JP2002206951A - Apparatus for detecting original point of feed mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect the original position and the feed rate of a moving document stand. SOLUTION: A detection plate 52 is integrally attached to the moving document stand. The end of the detection plate 52 comprises a feed rate detecting portion 55 and an original point detecting portion 56. The feed rate detecting portion 55 is provided with detecting portions 55a and non-detecting portions 55b. The detecting portions 55a and the non-detecting portions 55b are alternately arranged with equal intervals. When the feed rate detecting portion 55 moves at a constant speed as the document stand moves, a second sensor 53 detects the detecting portions 55a every predetermined time. By simply detecting the detecting portions 55a using the second sensor 53, a determination can be made as to whether or not the document stand is moving at the constant speed. The boundary between the moving speed detecting portion 55 and the original point detecting portion 56 serves as the original position. By simply detecting the boundary using the second sensor 53, the original position of the document stand can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an origin detecting device for a feed mechanism, and more particularly to an origin detecting device for a feed mechanism used in a film carrier for feeding an image original such as a slide mount in a sub-scanning direction.

[0002]

2. Description of the Related Art Office automation equipment such as copiers, image scanners and printers, X-Y tables, and F
2. Description of the Related Art In a wide field such as an optical apparatus such as an A-apparatus or a camera, a feed mechanism for conveying or moving a feed member in a predetermined direction is used. As such a feed mechanism, a device for accurately feeding a feed member or efficiently feeding a feed member is disclosed in, for example, Japanese Utility Model Application Laid-Open No. 58-21151 and Japanese Patent Application Laid-Open No. 9-200.
No. 443 and Japanese Patent Application Laid-Open No. H11-154019.

[0003] One of the types in which a feed mechanism is used is a film carrier, for example. The film carrier is used by being set in an image reading apparatus, reading an image of a photographic film with a CCD, digitally processing the read image, and then printing the image on a printing paper or the like. The image is read by irradiating the photographic film with light from a light source from a light transmitting portion provided in the film passage, and capturing the transmitted light of the photographic film with a CCD.

Further, in order to efficiently perform an image reading process when reading an image from a slide mount, a film carrier that automatically conveys the slide mount has been proposed. In such a film carrier, for example, a supply cartridge for vertically stacking a plurality of slide mounts is provided, and the slide mounts are sent from the supply cartridge one by one to a movable document table. The movable platen is movably provided by a platen feed mechanism between a receiving position for receiving the slide mount and a discharge position for discharging the slide mount. Then, by moving the movable platen while holding the slide mount, the slide mount is sent in the sub-scanning direction at the reading position of the scanner unit of the image reading device to perform pre-scan and fine scan. The slide mount is sent from the table to the collection cartridge and stored.

In the above-described film carrier, since the moving platen is moved between the receiving position and the discharging position of the slide mount by controlling the motor, it is necessary to detect the origin position of the moving platen. Therefore, for example, it is conceivable to provide a detection plate on the moving document table and provide a sensor for detecting the detection plate at the origin position to detect the origin position of the moving document table.

Further, in the case of performing image reading using the above-described film carrier, the image on the slide mount cannot be accurately read unless the moving platen is fed at a constant speed during fine scanning. Further, a light source for irradiating the slide mount with light is provided near the reading position in order to irradiate a sufficient amount of light to the slide mount. Stops at the reading position. In this case, the heat from the light source may damage the slide mount such as deformation or deterioration. From these, for example, by providing a sensor that detects the rotation of the motor that drives the moving platen, it is detected whether the moving platen is moving at a constant speed, and the moving platen is moved at a constant speed. If it has not moved, it is conceivable that it is determined that the feeding is abnormal and the power supply of the image reading apparatus is stopped.

[0007]

However, in the above-described method, a sensor used for detecting the origin position of the moving platen and a sensor for detecting whether or not the moving platen is moving at a constant speed are used. Therefore, there is a problem that the mechanism of the film carrier is complicated and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an origin detecting device for a feed mechanism which can easily detect the origin position and feed speed of a feed member. I do.

[0009]

According to a first aspect of the present invention, there is provided an apparatus for detecting the origin of a feed mechanism, comprising: a feed mechanism for feeding in a first direction from an origin position to a target position; A feed member that feeds in a second direction toward a position, and a feed speed that is arranged along the feed direction of the feed member, and in which the detection unit and the non-detection unit are alternately arranged at a constant pitch in the feed direction. A detection member, an origin detection unit formed by forming the detection unit or the non-detection unit at the end on the origin position side of the feed speed detection member longer than the other detection units or the non-detection units, and the detection unit A sensor provided at a position relatively moved with respect to the feed speed detecting member so as to detect the non-detecting portion and the origin detecting portion, and an origin position detecting portion detecting an origin position based on a detection signal of the origin detecting portion of the sensor It is provided with.

In addition, the origin position detecting section, when detecting the origin position, detects the same signal as the signal generated when the sensor is located at the origin detecting section, and moves the feed member in the first direction. And a first step of sending the feed member in the second direction when the signal of the sensor is switched during the feed, and when the origin position is detected, the sensor is located at the origin detection unit. A second step of sending the feed member in the second direction when detecting a signal different from a signal that is occasionally emitted, and based on a signal of the sensor during the feed in the second direction of the first and second steps. It is preferable to detect the origin position by detecting the passage of the origin detecting unit, thereafter feeding the feed member in the first direction, and stopping the feed when the signal of the sensor is switched. .

Preferably, the detecting section and the non-detecting section of the feed speed detecting member are formed from the origin position to the target position, and it is preferable to determine that the feeding is abnormal when the detecting section is not detected at regular intervals. .

In this case, the feeding member is configured to hold the photographic film and is provided so as to be able to be fed in a direction crossing the imaging optical axis. It is preferable to stop light emission of the light source to be illuminated. Further, it is preferable that the feed member performs pre-scanning in the first reciprocating movement and performs main scanning in the second reciprocating movement, and the predetermined interval of the pre-scanning is longer than that of the main scanning.

[0013]

FIG. 1 is a perspective view showing the appearance of a film carrier embodying the present invention. The film carrier 10 has a supply cartridge loading port 11 and a collection cartridge loading port 12 formed therein. Mount cartridges 13 are removably loaded into these loading ports.
Hereinafter, what is set in the supply cartridge loading port 11 will be described as a supply cartridge 14, and what is set in the recovery cartridge loading port 12 will be described as a recovery cartridge 15. A reading opening 16 is formed between the loading openings 11 and 12, and a slide mount 17 is provided through the reading opening 16 by, for example, a line CCD scanner.
Is read.

The mount cartridge 13 comprises a cartridge body 18 and a lid 19. The cartridge body 18 is formed in a groove shape by a transparent synthetic resin, and the slide mount 17 and the sort card 20 are stacked and stored in the groove. Lid 19 is hinged part 2
It is attached to the upper part of the cartridge body 18 via 1 and is displaced between an open position and a closed position. In the open position, the side opening and the upper opening of the cartridge body 18 are opened, so that the slide mount 17 can be easily loaded. In the closed position, the cartridge body 18 and the lid 1 are closed.
With 9, the mount cartridge 13 has a rectangular tube shape.

The slide mount 17 is configured by holding one frame of a reversal film 17a between frames 17b. The sort card 20 is for separating the slide mount 17 for each order into one unit.
It is inserted between the slide mounts 17 of each order unit.
The sort card 20 has an identification hole 20a formed therein.
7 is enabled.

FIG. 2 is a front sectional view showing a schematic configuration of the film carrier 10 and FIG.
It is a top view which shows the outline of 0 inside. Inside the film carrier 10, there are provided a feeding claw 29, a mount supply / conveyance unit 30, a movable document table 32, a mount collection / conveyance unit 33, and a draw-in roller.

The delivery claw 29 sends out the slide mount 17 to the mount supply / transport section 30. The cam 31 is driven by the rotation of the supply motor 36 being transmitted via the clutch 35. The clutch 35 and the supply motor 36 are controlled by a controller 38 via a driver 37. The supply motor 36 includes a cam 32 and a transport roller pair 3 described later.
9 is also used as the drive source. For this reason, the delivery claw 29
When the slide mount 17 is reciprocated and the slide mount 17 is sent out to the mount supply conveyance section 30, the controller 38 turns off the clutch 35 and releases the transmission of rotation from the supply motor 36 to the cam 31 by the clutch 35.

The mount supplying / unloading section 30 sandwiches the slide mount 17 sent out from the sending claw 29 from both sides by three pairs of conveying rollers 39 and sends the slide mount 17 to the movable document table 32. The transport roller pair 39 is driven to rotate by the supply motor 36. In addition, a first sensor 40 that also serves to detect the sort card 20 is disposed in the mount supply / unload unit 30. The first sensor 40 detects the leading ends of the slide mount 17 and the sort card 20, and outputs a detection signal to the controller 38. Further, the slide mount 17 and the sort card 20 are identified by detecting the identification hole 20 a of the sort card 20.

The movable platen 32 includes a platen main body 41 and 2.
It is composed of a pair of conveying rollers 42, a slide holding section 43, a document table moving mechanism 44, and a moving state detecting device 45. The platen body 41 is moved from the mount supply / transport unit 30 to the slide mount 17 by the platen moving mechanism 44.
Is moved between the receiving position for receiving the slide mount 17 and the discharge position for discharging the slide mount 17 to the mount collection / conveyance section 33. The conveyance roller pair 42 sends the slide mount 17 sent from the mount supply / conveyance unit 30 to the image reading position of the movable document table 32, and sends the slide mount 17 after image reading to the mount collection / conveyance unit 33. The slide holding portion 43 holds positioning projections 46 and 4 for holding and fixing the slide mount 17 set at the image reading position.
7.

The document table moving mechanism 44 includes a scan motor 4
8, a feed screw rod 49, and a female screw portion 50. The forward / reverse rotation of the feed screw rod 49 by the scan motor 48 is converted into a reciprocating motion of the document table main body 41. Then, the platen body 41 is reciprocated in the left-right direction in the figure,
Prescan is performed by the first feed in the direction of arrow A,
During the return (in the direction B in the drawing), the focus is temporarily stopped to perform autofocus for fine scan, and the second feed in the direction of arrow A performs fine scan. The pre-scan and the fine scan are performed by operating a line CCD scanner (not shown) in synchronization with the movement of the movable document table 32. Reference numeral 51 denotes the scan motor 49.
Driver.

The moving state detecting device 45 includes a detecting plate 52 and a second
It comprises a sensor 53, a controller 38, and an origin detection start switch 54. The detection plate 52 is a platen body 4
1 is provided integrally with the rear end face and moves together with the document table main body 41. FIG. 4 shows a front view of the detection plate 52. The detection plate 52 is formed of a metal plate, and a feed speed detection unit 55 and an origin detection unit 56 are provided at a lower end thereof.

The feed speed detecting section 55 is formed by cutting out the lower end of the detecting plate 52 in a comb shape, and includes a detecting section 55a and a non-detecting section 55b. The non-detection portion 55b may be formed by etching or laser processing, in addition to being formed by ordinary cutting. The detection units 55a and the non-detection units 55b are alternately arranged along the movement direction of the detection plate 52, and each of the detection units 55a and the non-detection units 55b
Are L = L1. When the detection unit 55a passes through the second sensor 53, the second sensor 5
3 sends a detection signal to the controller 38. Based on the detection signal from the second sensor 53, the controller 38 determines whether or not the document table main body 41 is moving at a constant speed based on whether or not the detection unit 55a is detected at regular intervals. When the detection unit 55a is not detected at regular intervals, the controller 38 determines that the feeding of the document table main body 41 is abnormal, and turns off the power switch 57 of the image reading apparatus in which the film carrier 10 is set.

In the pre-scan, since an image is read with a relatively rough reading accuracy, the image reading is not affected even if the speed of the document table main body 41 slightly varies. Also, during the return of the platen body 41 after the pre-scan is completed,
Since the auto focus is temporarily stopped, even if the speed of the document table main body 41 slightly varies, the auto focus is not affected. For this reason, during the pre-scan and during the return after the pre-scan, the controller 38 detects the detection signal from the second sensor 53 every other time,
The feeding speed of the document table main body 41 is managed with rough accuracy.

In the fine scan, since the image is read with strict accuracy based on the reading conditions obtained in the pre-scan, the speed of the document table main body 41 must be strictly controlled. For this reason, in the fine scan, the controller 38 detects a detection signal from the second sensor 53 for each of the detection units 55a, and strictly controls the feed speed of the document table main body 41.

The origin detecting section 56 is arranged in series with the feed speed detecting section 55, and the boundary with the feed speed detecting section 55 is the origin position. Then, when this origin position is detected by the second sensor 53, the document table main body 41 is set in the receiving position. The length L2 of the origin detection unit 56 along the movement direction of the detection plate 52 is formed longer than the length L of the detection unit 55a. The second sensor 53 is an origin detection unit 5
When 6 passes, a detection signal is sent to the controller 38. The home position detection start switch 54 is mounted on the feeder 3
When the document table main body 41 moves to the receiving position, it comes into contact with the side surface of the document table main body 41 and turns on. This ON signal is sent to the controller 38. The controller 38 controls the scan motor 48 via the driver 51 based on the detection signal of the second sensor 53 and the ON signal of the origin detection start switch 54 to detect the origin position of the document table main body 41.

A non-detection section 58 is provided beside the feed speed detection section 55. By using the non-detection section 58 in the same manner as the origin detection section 56, the document table main body 41 is set at the discharge position. It can be used to detect what has been done.

The slide mount 17 from which the image has been read
Is sent to the mount collection / conveyance unit 33. The mount collection and transport section 33 also includes three transport roller pairs 59,
The document from the movable document table 32 is sent to the collection cartridge 15.

A pull-in roller 34 is provided at the collection cartridge loading port 12. As shown in FIGS. 1 to 3, the pull-in roller 34 is rotated for a predetermined time by the collecting motor 60, and pulls the slide mount 17 from the mount collecting and transporting unit 33 into the collecting cartridge 15.
The retracted slide mount 17 is placed in the lowermost layer of the recovered slide mount 17. Note that reference numeral 6
Reference numeral 1 denotes a driver for the collection motor 60.

Next, the operation of the above embodiment will be described. When the reading start key on the operation panel is operated, the clutch 35 is first turned on, and then the supply motor 36 is turned on. As a result, the slide mount 17 at the lowermost layer of the supply cartridge 14 is locked by the delivery claw 29 and is sent to the mount supply / conveyance unit 30. Mount supply transport section 30
The transport roller pair 39 is driven to rotate by the supply motor 36, and the slide mount 17 is nipped by the transport roller pair 39 and sent to the movable document table 32. The document table main body 41 is set at the receiving position, which is the origin position, and the drive of the supply motor 36 is transmitted to the transport roller pair 42.
Thus, the slide mount 17 is transported to the document table main body 41 and set.

The platen body 4 of the slide mount 17
During the transfer to 1, based on the output signal of the first sensor 40,
What is passing is the slide mount 17 or sort card 2
0 is determined. In the case of slide mount 17,
The document table main body 41 reciprocates at the image reading position. Then, the pre-scan is performed by the first movement in the direction A, the autofocus for fine scan is performed while the return to the direction B is temporarily stopped, and the fine scan is performed by the second movement in the direction A. While the platen body 41 is moving, the controller 38 determines whether the platen body 41 is moving at a constant speed.

The detection of the moving speed of the platen main body 41 is performed as follows.
Along with the movement of the document table main body 41, this is performed when the feed speed detection unit 55 of the detection plate 52 passes through the second sensor 53. The second sensor 53 detects the detection unit 55a and sends a detection signal to the controller 38. When the feed speed detection unit 55 passes through the second sensor 53 at a constant speed, the detection signal is detected at regular intervals because the detection unit 55a passes through the second sensor 53 at regular intervals. And
If the detection signal is detected at regular intervals, the controller 38 detects that the document table main body 41 is moving at a constant speed.

Here, if the document table main body 41 is stopped due to a failure of the scan motor 48, a control error of the scan motor 48 by the controller 38, or the entry of a foreign substance, the detection signal of the second sensor 53 is output for a predetermined time. Will not be detected each time. In response to this, the controller 38 determines that the feeding is abnormal, and turns off the power switch 57 of the image reading apparatus. In this way, the number of drive pulses of the scan motor 48 is counted, and the feed control of the platen body 41 is controlled by software. Even if software runs away, the moving state of the platen body 41 is controlled by hardware. Since the detection has been performed, the power switch 57 of the image reading apparatus can be turned off. Thereby, for example, the platen body 41
Even if the light source stops near the light source (not shown) of the image reading apparatus, the light source stops emitting light, so that the slide mount 17 is prevented from being deteriorated or deformed. In addition, since the accuracy of the feed determination of the document table main body 41 is changed between the time of the pre-scan and the time of the fine scan, the document table main body 41 may stop needlessly during the pre-scan or during the return after the pre-scan. And the efficiency of image reading can be improved.

When the fine scan is completed, the platen main body 41 moves to the discharge position, and the mount collecting and conveying section 33 is moved.
The slide mount 17 is sent out. Thereafter, the platen body 41 is sent in the direction B in the drawing and returned to the receiving position.
When the movable document table 32 is returned to the receiving position, first, the document table body 41 comes into contact with the origin detection start switch 54 and turns on.
An ON signal is sent to the controller 38. In response to the ON signal, the controller 38 stops the document table main body 41. At this time, the platen main body 41 stops roughly near the receiving position, and thereafter, the platen main body 41 is positioned at the origin position. In this embodiment, the origin detection switch 54 is provided, but this may be omitted. In this case, the number of drive pulses of the scan motor 48 of the movable document table 32 is counted to detect whether or not it is near the origin position.

FIG. 5 is a flowchart showing a processing procedure for positioning the document table main body 41 at the origin position.
FIG. 6 shows positioning of the original table main body 41 to the origin by reciprocating movement. First, based on the detection signal of the second sensor 53, the stop position of the detection plate 52 is identified. Second sensor 5
For example, when the origin detection unit 56 is stopped at the detection position 3 as shown in FIG. 6A, and at the detection position of the second sensor 53 as shown in FIG. When the detection unit 55a of the detection unit 55 is stopped, the second sensor 53 detects the origin detection unit 56 and the detection unit 55a and turns on. When detecting the ON signal, the controller 38 first moves the document table main body 41 in the direction A in the drawing. Then, when the origin detecting unit 56 has completely passed through the second sensor 53 or the detecting unit 55a has completely passed through the second sensor 53 and the second sensor 53 has been turned off, the feeding direction is switched and the document table is switched. The main body 41 is sent in the direction B in the figure.

Here, the controller 38 stores in advance a detection time t1 when the detector 55a passes through the second sensor 53. This detection time t1 corresponds to the second sensor 53
Is turned on, the ON signal sent to the detecting unit 55
This is used as a determination value when discriminating which of a and the origin detection unit 56 is used. Since the length L2 of the origin detecting section 56 is formed to be longer than the length L of the detecting section 55a, when the detection time t by the second sensor 53 exceeds the detection time t1, the controller 38 causes the second sensor 53 to operate.
Is detected by the origin detecting unit 56. During the feeding of the platen body 41 in the direction B, the controller 38 detects the detection time t from the second sensor 53 by the detection unit 55.
When the detection time t1 of a is exceeded, the feeding direction of the document table main body 41 is switched, and the moving document table 32 is fed in the direction A again. Thereafter, when the second sensor 53 is switched from on to off, the controller 38 detects the origin position of the detection plate 52, stops feeding the platen body 41, and moves the platen body 41
Is stopped at the home position.

As shown in FIG. 6C, when the non-detection section 55b is stopped at the detection position of the second sensor 53, the second sensor 53 is turned off. Controller 38
When the second sensor 53 is off, the document table main body 41 is fed in the B direction. Thereafter, the document table main body 41 is continuously fed in the direction B until it is detected that the origin detecting section 56 has passed through the second sensor 53. The detection time t from the second sensor 53 is the detection time t1 of the detection unit 55a.
, The feed direction of the platen body 41 is switched,
The document table main body 41 is sent in the direction A again. Then, when the detection signal from the second sensor 53 switches from ON to OFF, the controller 38 detects the origin position of the detection plate 52, stops the feeding of the platen body 41, and moves the platen body 41
Is stopped at the home position.

In the above embodiment, the detecting portions 55a and the non-detecting portions 55b are arranged alternately at a constant pitch. However, the present invention is not limited to this. May be arranged apart from each other, or two types of colors such as a white portion and a black portion may be alternately arranged.
Two surfaces having different reflectivities may be alternately arranged to detect either one. In the above embodiment,
Although the detection unit 55a and the non-detection unit 55b are configured in a 1: 1 ratio, this ratio may be changed as appropriate. Further, in the above embodiment, the detection plate is constituted by the optical detection unit and the optical non-detection unit. However, when a magnetic sensor is used as the sensor, the magnetic detection unit and the magnetic non-detection unit are alternately used. May be provided to form a detection plate.

In the above embodiment, the present invention is applied to the film carrier 10. However, the present invention is not limited to this.
OA equipment such as copiers, image scanners and printers,
The present invention can be applied to various feed mechanisms such as an XY table, FA equipment such as an article transport device, and optical equipment such as a camera.

[0039]

As described above, according to the present invention, the feed speed detecting member is arranged along the feed direction of the feed member, and the detecting section and the non-detecting section are alternately arranged at a constant pitch in the feed direction. And an origin detection unit formed by forming a detection unit or a non-detection unit at the end of the feed speed detection member on the origin position side longer than other detection units or non-detection units; and a detection unit, a non-detection unit, and an origin. A sensor provided at a position relatively moved with respect to the feed speed detecting member so as to detect the detecting portion, and an origin position detecting portion for detecting the origin position based on a detection signal of the origin detecting portion of the sensor; Thus, the origin position and the moving speed of the feed member can be easily detected, so that the configuration of the apparatus can be simplified and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a film carrier embodying the present invention.

FIG. 2 is a front view schematically showing the internal structure of the film carrier.

FIG. 3 is a plan view schematically showing the internal structure of the film carrier.

FIG. 4 is an explanatory diagram illustrating a configuration of a detection plate.

FIG. 5 is a flowchart of origin detection.

FIG. 6 is a timing chart when an origin is detected.

[Explanation of symbols]

 10 Film carrier 17 Slide mount 52 Detector plate 53 Second sensor 55 Feed speed detector 55a Detector 55b, 58 Non-detector 56 Origin detector

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hirofumi Kumagai 1005 Kozono, Ayase-shi, Kanagawa Prefecture F-term in Fuji Micro Graphics Co., Ltd. TT24 TT62 5C062 AB02 AB03 AB32 AC11 AC66 5C072 AA01 AA03 NA01 NA08 VA03 WA04

Claims (5)

[Claims] A feed member that feeds in a first direction from an origin position to a target position and feeds in a second direction from a target position to an origin position, along a feed direction of the feed member. A feed speed detecting member in which detection units and non-detection units are alternately arranged at a constant pitch in the feed direction; and the detection unit or the non-detection unit at the end of the feed speed detection member on the origin position side. An origin detection unit formed to be longer than the other detection units or non-detection units, and a position relatively moved with the feed speed detection member to detect the detection unit, the non-detection unit, and the origin detection unit. An origin detection device for a feed mechanism, comprising: a sensor provided; and an origin position detection unit that detects an origin position based on a detection signal of the origin detection unit of the sensor. 2. The method according to claim 1, wherein the origin position detecting unit detects the origin position and, when detecting the same signal as a signal generated when the sensor is located at the origin detecting unit, causes the feed member to move in the first direction. A first step of sending the feed member in the second direction when the signal of the sensor is switched during the feed; and when the origin position is detected, the sensor is located at the origin detection unit. A second step of sending the sending member in the second direction when detecting a signal different from a signal generated at the time, and sending the sending member in the second direction in the first and second steps based on a signal of the sensor. Detects passage through the origin detector,
3. The feed mechanism according to claim 1, wherein the feed member is sent in the first direction, and the feed is stopped when the signal of the sensor is switched. Origin detection device. 3. A detecting section and a non-detecting section of the feed speed detecting member are formed from the origin position to a target position, and when the detecting section is not detected at regular intervals, it is determined that a feed abnormality is present. 3. The origin detecting device for a feed mechanism according to claim 1, wherein: 4. The feed member is configured to hold a photographic film, and is provided so as to be capable of being fed in a direction intersecting with an imaging optical axis, and illuminates the photographic film when it is determined that the feed is abnormal. 4. The origin detecting device for a feed mechanism according to claim 3, wherein the light source stops emitting light. 5. The feed member performs pre-scanning in a first reciprocating movement, performs main scanning in a second reciprocating movement, and the predetermined interval of the pre-scanning is longer than that in the main scanning. The origin detecting device for a feed mechanism according to claim 4.