JP3181404B2 - 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 applied to a facsimile apparatus having a document reading section capable of reading high quality images.

[0002]

2. Description of the Related Art In an image reading apparatus for reflecting light of a light source on a document, converting the light into an electric signal using a photoelectric conversion element, and reading the original signal, an appropriate level of an image information signal is detected in real time, and an accumulation time is accordingly determined. That is, the means for changing the image information signal, that is, the appropriate level detecting means for the image information signal, while reading the original with the effective pixels, simultaneously reads the white reference plate arranged in the sub-scanning direction with the other pixels (output Vwout),
The accumulation time is varied without outputting the next accumulation pulse until the white output value (Vref) reaches a preset white output value (Vref).

Therefore, according to this conventional technique, for example, even if a fluorescent lamp having a poor lighting start-up characteristic is used as a light source, Vwo
No accumulated pulse is output until ut reaches the specified level Vref, so that a stable image information signal can always be obtained.

As a countermeasure for preventing image deterioration caused by document conveyance, the component in the sub-scanning direction of the sensor light receiving section is shortened to reduce
There is also a method of reducing the document conveyance amount in the step. In this method, reading of a document in the sub-scanning direction is subdivided by reducing the size of the light receiving window and finely feeding the document.

[0005]

The reading resolution of the facsimile is 8 lines / mm in the main scanning direction and 3.85, 7.7 or 15.4 lines / mm in the sub-scanning direction. This resolution is lower than that of copiers and scanners, and in particular, thin lines extending in the main scanning direction tend to be missed due to the effect of the document conveyance amount compared to thin lines in the sub-scanning direction. Deterioration has occurred. In addition, there is a problem of reading deterioration of a document having a high spatial frequency in the sub-scanning direction (for example, horizontal collapse of a character in the Mincho style) caused by uneven conveyance. At present, there is a limit to the performance of the original conveying motor, and therefore, it is impossible to avoid uneven conveyance.
In addition, when performing facsimile communication, there is a limit on the processing speed and data transfer speed on the receiving side, and irregular intermittent feeding at the document reading unit on the transmitting side is inevitable, so it stops due to problems with the characteristics of the motor. In this case, the conveyance amount becomes slow in a transition state of the conveyance, and the above-described image deterioration occurs.

As shown in the prior art, there is a method of compensating for unevenness in document conveyance by changing the accumulation time of the CCD, or performing reading by making the light receiving section smaller and making the conveyance amount finer. In this case, if the accumulation time is too short, a reset may occur before the signal outputs of all the pixels are transferred from the shift register, which may cause a problem. In the latter case, not only the sensitivity is reduced due to the reduction of the light receiving area, but also the reading speed is considered to be reduced due to the reduction in the transport amount of one step.

SUMMARY OF THE INVENTION An object of the present invention is to provide a document reading apparatus which can prevent image reading deterioration which occurs during a transitional period between the start of conveyance and the stop of conveyance in a reading section which conveys a document while intermittently moving with a facsimile. It is in.

[0008]

The above object is achieved byTransport state
Intermittent exercise by repeating the stop state alternately
Of the conveyed documentIlluminate the original surface with a light source,ThatReflected light
Image with lenshandLine CCDBy typing inoriginal
Reduction optical system that reads manuscript informationDocument reading device
hand,ManuscriptofTransportStateStopTo stateTransferTransportLinear delivery
NotOutput from the line CCD corresponding to the first transition period
The output value of the input image data is V _n , The stoppage of the original
The transport amount that moves from the state to the next transport state is not linear.
Image output from the line CCD corresponding to the transition period
Data output value is V _m age,  X = (V_n+ V_m) / 2The value of X given by the first transient period and the second transient period
Correction means to output image data corresponding to the period
Was This is achieved by the first means.

[0009] Further, the object is toSwitch the transport state and stop state
Originals conveyed intermittently by repeating each other
DraftIlluminate the original surface with a light source,ThatReflected light is imaged with a lens
IhandLine CCDBy typing inRead manuscript information
Take reduction opticsDocument reading device, The lie
The light receiving part of CCD is divided into two parts andUpstream
PU and PL on the downstream side,Stops from document transport state
In the first transitional period when the transported amount to move to the state is not linear,
Only the output from the upstream light-receiving part
Is V (PU, n),Also,From the stop state of the original,
In the second transitional period when the transport distance to the transport state is not linear,
CorrespondinglyExtracts only the output from the upstream receiverhand
Let this output be V (PU, m)Xn = 2 × V (PU, N)The value of X given by
Data output value,  Xm = 2 × V (PU, M)The value of X given by
Equipped with a correction means to output data By the second means
Is achieved.

The object of the present invention is to exchange the transport state and the stop state.
Originals conveyed intermittently by repeating each other
The original surface of the draft was irradiated by a light source, a document reading apparatus of the reduction optical system for reading a document information by inputting the reflected light is imaged on the line CCD lens, the line
If the light receiving part of the CCD is divided into two parts and the upstream side is PU and the downstream side is PL in the transport direction , the document is stopped from the transport state.
In the first transitional period when the transported amount to move to the state is not linear,
Only the output from the upstream light-receiving part
To V (PU, n), and from the stopped state of the original,
In the second transitional period when the transport distance to the transport state is not linear,
Extracting only the output from the light receiving portion of the upstream side to respond
Let this output be V (PU, m), and let X = [V ( PU , n) + V ( PU , m) be the value of X given by the first transient period and the second transient period.
Correction means to output image data corresponding to the transition period
This is achieved by the third means provided .

[0011]

In the first means, since the document conveyance state can be known only by monitoring the control signal sent to the document conveyance motor, the read output when the conveyance is not linear at the start and stop of the conveyance is corrected, so that the facsimile can be obtained. The image deterioration caused by the intermittent movement of the original reading section conveying system during communication is prevented.

In the second means, the state of document conveyance can be known only by monitoring a control signal sent to the document conveyance motor, and reading when the conveyance is not linear in starting and stopping conveyance is performed within a narrow pixel range. Reading is eliminated, correction can be performed more accurately, and image deterioration caused by intermittent movement of the document reading unit transport system during facsimile communication is prevented.

According to the third means, the state of document conveyance can be known only by monitoring a control signal sent to the document conveyance motor, and reading when the conveyance is not linear in starting and stopping conveyance can be performed within a half pixel range of the conventional one. Since the correction is performed, the correction can be performed more accurately, and the image deterioration caused by the intermittent movement of the document reading unit conveyance system during the facsimile communication can be prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a facsimile scanner.

In FIG. 1, reference numerals 1 and 2 denote a pair of transport rollers for transporting a document sheet, 3 a light source for irradiating the document surface of the document sheet, 4 a mirror for guiding a reflected light image of the document to a lens 5, and 6 a lens of the lens 5. A line CCD (hereinafter, referred to as a CCD) is disposed at an image forming position and photoelectrically converts the image.

FIG. 2 is a schematic block diagram of the original reading apparatus according to the first embodiment, FIG. 3 is a timing chart showing the original conveyance amount, motor driving pulse, video signal, and CCD eye movement, and FIG. FIG. 5 is a flow chart.

In FIG. 2, 10 is an image input unit, 11 is a video signal correction unit, 12 is an image processing unit, 13 is a motor drive pulse detection unit, 14 is a motor control unit, 15 is an input unit drive motor, and 16 is an output. Unit drive motor, 17 is a communication control unit, 18 is a CPU, 19 is a RAM, 20 is an operation unit, 21
Is an output unit, which is connected between the units by lines shown in the drawing, and outputs signals in the direction of the arrow.

In FIG. 4, reference numeral 22 denotes the output of the CCD 6,
The switch switches between the video signal side and the later-described transition period image information _Vm side by a switch switching pulse from the motor drive pulse detection unit 13.

In the intermittently moving optical reading system, the document is not linear as shown in FIG. 3 in the transition period from the stop state of the document to the start of the conveyance or in the transition period from the conveyance state of the document to the stop. Since the reading in this period is different from the period of the linear feeding, the image may be deteriorated. Therefore, it is necessary to correct the image signal in this portion.

[0021] monitors the control signal for driving the motor, when detecting a document conveying state (n-1) from the stop transition period (n), each of output and V _n-1, V _n, also stopped the output when it detects a displacement of the conveyance state (m) from the state (m-1) and V _m-1, V _m. Since V _n and V _m of these outputs is image information of the transition, it has deteriorated includes a feeding irregularity falling and rising of the document transport.

[0022] In the transition period of the stop from the transport state, the output V _n for the feed becomes blunt is happening image degradation since the output obtained by reading repeatedly previous line. Once again start moving after a while stopped, the output V _m is the output that was read overlaid also because it is a transition period. So by taking the average of both outputs,
X = a _{(V n + V m) /} 2 in X a transitional image information obtained.

In the flowchart of FIG. 5, it is determined in step S1 whether or not the document is in a transitional period from document conveyance to stop, and if it is in a transitional period from stop to conveyance in S2, the output is corrected in S3. If it is not in the transition period, video output is performed in S4.

