JPH02177663A - Original reader - Google Patents

Abstract

PURPOSE:To miniaturize an original reader and to improve accuracy in detecting the front edge and the rear edge of an original by detecting the change of the picture of a mark in the original front edge and rear edge detecting area of a photoelectric converting means when the front edge and the rear edge of the original pass through the mark. CONSTITUTION:The width of a photoelectric converting means 33 is set wider than an original readable width, the means 33 is divided into a picture reading area 34a and an original front edge and rear edge detecting area 34b, further, an original front edge and rear edge detecting mark 35 is disposed on the reflection side of a light source 30 at an original reading position by interposing an original carrying path at the original reading position between the light source 30 and the mark 35, and a light beam from this mark 35 is introduced to the original front edge and rear edge detecting area of the photoelectric converting means 33. In this manner, the change of the picture of the mark 35 when the front edge and the rear edge of the original pass through the mark 35 is detected in the original front edge and rear edge detecting area of the photoelectric converting mean 33. Thus, the cost of the original reader can be reduced, the original reader can be miniaturized, and the accuracy in detecting the front edge and the rear edge of the original can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a document reading device, and more particularly to a document reading device with an improved method for detecting the leading edge and trailing edge of a document.

(Prior Art) Document reading devices are used as standalone document reading devices, as well as facsimile scanners and copying machines.
Some of such document reading devices transport documents one by one to a document reading section and read them.

Conventionally, such a document reading device has, for example, a sixth document reading device.
There is something like the one shown in the figure. In FIG. 6, when a document is set on the document table 2 of the document reading device 1, the document presence/absence detector 3 detects the document, and when the start button is pressed, the document automatic separation and conveyance device 4 detects the document. The documents are separated one by one and sent to the document reading section 5. The document sent from the automatic document separation/conveyance device 4 to the document reading section 5 on the lower guide plate 6 is sent to the document reading position 9 between the lower guide plate 6 and the upper guide plate 8 by conveyance rollers 7a and 7b. Original reading position 9
The leading edge and trailing edge of the original sent to the original document are detected by a leading edge/rear end detector 10 of the original. When the document leading edge and trailing edge detector 10 detects the leading edge of the document, the light source 11 is turned on, and the light from the light source 11 is irradiated onto the document conveyed to the document reading position 9. The light reflected on the document surface is passed through a reduction optical system (not shown) to a photoelectric conversion device, such as a CCD (Charge Co., Ltd.).
The photoelectric conversion device photoelectrically converts incident light to read an image of a document. When the document leading edge and trailing edge detector 10 detects the trailing edge of the document, after a predetermined period of time, the light in is turned off to finish reading the image, and the document whose image has been read is transferred to the discharge roller 1.
2a and 12b, the document is discharged to the outside of the document reading device l.

In this way, the reading operation is controlled by detecting the leading and trailing edges of the original using the leading and trailing edge detector 10, and the reading operation is controlled by detecting the leading and trailing edges of the original. Detecting edges is important.

Conventionally, the document leading edge and trailing edge detector 10 is composed of an actuator that is moved in one direction at the leading edge of the document and returns to its original state at the trailing edge of the document, and a photocoupler that detects the operation of this actuator. A so-called actuator type photosensor is used.

(Problem to be Solved by the Invention) However, in such conventional document reading devices, the leading and trailing edges of the document being conveyed to the document reading position are disposed between the conveying roller and the ejection roller. Detection was performed using a dedicated document leading/rear end detector using an actuator-type photo sensor, which required a dedicated document leading/rear end detector and a harness and connector to be connected to it. It was expensive. Furthermore, since the document leading and trailing edge detectors were disposed between the transport roller and the ejection roller, there was a problem in that the interval between the separation rollers was widened, resulting in an increase in the size of the document reading device. Furthermore, the document front/back edge detector using an actuator-type photosensor has a problem in that detection errors are large due to variations in the mounting position of the actuator, variations in the detection position of the photocoupler, and the like.

(Object of the Invention) Therefore, the present invention makes the width of the photoelectric conversion means wider than the document readable width, divides it into an image reading area and a document leading and trailing edge detection area, and furthermore, furthermore, A mark for detecting the leading edge and trailing edge of the original is provided on the opposite side of the light source at the original reading position, and the light from this mark is introduced into the leading edge and trailing edge detection area of the photoelectric conversion means. Changes in the images of the landmarks when the leading edge and trailing edge pass through the landmarks are detected in the document leading edge and trailing edge detection areas of the photoelectric conversion means, thereby reducing the cost and miniaturization of the document reading device and reducing the leading and trailing edges of the document. The aim is to improve detection accuracy.

(Structure of the Invention) In order to achieve the above object, the present invention includes a light source that projects light over a predetermined readable width in the main scanning direction onto a document being conveyed to a document reading device; A document reading device comprising a photoelectric conversion means in which a photoelectric conversion element is disposed, and a reduction optical system that reduces light reflected by the document and introduces it into the photoelectric conversion means. The element is arranged to be wider by a predetermined width than the optical path width through which the reflected light having the readable width is reduced by the reduction optical system and introduced, and the image reading area for reading the image of the original and the leading and trailing edges of the original are detected. a leading edge and trailing edge detection area, and marks for detecting the leading edge and trailing edge of the document are arranged on the opposite side of the light source across the document conveying path within the readable width of the document reading position; The present invention is characterized in that a second optical system is provided for introducing light from the mark into the front and rear end detection regions of the photoelectric conversion means.

Hereinafter, the present invention will be specifically explained based on examples.

1 to 4 are diagrams showing an embodiment of the present invention, which is applied to a scanner of a facsimile machine.

FIG. 1 is a diagram illustrating a main part of a scanner 21 of a facsimile machine serving as a document reading device. In the scanner 21, a document set on a document table 22 is conveyed to a document reading section 23. As shown in FIG. The original set on the original platen 22 is detected by the original existence detector 2.
4, the documents are separated one by one by the automatic document separation and conveyance device 25, and sent to the document reading section 23. Original reading section 23
includes a lower guide plate 26, an upper guide plate 27, and a conveyor roller 2.
8a, 28b, discharge rollers 29a, 29b and light a!
At least the document reading position 31 and its vicinity of the lower guide plate 26 are formed of a light-transmissive member such as transparent glass. The lower guide plate 26 guides the document fed by the automatic document separation/conveyance device 25 to the document reading position 31 and outside the scanner 21, and the temporary upper guide 27 guides the document being conveyed to the temporary lower guide 2G at the document reading position 31. Guide them in close contact. Conveyance roller 28
a and 28b are rotationally driven by a drive mechanism (not shown), and convey the original sent out from the automatic original separation/conveyance device 25 to the original reading section 23. The discharge rollers 29a and 29b are rotationally driven by a drive mechanism (not shown), and discharge the document whose image has been read at the document reading position 31 to the outside of the scanner 21. The light source 30 projects light onto the document at the document reading position 31, and this projected light is projected over a predetermined effective reading width W in the main scanning direction, as shown in FIG. The light reflected by the original at the original reading position 31 is introduced into the reduction optical system 32 shown in FIG.
It is reduced by a reduction optical system 32 and converted into a photoelectric conversion device (means) 33
is projected on. The reduction optical system 32 is composed of a lens, and reduces the image of the document at the document reading position 31 and forms the image on the photoelectric conversion device 33 . The photoelectric conversion device 33 has a plurality of photoelectric conversion elements 34 arranged in rows over a predetermined width in the main scanning direction, and the photoelectric conversion elements 34 include, for example, a CCD (Charge Coupled Device).
ce) is used. The photoelectric conversion element 34 is disposed to be wider by a predetermined width than the optical path width through which the reflected light of the width W of the document reading position 31 is reduced by the reduction optical system 32 and introduced, and is arranged so as to separate the image reading area 34a and the document. It is divided into a front end detection area 34b and a rear end detection area 34b. The arrangement width of the photoelectric conversion elements 34 of this photoelectric conversion device 33 is not particularly wide for the purpose of the present invention. That is, in general, when the photoelectric conversion device 33 used in the scanner 21 is for A4 width reading, the 84 width photoelectric conversion element 34 is usually cheaper than the A4 width photoelectric conversion element 34. Therefore, the photoelectric conversion element 34 having a width of 84 mm is used, and the width thereof is wider than the effective reading width W of the A4 width. Therefore, for example, if the resolution is 8 lines/llI
n! In this case, it is not necessary to read the effective reading width W of 1680680 pixels for A4 width, whereas it is 2048048 pixels for 84 width. As a result, 368 pixels were left unused. Therefore, in the present invention, this photoelectric conversion element 34
The unused portion of the document is used as the document leading edge and trailing edge detection area 34b.

A pattern 35 as a mark as shown in FIG. 3 is formed on the optical iso side surface of the upper guide plate 27, and the pattern 35 is formed over a predetermined width P in the main scanning direction in the effective reading width W. ing. In this embodiment, a white and black striped pattern is used as the pattern 35, but the pattern is not limited to this.
It is sufficient if the image pattern of the pattern 35 can be distinguished from the image pattern of a normal original and can be easily recognized in memory.

The reflected light of the light projected onto this pattern 35 from the light source 11 is reflected by a reflection mirror 36 as a second optical system and introduced into a reduction optical system 32, where it is reduced and converted into an original on a photoelectric conversion element 34. The leading and trailing end detection regions 34b are irradiated. Therefore, the light reflected by the document having the effective reading width W is introduced into the image reading area 34a via the reduction optical system 32, and the light reflected by the pattern 35 having the effective reading width W is transmitted to the reflection mirror 36 and the reduction optical system 32. is introduced into the document leading edge and trailing edge detection area 34b. As a result, the image of the document is read in the image reading area 34a, and the image of the pattern 35 is read in the document leading and trailing edge detection area 34b.

Next, the operation will be explained based on the flowchart shown in FIG.

When the scanner 21 is powered on, the document existence detector 2
4 is in a standby state until it detects the original (step S
,,S,), when the operator sets a document on the document table 22 and the document presence/absence detector 24 detects the document (step S
), Next, wait for the start button to be pressed (step s3). When the start button is turned on, the light source 30
is turned on, and the document on the document table 22 is separated one by one by the automatic document separation and conveyance device 25 and conveyed to the document reading section 23 (step 35). The document sent out from the automatic document separation/conveyance device 25 toward the document reading section 23 is further conveyed toward the document reading position 31 by conveyance rollers 28a and 28b. At this time, light from the light source 30 is projected onto the pattern 35, and the light reflected from the pattern 35 passes through the reflection mirror 36 and the reduction optical system 32 to the document front/back edge detection area 34b of the photoelectric conversion element 34. It has been introduced. Pattern 3 incident on the document leading edge/back edge detection area 34b
The image No. 5 is photoelectrically converted in the document leading and trailing edge detection area 34b, and then sent to the CPU (Ce-ntral Pro) in the scanner 21.
It is compared with the image pattern of the pattern 35 stored in advance in the memory of the scanner 21 and recognized. In this state, the leading edge of the document reaches the vicinity of the document reading position 31 and begins to cover the image of pattern 35. When the leading edge of the document reaches the document reading position 31 and covers the pattern 35, the CPU detects the image pattern of pattern 35. Due to the disappearance, the leading edge of the document is at the document reading position 31
When the leading edge of the document is detected in this way, the image of the document is transferred to the image reading area 3 of the photoelectric conversion element 34 while the document is further forwarded.
4a (step 37.S8), and when the trailing edge of the document passes the document reading position 31, the image of the pattern 35 is again incident on the document leading edge/back edge detection area 34b, and the CPU recognizes this pattern 35 image. By this, the trailing edge of the document is detected (step S9). When the trailing edge of the original is detected, the original is ejected by the ejection rollers 29a and 29b (step S1°), and if the original presence/absence detection 324 still detects that the original is placed on the original platen 22 (step S1).
, ), return to step S and perform similar processing. When the document presence/absence detector 24 detects that there is no document on the document table 22 (step Sz), the scanner 21 returns to the standby state.

In this way, in this embodiment, the pattern 35 is simply applied as a mark without providing an actuator type photocoupler as in the conventional case, and the image of the pattern 35 is used to identify the original of the photoelectric conversion element 34 which is not normally used. Detection can be performed using the front and rear end detection areas 34b, and the cost of the scanner 21 can be reduced, and the scanner 21 can be made smaller. Furthermore, since the leading edge and trailing edge of the document are detected in the leading edge and trailing edge detection area 34b of the photoelectric conversion element 34, detection accuracy and reliability can be improved.

In the above embodiment, the pattern 35 is used as a mark.
Although the mark is applied to the upper guide plate 27, the mark is not limited to this. For example, as shown in FIG.
They may be arranged in one effective reading width W. In this case as well, the leading and trailing edges of the document can be detected by projecting the light from the light emitting element 40 onto the leading and trailing edge detection area 34b of the document via the reflecting mirror 36 and the reduction optical system 32 and recognizing it by the CPU. .

(Effects) According to the present invention, the change in the image of the mark when the leading edge and the trailing edge of the original pass the mark can be detected in the leading and trailing edge detection area of the original of the photoelectric conversion means, so that The cost can be reduced, the document reading position can be downsized, and the detection accuracy of the leading edge and trailing edge of the document can be improved.

[Brief explanation of the drawing]

FIGS. 1 to 4 are diagrams showing an embodiment in which the document reading device of the present invention is applied to a scanner of a facsimile machine. FIG. 1 is a configuration diagram of the main parts of the scanner, and FIG. , a block diagram of the optical system and the photoelectric conversion device, FIG. 3 is a front view of a pattern as a mark, and FIG. 4 is a flowchart showing the leading and trailing edge detection processing and image reading processing of the document. FIG. 5 is a diagram showing the main part of another embodiment in which the document reading device of the present invention is applied to a scanner of a facsimile machine. FIG. 6 is a block diagram of the main parts of a conventional document reading device. 21...Scanner, 22...Original table 22. 23... Original reading unit, 24... Original presence/absence detector, 25... Original automatic separation and conveyance device, 26...
...Lower guide plate, 27...Upper guide quick turn, 28a, 28b...Conveyance roller, 29a, 29
b...Discharge roller, 30...Light source, 31...Document reading position, 32...Reduction optical system, 33...Photoelectric conversion Device (photoelectric conversion means) 34.
...Photoelectric conversion element, 34a...Image reading area, 34b...Document leading edge and trailing edge detection area, 35...
...Pattern, 36...Reflection mirror (second optical system), 40...
...Light emitting element, W...Effective reading width. Substitute Patent Attorney Arigagun

Claims (1)

[Claims] A light source that projects light over a predetermined readable width in the main scanning direction onto a document being conveyed to a document reading device; a photoelectric conversion means in which a plurality of photoelectric conversion elements are arranged over a predetermined width; and a reduction optical system that reduces the reflected light and introduces it into the photoelectric conversion means, wherein the reflected light of the width that can read the photoelectric conversion element of the photoelectric conversion means is reduced by the reduction optical system. It is arranged a predetermined width wider than the width of the optical path to be introduced, and is divided into an image reading area for reading the image of the original and a front/back edge detection area for detecting the leading edge and the trailing edge of the original. Marks for detecting the leading edge and trailing edge of the original are provided on the opposite side of the light source across the original transport path within a possible width, and light from the marks is directed to the leading edge and trailing edge detection area of the photoelectric conversion means. A document reading device characterized in that a second optical system is provided.