JPH01290370A - Picture reader - Google Patents

Abstract

PURPOSE:To attain high speed reading by applying acceleration control for high speed movement on an original read position in the detection of the tip of an original and applying pre-scan at a prescribed timing without interrupting acceleration. CONSTITUTION:An original 6 detected by an original sensor 5 in an original carrying path is carried by a carrier roller 15 and when the tip of the original 6 is detected by an original tip sensor 18, the carrier speed is increased stepwise and accelerated to be a prescribed carrier speed, pre-scan is applied, that is, a reflected light from a shading plate 26 is led to an image sensor 25 in the absence of the original 6 at a read position 17 to apply read scanning of the plate 26. Since the original 6 passes the read position at a prescribed speed while its acceleration control is not interrupted, high speed original reading is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device that reads an image of a document.

[Conventional technology]

2. Description of the Related Art Conventionally, in a facsimile machine, a sheet-like original is conveyed by a roller or the like, and an image of the original conveyed to a predetermined reading position is photoelectrically read using a CCD image sensor or the like.

Further, when reading a document using COD, shading correction is performed due to variations in each bit of the COD or non-uniform illuminance of a fluorescent lamp. In other words, the conveyance of the original is temporarily stopped before the reading position, the light source is turned on at that point, and the all-white reference member above the reading position is read (briscan) before the original is read, and the information obtained by this pre-scan is read. The image signals output by subsequent document reading are corrected using the data thus obtained.

[Problem to be solved by the invention] Recently, high-speed image reading has become possible due to improvements in the performance of image reading sensors and image signal processing circuit elements. have to move.

However, when a pulse motor is used as a drive source for the document conveyance roller, the pulse motor is
In order to rotate at a high speed such as ps, it is necessary to increase the number of drive pulses to the pulse motor in multiple steps from 400 pps to 1440 pps as shown in Figure 5. It takes a certain amount of time to achieve a predetermined high speed rotation from a stopped state.

Therefore, when performing such high-speed reading, as described above, in a configuration in which the document being conveyed is temporarily stopped and pre-scanned, and then the document is conveyed again after pre-scanning, it is difficult to convey the document at a predetermined high speed. In addition, it is necessary to construct a long conveyance path for the run-up.

[Means for solving problems]

The present invention has been made in view of the above points, and includes a conveying means for conveying a document to a document reading position, a reading means for reading an image of the document conveyed to the document reading position, and a reference member being read by the reading means. and a correction means for correcting the reading signal of the original image based on the signal obtained by the reading means, while the original is being transported by the transporting means and before the original reaches the original reading position mentioned above. The present invention provides an image reading device that reads the reference member, and further includes:
The conveyance means provides an image reading device by increasing the conveyance speed sequentially so that the document conveyance speed reaches a predetermined speed when the document reaches the document reading position.

〔Example〕

The present invention will be explained below using preferred embodiments.

FIG. 2 is a block diagram of a facsimile transmitting apparatus to which the present invention is applied.

In FIG. 2, the reference numeral 6 is a manuscript, and this manuscript 6
is placed on the original table 7 with the original surface facing down, and at this time, it is placed between two sliders (not shown) that are slidably attached to the left and right sides on the original table 7. A document sensor 5 is provided to detect the presence or absence of a document on the document table 7.

An operation display section constituting the upper part of the document feeding mechanism section 2 is provided above the rear half of the top surface of the apparatus, and a start key is provided in a part of this operation display section.

When the original 6 is set as described above and the start key is pressed, the drive mechanism starts operating and feeds the original 6 into the original feeding mechanism section 2.

A corner roller 11 and a backup roller 12 in contact with the corner roller 11 are arranged on the entrance end side of the document feeding mechanism section 2.
The document 6 is sent intermittently by the cooperation of both.

A separation roller 13 is provided behind the square roller 11, and a separation piece 14 is placed above the separation roller 13 in a state in which it is in slight contact with the separation roller 13.

By the cooperation of the separating roller 13 and the separating piece 14, the plurality of originals are separated one by one from the bottom and further sent to the downstream side.

The document 6 that has left the separation roller 13 is further conveyed while being sandwiched between conveyance rollers 15.degree. 15, and is discharged out of the apparatus by a discharge roller 16.degree. The conveyance roller 15 and discharge roller 16 are rotationally driven by a pulse motor.

A document reading position 17 is arranged between the aforementioned transport roller 15 and discharge roller 16.

Further, reference numeral 18 denotes a document leading edge sensor provided a predetermined distance in front of the document reading position 17, which detects the leading edge of the document 6 and controls the timing of reading start, etc.

On the other hand, a light source 19 using a fluorescent lamp or the like is arranged below the reading position 17, and a contact glass 20 is arranged at the reading position 17. The original is read through this contact glass 20, but by providing this glass, foreign matter such as dust can fall into the apparatus from near the reading position 17 and adhere to the optical system, and the mechanism due to falling bottles or clips can be prevented. damage to the parts can be prevented.

The light from the light source 19 illuminates the document 6 on the contact glass 20, and the reflected light is reflected forward by the first mirror 21 located directly below the reading position 17, reflected again by the second mirror 22, and An image is formed on an image sensor 25 on a printed circuit board 24 via a lens 23 disposed below a mirror 21 . The image sensor 25 is composed of a plurality of light receiving elements arranged in a line, and repeatedly reads the original image line by line.

When there is no original at the reading position 17, reflected light from the shading plate 26 is guided to the image sensor 25.

This shading plate 26 is a uniform white plate, and is designed to prevent uneven illuminance distribution in the longitudinal direction of the light source 19 and the lens 23.
This is a reference member used to measure shading distortion caused by the unevenness of the light quantity ratio between the central and peripheral parts of the light passing through. This reading scan of the shading plate 26 is called a bliss scan.

The above-mentioned components such as mirrors and lenses constitute the reading optical system section 3.

Figure 3 shows the document sensor (DS sensor) in the document transport path.
5. Document leading edge sensor (DES sensor) 18, reading position (R, P) 17 and bliscan start position (p, s)
It is a figure showing the positional relationship of. The interval between the document detection position of the DES sensor and the reading position (RSP) is set to B, and prescanning is started when the leading edge of the document is conveyed to the prescanning start position (p, s), which is a distance A away from the DES sensor. do. Note that the distance B is a short distance (both are the run-up distance required for the document to be transported to the reading position (R, P) at a predetermined speed by acceleration control, and the distance A is the run-up distance required for the document to be conveyed to the reading position (R, P) at a predetermined speed by acceleration control. The distance is set to satisfy the relationship A+C<B, where C is the distance over which the original is conveyed.

Furthermore, the number of originals detected by the DS sensor is, for example, 40.
The document is transported by a roller driven by a pulse motor driven at 0 pps. When the leading edge of the document is detected by the DES sensor, the rotation speed of the pulse smoke is increased in steps, and the document is moved to the document reading position (R .

FIG. 1 is a block diagram showing an example of the circuit configuration of the facsimile transmitting apparatus shown in FIG.

31 is a reading unit, which includes a CCD 32 corresponding to the image sensor 25 shown in the second figure; a COD driver 36 that drives the CCD 32; and an analog-to-digital (A/D) converter that converts an analog image signal from the CCD 32 into a digital image signal. 33, CCD 32 is the shading board 2 shown in the second diagram
Shading correction is performed on the original image signal outputted from the A/D converter 33 when reading the original image based on the readout signal from the line memory 34 and the line memory 34 which stores the output signal of one line of reading 6. A correction circuit 35 is included.

37 is a communication control unit; an encoding circuit 38 performs compression encoding such as well-known MH encoding or MR encoding on the original image signal from the reading unit 31; and a modulation circuit 38 that performs modulation processing on the encoded image signal. circuit 39 and a network control circuit (NCU) that controls sending out the modulated image signal to a transmission line such as a public line.
40 included.

Reference numeral 42 denotes a document transport section, which includes a pulse motor 43 and a pulse motor 43 that drive the transport roller 15 and the discharge roller 16.
A motor driver 44 outputs pulses to the pulse motor 43 to drive the pulse motor 43, and a timing controller 45 controls the rotation direction, speed, and number of steps of the pulse motor 43.
is included.

Reference numeral 46 indicates a light source corresponding to the light source 19 shown in the second diagram; 47 indicates an operator for inputting a telephone number and issuing a start command;
This is an operation display section on which various displays are displayed.

48 and 49 are a DS sensor and a DES sensor corresponding to the document sensor 5 and the document leading edge sensor 18 shown in the second figure, respectively.

30 has a microcomputer as its main element, and has a memory RO
This is a main control unit that controls the operation of each block described above using M50 and memory RAM51.

When the pulse motor 43 is driven one step, the original is conveyed by a distance l. Further, by changing the number of steps per unit time, the conveyance speed of the document can be changed. Therefore, the main control section 30 controls the document conveyance speed of the document conveyance section 42 by controlling the number of drive steps of the pulse motor 43 per unit time by the timing controller 43, and also controls the number of drive steps of the pulse motor 43 by controlling the number of drive steps of the pulse motor 43 per unit time. The document position is recognized by counting.

For this purpose, a table for speed control of the pulse motor 43 is stored in the memory ROM 50 of the main control unit 30 in advance. That is, as described above, for acceleration control that increases the number of driving steps per unit time of the pulse motor 43 in steps from when the leading edge of the document is detected by the DES sensor until reaching the document reading position (R, P). In the memory ROM 50, there is a table that is addressed by data indicating the document position and outputs data of the number of steps corresponding to the position.
is stored in

FIG. 4 is a flowchart showing the operation control procedure by the main control section 30. When the start key of the operation/display unit 43 is pressed, it is checked in step S1 whether the DS sensor is ON (original is present), and if it is 0FF (original heat), the process ends, and if it is ON, the light source 46 is turned on. , proceed to step S2. Step S2. In S3, the pulse motor 43 (hereinafter referred to as P, M43) is driven one step at a time, and this is repeated until the DES sensor is turned on (the starting edge of the document is on the sensor). When the DES sensor is turned on, the register X of the RAM 51 is set to O in step S4. From this P,
M4.3 enters the aforementioned acceleration control. That is, step S
In step S5, the number of steps of P and M2S per unit time is sequentially changed stepwise according to data preset in a table in the ROM 50, and in step S6, P and M2S are driven accordingly.

In step S7, the number of steps in which P and M2S are driven is accumulated in register X. And step S8
, the value of register X is the distance A from the DES sensor to the P and S positions, which is the document movement amount per step! Check whether it is smaller than All divided by . If the value of register X is smaller than A/n, the process returns to step S5 and the acceleration control of P and M2S is repeated. On the other hand, if the value of the register X is not smaller than All and it is determined in step S9 that the briscan has not been performed yet, a command to start the briscan is sent to the reading unit 31 in step SIO.

In response to this command to start bliscan, the reading section 31 stores a read signal obtained by scanning the shading plate 26 with the CCD 32 in the line memory 34.

If the briscan operation has already been performed in step S9 or after the briscan operation is performed in step SIO, the value of the register X is changed to DES in step Sll.
It is checked whether B/f is obtained by dividing the distance B from the sensor to the document reading positions R and P by l. The value of register X is B/I! If not, return to step S5,
Continue acceleration control of P and M2S. On the other hand, the value of register X is B/I! If this happens, the document has reached the reading position, so the acceleration control of P and M2S is finished, and the CCD 32 starts reading the document image.

In the original image reading operation, shading correction processing is performed on the original image signal from the CCD 32 based on the data stored in the line memory 34 by the briscan operation in step SIO. The shading-corrected image signal is then transmitted to the communication control section 37, subjected to predetermined processing, and then sent to an external receiving device via a transmission line.

When one page of original reading is completed, return to step S1D
The document is detected by the S sensor, and if the document is further detected, the process proceeds to step S2 and the same process as described above is executed.
If the S sensor is OFF, it is assumed that all document sending has been completed, and the light source is turned off and the sending operation is ended.

In this way, once the leading edge of the original is detected by the original leading edge sensor DES, acceleration control is performed to move the original over the reading position at high speed, and the briscan operation is performed at a predetermined timing without interrupting the acceleration control. This is what we do. This enables efficient (briscan operation) without extending the time required for high-speed conveyance.

In this embodiment, the shading correction of the image signal was performed using the data obtained by the Briscan operation, but the present invention is not limited to this, and correction of defective pixels of the CCD line sensor, correction of the density characteristics of the read signal, etc. can also be performed. It is also possible to perform color balance correction in the case of reading a color image.

Further, although the present embodiment has been described using a pulse motor as a drive source, the present invention is similarly applicable to the case where a motor having another configuration is used.

Furthermore, it goes without saying that the present invention is applicable not only to facsimile transmission devices but also to document reading devices such as digital copying machines and electronic file devices.

〔Effect of the invention〕

As explained above, according to the present invention, the reference member is read by the reading means while the original is being transported by the transporting means and before the original reaches the original reading position, so that the original is moved to the original reading position at a predetermined speed. It is possible to shorten the time for movement and shorten the conveyance path, etc., thereby making it possible to perform high-speed document reading.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the circuit configuration of a facsimile transmitter to which the present invention is applied, Fig. 2 is a block diagram of a facsimile transmitter, and Fig. 3 shows the arrangement of various elements in the document conveyance path. 4 is a flowchart showing the control procedure, and FIG. 5 is a diagram showing acceleration control of the pulse motor, 30 is a main control section, 32 is a COD, 37 is a communication control section, 4
Reference numeral 2 denotes a document conveying section, 43 a pulse motor, 48 a document sensor, and 49 a document leading edge sensor.

Claims (2)

[Claims] (1) A conveyance means for conveying a document to a document reading position, a reading means for reading an image of the document conveyed through the document reading position, and a reading of the document image based on a signal obtained by reading a reference member by the reading means. a correction means for correcting a signal, and the reference member is read by the reading means before the original reaches the original reading position while the original is being transported by the transporting means and before the original reaches the original reading position. reading device. (2) In the image reading device according to claim (1), the conveyance means sequentially increases the conveyance speed so that the document conveyance speed reaches a predetermined speed when the document reaches the document reading position. An image reading device characterized by: