HK1066055B

HK1066055B - Reflection-type optical sensor, carriage, and data processing device

Info

Publication number: HK1066055B
Application number: HK04108902.6A
Authority: HK
Inventors: 加藤哲也
Original assignee: 兄弟工业株式会社
Priority date: 2002-12-04
Filing date: 2004-11-11
Publication date: 2008-11-28

Description

Reflection type optical sensor, carriage and data processing apparatus

Technical Field

The present invention relates to a reflection type optical sensor having a light emitting element and a light receiving element to detect an object, a carriage capable of moving above the detected object, and a data processing apparatus that performs a data control process on the object while the object is moving.

Background

Reflection type optical sensors such as those disclosed in japanese unexamined patent application publication No. hei-6-222156 are known in the art, and have a light emitting element and a light receiving element to detect an object. The light emitting element and the light receiving element of the reflective optical sensor are placed at different angles with respect to the object. The light emitting element emits a light beam onto an object at a predetermined incident angle, and the light receiving element detects the presence of the object by receiving light reflected from the object.

In order to allow light emitted from a light emitting element to be easily reflected onto a light receiving element, a reflection type optical sensor is constructed to have a light emitting element of high directivity (narrow beam dispersion) and a light receiving element of high directivity (narrow light receiving angle).

Disclosure of Invention

By mounting the reflective optical sensor on the carriage, the carriage can be moved, for example, over the object, so that the reflective optical sensor can detect the object. The reflection type optical sensor may also be used in a data processing apparatus that performs a data control process on an object when the object is moved using the moving mechanism.

However, in the reflection type optical sensor disclosed in the aforementioned patent application, a slight change in the incident angle of the emitted light causes a large change in the angle of the reflected light, so that the light receiving element cannot receive the reflected light. Therefore, it is necessary to accurately set the positions (angles) of the light emitting element and the light receiving element with respect to the object so that the incident angle of the light emitting element is equal to the receiving angle of the light receiving element. However, even a small error in positioning can greatly affect the detection error, and it is difficult to accurately position the component.

In addition, there are light emitting elements and light receiving elements in the art having low directivity (emitted light has wide beam dispersion and wide reception angle), which are inexpensive and allow a large error in positioning the angle. If a reflection type optical sensor is constructed with these light emitting element and light receiving element, this proposed reflection type optical sensor can suppress a decrease in detection accuracy caused by an angular positioning error and has a low cost.

However, the envisaged reflection type optical sensor constructed with the light emitting element and the light receiving element having low directivity is capable of detecting an object in a wide area. When the required detection area is narrow, the detection accuracy is lowered. More specifically, the proposed reflective optical sensor using the low directivity element has a detection result strongly affected by disturbance light reflected from an area outside a desired detection area because a light beam emitted from a light emitting element thereof is dispersed over a wide range while a light receiving element receives light over a wide angle. Such interference may reduce the detection accuracy of the reflection type optical sensor.

The detection accuracy of a carriage or a data processing apparatus having such a reflection type optical sensor is low due to interference in an area outside a desired detection area. Therefore, the accuracy of the carriage or the data processing apparatus is not good at detecting the positioning of the object.

In addition, when the light emitting element and the light receiving element are directed toward the object at different angles, the reflection type optical sensor having such a structure must be constructed to have a large volume to ensure a sufficient internal space to accommodate the elements thus arranged. When the sensor is large, the range of application of the sensor is limited, because, for example, the space available for mounting the sensor is limited.

In view of the foregoing problems, it is an object of the present invention to provide a reflection type optical sensor capable of suppressing a reduction in detection accuracy due to an error in angular positioning of an element while ensuring low cost, and capable of suppressing a reduction in detection accuracy due to external disturbance while being manufactured to have a small size.

It is another object of the present invention to provide a carriage and a data processing apparatus provided with a reflective optical sensor of this type.

To achieve the above and other objects, the present invention provides a reflection type optical sensor for detecting an object, the sensor comprising: a light emitting element having a central axis extending in a predetermined direction extending in a direction substantially orthogonal to a surface of the object to be detected, the light emitting element further having a light emitting portion that emits detection light toward the surface of the object, the detection light propagating toward the surface of the object defining an irradiation area on the object; a light receiving element having a central axis parallel to the central axis of the light emitting element and having a light receiving portion which receives reflected light reflected from a detection region on the object, the detection region and an irradiation region overlapping at an overlapping region of the object surface, the irradiation region having a remaining irradiation region other than the overlapping region of the irradiation region, the detection region having a remaining detection region other than the overlapping region of the detection region; and a restricting member having a restricting portion that defines an aperture that allows a portion of the probe light and a portion of the reflected light to pass therethrough, the restricting portion restricting a size of the aperture to reduce an area of an overlapping region on a surface of the object through which the probe light is projected, the irradiation region corresponding to an area of the object through which the probe light is projected, the probe light reflected from the irradiation region having the overlapping light reflected from the overlapping region of the irradiation region and a remaining probe light reflected from a remaining irradiation region, the light receiving portion receiving the overlapping light reflected from the overlapping region through the aperture, and the restricting portion preventing the remaining probe light from reaching the light receiving portion.

According to another aspect of the present invention, there is provided a carriage which moves over and detects an object, the carriage comprising: a moving member which moves above the object; and a detecting unit provided on the moving member and detecting the object to determine a position of the object, the detecting unit including a reflective optical sensor including: a light emitting element having a central axis extending in a predetermined direction extending in a direction substantially orthogonal to a surface of the object to be detected, the light emitting element further having a light emitting portion that emits detection light toward the surface of the object, the detection light propagating toward the surface of the object defining an irradiation area on the object; a light receiving element having a central axis parallel to the central axis of the light emitting element and having a light receiving portion which receives reflected light reflected from a detection region on the object, the detection region and an irradiation region overlapping at an overlapping region of the object surface, the irradiation region having a remaining irradiation region other than the overlapping region of the irradiation region, the detection region having a remaining detection region other than the overlapping region of the detection region; and a restricting member having a restricting portion that defines an aperture that allows a portion of the probe light and a portion of the reflected light to pass therethrough, the restricting portion restricting a size of the aperture to reduce an area of an overlapping region on a surface of the object through which the probe light is projected, the irradiation region corresponding to an area of the object through which the probe light is projected, the probe light reflected from the irradiation region having the overlapping light reflected from the overlapping region of the irradiation region and a remaining probe light reflected from a remaining irradiation region, the light receiving portion receiving the overlapping light reflected from the overlapping region through the aperture, and the restricting portion preventing the remaining probe light from reaching the light receiving portion.

According to another aspect of the present invention, there is provided a data processing apparatus comprising: a moving member which moves above the object; a detecting unit which moves together with the moving member and detects the object, the detecting unit including a reflective optical sensor which detects an edge of the object, the reflective optical sensor including: a light emitting element having a central axis extending in a predetermined direction extending in a direction substantially orthogonal to a surface of the object to be detected, the light emitting element further having a light emitting portion that emits detection light toward the surface of the object, the detection light propagating toward the surface of the object defining an irradiation area on the object; a light receiving element having a central axis parallel to the central axis of the light emitting element and having a light receiving portion which receives reflected light reflected from a detection region on the object, the detection region and an irradiation region overlapping at an overlapping region of the object surface, the irradiation region having a remaining irradiation region other than the overlapping region of the irradiation region, the detection region having a remaining detection region other than the overlapping region of the detection region; and a restricting member having a restricting portion defining an aperture for allowing a portion of the probe light and a portion of the reflected light to pass therethrough, the restricting portion restricting a size of the aperture to reduce an area of an overlapping region on a surface of the object, the irradiation region corresponding to an area of the object through which the probe light is projected, the probe light reflected from the irradiation region having the overlapping light reflected from the overlapping region of the irradiation region and the remaining probe light reflected from the remaining irradiation region, the light receiving portion receiving the overlapping light reflected from the overlapping region through the aperture, and the restricting portion preventing the remaining probe light from reaching the light receiving portion, a movement control unit controlling the moving member to move in a reciprocating manner; an object moving unit that moves the object in a direction different from a direction in which the moving control unit controls the moving member to move; and a process executing unit which moves together with the moving member and executes a data control process based on the detection result obtained by the detecting unit, the data control process including at least one of a data adding process of adding data to the object and a data obtaining process of obtaining data from the object.

Drawings

In the drawings:

fig. 1 is a perspective view showing a multifunction apparatus equipped with a printing function, a copying function, a scanning function, a facsimile function, and a telephone function;

fig. 2 is a plan view showing an internal structure of a printer in the multifunction apparatus;

FIG. 3 is a block diagram showing the electrical configuration of a control process unit in the multifunction device;

fig. 4 is an explanatory view showing a cross-sectional structure of a media sensor mounted on a carriage (print head) in the multifunction apparatus;

fig. 5(a) is an explanatory view showing a target detection region of a media sensor;

fig. 5(b) is an explanatory view showing a target detection region of the main sensor unit;

fig. 6(a) is an explanatory view showing a target detection region of the media sensor when the light emitting element and the light receiving element are aligned in the first scanning direction;

FIG. 6(b) is a waveform diagram of the sensor output for sheet edge detection when the media sensor is moving in a first scanning direction, which is the direction in which the light emitting and light receiving elements are aligned;

FIG. 6(c) is a waveform diagram of the sensor output for sheet edge detection when the media sensor is moved in a second scanning direction, which is perpendicular to the direction in which the light emitting and light receiving elements are aligned;

fig. 6(d) is an explanatory view showing a target detection region of the media sensor when the light emitting element and the light receiving element are aligned in the second scanning direction;

fig. 7 shows a sensor output value measured when changing the inner diameter of the hole formed in the cover member;

FIG. 8 is an explanatory view showing a cross-sectional structure of a modified media sensor provided with a modified cover member having two holes; and

fig. 9 is an explanatory view showing a target detection region of the medium sensor in fig. 8.

Detailed Description

A reflective optical sensor, a carriage, and a data processing apparatus according to preferred embodiments of the present invention will be described with reference to the accompanying drawings, and like parts and components will be given the same reference numerals to avoid repetitive description.

Fig. 1 is a perspective view of a multifunction apparatus 1 of a preferred embodiment to which the present invention is to be applied. The multifunction device has a printing function, a copying function, a scanning function, a facsimile function, a telephone function, and the like.

As shown in fig. 1, the paper feed unit 2 is provided at the rear of the multifunction apparatus 1. The ink-jet printer 3 is provided below the front of the paper feed unit 2. A scanner unit 4 that implements a copy function and a facsimile function is provided above the printer 3. The sheet discharge tray 5 is provided on the front side of the printer 3. An operation plate 6 is provided on the top surface of the front end of the scanner unit 4.

The sheet supply unit 2 includes an inclined wall portion 66 and a projected sheet guide tray 67, wherein the inclined wall portion 66 holds the sheet in an inclined position, and the sheet guide tray 67 is detachably mounted on the wall portion 66. A plurality of sheets of paper may be stacked on the paper supply unit 2. A sheet feed motor 65 (see fig. 3), a sheet feed roller (not shown), and the like are built in the wall portion 66. When the sheet feed motor 65 drives the sheet feed roller to rotate, the sheet feed roller conveys a sheet to the printer 3.

The printer 3 is described in more detail below. Fig. 2 is a plan view showing the internal structure of the printer 3.

As shown in fig. 2, the printer 3 includes a print head 10, a carriage 11, a guide mechanism 12, a carriage moving mechanism 13, a paper conveying mechanism 14, and a maintenance mechanism 15 of the print head 10. The printhead 10 is mounted on a carriage 11. The guide mechanism 12 supports and guides the carriage 11 so that the carriage 11 can reciprocate in a scanning direction, which is a left-right direction of fig. 2. The carriage moving mechanism 13 moves the carriage 11 in the right-left direction. The sheet conveying mechanism 14 conveys the sheet supplied from the sheet supply unit 2.

In the printer 3, a rectangular bracket 16 is provided, which is long in the left-right direction and short in the front-rear direction. Various components are mounted on a rectangular support 16, including a guide mechanism 12, a carriage moving mechanism 13, a sheet conveying mechanism 14, and a maintenance mechanism 15. The print head 10 and the carriage 11 are also accommodated inside the rectangular support 16 so that they can reciprocate in the left-right direction.

The rectangular bracket 16 includes a rear plate 16a and a front plate 16 b. A paper introduction port and a paper discharge port (not shown) are formed on the rear plate 16a and the front plate 16b, respectively. The sheet supplied from the sheet supply unit 2 is introduced into the rectangular frame 16 through the sheet introduction port, is then conveyed to the front of the rectangular frame 16 by the sheet conveying mechanism 14, and is finally discharged to the sheet discharge tray 5 (fig. 1) in front of the multifunction apparatus 1 through the sheet discharge port. A black platen 17 having a plurality of ribs is mounted on the bottom surface of the rectangular support 16. The print head 10 performs a printing operation on the paper inside the rectangular holder 16 while the paper is moved on the black platen 17.

The print head 10 is provided with four sets of ink jetting nozzles 10a-10d, which are directed downwards. Four colors of ink (black, cyan, yellow, and magenta) are ejected downward onto the paper sheet through these sets of ink ejection nozzles 10a to 10 d. Since the four groups of ink jetting nozzles 10a-10d are placed on the bottom side of the print head 10, their positions are indicated by broken lines in fig. 2.

Ink cartridges 21a to 21d of four color inks are mounted on the cartridge holder 20 on the front side of the rectangular holder 16. The ink cartridges 21a to 21d are connected to the print head 10 through four ink hoses 22a to 22d, and these ink hoses 22a to 22d pass through the rectangular holder 16 to supply each of the four colors of ink to the print head 10.

A left Flexible Printed Circuit (FPC)23 and a right Flexible Printed Circuit (FPC)24 are placed inside the rectangular support 16. The left FPC23 extends with the ink hoses 22a, 22b and connects with the printhead 10. The right FPC24 extends together with the ink hoses 22c, 22d and is connected to the printhead 10. The left FPC23 and the right FPC24 include a plurality of signal lines that electrically connect the printhead 10 to a control process unit 70 (shown in fig. 3) described later.

The guide mechanism 12 has a guide shaft 25 and a guide rail 26. The guide shaft 25 extends in the left-right direction at the rear of the rectangular support 16. The left and right ends of the guide shaft 25 are connected to the left and right plates 16c and 16d of the rectangular bracket 16, respectively. The guide rail 26 extends in the left-right direction in the front of the rectangular bracket 16. The rear end of the carriage 11 is fitted on the guide shaft 25 so as to be slidable along the guide shaft, while the front end of the carriage 11 is fitted on the guide rail 26 and is slidable along the guide rail.

The carriage moving mechanism 13 includes a carriage motor 30, a driving pulley 31, a follower pulley 32, and a belt 33. The carriage motor 30 is mounted on the right end of the rear side of the rear plate 16a of the rectangular bracket 16 with the motor facing forward. The driving pulley 31 is rotatably supported at the right end of the rear plate 16a, and is driven to rotate by the carriage motor 30. The follower pulley 32 is rotatably supported at the left end of the rear plate 16 a. A belt 33 is looped around the pulleys 31 and 32 and fixed to the bracket 11. The carriage conveyance encoder 39 is disposed in the vicinity of the carriage motor 30 to detect the movement (position) of the carriage 11 (print head 10).

The sheet conveying mechanism 14 includes a sheet conveying motor 40, registration rollers 41, a drive pulley 42, a follower pulley 43, and a belt 44. The sheet conveying motor 40 is mounted leftward on a portion of the left plate 16c, which protrudes rearward to a position beyond the rear plate 16 a. The registration rollers 41 extend in the right and left direction in the rectangular support 16 below the guide shaft 25. The left and right ends of the registration roller 41 are rotatably supported on the left and right plates 16c and 16d, respectively. The sheet conveying motor 40 drives the driving pulley 42 to rotate. The follower pulley 43 is connected to the left end of the registration roller 41. A belt 44 is looped around pulleys 42 and 43. When the paper conveying motor 40 is driven, the registration rollers 41 rotate and convey the paper on the platen 17 in the front-rear direction. Although the registration rollers 41 are emphasized in fig. 2, the registration rollers 41 are actually placed below the guide shaft 25.

The sheet conveying mechanism 14 further includes a sheet discharging roller 45, a follower pulley 46, a follower pulley 47, and a belt 48. The sheet discharge rollers 45 extend in the left-right direction at the front of the rectangular bracket 16. Left and right ends of the discharge rollers 45 are rotatably supported on the left and right plates 16c and 16d, respectively. The follower pulley 46 is integrally provided with the follower pulley 43. A follower pulley 47 is attached to the left end of the sheet discharge roller 45. A belt 48 is looped around pulleys 46 and 47. When the sheet conveying motor 40 is driven, the sheet discharging roller 45 rotates and discharges the sheet to the sheet discharging tray 5 in front of the multifunction apparatus 1.

The encoder disk 51 is fixed to the follower pulley 43. A photo-interrupter 52 having a light emitting unit and a light receiving unit is mounted on the left plate 16c such that the encoder disk 51 is placed between the light emitting unit and the light receiving unit. The encoder tray 51 and the photo interrupter 52 together constitute the sheet transport encoder 50. The control process unit 70, which will be described below, controls the driving of the sheet conveying motor 40 in accordance with a detection signal from the sheet conveying encoder 50 (more specifically, from the photo-interrupter 52).

The maintenance mechanism 15 includes a wiper 15a, two caps 15b, and a drive motor 15 c. The wiper 15a wipes the surface of the print head 10. Each cap 15b may seal two sets of the ink jetting nozzles 10a-10 d. The driving motor 15c drives the wiper 15a and the cap 15 b. The wiper 15a, the cap 15b, and the drive motor 15c are mounted on the mounting plate 15 d. The mounting plate 15d is fixed to the right of the bottom plate lower surface side of the rectangular bracket 16. Since the cap 15b is placed on the bottom side of the print head 10, the position of the cap 15b on the opposite side in fig. 2 is shown by the dotted lines.

As shown in fig. 2, a media sensor 68 is provided at the left end of the print head 10 as a downstream sensor for detecting the leading edge, the trailing edge, and the edge in the width direction of the sheet. The media sensor 68 is a reflection type optical sensor, as shown in fig. 4, which includes a light emitting element 82 (light emitting diode) and a light receiving unit 83 (photo transistor), wherein the light emitting element 82 has a light emitting portion 82a, and the light receiving unit 83 has a light receiving portion 83 a. The media sensor 68 is mounted downward on the sensor mounting unit 10e, and the sensor mounting unit 10e protrudes toward the left side of the print head 10. When the carriage 11 moves in the carriage moving direction, the media sensor 68 moves in the carriage moving direction. When the media sensor 68 is positioned above the area within the sheet P, the media sensor 68 is facing the sheet P. When the media sensor 68 is positioned above the outer area of the paper P, the media sensor 68 faces the platen 17.

In addition, a registration sensor 69 (see fig. 3) is disposed upstream (behind) the media sensor 68 in the sheet conveying direction, and serves as an upstream sensor for detecting the presence of the sheet and the leading and trailing edges of the sheet. More specifically, the registration sensor 69 is mounted in a front end of a top cover (not shown) that is provided in the paper supply unit 2 and forms a conveyance path in the paper supply unit 2.

The alignment sensor 69 may be configured as a mechanical sensor having a detector, a photo-interrupter and a torsion spring. The feeler projects into the sheet transport path and rotates when in contact with the sheet. The photo interrupter includes a light emitting unit and a light receiving unit that detect rotation of the detector. The torsion spring urges the feeler into the sheet transport path. The guard portion is integrally formed on the detector. When the detector rotates due to contact with the sheet, the protective portion becomes located in an area outside an area between the light emitting unit and the light receiving unit of the photointerrupter. Therefore, when light is transmitted from the light emitting unit to the light receiving unit, the alignment sensor 69 is in an on state. Since the torsion spring urges the feeler into the sheet conveying path when the sheet is not conveyed, the protection portion is now located between the light emitting unit and the light receiving unit of the photointerrupter. Therefore, the protection portion interrupts the transmission of light from the light emitting unit to the light receiving unit, placing the alignment sensor 69 in an off state.

The control process element 70 will be described in detail below. FIG. 3 is a block diagram showing the electrical configuration of the control process unit 70.

As shown in FIG. 3, the control process unit 70 includes a microprocessor having a CPU71, ROM72, RAM73 and EEPROM 74. The registration sensor 69, the media sensor 68, the sheet feed encoder 50, the operation panel 6, and the carriage feed encoder 39 are electrically connected to the control process unit 70.

The control process unit 70 is also electrically connected to the drive circuits 76a-76c and the printhead drive circuit 76 d. The drive circuits 76a to 76c drive the sheet feed motor 65, the sheet transport motor 40, and the carriage motor 30, respectively. The print driving circuit 76d drives the print head 10. The control process unit 70 may also be connected to a personal computer 77.

Based on the result of the detection of the paper P by the media sensor 68, the control process unit 70 outputs a carriage control command signal to the carriage moving mechanism 13 so as to move the relative position of the carriage 11 with respect to the paper P to a position close to a target relative position determined according to the content to be printed. In order to reciprocally move the carriage 11 along the guide shaft 25, the carriage moving mechanism 13 drives the carriage motor 30 in accordance with the received carriage control command signal so that the relative position of the carriage 11 with respect to the sheet P approaches the target relative position.

The structure of the media sensor 68 will be described in more detail below. Fig. 4 is an explanatory view showing a cross-sectional structure of the media sensor 68 mounted on the print head 10 (carriage 11). The media sensor 68 shown in fig. 4 corresponds to a view obtained by viewing from the rear side of the printer 3.

As shown in fig. 4, the media sensor 68 includes: a main sensor unit 80 and a cover 85. The main sensor unit 80 has a cylindrical shape and has a light emitting element 82, a light receiving element 83, and a filling material 81. The cover 85 is cylindrical in shape and can accommodate the main sensor unit 80. The main sensor unit 80 is mounted inside the cover 85. The cover 85 has a bottom wall portion 85 a.

The light emitting element 82 is substantially cylindrical and has a central axis 82c, the outer diameter of which is 2.2 mm. The light emitting element 82 has a hemispherical shaft end (bottom end in fig. 4). The light emitting element 82 has an emitting portion 82a at the hemispherical bottom end. The emitting portion 82a is located substantially on the central axis 82 c. The light emitting element 82 has a low directivity, that is, the emitting portion 82a emits the probe light in a wide angle. (the angle of emission corresponds to directivity). The emitting portion 82a emits the probe light downward at a wide emission angle, i.e., toward the platen 17. The light emitted from the emitting portion 82a thus travels toward the platen 17 in the direction along the center axis 82c while being dispersed by the amount of the emission angle. When the sheet P is positioned below the media sensor 68 and above the platen 17, the emitting portion 82a emits detection light toward the sheet P at a wide emission angle. The light emitted from the emitting portion 82a travels toward the paper P in the direction along the central axis 82c while being dispersed by the amount of the emission angle.

The light receiving element 83 is substantially cylindrical and has a central axis 83c, the outer diameter of which is 2.2 mm. The light receiving element 83 has a hemispherical shaft end (bottom end in fig. 4). The light receiving element 83 has a light receiving portion 83a at the hemispherical bottom end. The light receiving portion 83a is located substantially on the central axis 83 c. The light receiving element 83 has a low directivity, that is, the light receiving portion 83a receives light in a wide angle. (the light receiving angle corresponds to the directivity). The light receiving portion 83a receives external light within a wide light receiving angle. When no sheet P is positioned under the media sensor 68, the light receiving portion 83a receives light reflected from the platen 17, traveling in a direction within a light receiving angle of the light receiving element 83 with the central axis 83c as an axis, and reaching the light receiving portion 83 a. When the sheet P is positioned under the media sensor 68, the light receiving portion 83a receives the light reflected from the sheet P, traveling in a direction within the light receiving angle of the light receiving element 83 with the central axis 83c as the axis, and reaching the light receiving portion 83 a.

The light emitting element 82 and the light receiving element 83 are disposed such that their central axes 82c and 83c are substantially parallel to each other and substantially perpendicular or orthogonal to the upper surface (detection surface) of the platen 17. When the sheet P is placed on the platen 17, the central axis 82c and the central axis 83c are substantially perpendicular or orthogonal to the upper surface (detection surface) of the sheet P.

In this example, the filling material 81 is made of a resin having a light shielding property, and has an end face 81a at its bottom. The filling material 81 may be made of, for example, a colored resin. The filling material 81 supports the light emitting element 82 and the light receiving element 83, and the centers of the emitting portion 82a and the light receiving portion 83a are exposed on the end surface 81 a. The transmitting portion 82a and the light receiving portion 83a are placed in the cover 85 with their centers on the end face 81a with a gap of 2.8mm therebetween.

As described above, the cover 85 has the bottom wall portion 85 a. In addition, a common hole 85b is formed through the bottom wall portion 85a to allow the probe light and the reflected light to pass therethrough. The bottom wall portion 85a is formed to reduce an overlapping area, which refers to two areas, i.e., an area on the platen 17 (or the sheet P) to which the probe light emitted from the light emitting portion 82a is irradiated, and an area on the platen 17 (or the sheet P) from which the reflected light is received by the light receiving portion 83a, and the overlapping area refers to an overlapping between the two areas. The common hole 85b is circular and the inner diameter Xc is 3.0 mm. The thickness Xd of the bottom wall portion 85a is 1.0 mm. An internal gap Xa between the inner surface of the bottom wall portion 85a and the end surface 81a (the light emitting portion 82a and the light receiving portion 83a) of the filling material 81 is set to 5.0 mm. In other words, the gap between the inner surface of the bottom wall portion 85a and the light emitting portion 82a and the gap between the inner surface of the bottom wall portion 85a and the light receiving portion 83a are equal to each other and are set to 5.0 mm.

The media sensor 68 is mounted on the sensor mounting assembly 10e of the printhead 10. An outer gap Xb from the outer surface of the bottom wall portion 85a to an imaginary plane on which the platen 17 and the sheet P are located is 5 mm. The media sensor 68 is mounted on the sensor mount assembly 10e such that the common hole 85b is aligned with an imaginary line 85c that is perpendicular or orthogonal to the surface of the platen 17 (the surface of the paper P) and extends from substantially the center of a line segment L0, the line segment L0 connecting the center of the emitting portion 82a and the center of the light receiving portion 83 a.

The size of the target detection zone, which means that an object in this zone can be detected by the media sensor 68, is described below with reference to fig. 5(a) and 5 (b). The description will show that the size of the target detection region is different in the case where the main sensor unit 80 is combined with the cover 85 to constitute the medium sensor 68 and in the case where the cover 85 does not cover the main sensor unit 80.

Fig. 5(a) is an explanatory view showing the target detection region S1 of the media sensor 68 (the main sensor unit 80 is combined with the cover 85). Fig. 5(b) is an explanatory view showing the object detection region S2 of the main sensor unit 80 itself.

As shown in fig. 5(b), when only the main sensor unit 80 itself exists, the target detection region S2 is a region defined by an overlapping portion of two regions, an irradiation region S2a and a light receiving region S2b, wherein the irradiation region S2a is a region to which the detection light of the light emitting element 82 is irradiated, and the light receiving region S2b means that the light reflected from this region can be received by the light receiving element 83. The irradiation region S2a is determined in accordance with the directivity (emission angle) of the light-emitting element 82, and the light-receiving region S2b is determined in accordance with the directivity (light-receiving angle) of the light-receiving element 83. The target detection region S2, the irradiation region S2a, and the light receiving region S2b are all defined on an imaginary plane on which the sheet P or the platen 17 is located.

As shown in fig. 5(a), the object detection region S1 is a region defined by an overlapping portion of two regions, an irradiation region S1a and a light receiving region S1b, wherein the irradiation region S1a is a region irradiated with the detection light of the light emitting element 82 and limited by the common hole 85b, and the light receiving region S1b is a region from which the light modulated by the common hole 85b reflected can be received by the light receiving element 83. The target detection region S1, the irradiation region S1a, and the light receiving region S1b are all defined on an imaginary plane on which the sheet P or the platen 17 is located.

Since the medium sensor 68 is provided with the cover 85 covering the emitting portion 82a and the light receiving portion 83a, both the angular region of the light emitted from the light emitting element 82 and the angular region of the light that the light receiving element 82 can receive are restricted. Thus, the target detection region S1 of the media sensor 68 is smaller than the target detection region S2 of the main sensor unit 80.

If the desired detection area (ideal detection area) is small, the larger the target detection area of the sensor, the more susceptible the sensor is to interference outside the ideal detection area, and therefore, larger detection errors and smaller detection accuracy may result. In detecting the edge of the paper P, the ideal detection area is a boundary line between the paper P and the area outside the paper P (black platen 17), which is a very small area.

As shown in fig. 5(a) and 5(b), the media sensor 68 may narrow the object detection region S1 to a smaller region than the object detection region S2 of the main sensor unit 80 itself. Therefore, the media sensor 68 can prevent a decrease in detection accuracy when applied to detecting the edge of the paper P.

In addition, the media sensor 68 is mounted on the sensor mounting unit 10e on the print head 10, which aligns the light emitting element 82 and the light receiving element 83 with the scanning direction of the carriage 11 (the moving direction of the carriage 11).

Next, the shape of the object detection region S1 is described in more detail with reference to fig. 6(a) -6 (c).

Fig. 6(a) shows the target detection region S1 of the media sensor 68, and the irradiation region S1a of the probe light emitted by the light-emitting element 82 and the light-receiving region S1b of the light-receiving element 83. The light emitting element 82 and the light receiving element 83 are aligned with the first scanning direction in fig. 6 (a). The object detection region S1 is substantially elliptical, having a dimension (width) Lw in the direction in which the light emitting element 82 is aligned with the light receiving element 83 (the left-right direction in the drawing), and another dimension (length) Lh in another direction perpendicular to this direction (the up-down direction in the drawing), the light emitting element 82 being aligned with the light receiving element 83 in the up-down direction. The width Lw is shorter than the length Lh. In other words, the object detection region S1 has a width Lw in the first scanning direction and a length Lh in the second scanning direction perpendicular to the first scanning direction.

Fig. 6(b) shows a sensor output (output of the light receiving element 83) waveform (first sensor output waveform) for detecting the edge of the sheet P when the media sensor 68 is moved in the first scanning direction (fig. 6(a)) in which the light emitting element 82 and the light receiving element 83 are placed. Fig. 6(c) shows a sensor output (output of the light receiving element 83) waveform (second sensor output waveform) for detecting the edge of the sheet P when the media sensor 68 is moved in a second scanning direction (fig. 6(a)) which is perpendicular to the first scanning direction in which the light emitting element 82 and the light receiving element 83 are disposed. In fig. 6(b) and 6(c), the vertical axis shows the sensor output value (voltage), and the horizontal axis shows the amount of movement of the media sensor 68.

The media sensor 68 has a feature that the output value (voltage) of the sensor becomes large when the color of the object in the target detection region S1 approaches white, and the output value becomes small when the color of the object approaches black. Therefore, when the paper P is located in the target detection region S1, the output of the media sensor 68 is switched to the high level, and when the paper P is not in the target detection region S1 and the black platen 17 is located in the target detection region S1, the output of the media sensor 68 is switched to the low level. In other words, the output of the media sensor 68 is switched to a high level when the paper P is detected, and is switched to a low level when the black platen 17 is detected instead of the paper P. However, when both the paper P and the black platen 17 are present in the object detection region S1, the sensor output value changes according to the proportion of the region occupied by each portion.

As the width of the interval (distance) in which the sensor output changes between the low level and the high level increases, the response of the sensor becomes slow and the error of the paper edge detection increases.

As shown in fig. 6(b) and 6(c), the output variation interval W1 of the first sensor output waveform is smaller than the output variation interval W2 of the second sensor output waveform. Therefore, when the edge of the paper P is detected by the media sensor 68, the detection error can be reduced by moving the media sensor 68 in the first scanning direction in which the light emitting element 82 and the light receiving element 83 are aligned, instead of in the second scanning direction.

In the preferred embodiment, to detect the left and right edges of the sheet P, the light emitting element 82 and the light receiving element 83 of the media sensor 68 are aligned along the scanning direction of the carriage 11. That is, the light emitting element 82 and the light receiving element 83 are aligned in the carriage scanning direction (first scanning direction in fig. 6(a)), and scanned in the carriage scanning direction (first scanning direction in fig. 6 (a)). As shown in fig. 6(b), this arrangement reduces the detection error by reducing the width of the output variation interval.

It should be noted that if the media sensor 68 has the light emitting element 82 and the light receiving element 83 arranged in the first scanning direction (carriage moving direction), and the leading edge and the trailing edge of the sheet P conveyed in the second scanning direction are detected by the media sensor 68, the width of the output change interval increases as shown in fig. 6(c), and thus the detection error increases. Thus, if it is necessary to detect the leading edge and the trailing edge of the sheet P with high accuracy with the media sensor 68, the light emitting element 82 and the light receiving element 83 should be aligned in the sheet conveying direction (second scanning direction) as shown in fig. 6 (d).

The inventors measured the sensor output during the process of changing the inner diameter Xc (fig. 4) of the common hole 85 b. These measurement results are described using a waveform diagram shown in fig. 7. In fig. 7, the horizontal axis represents the amount of movement (mm) of the media sensor 68, and the vertical axis represents the sensor output (V).

Measurements were performed with 6 kinds of caps 85 having different inner diameters Xc, which are respectively: 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm and 5.0 mm. It should be noted that each outer diameter of the light emitting element 82 and the light receiving element 83 is set to 2.2 mm; the distance from the center of the light emitting portion to the center of the light receiving portion was 2.8 mm; the thickness Xd of the wall portion 85d is 1.0 mm; the distances Xa from the light emitting portion 82 and the light receiving portion 83 to the wall portion 85a are both 5.0 mm; the distance Xb from the wall portion 85a to the paper P and to the platen 17 is 5.0 mm. The inventors placed the media sensor 68 in an area outside the sheet P and moved it 52.8mm away from the edge of the sheet P. The inventors then moved the media sensor 68 from an area outside the paper P (black platen 17) toward the paper P while recording the sensor output, thereby performing measurement. It should be noted that the light emitting element 82 and the light receiving element 83 are aligned in the moving direction of the media sensor 68. In fig. 7, the position indicated by the arrow and moved by 52.8mm is the actual position of the edge of the sheet P.

According to the waveform of the measurement value shown in fig. 7, as the inner diameter Xc increases, the interval width at which the sensor output changes from a high level to a low level increases. As described above, as the output variation interval width increases, the sensor response becomes slow, and the error of the paper edge detection increases. Therefore, the inner diameter Xc having a small value is preferable. For example, by setting the inner diameter Xc to 3.5mm or less, the output variation interval can be limited to 2mm or less. At this level, the detection error has been reduced enough to avoid problems in using the printer 3, thus preventing a drop in detection accuracy.

On the other hand, if the inner diameter Xc is set smaller, the difference between the sensor output at the high level and the low level becomes smaller. Therefore, if the inner diameter Xc is set too small, a change in sensor output cannot be detected. The inner diameter Xc is set large enough to distinguish between a high level and a low level of the sensor output.

For example, if the inner diameter Xc is set to 2.5mm or more, the difference between the sensor output at the high level and the low level may reach 0.5V or more, so that the change in the sensor output level can be easily detected. In this way, a sufficiently large variation in sensor output can be achieved, which does not cause a problem when the printer 3 is used, thereby preventing a decrease in detection accuracy.

From these measurement results, if the common hole 85b is made to have the inner diameter Xc between 2.5mm and 3.5mm, the media sensor 68 will have sufficient detection accuracy. Since the inner diameter Xc is set to 3.0mm in the preferred embodiment, the media sensor 68 has sufficient detection accuracy, and the printer 3 can accurately detect the edge of the paper P.

The measurement results confirmed that by setting the inner diameter Xc between 2.5mm and 3.5mm, the variation region of the sensor output signal (voltage) in the boundary region between the paper P and the region other than the paper P, which is the region between the paper P and the region other than the paper P, can be reduced, while the difference (high level and low level) in the sensor output signal level between the paper P and the region other than the paper P can be set large enough so that the two levels can be distinguished. It should be noted that the region where the sensor output signal changes is the output change interval between the sensor output at the low level and the high level. By reducing the region in which the sensor output signal changes, the sheet P can be distinguished from the region outside the sheet P in smaller units of measurement, thereby realizing a high-performance sensor having the smallest detectable unit of measurement. Since the difference in the sensor output signal level between the paper P and the area other than the paper P is set sufficiently large to be distinguishable, the paper P can be easily distinguished, so that the present embodiment can prevent the detection accuracy from being degraded. Therefore, such a reflection type optical sensor 68 can reduce the minimum detectable unit of measurement, and can achieve high performance of avoiding a decline in detection accuracy.

As described above, the media sensor 68 provided in the multifunction apparatus 1 (more specifically, the printer 3) of the preferred embodiment includes the cover 85 having the common hole 85 b. The cover 85 can restrict the angular range in which light is emitted from the light emitting element 82 and the angular range in which the light receiving element 83 can receive light, and can suppress the influence of external disturbance. Therefore, even if less expensive elements having lower directivity are used as the light emitting element 82 and the light receiving element 83, it is possible to prevent a decrease in detection accuracy when applied to a detection device having a narrow ideal detection region. In addition, since the bottom wall portion 85a is designed to reduce the overlapping area of the sheet P, which is the overlapping area of the irradiation area of the detection light and an area from which the light reflected from the area can be received by the light receiving element 83, the change in the amount of reflected light in the target detection area can be detected satisfactorily. Since the light emitting element and the light receiving element having lower directivity are less expensive than those having higher directivity, the reflective optical sensor 68 of the present embodiment can be manufactured at a lower cost than those provided with elements having higher directivity.

In the media sensor 68 of the preferred embodiment, the light emitting element 82 and the light receiving element 83 are disposed with their central axes 82c and 83c extending parallel to each other and with their directions perpendicular to the surface (detection surface) of the paper P, and with their directions not inclined with respect to the paper P (detection object). This structure reduces the amount of change in the angle of reflected light due to the change in the angle of probe light projected onto the sheet P, as compared with a sensor in which the elements are placed at a position inclined with respect to the sheet P. Therefore, the present embodiment suppresses a decrease in detection accuracy due to an angle error, which is an angle error in which the light emitting element and the light receiving element are placed and an angle error in which the medium sensor 68 is placed.

By having their central axes 82c, 83c extend parallel to each other when placing the light-emitting element 82 and the light-receiving element 83, the area of the media sensor 68 where the elements 82 and 83 are placed can be smaller than when placing the elements obliquely.

Therefore, the media sensor 68 of the present embodiment can prevent a decrease in detection accuracy due to a positioning angle error and can keep the cost low. The media sensor 68 can also prevent a decrease in detection accuracy due to external disturbance and can be manufactured in a smaller size.

In addition, by projecting the central axes 82c, 83c of the light emitting element 82 and the light receiving element 83 in parallel with each other when placing these elements, the optical path distance of the detection light and the reflected light can be made shorter than when placing these elements obliquely, thus shortening the degree of attenuation of the reflected light on the propagation optical path before reaching the light receiving element 83. Therefore, even the light receiving element 83 having a lower directivity can satisfactorily receive the reflected light while preventing a decrease in accuracy in detecting the sheet P.

In constructing the media sensor 68, the light-emitting element 82 and the light-receiving element 83 are disposed such that the distance from the emitting portion 82a to the common hole 85b is substantially equal to the distance from the light-receiving portion 83a to the common hole 85 b. This structure prevents the light emitting element 82 and the light receiving element 83 from interrupting the optical paths of the detection light and the reflected light. If the distance from the emitting portion 82a to the common hole 85b is different from the distance from the light receiving portion 83a to the common hole 85b, the light receiving element 83 placed on the propagation path of the probe light interrupts the optical path of the probe light, or the light emitting element 82 placed on the propagation path of the reflected light interrupts the optical path of the reflected light. In contrast, according to the present embodiment, if the distance from the emitting portion 82a to the common hole 85b is substantially equal to the distance from the light receiving portion 83a to the common hole 85b, the light receiving element 83 is not located at a position to interrupt the optical path of the detection light, and the light emitting element 82 is not located at a position to interrupt the optical path of the reflected light, because the light emitting element 82 and the light receiving element 83 are juxtaposed. Therefore, the media sensor 68 enables the light receiving element 83 to continuously receive the reflected light, thereby preventing a decrease in detection accuracy.

The media sensor 68 is also configured such that the center of the common hole 85b is positioned along an imaginary line 85c, wherein the imaginary line 85c extends in a direction perpendicular to the surface of the sheet P and extends from near the center of a line segment L0, which line segment L0 connects the emitting portion 82a and the light receiving portion 83 a.

Therefore, the shortest optical path from the light-emitting element 82 to the light-receiving element 83 through the paper P (in other words, the shortest of the propagation optical paths of all the detection light and the reflected light) falls in the target detection region S1. When the propagation optical path is the shortest, the attenuation of the detection light and the reflected light can be reduced, thereby suppressing a decrease in the amount of reflected light received by the light receiving element 83.

To detect the position of the sheet P (or rather the edge of the sheet P), the carriage 11 can be moved along a guide shaft 25 above the sheet P. The carriage 11 includes a media sensor 68 on the print head 10 that detects the sheet P. As described above, the media sensor 68 is a small, inexpensive sensor having excellent detection accuracy. Therefore, by detecting the position of the paper P with the media sensor 68, the carriage 11 can suppress adverse effects such as a placement angle error of the media sensor 68, and can improve the accuracy of detecting the position of the paper P. The cost of the carriage 11 may also be reduced since the media sensor 68 is less expensive to manufacture. In addition, since the media sensor 68 is compact, the overall size of the carriage 11 can be made smaller. Therefore, the carriage 11 can detect the position of the sheet P with good accuracy and can be made small at low cost, thereby enabling the carriage 11 to have a wide range of applications.

The printer 3 in the preferred embodiment is a printing apparatus that prints characters and images on a sheet of paper P. During printing, the carriage moving mechanism 13 receives commands from the control process unit 70 and moves the carriage 11 and the print head 10 in accordance with these commands while the paper conveying mechanism 14 conveys the paper P, the received commands depending on the detection results of the media sensor 68 when detecting the edge of the paper P.

As described above, the media sensor 68 suppresses adverse effects such as a placement angle error of the media sensor 68 and external disturbance, thereby providing accuracy in detecting the edge of the paper P. Therefore, the printer 3 can determine the position of the print head 10 with respect to the paper P with improved accuracy from the detection result of the media sensor 68, and thus can accurately determine the position at which the printing operation is performed on the paper P. In addition, since the media sensor 68 can be made compact at a low cost, the overall cost and size of the printer 3 can be reduced.

The printer 3 can perform a printing operation on the paper P with high accuracy and can reduce the cost and size of the printer 3, thus obtaining a data processing apparatus that can be applied to a wide range of fields.

The media sensor 68 is placed in the printer 3 such that an external gap Xb from the common hole 85b (to be exact, the outer surface of the bottom wall portion 85 a) to the paper P is substantially equal to an internal gap Xa from the emitting portion 82a and the light receiving portion 83a to the common hole 85b (to be exact, the inner surface of the bottom wall portion 85 a). This makes it possible to set the angle at which the detection light and the reflected light can travel to an appropriate range, and to set the target detection area S1 of the media sensor 68 to an appropriate size. In contrast, if the distance from the common hole 85b to the sheet P is far greater or smaller than the distance from the emitting portion 82a and the light receiving portion 83a to the common hole 85b, the angle at which the detection light and the reflected light can travel is set to an inappropriate range, which makes the target detection area S1 too small or too large.

Since the target detection area S1 can be set to an appropriate size, the printer 3 can improve the accuracy of detecting the paper P and can improve the accuracy of performing the data control process on the paper P.

Since the media sensor 68 is disposed in the printer 3 such that the light-emitting element 82 and the light-receiving element 83 are aligned in the direction in which the carriage 11 reciprocates, the portion of the object detection region S1 through which the sheet P passes is shortened, thereby reducing the effective object detection region S1 (the width in the detection direction). Therefore, the printer 3 can suppress the consequences caused by the disturbance and reduce the detection error. In this embodiment, since the direction in which the carriage 11 moves is the same as the width direction of the sheet P, the printer 3 can improve the accuracy of detecting both edges of the sheet P in the width direction.

As described above, according to the present embodiment, the media sensor 68 includes the cover 85 having the common hole 85b, and the common hole 85b can restrict the dispersion of the light beam emitted from the light emitting element 82 and also can restrict the range of light that can be received by the light receiving element 83, while also suppressing the consequences caused by disturbance. Therefore, the media sensor 68 can prevent a decrease in detection accuracy while using a low-directivity, relatively inexpensive element. Since the light-emitting element 82 and the light-receiving element 83 are oriented perpendicularly to the sheet P, the media sensor 68 is superior to a sensor equipped with elements placed at an angle to the sheet P because the media sensor 68 avoids a decrease in detection accuracy caused by errors including: the advantages of the sensor are that the space required for placing the elements in the sensor is reduced, thereby reducing the size of the sensor.

Improvements in or relating to

The above embodiment is for a case where it is intended to improve the accuracy of detecting the left and right edges of the paper P. However, if it is desired to improve the accuracy of detecting the leading edge of the sheet P more than the accuracy of detecting the left and right edges of the sheet P, the media sensor 68 is provided on the print head 10 such that the light emitting element 82 and the light receiving element 83 are aligned in a direction perpendicular to the moving direction of the carriage 11. In other words, the light emitting element 82 and the light receiving element 83 are aligned in the direction in which the sheet P is conveyed by the sheet conveying mechanism 14. In other words, the light emitting element 82 and the light receiving element 83 are aligned in the second scanning direction shown in fig. 6 (d). Therefore, the width Lw of the effective target detection region S1 of the media sensor 68 in the detection direction is smaller relative to the length Lh. The light emitting element 82 and the light receiving element 83 are thus arranged to reduce the size of the sheet P passing through the target detection region S1.

Therefore, the printer 3 can reduce the effective target detection area S1 of the media sensor 68 and suppress the consequences of the disturbance, thereby reducing the detection error. The carriage 11 moves in the same direction as the width direction of the sheet P. The accuracy of detecting the edges (leading edge and trailing edge) of the paper P at the length end can be improved.

In order to improve the accuracy of detecting both the left and right edges and the leading and trailing edges of the paper P, it is necessary to provide two media sensors 68 on the print head 10, each having a light emitting element and a light receiving element aligned in an appropriate direction to improve the accuracy of detecting each edge. That is, one of the two media sensors 68 is placed such that its light emitting element 82 and light receiving element 83 are aligned in the carriage moving direction (first scanning direction) perpendicular to the sheet conveying direction (second scanning direction) shown in fig. 6 (a). This improves the accuracy of detecting the left and right edges. The other media sensor 68 is disposed such that its light emitting element 82 and light receiving element 83 are aligned in the sheet conveying direction (second scanning direction) shown in fig. 6 (d). This improves the accuracy of detecting the leading and trailing edges.

In this case, the media sensor 68 can detect the leading edge of the sheet P and detect the left and right edges of the sheet P in the direction in which the sheet P is conveyed by the sheet conveying mechanism 14. By detecting the leading edge and the left and right edges of the paper P with the media sensor 68, the printer 3 can appropriately detect the size of the paper P. The printer 3 is also capable of correctly detecting the current position of the sheet P based on the leading edge position of the sheet P detected by the media sensor 68 and the amount by which the sheet P is conveyed by the sheet conveying mechanism 14. By correctly determining the size and position of the paper P, the printer 3 can accurately set the position on the paper P at which the printing operation is performed and can perform accurate printing on the paper P.

The media sensor is not limited to such a form that a single hole is formed on the bottom of the cover, and a cover having a plurality of holes may be provided.

Fig. 8 is an explanatory view showing a cross-sectional structure of the improved media sensor 68 (hereinafter referred to as a second media sensor 91). The second media sensor 91 is provided with a cover 93 having two holes (hereinafter referred to as a second cover 93).

The second media sensor 91 is the same as the media sensor 68 described in the above embodiment, except that the cover 85 is replaced with a second cover 93.

The second cover 93 is cylindrical and has a bottom wall portion 93 a. The second cover 93 can accommodate the main sensor unit 80. The main sensor unit 80 is mounted in the second housing 93. An emission hole 93b allowing passage of the detection light and a reception hole 93c allowing passage of the reflected light are formed through the bottom wall portion 93 a. The emitting hole 93b and the receiving hole 93c are both circular and their inner diameter Xg is 2.0 mm.

Since the light emitting element 82 has high directivity near the center of the element, the luminance near the center is high. Similarly, since the light receiving element 83 has a high directivity near the center of the element, the light receiving sensitivity near the center is also high. Therefore, the media sensor 91 having the second cover 93 in which the holes 93b, 93c having the inner diameter Xg of about 2.0mm are formed can obtain the same output as the media sensor 68 having the cover 85.

The second cover 93 is configured such that the thickness Xh of the bottom wall portion 93a is 1.0mm and the internal distance Xe from the inner surface of the bottom wall portion 93a to the end face 81a of the main sensor unit 80 (filler 81) is 5.0 mm.

The second media sensor 91 is mounted on the sensor mounting unit 10e such that the distance Xf from the outer surface of the bottom wall portion 93a to the outside of the platen 17 and the paper sheet P is 5.0 mm.

The emitting hole 93b is centered on an imaginary line 93bc which is perpendicular to the surface of the sheet P and extends from a point on the first line segment L1. The first line segment L1 extends from the center point of the emitting portion 82a to the center point of the line segment L0, and the line segment L0 connects the center of the emitting portion 82a and the center of the light receiving portion 83 a.

Similarly, the center of the receiving hole 93c is on another imaginary line 93cc which is perpendicular to the surface of the sheet P and extends from a certain point on the second line segment L2. The second line segment L2 extends from the center point of the light receiving portion 83a to the center point of the line segment L0.

Fig. 9 is an explanatory view illustrating the target detection region S3 of the second media sensor 91. The target detection region S3 is a region defined by an overlapping portion of two regions, the irradiation region S3a and the light receiving region S3b, wherein the irradiation region S3a is a region irradiated with the detection light of the light emitting element 82 and limited by the emission hole 93b, and the light receiving region S3b means that the light reflected from this region and adjusted by the receiving hole 93c can be received by the light receiving element 83. The target detection region S3, the irradiation region S3a, and the light receiving region S3b are all defined on an imaginary plane on which the sheet P and the platen 17 are located.

The second media sensor 91 is provided with holes 93b and 93c corresponding to the light emitting element 82 and the light receiving element 83, respectively. Changing the sizes of the holes 93b and 93c according to the application and measurement environment of the sensor 91 enables independent adjustment of the amount of detected light passing through the holes 93b and the amount of reflected light passing through the holes 93 c. Therefore, since the correct values can be independently set for the amount of detected light passing through the hole 93b and the amount of reflected light passing through the hole 93c, the second media sensor 91 can improve the detection accuracy.

Although the invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that many modifications and variations can be made without departing from the spirit of the invention, the scope of which is defined in the appended claims.

The application of the media sensor 68 is not limited to a printer, but may be applied to other data processing apparatuses such as a copying machine, a scanner, and a facsimile device. In these apparatuses, the detection accuracy of detecting the size of the original sheet being scanned can be improved. For example, a scanning mechanism that scans an original to obtain characters, curves, images, and the like from the original P is mounted on the carriage 11. The scanning mechanism moves together with the carriage 11 and performs a data acquisition process. Both the scanning mechanism and the print head may be mounted on the carriage 11.

In addition, the outer diameters of the light emitting element 82 and the light receiving element 83 are not limited to 2.2mm, and if they are set in the range between 2.0 and 2.4mm, the detection accuracy can still be improved.

In the above-described embodiment, the media sensor 68 is mounted on the print head 10, but the media sensor 68 may be directly mounted on the carriage 11.

In addition, the carriage 11 is not limited to be constructed so that it supports the printhead 10, and the printhead 10 and the carriage 11 may be integrally formed. Since the media sensor 68 has the cover 85, it prevents the light emitting element 82 and the light receiving element 83 from being contaminated by ink droplets or ink mist, thus preventing the detection accuracy from being lowered due to adhesion of ink droplets or the like. Further, the cover 85 can suppress a decrease in detection accuracy due to interference from light outside the sheet P.

In the above description, the light emitting element 82 and the light receiving element 83 are disposed such that the distance from the light emitting portion 82a to the wall portion 85a is substantially equal to the distance from the light receiving portion 83a to the wall portion 85 a. However, the distance from the light emitting portion 82a to the wall portion 85a may not be equal to the distance from the light receiving portion 83a to the wall portion 85 a. Thus, the distance from the hole 85b to the sheet P may be substantially equal to the distance from the light emitting portion 82a to the wall portion 85a or the distance from the light receiving portion 83a to the wall portion 85 a.

Claims

1. A reflective optical sensor for detecting an object, the sensor comprising:

a light emitting element having a central axis extending in a predetermined direction extending in a direction substantially orthogonal to a surface of the object to be detected, the light emitting element further having a light emitting portion that emits detection light toward the surface of the object, the detection light propagating toward the surface of the object defining an irradiation area on the object;

a light receiving element having a central axis parallel to the central axis of the light emitting element and having a light receiving portion which receives reflected light reflected from a detection region on the object, the detection region and an irradiation region overlapping at an overlapping region of the object surface, the irradiation region having a remaining irradiation region other than the overlapping region of the irradiation region, the detection region having a remaining detection region other than the overlapping region of the detection region; and

a restricting member having a restricting portion defining an aperture for allowing a portion of the detection light and a portion of the reflected light to pass therethrough, the restricting portion restricting a size of the aperture to reduce an area of an overlapping region on a surface of the object,

the illumination area corresponds to an area of the object projected by the probe light through the aperture,

the probe light reflected from the irradiation region has an overlapping light reflected from an overlapping region of the irradiation region and a remaining probe light reflected from a remaining irradiation region,

the light receiving portion receives the overlapping light reflected from the overlapping area through the hole, an

The restricting portion prevents the remaining detection light from reaching the light receiving portion.

2. The reflective optical sensor of claim 1, wherein the light emitting element has a light emitting end facing the object and located on a central axis of the light emitting element, the light emitting portion being located on the light emitting end and having a predetermined directivity defining an irradiation area on the object; and

wherein the light receiving element has a light receiving end facing the object and located on a central axis of the light receiving element, and the light receiving portion is located on the light receiving end and has another predetermined directivity defining a detection area on the object.

3. The reflective optical sensor of claim 1, wherein the light emitting element emits the probe light at an emission angle toward an irradiation area on the surface of the object,

the light receiving element receives reflected light from a detection area on the surface of the object at a light receiving angle, an

The limiting section reduces the amount of the emission angle and the light receiving angle.

4. The reflective optical sensor of claim 1, wherein the limiting member comprises a wall portion between the object and the light emitting and light receiving portions.

5. The reflective type optical sensor according to claim 1, wherein the restricting member comprises a cover member, the light emitting element and the light receiving element being mounted inside the cover member, the cover member having a wall portion between the object and the light emitting and light receiving portions, the wall portion being formed with at least one hole allowing a part of the detection light and a part of the reflection light to pass therethrough.

6. The reflective optical sensor of claim 4, wherein the light emitting element and the light receiving element are positioned such that a distance from the light emitting portion to the wall portion is substantially equal to a distance from the light receiving portion to the wall portion.

7. The reflective optical sensor of claim 4, wherein the wall portion is formed with a single aperture that allows a portion of the probe light and a portion of the reflected light to pass therethrough; and

the centers of the individual holes are located on a line extending from approximately the center of a line segment connecting the light emitting portion and the light receiving portion in a direction substantially orthogonal to the surface of the object.

8. The reflective optical sensor of claim 7, wherein the individual apertures are circular.

9. The reflective optical sensor of claim 8, wherein the light emitting element and the light receiving element are both approximately cylindrical in shape extending along respective central axes; the outer diameters of the light emitting element and the light receiving element are both in the range of 2.0 to 2.4 mm; the distance between the light emitting portion and the light receiving portion was 2.8 mm; the distance from the light emitting portion to the wall portion and the distance from the light receiving portion to the wall portion were both 5.0 mm; and the inner diameter of the individual holes is 2.5-3.5 mm.

10. The reflective optical sensor of claim 4, wherein the wall is formed with a plurality of apertures including an emission aperture for allowing a portion of the probe light to pass therethrough and a reception aperture for allowing a portion of the reflected light to pass therethrough;

the center of the emission hole is located on a line which is substantially orthogonal to the surface of the object and extends from a point on a first line segment defined between the light emitting portion and the center point of a second line segment connecting the light emitting portion and the light receiving portion, and

the center of the receiving hole is located on another line which is substantially orthogonal to the surface of the object and extends from a point on a third line segment which is defined between the light receiving section and the center point of the second line segment.

11. A carriage that moves over and detects an object, the carriage comprising:

a moving member which moves above the object; and

a detection unit disposed on the movable member and detecting the object to determine a position of the object, the detection unit including a reflective optical sensor, the reflective optical sensor including:

12. A data processing apparatus comprising:

a moving member which moves above the object;

a detecting unit which moves together with the moving member and detects the object, the detecting unit including a reflective optical sensor which detects an edge of the object, the reflective optical sensor including:

The restricting portion prevents the remaining detection light from reaching the light receiving portion,

a movement control unit which controls the moving member to move reciprocally;

an object moving unit that moves the object in a direction different from a direction in which the moving control unit controls the moving member to move; and

and a process executing unit which moves together with the moving member and executes a data control process based on the detection result obtained by the detecting unit, the data control process including at least one of a data adding process of adding data to the object and a data obtaining process of obtaining data from the object.

13. The data processing apparatus according to claim 12, wherein the restricting member includes a wall portion between the object and the light emitting portion and the light receiving portion.

14. The data processing apparatus according to claim 12, wherein the restricting member includes a cover member which encloses both the light emitting element and the light receiving element in its interior, and the cover member further has a wall portion which faces the object and is located between the object and the light emitting portion and the light receiving portion, the wall portion being formed with at least one hole which allows a part of the detection light and a part of the reflection light to pass therethrough.

15. The data processing apparatus according to claim 12, wherein the object is a recording medium; and

wherein the process execution unit includes a printing unit that prints various data on a recording medium.

16. The data processing apparatus according to claim 12, wherein a distance from the hole to the object is substantially equal to a distance from the light emitting portion to the wall portion and a distance from the light receiving portion to the wall portion.

17. The data processing apparatus of claim 12, wherein the detection unit detects a leading edge of the object, the leading edge being defined in a direction parallel to a moving direction of the object, the object moving unit moving the object in the moving direction of the object, the detection unit further detecting other edges of the object, the other edges being defined in another direction perpendicular to the moving direction of the object moving unit.

18. The data processing apparatus according to claim 12, wherein the detecting unit detects an edge of the object defined in a moving direction of the moving member, the moving member moving in the moving direction of the moving member; and

the light emitting element and the light receiving element are aligned in a moving direction of the moving member.

19. The data processing apparatus according to claim 12, wherein the detecting unit detects an edge of the object defined in a direction perpendicular to a moving direction of the moving member, the moving member moving in the moving direction of the moving member; and

the light emitting element and the light receiving element are aligned in a direction perpendicular to a moving direction of the moving member.

20. The reflective optical sensor of claim 1, further comprising:

a cover that holds the light emitting element, the light receiving element, and the restriction member, the light emitting element and the light receiving element being arranged along an arrangement direction; and

at least one of a carriage and a paper conveying mechanism for changing a relative position between the hood and the object in the arrangement direction.

21. The data processing apparatus according to claim 12, wherein the light emitting element and the light receiving element are aligned with a moving direction in which the moving member moves.

22. The data processing device of claim 12, wherein the light emitting element and the light receiving element are aligned with a direction in which the object moves.

23. The reflective optical sensor of claim 1, wherein the overlap region has one width in an alignment direction in which the light emitting element and the light receiving element are aligned, and the overlap region has another width in another direction orthogonal to the alignment direction, the one width being shorter than the other width.

24. The data processing device according to claim 12, wherein the overlapping region has one width in an alignment direction in which the light emitting element and the light receiving element are aligned, and the overlapping region has another width in another direction orthogonal to the alignment direction, the one width being shorter than the another width.

25. The data processing apparatus according to claim 12, further comprising a print head that ejects ink and is provided with the detection unit.