport pinch roller 15 is further driven. For example, the pulse motor 11 is driven by a predetermined number of drive pulses, that is, the pulse motor 11 is driven by a length corresponding to the distance d1 from the detection position of the optical sensor 10 to the reading position 18, and the image reading is completed.

Therefore, in order to accurately set the distance between the position of the optical sensor 10 and the reading position 18, it is necessary to adjust the set position of the optical system, and a long adjustment time is required. Further, for example, an accurate sensor such as a reflection type photo sensor is required as the optical sensor 10, and there is a problem that the image reading apparatus 1 becomes expensive.

Further, due to the variation in the detection position of the leading edge of the original due to the mounting position of the optical sensor 10 and the detection error, or the variation in the adjustment of the mounting position of the optical system,
There is a case where the distance from to the reading position 18 does not match for each device. For this reason, a reading error such as a missing image leading end or a trailing end of an image to be read, or a margin portion downstream of the leading end of the image in the transport direction or a margin upstream of the trailing end of the image in the transport direction is longer. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus capable of faithfully reading an original from the front end to the rear end thereof with a simple configuration and obtaining an image with improved reading operation quality.

[0012]

To achieve the above object, the present invention provides a reading means for irradiating a document on a transport path with light, reading the reflected light, converting the reflected light into an image signal, and outputting the image signal. A white plate disposed at an image reading position by the reading unit, a document detecting unit that detects a document on a transport path upstream of the reading unit in the transport direction, and a document detecting unit that detects the document. starts measuring of the document feed distance, then, when the signal read by said reading means is different from the normal signal by the white plate, image signals read by said reading means with ends the measurement of the document conveyance distance The image reading is started as a signal, and thereafter, when the document is conveyed by the document conveying distance from the non-detection of the document by the document detecting means, the signal read by the reading means. In which a structure is provided and control means for terminating the reading of the image to the image signal.
In addition, the present invention irradiates a document on a transport path with light, and
A reader that reads the reflected light, converts it into an image signal, and outputs it.
Step and a white color arranged at the image reading position by the reading means
Plate and the transport path upstream of the reading means in the transport direction.
Document detecting means for detecting a document on a road, and the document detecting means
Measurement of document transport distance starts with document detection by
After that, the signal read by the reading means is
When it is different from the steady signal by the white plate,
When the measurement of the separation is completed and the original is conveyed by the first predetermined distance, a signal read by the reading unit is output.
One to initiate the reading of the image as an image signal, after non-detection of the document by the document detecting unit, the measured distance partial document from the original <br/> manuscript conveying distance component by subtracting the second predetermined distance When transported , read by the reading means
Control to end reading of an image using the image signal as the image signal
Means is provided.

[0013]

Therefore, according to the present invention, when the original detecting means detects that the original has been supplied, measurement of the original conveying distance is started, and thereafter, the original is read by the reading means.
Signal is-out bets that differ from the normal signal by the white plate, reading by the reading means with ends the measurement of the original conveying distance
Start reading the image as the image signal ,
Thereafter, when the document is transported by the document transport distance after the document is no longer detected by the document detection means, the reading means
By terminating the reading of the image with the signal read by the image signal as the image signal, there is no image reading defect due to the variation in the distance between the reading unit and the document detecting unit unlike the related art. A faithful image can be read.

Further, according to the present invention, the original detecting means
The document feed distance when it is detected that
Measurement of the separation, and then read by the reading means.
When the original signal is different from the steady signal
When the measurement of the distance is completed and the original is conveyed by the first predetermined distance, the signal read by the reading unit is output.
While reading an image as an image signal is started, measurement is performed after the document is no longer detected by the document detection means.
And when the original conveying distance second distance partial document obtained by subtracting a predetermined distance transported, Shin read by the reading means
By terminating the reading of the image with the signal as the image signal, the distance between the reading means and the
There is no image reading failure due to variation in
It is possible to read a faithful image for each original.
In addition, a black image generated by a signal when the leading end and the trailing end of the document reach the image reading position can be removed.

[0015]

Embodiment 1 FIG. 1 is a system diagram showing a structure of an image reading device 28 according to one embodiment of the present invention, and FIG. 2 is a block diagram showing an electrical configuration of the image reading device 28. .

The image reading device 28 receives the original 40
Are transported one by one by a document separating roller 41 and a rubber separating plate 42 pressed against the outer peripheral surface thereof, and further transported to a reading position 46 along a transport path 45 by transport pinch rollers 43 and transport rollers 44. The image is read, and the read document is discharged by the transport pinch roller 47 and the transport roller 48.

At the reading position 46, light from a light source 49 is applied to the image surface, and reflected light 50 from the image surface is reflected by a first mirror 51, a second mirror 52, a third mirror 53 and a lens 5
4 and is incident on the reading means 36. Reading means 36
Is implemented by a CCD (Charge Coupled Device) or the like, converts incident light into an electric signal, and outputs the electric signal to the read signal processing circuit 30.
On the back side of the light source 49 at the reading position 46, a white back plate 55 is arranged. In addition, a document detection sensor 37 is disposed near the downstream side of the transport pinch roller 43 in the transport direction.

Next, referring to FIG.
Has a central control circuit (CPU) 29 for controlling the entire apparatus, and the central control circuit 29 includes a read signal processing circuit 30,
Value determination circuit 31, input / output port 32, light source control circuit 3
3. Document transport control circuit 34 and pulse number memory circuit 3
5 are respectively connected.

The read signal processing circuit 30 amplifies and shapes the output signal from the reading means 36 implemented by a CCD (Charge Coupled Device) or the like, and supplies the output signal to a binary decision circuit 31. The binary determination circuit 31 converts the read signal from the read signal processing circuit 30 into a binary signal based on a predetermined threshold level and supplies the binary signal to the central control circuit 29.

The input / output port 32 is connected to a document detection sensor 37 realized by a micro switch or the like. The document detection sensor 37 determines that the document has been supplied to the image reading device 28 when the central control circuit 29 detects, for example, that the supplied document is pressed and the electricity flows. The light source control circuit 33 controls turning on / off of the light source based on a control signal from the central control circuit 29.
The document conveyance control circuit 34 detects the number of driving pulses input based on a control signal from the central control circuit 29, and conveys the document by driving the pulse motor 38 as the number of motor conveyance steps. The pulse number memory circuit 35 stores the number of drive pulses of the pulse motor 38 measured by the counter 39 provided in the central control circuit 29.

FIG. 3 is a flowchart showing the operation of the image reading device 28. The document 40 is separated and transported one by one by a document separation roller 41 and a separation plate 42, and is transported to a transport path 45 by a transport pinch roller 43 and a transport roller 44 driven by a pulse motor 38. In step a1, it is determined whether or not the document detection sensor 37 is on. If the document detection sensor 37 is on, the process proceeds to step a2. If not, the process proceeds to step a13 to continuously transport the document and returns to step a1.

In step a2, monitoring of the read signal from the reading means 36 by the central control circuit 29 is started, and in step a3, the original is continuously conveyed.

In step a4, it is determined whether or not the leading end of the document 40 has been detected based on a change in the read signal from the reading means 36. Step a when the tip is detected
The process proceeds to step 5, and if not detected, the process returns to step a3, and the document is continuously conveyed.

In step a5, the number of drive pulses of the pulse motor 38 required for conveying the original during a distance d3 from the original detection sensor 37 to the reading position 46 is stored. Thereafter, in step a6, the images are sequentially read, and in step a7, it is determined whether or not the document detection sensor 37 is off. If it is off, the process proceeds to step a8. If it is not off, the process returns to step a6 and the image reading process is continued.

In step a8, the number of drive pulses of the pulse motor 38 stored in step a5 is read out, and in step a9, a document reading process is performed. Thereafter, it is determined in step a10 whether the number of drive pulses has ended. When the reading is completed, the reading operation of the document is completed. When the reading is not completed, the process returns to step a9 to continuously perform the reading process of the document.

FIG. 4 is a waveform diagram showing an example of each output signal of the reading means 36 and the binary decision circuit 31. FIG.
FIG. 4A shows a so-called stationary signal which is a read signal of the white back plate 55, and FIG. 4C shows a binary determination output of the read signal. FIG. 4 (2) shows a read signal near the edge of the document, and FIG. 4 (4) shows a binary determination output of the read signal.

In the image reading device 28, the document detection sensor 3
When the central control circuit 29 detects that the original 40 to be read is supplied by the central processing unit 7, the central control circuit 29 monitors the output of the reading means 36 and determines whether or not the leading end of the original is detected.
As shown in FIGS. 4 (2) and 4 (4), the original 4
At the end of 0, the light emitted from the light source 49 is blocked by being conveyed to the vicinity of the reading position 46, and the output signal from the reading means 36 changes (the portion indicated by the reference symbol S in FIG. 4B). ). By detecting this change, the central control circuit 29 recognizes that the end of the document 40 has reached the reading position 46. Further, at the same time that the document detection sensor 37 detects that the document 40 to be read has been supplied, the counter 39 in the central control circuit 29 starts counting the number of motor drive pulses. This measurement is performed until the leading end of the document 40 reaches the reading position 46, that is, for a distance d3 from the document detection sensor 37 to the reading position 46. The measured number of drive pulses is connected to the central control circuit 29. The stored pulse number is stored in the memory circuit 35.

Thereafter, the central control circuit 29 controls the document transport control circuit 34 to transport the document 40 and read an image. When the document 40 is conveyed and the trailing edge of the document is detected by the document detection sensor 37, the stored pulse motor 3
When the number of drive pulses of 8 is read out and the pulse motor 38 is driven by the number of drive pulses and the document 40 is conveyed, the reading of the image is terminated.

As described above, according to the present embodiment, the leading end of the document 40 is detected based on the output of the reading means 36, and the document 40 is further detected by the document detection sensor 37 at the image reading position 46.
Is stored, and when the document detection sensor 37 detects the trailing end of the document, the pulse motor 38 is driven by the stored number of drive pulses and the document 40 is conveyed. Since the reading is completed, it is possible to faithfully read from the leading edge to the trailing edge of the document 40.

Therefore, it is not necessary to adjust the position of the document detection sensor, the position of the reading position, and the positioning of the optical system as in the related art, and the manufacturing process and adjustment process of the image reading apparatus can be greatly reduced. Further, it is not necessary to use a high-precision original detection sensor such as a photosensor used conventionally, and a low-precision original detection sensor, such as a microswitch, may be used, and an inexpensive sensor may be used. An image reading device can be provided.

Embodiment 2 Hereinafter, a second embodiment will be described.

This embodiment is similar to the first embodiment described above, and refers to FIGS. 1 and 2 in common. The features of this embodiment are as follows.
The reading of the document is started at the timing when the leading end of the document reaches the reading start position 56 downstream of the reading position 46 of the first embodiment by the distance d4 along the document conveying direction A1 and by the distance d4. The reading end is performed at a timing when the rear end of the document reaches the reading end position 57 on the upstream side by a distance d5 along the document conveying direction A1 from the reading position 46 of the first embodiment. .

In the image reading device 28, the document detection sensor 3
7 detects that the original 40 to be read has been supplied, the central control circuit 29 starts monitoring the output of the reading means 36, and at the same time, the counter 3 in the central control circuit 29.
9 starts counting the number of drive pulses of the pulse motor 38.
When the leading end of the document 40 reaches the reading position 46, the output signal of the reading means 36 changes, and the central control circuit 29 sends the document 4
It is determined that the leading end of the “0” has reached the reading position 46. At the same time, the number of drive pulses of the pulse motor 38 by the counter 39 in the central control circuit 29, that is, the original detection sensor 3
The measurement of the number of drive pulses of the pulse motor 38 required for transporting the original 40 during the distance d3 from 7 to the reading position 46 of the first embodiment is completed, and is stored in the pulse number memory circuit 35. When the central control circuit 29 determines that the leading end of the document 40 has reached the reading position 46, the transport pinch roller 43 is further driven, and for example, the pulse motor 38 is driven by a predetermined number of drive pulses. The document 4 is driven by the number of drive pulses required to transport the document 40 for a distance d4 from the reading position 46 in the example to the reading start position 56 set downstream on the document A in the transport direction A1.
At the time when the leading end of the zero reaches the reading start position 56, reading of the image by the reading means 36 is started. In the present embodiment, a change in the output signal of the reading means 36 is used only for determining that the leading end of the document 40 has reached the reading position 46, and the central control circuit 29 does not read an image. Therefore, a black image near the leading edge of the document caused by a change in the output signal is removed.

Subsequently, when the trailing end of the document 40 is detected by the document detection sensor 37, the number of drive pulses of the motor stored in the pulse number memory circuit 35, that is, reading of the first embodiment from the document detection sensor 37 Distance d to position 46
The number of drive pulses of the pulse motor 38 required to transport the document 40 during the period 3 is read. The original 40 is read from the stored number of drive pulses, for example, the number of drive pulses of a predetermined motor, that is, the read end position 5 set upstream from the read position 46 in the first embodiment along the original transport direction A1.
Then, the pulse motor 38 is driven by the number of drive pulses obtained by subtracting the number of drive pulses of the motor required to convey the document 40 for a distance d5 up to 7, and the image reading is completed. Therefore, the reading of the image is terminated before the output signal of the reading means 36 changes due to the rear end of the document 40, so that the black image near the rear end of the document caused by the change of the output signal is removed.

FIG. 5 shows an image reading apparatus 2 according to this embodiment.
8 is a flowchart showing the operation of FIG. The document 40 is separated and transported one by one by a document separation roller 41 and a separation plate 42, and is transported to a transport path 45 by a transport pinch roller 43 and a transport roller 44 driven by a pulse motor 38. In step b1, it is determined whether or not the document detection sensor 37 is on. If it is on, the process proceeds to step b2. If it is not on, the process proceeds to step b13, where the document is continuously conveyed and the process returns to step b1.

At step b2, monitoring of the read signal from the reading means 36 by the central control circuit 29 is started. Thereafter, the document is continuously conveyed in step b3.

In step b4, it is determined whether or not the leading end of the document 40 has been detected based on a change in the read signal from the reading means 36. When the leading end is detected, the process proceeds to step b5. When the leading end is not detected, the process returns to step b3 to continuously convey the document.

In step b5, the number of drive pulses of the pulse motor 38 required for transporting the document 40 during the distance d3 from the document detection sensor 37 to the reading position 46 is stored.
Subsequently, the document 40 is transported by the distance d4 in step b6, and an image reading process is performed in step b7.

At step b8, it is determined whether or not the document detection sensor 37 is off. If it is off, the process proceeds to step b9, and if it is not off, the process returns to step b7 to continue the image reading process.

In step b9, the number of drive pulses of the pulse motor 38 stored in step b5 is read, and the distance d is calculated from the number of drive pulses stored in step b10.
The pulse motor 38 is driven by the number of drive pulses obtained by subtracting the number of drive pulses of the pulse motor 38 corresponding to 5, and the image reading process is performed in step b11.

In step b12, it is determined whether or not the number of drive pulses has been completed. If the number has been completed, the image reading process is terminated. If not, the process returns to step b11 to continue the image reading process.

As described above, according to the present embodiment, the leading end of the document is detected by the reading means 36, and after the document is conveyed by a predetermined distance, reading of the image is started.
Since the reading of the image is completed before the trailing end of the document is detected by the reading means 36, the output signal of the reading means 36 changes as the leading end and the trailing end of the document are conveyed to the reading position 46, It is possible to remove black portions (so-called document shadows) at the leading and trailing edges of the document, which are caused by a change in the output signal, and a clear image can be obtained.

The reading start position 56 and the reading end position 5
An example employing either one of the examples 7 is also included in the scope of the present invention.

Further, the reading means 3 which changes when the leading end of the original 40 reaches the reading position 46 in the present embodiment.
The example of using the cancellation of reading of the output signal of No. 6 as an image at the leading end and / or the trailing end of the first embodiment is also included in the scope of the present invention.

[0045]

As described above, according to the present invention, each original
The distance between the document detection means and the document reading position (document conveyance
Distance), and based on the measured distance,
Determines the timing for ending the reading of the scanned original.
To read images faithfully for each document
During transport due to differences in the paper quality of the original, etc.
Reliable and accurate image reading operation even if the time is different
Can be performed. Moreover, according to the present invention,
When the leading and trailing edges of the document reach the image reading position,
The resulting black image can be removed.
It is possible to improve the read image quality of a draft.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a structure of an image reading device according to first and second embodiments of the present invention.

FIG. 2 is a block diagram illustrating an electrical configuration of an image reading device according to first and second embodiments.

FIG. 3 is a flowchart illustrating an operation of the image reading device according to the first exemplary embodiment.

FIG. 4 is a waveform chart showing an example of various signals of the image reading device according to the first embodiment.

FIG. 5 is a flowchart illustrating an operation of the image reading apparatus according to the second embodiment.

FIG. 6 is a system diagram showing a structure of a conventional image reading apparatus 1.

FIG. 7 is a block diagram illustrating an electrical configuration of the image reading apparatus 1.

[Explanation of symbols]

 28 Image Reading Device 29 Central Control Circuit 30 Read Signal Processing Circuit 31 Binary Judgment Circuit 32 I / O Port 33 Light Source Control Circuit 34 Document Transport Control Circuit 35 Pulse Number Memory Circuit 36 Reading Unit 37 Document Detection Sensor 38 Pulse Motor 39 Counter 40 Document 43, 47 conveyance pinch rollers 44, 48 conveyance rollers 46 reading position 56 reading start position 57 reading end position

Claims (2)

(57) [Claims] 1. A reading means for irradiating a document on a transport path with light, reading the reflected light, converting the reflected light into an image signal, and outputting the image signal; a white plate disposed at an image reading position by the reading means; a document detection means for detecting a document on the transportation path even at the upstream side in the transport direction than the unit, starts measurement of the document feed distance with the detection of the document by the document detecting unit, then, by the reading means when read is the signal differs from the stationary signal by the white plate, on
Serial signals read by said reading means to read the image is started as an image signal with ends the measurement of the original conveying distance, then, the document conveyance distance minute original is conveyed from the non-detection of the document by the document detecting means when in the image reading apparatus characterized by comprising a control means for terminating the reading of the image to signal an image signal read by said reading means. 2. A method of irradiating a document on a transport path with light.
A reader that reads the reflected light, converts it into an image signal, and outputs it.
A step, a white plate disposed at an image reading position by the reading unit , and the transport path on the upstream side of the reading unit in the transport direction.
A document detecting means for detecting the upper document, and a document transport distance in accordance with the detection of the document by the document detecting means.
Measurement, and then read by the reading means.
If the signal obtained differs from the steady signal from the white plate,
When the measurement of the original transport distance is completed, and the original is transported by the first predetermined distance, the reading unit reads the original.
While reading the image using the taken signal as an image signal, the non-detection of the original by the original detecting means
When distance partial document obtained by subtracting the second predetermined distance from the document conveyance distance fraction measured is conveyed to the reading means
And control means for terminating the reading of an image using the signal read as an image signal as an image signal.
apparatus.