According to the first embodiment, since the state of document conveyance can be known only by monitoring the control signal sent to the document conveyance motor, the read output when the conveyance is not linear in starting and stopping conveyance is corrected. Thus, it is possible to prevent the image deterioration caused by the intermittent movement of the original reading section conveying system during the facsimile communication.

FIG. 6 is a block diagram of the CCD of the document reading apparatus according to the second embodiment. FIG.
8 is a timing chart showing the movement of the eye D, FIG. 8 is a detailed block diagram of a main part, and FIG. 9 is a flow chart.

The photoelectric conversion unit 6a uses a CCD 6 divided into an upstream PU and a downstream PL in the document transport direction.
A common accumulated pulse signal S is provided on the PU side for each light receiving section.
The electrode of H is connected, and the electrode of the common accumulated pulse signal SH 'is connected to the PL side separately. The latter electrode SH 'can be turned on and off with the former electrode SH by a switch SW. The charge output from each pixel is sequentially transferred by the shift register 6b and output as image information.

The drive control signal of the motor is monitored, and when it is determined that the transition period is from the document conveyance state (n-1) to the stop (n), the SW is switched to the ground GND side at time tn, and the downstream light receiving element PL Flows through GND, and only the current of the upstream light receiving element PU flows through the shift register 6B. Wherein Xn = 2 × V (P shown below the output _{V n} obtained by the multiplier
U , n).

After a short time, when the drive starts again and the transition period of the conveyance (m) is detected from the original stopped state (m-1), the image information signal V ( PU , m) is changed to Xm = 2 × V ( PU , m). ), And at time tm, SW is turned on to connect to the accumulation pulse SH 'of the electrode SH and return to the original state.

In the flow chart of FIG. 9, it is determined in step S11 whether or not the document transport is in a transitional period from the conveyance of the document, and if it is in the transitional period, the output V ( PU , PU , PU) from the PU is determined in S12.
n) is corrected and output. Then if it is determined that transition of the transport from the stop state S13, S14, S15 at the output V (PU, m) from PU corrected outputs a. If it is not a transition period, a video signal is output in S16.

According to the second embodiment, the state of document conveyance can be determined only by monitoring the control signal sent to the document conveyance motor, and reading when the conveyance is not linear in starting and stopping conveyance can be performed within a narrow pixel range. As a result, overlapping reading is eliminated, correction can be performed more accurately, and image deterioration caused by intermittent movement of the document reading section transport system during facsimile communication can be prevented.

FIG. 10 is a detailed block diagram of a main part of the document reading apparatus according to the third embodiment, and FIG. 11 is a flowchart.

FIG. 10 shows a configuration similar to that of the second embodiment. The drive control signal of the motor is monitored, and if it is determined that the document is being transported (n-1) and the stop (n) is determined to be in a transition period,
At time tn, the switch SW is switched to the ground GND, the output charge of the downstream light receiving element PL flows to GND, and only the charge of the upstream light receiving element PU flows to the shift register.
The output obtained at this time is stored in a buffer or the like as V ( PU , n). Eventually, when the drive is started again and the transition period of the conveyance (m) is detected from the document stopped state (m-1), the image information signal V ( PU , m) is output, and the transition period obtained in the previous line is output. X = [V ( PU , n) + V
( PU , m)] and output. Then, at time tm, SW is turned on to connect the accumulation pulse of the electrode SH to SH 'and return to the original state.

In the flowchart of FIG.
It is determined whether or not it is in the transition period from the document conveyance to the stop, and if it is in the transition period, V (PU, n) is output in S22. Next, when it is determined in S23 that the transfer state is a transition period from the stop state,
V (PU, m) is output (S24). Then, in step S25, a correction value X is calculated based on the above formula, and output in step S26. If the transition period is not reached in S21, video output is performed in S27.

According to the third embodiment, the state of document conveyance can be known only by monitoring the control signal sent to the document conveyance motor, and the reading when the conveyance is not linear in the start and stop of the conveyance can be reduced by half the conventional pixel. Since the correction is performed within the range, the correction can be performed more accurately, and it is possible to prevent the image deterioration caused by the intermittent movement of the document reading unit conveyance system during the facsimile communication.

[0035]

According to the first aspect of the present invention, the state of document conveyance can be known only by monitoring the control signal sent to the document conveyance motor, so that the read output when the start and stop of conveyance are not linear is corrected. By doing so, it is possible to prevent image degradation caused by the intermittent movement of the document reading unit transport system during facsimile communication.

According to the second aspect of the present invention, the state of document conveyance can be determined only by monitoring the control signal sent to the document conveyance motor, and reading when the conveyance is not linear in starting and stopping conveyance can be performed within a narrow pixel range. As a result, overlapping reading is eliminated, correction can be performed more accurately, and image deterioration caused by intermittent movement of the document reading section transport system during facsimile communication can be prevented.

According to the third aspect of the present invention, the state of document conveyance can be determined only by monitoring the control signal sent to the document conveyance motor. Since the correction is performed within the range, the correction can be performed more accurately, and it is possible to prevent the image deterioration caused by the intermittent movement of the document reading unit conveyance system during the facsimile communication.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a facsimile scanner.

FIG. 2 is a schematic block diagram of a document reading apparatus according to the first embodiment of the present invention.

FIG. 3 shows a document conveyance amount, a motor drive pulse, a video signal,
This is a timing chart showing the movement of the eyes of the CCD.

FIG. 4 is a detailed block diagram of a main part of the document reading apparatus.

FIG. 5 is a flowchart of control contents according to the first embodiment.

FIG. 6 is a configuration diagram of a CCD of a document reading apparatus according to a second embodiment of the present invention.

FIG. 7 shows a document conveyance amount, a motor drive pulse, a video signal,
This is a timing chart showing the movement of the eyes of the CCD.

FIG. 8 is a detailed block diagram of a main part of the document reading apparatus.

FIG. 9 is a flowchart of control contents according to the second embodiment.

FIG. 10 is a detailed block diagram of a main part of a document reading apparatus according to a third embodiment of the present invention.

FIG. 11 is a flowchart of control contents according to a third embodiment.

[Explanation of symbols]

 Reference Signs List 3 light source 4 mirror 5 lens 6 line CCD 10 image input unit 11 video signal correction unit 12 image processing unit 13 motor drive pulse detection unit 14 motor control unit 15 input unit drive motor 16 output unit drive motor 17 communication control unit 18 CPU 19 RAM 20 operation unit 21 output unit

Claims (3)

(57) [Claims] (1)Repeat the transport state and the stop state alternately.
And the document conveyed intermittentlyLight the original surface
Irradiation at the source,ThatThe reflected light is imaged with a lenshandLine CC
DBy typing inReduction optical system for reading document information
Document reading device,  ManuscriptofTransportStateStopTo stateTransferTransportThe delivery volume is linear
IThe output from the line CCD corresponds to the first transition period.
The output value of the image data _n , Whether the original is stopped
The second transition in which the transport distance from the next transport state to the next transport state is not linear
Image data output from the line CCD in accordance with the
Output value to V _m age,  X = (V_n+ V_m) / 2The value of X given by the first transient period and the second transient period
Correction means to output image data corresponding to the period
Was An original reading apparatus, comprising: (2)Repeat the transport state and the stop state alternately.
And the document conveyed intermittentlyLight the original surface
Irradiation at the source,ThatThe reflected light is imaged with a lenshandLine CC
DBy typing inReduction optical system for reading document information
Document reading device, Divide the light receiving part of the line CCD into two parts and
 When the upstream side is PU and the downstream side is PL,The transport distance from the original transport state to the stop state is not linear.
Of the output from the upstream light-receiving unit corresponding to the first transition period.
And take this output as V (PU, n), Also,Said
The transport distance from the original stopped state to the next transport state is linear.
Not corresponding to the second transition periodFrom the upstream receiver
Extract only the output ofThe output of the lever is V (PU, m)
IXn = 2 × V (PU, N)The value of X given by
Data output value, Xm = 2 × V (PU, M)The value of X given by
Equipped with a correction means to output data Characterized by
Document reading device. (3)Repeat the transport state and the stop state alternately.
With intermittent exercise Of the original being conveyedLight the original surface
Irradiation at the source,ThatThe reflected light is imaged with a lenshandLine CC
DBy typing inReduction optical system for reading document information
Document reading device, Divide the light receiving part of the line CCD into two parts and
 When the upstream side is PU and the downstream side is PL,The transport distance from the original transport state to the stop state is not linear.
Of the output from the upstream light-receiving unit corresponding to the first transition period.
And take this output as V (PU, n), Also,Said
The transport distance from the original stopped state to the next transport state is linear.
Not corresponding to the second transition periodFrom the upstream receiver
Extract only the output ofThe output of the lever is V (PU, m)
I, X = [V (PU, N) + V (PU, M)The value of X given by the first transient period and the second
Correction means to output image data corresponding to the transition period
Equipped An original reading apparatus, comprising: