JP2003300334A - Optical detecting unit, ink tank and ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose an optical detecting unit capable of accurately and certainly detect the ink end of a foam type ink tank. <P>SOLUTION: A sub ink chamber 30 is formed between a main ink chamber and an ink taking out hole of the foam type ink tank 1. In the case the amount of the air entering thereto is increased, a prism reflection surface 61 of a prism 62, providing the ink interface, returns to the reflection surface so as to detect the ink end. The prism reflection surface 61 has a reflection surface shape capable of scanning an optical sensor 80 on the ink jet printer side in the arrow direction A for executing a detecting operation at three detection points 80(1)-80(3). Thereby, even in the case bubbles B adhere or flow on the rear surface part of any of first reflection parts 110(1)-110(3), and second reflection parts 120(1)-120(3), which define a detection point, so as to hinder the function as the reflection surface, the ink end can be detected certainly at another detection point. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical detection device using a prism configured to detect light emitted from a light emitting element and reflected by a prism reflecting surface by a light receiving element. The present invention also relates to an optical detection device for an ink tank, which uses such an optical detection device to detect whether or not the ink tank is attached to an inkjet printer or the like, and to detect the ink end of the ink tank. Furthermore, the present invention relates to an inkjet printer using such an ink tank as an ink supply source.

[0002]

2. Description of the Related Art A cartridge type ink tank is generally adopted as an ink supply source for an ink jet printer. When a cartridge type ink tank is used, it is necessary to have a detection mechanism for detecting whether or not the ink tank is mounted in the tank mounting portion of the inkjet printer and for detecting the ink end of the mounted ink tank.

As such a detection mechanism, an optical detection mechanism using a prism is known. As shown in FIG. 11B, an optical detection mechanism using a prism generally includes a detected portion 200 having a pair of orthogonal prism reflection surfaces 201 and 202, a light emitting element 211 and a light receiving element 212. And a detection unit 210. The detection unit 21 is provided at a position near the tank mounting unit of the inkjet printer
If 0 is arranged and prism reflection surfaces 201 and 202 are arranged on the side surface of the ink tank or the like, when the ink tank is mounted, the light L emitted from the light emitting element 211 of the detection unit 210 is a pair of prisms. An optical path that is reflected by the reflecting surfaces 201 and 202 and returns to the light receiving element 212 is formed, and the optical path is blocked when the ink tank is not attached. Therefore, whether or not the ink tank is attached can be detected based on the amount of light received by the light receiving element 212.

An optical detection mechanism using a prism is also applied to ink end detection. In this case,
The back surface of the pair of prism reflection surfaces placed in the ink tank is set as an ink interface, and when ink runs out and the back surface of the prism reflection surface is exposed from the ink liquid surface and becomes an air interface, the prism reflection surface returns to its original reflection surface. The optical characteristics are used to detect the ink end of the ink tank.

An optical detection mechanism using such a prism is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-323993 and US Pat. No. 5,616,929.

[0006]

In the optical detecting mechanism using the prism, the light emitting element and the light receiving element of the detecting section are arranged at a constant interval. Therefore, the optical path in which the light emitted from the light emitting element is reflected by the pair of prism reflection surfaces orthogonal to each other and returns to the light receiving element is formed only when the detecting portion and the detected portion have a specific relative positional relationship. . That is, as shown in FIG. 11B, it is formed only when the optical axis centerlines 213 of the light emitting element 211 and the light receiving element 212 coincide with the centerlines of the pair of prism reflecting surfaces 201 and 202. In other relative positional relationships, the optical path of the return light Lr to the light receiving element 212 is not formed,
No detection can be done.

Since there is only one detection position as described above, when detecting the presence or absence of the ink tank, for example, the detection unit fixed to the ink jet printer side is attached to the installed ink tank side. Even if the position of the prism reflection surface located in the position is slightly displaced, the amount of light received by the light receiving element decreases, and there is a risk of erroneous detection that the ink tank is not installed even though it is installed. There is.

Here, in an ink jet printer of the type in which an ink jet head is reciprocally moved in the print width direction by a head carriage, if a detection unit is mounted on the head carriage, the detection unit will have a prism reflection surface in the moving direction of the head carriage. Since the scanning is performed, there is no problem even if the prism reflection surface is slightly displaced in the head carriage movement direction. However, if foreign matter, ink, or the like adheres to and is contaminated at the reflection position of the prism reflection surface where the optical path of the return light is formed, erroneous detection may occur.

Next, when the optical detection mechanism using the prism is used to detect the ink end in the foam type ink tank, there are the following problems.

The foam type ink tank includes a foam storage portion for storing a foam that absorbs and holds ink, and an ink outlet hole communicating with the foam storage portion.
And a vent for opening the foam storage portion to the atmosphere. When the ink is sucked from the ink take-out hole by the ejection pressure of the ink jet head, the air corresponding to the sucked ink amount flows into the foam storage portion from the vent hole. The present applicant has proposed the following configuration as an ink end detection mechanism of a foam type ink tank. A small volume ink chamber is formed between the foam storage section and the ink outlet so that the back surface of the prism reflection surface becomes the ink interface, and when the ink chamber is full of ink, the prism reflection surface functions as a reflection surface. When the ink does not work and the ink runs out, the prism reflection surface is exposed from the ink liquid surface and becomes an air interface, and functions again as a reflection surface. The ink end of the foam type ink tank is detected by detecting the change in the reflection state due to the decrease in the ink by the detection unit.

In the ink end detection mechanism of this structure, as the amount of ink decreases, air enters the ink chamber from the side of the foam storage section to form bubbles, and the formed bubbles adhere to the rear surface of the prism reflection surface. Or it floats in the vicinity. As shown in FIG. 11B, the reflection position 2 of the prism reflection surfaces 201 and 202 in which the optical path of the return light Lr is formed.
If bubbles B are attached to or float on 03 and 204,
The ink held between the bubbles may prevent the light emitted from the light emitting element from being reflected at the reflection position, which may make it impossible to detect the ink end.

As described above, in the conventional optical detection mechanism using the prism, the optical path of the returning light emitted from the light emitting element and reflected by the prism reflection surface and then returning to the light receiving element is formed at only one place. . In other words, there is only one detection point. For this reason, when the relative positional relationship between the detection part and the detected part is deviated due to an assembly error or the like, dirt or the like is attached to the prism reflection surface of the detection point or the rear surface of the prism reflection surface of the detection point. When is covered with bubbles, it may not be possible to perform accurate detection.

An object of the present invention is to propose an optical detection device using a prism having a plurality of detection points by devising the shape of the prism reflection surface in order to solve such a problem. .

Another object of the present invention is to apply an optical detection device using a prism having a plurality of detection points in order to accurately detect whether or not an ink tank is attached and the ink end of the ink tank. It is in.

[0015]

In order to solve the above-mentioned problems, an optical detection device of the present invention is directed to a detected portion composed of a prism reflection surface, and to the reflection surface of the prism while irradiating the prism reflection surface with light. And a detector for receiving the reflected light from the detector, the detector includes a light emitting element and a light receiving element, and the light receiving element is parallel to the emitted light emitted from the light emitting element at a constant interval. The incident detection light can be received, the prism reflecting surface includes a plurality of pairs of a first reflecting portion and a second reflecting portion, and the first reflecting portion in each pair is emitted from the light emitting element. The light is reflected toward the corresponding second reflecting portion, and the incident angle of the light emitted from the light emitting element with respect to the first reflecting portion is θ1, and the light is reflected by the first reflecting portion and the corresponding light is reflected. The incident angle of the reflected light incident on the second reflecting portion is θ When it is set to 2, the sum of these incident angles (= θ1 + θ2) is 90 degrees.

As described above, if the shape of the prism reflecting surface is defined so as to include a plurality of pairs of the first reflecting portion and the second reflecting portion, the light emitting element of the detecting portion is provided for the first reflecting portion of each pair. When the emitted light is emitted, it can be returned to the light receiving element as return light parallel to the emitted light after being reflected by the first and second reflecting portions. That is, it is possible to realize a detection device having detection points corresponding to the number of pairs. Therefore, it is possible to improve the detection accuracy as compared with the conventional optical detection device using a prism having a single detection point.

Here, the first and second reflecting portions of each pair can be defined as points on an elliptic curve.

Since the prism reflecting surface may include a plurality of pairs of the first and second reflecting portions, it may be defined by a curve or a polygon.

Further, the detecting portion and the detected portion can be configured to move relative to each other.

Next, the present invention relates to an optical detecting device for an ink tank for detecting whether or not the ink tank is attached to an ink jet printer and detecting the ink end of the ink tank. It is characterized in that it has an optical detection device having a plurality of detection points configured and an ink tank in which ink is stored, and the prism reflection surface is formed in this ink tank.

When detecting whether or not the ink tank is attached, the rear surface of the prism reflection surface may be always arranged as an air interface.

On the other hand, when the ink end is detected, the back surface of the prism reflection surface is used as an ink interface,
The prism reflection surface may be gradually exposed to the air from the liquid surface of the ink as the remaining ink amount in the ink tank decreases.

Here, in general, a state in which the ink in the ink tank is almost exhausted is called "real end", and a state in which the remaining amount of ink in the ink tank is less than a certain amount is called "near end". However, the “ink end” used in the present specification includes both unless otherwise specified.

Next, there is a foam type ink tank as the ink tank. The foam type ink tank according to the present invention comprises a foam in which ink is absorbed and held, and a main ink chamber which is open to the atmosphere and which stores the foam. Formed between the ink take-out hole and the main ink chamber and the ink take-out hole, the ink suction force acting on the ink take-out hole can introduce ink and bubbles from the side of the main ink chamber. An ink chamber and a detected portion capable of optically detecting whether or not ink has run out based on the amount of air that has entered the sub ink chamber from the main ink chamber, and the detected portion is the sub ink. The inside of the room is provided with a prism reflection surface having an ink interface, and the prism reflection surface is provided with a plurality of pairs of the first and second reflection parts having the above-mentioned configuration. It is characterized in that a prism reflecting surface.

In the foam type ink tank having this structure,
Even if bubbles are attached to the back surface of the prism reflection surface or bubbles are formed near it, there are multiple detection spots on the prism reflection surface, so you can reliably detect the ink end at any of the detection spots. it can.

Next, the present invention relates to an ink jet printer using a foam type ink tank having such a constitution as an ink supply source, and includes a prism reflecting surface having a plurality of pairs of the first and second reflecting portions to be detected. It is characterized in that it is provided with a detection section for detecting the ink end of the ink tank based on the amount of light reflected from the section.

According to the ink jet printer of the present invention, the ink end can always be detected with high accuracy.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments to which the present invention is applied will be described below with reference to the drawings. The following embodiments are examples in which the present invention is applied to an ink tank that is detachably attached to a tank attachment portion of an inkjet printer. However, the present invention can be similarly applied to an ink tank that is previously arranged in an inkjet printer.

(Overall Structure) FIGS. 1 (a) and 1 (b) are a plan view and a front view showing a foam type ink tank to which the present invention is applied, and FIG. 2 shows the ink tank as seen from the bottom side. FIG. 3 is a perspective view, and FIG. 3 is an exploded perspective view of the ink tank.

The ink tank 1 of this embodiment is detachably attached to a tank attachment portion (not shown) formed in an ink jet printer (not shown) for use.
The ink tank 1 has a rectangular parallelepiped container body 2 having an open upper side, and a container lid 4 that closes the upper opening 3, and a main ink chamber 5 is formed inside them.
A rectangular parallelepiped form 6 that accommodates the ink is stored.

An ink take-out portion 7 is formed on the bottom surface of the container body 2. The ink take-out portion 7 is provided with a disk-shaped rubber packing attached to an opening formed on the bottom surface of the container and opened at the center thereof. The through hole 8a serves as an ink outlet hole. A valve 9 capable of closing the ink take-out hole 8a is arranged in a portion of the ink take-out portion 7 that is deeper than the rubber packing 8, and the valve 9 is constantly pressed by the coil spring 10 to the rubber packing 8. The hole 8a is blocked.

The main ink chamber 5 communicates with the ink take-out hole 8a through the sub ink chamber 30 partitioned by the first filter 11 and the second filter 12. Further, the atmosphere is opened to the atmosphere through an atmosphere communication hole 13 formed in the container lid 4. Therefore, when the ink absorbed and held in the foam 6 mounted in the main ink chamber 5 is sucked through the ink take-out hole 8 a, the air corresponding to the sucked ink is mainly discharged from the atmosphere communication port 13. Enter the ink chamber 5.

The atmosphere communication hole 13 of the container lid 4 is connected to a curved groove 13a carved on the surface of the container lid, and the end 13b of the groove 13a extends to the vicinity of the edge of the container lid 4. . At the time of shipping the ink tank 1, a seal 14 is attached to a portion of the container lid 4 where the atmosphere communication hole 13 and the groove 13a are formed.
A part 1 of the seal 14 along the cutting line 14a of 4
By peeling off 4b, the end 13b of the groove 13a is exposed and the atmosphere communication hole 13 is opened to the atmosphere.

A seal 15 is also attached to the ink take-out hole 8a on the bottom of the container, and the ink tank 1
When the ink jet needle is attached to the tank attachment portion of the ink jet printer, the ink supply needle attached to the tank attachment portion (see FIG.
The reference (see (b)) breaks the seal 15 and is inserted into the ink take-out hole 8a, and the ink tank 1 is put in the mounted state.

Next, FIGS. 4A and 4B are a sectional view and a partially enlarged sectional view of the ink tank 1 taken along line IV-IV in FIG. 1, and FIG. −
FIG. 3 is a cross-sectional view of the ink tank 1 taken along the line V,
FIG. 6 is a sectional view of the ink tank 1 taken along the line VI-VI in FIG.

Referring to these drawings, the ink take-out hole 8
Sub ink chamber 30 formed between a and the main ink chamber 5
The structure of the ink passage portion including will be described. First, in the bottom plate portion 21 of the container body 2, a tubular frame 22 having a rectangular cross section penetrates the bottom plate portion 21 and extends vertically vertically. A rectangular communication port 25 is provided at the upper end of an upper tubular frame portion 23 of the tubular frame 22 which stands vertically in the main ink chamber 5.
A (main ink chamber side communication port) is formed. A rectangular first filter 11 is attached to the communication port 25.

The lower end opening of the lower tubular frame portion 24 vertically projecting downward from the container bottom plate portion 21 of the tubular frame 22 is closed by a frame bottom plate portion 24a formed integrally therewith, A cylindrical projecting portion 26 is integrally formed in a substantially central portion of the frame bottom plate portion 24a so as to extend vertically upward. The central hole of the protruding portion 26 is an ink passage 27 communicating with the ink take-out hole 8a.
The rubber packing 8, the valve 9 and the coil spring 10 are attached thereto, and the spring bearing 28 of the coil spring 10 is integrally formed on the inner peripheral surface of the projecting portion 26.

The projecting portion 26 extends to a position below the first filter 11 by a predetermined distance,
The second filter 12 is attached to the circular communication port 29 (mounting hole side communication port) formed at the upper end thereof.

The first filter 11 of this example is made of a porous material that allows air bubbles to pass therethrough by the ink suction force acting on the ink extraction holes 8a while allowing the ink to pass therethrough. That is, it is made of a porous material having a pore size that causes a capillarity to destroy the meniscus by the ink suction force. The first filter 11 is formed of, for example, a mesh filter.

On the other hand, the second filter 12 is made of a porous material that allows the ink to pass through but prevents bubbles from passing through due to the ink suction force acting on the ink outlet. That is, it is made of a porous material having a fine pore size that acts as a capillary force that does not destroy the meniscus due to the ink suction force. Further, the second filter 12 has a pore size capable of capturing foreign matter mixed in the ink. This second filter 12 can also be formed from a mesh filter.

Here, the ink suction force is the ink suction force that acts on the ink extraction hole 8a by the ink discharge pressure of the ink jet head (not shown) to which the ink is supplied.

Next, a cup-shaped cap 31 for sucking ink is arranged in the sub ink chamber 30 of this example.
The cup-shaped cap 31 sucks up the ink accumulated in the bottom of the sub ink chamber 30 to the communication port 29 to which the second filter 12 located above is attached.

FIGS. 7A and 7B are a perspective view and a sectional view showing the cup-shaped cap 31. Explaining with reference to FIGS. 4 to 7, the cup-shaped cap 31 includes a cylindrical body portion 32 and a top plate portion 33 that closes the upper end opening, and the lower end opening 34 has a circular shape. On the end surface 35, a plurality of protrusions formed at predetermined angular intervals vertically project. In this example, four protrusions 36 having the same height are formed at intervals of 90 degrees. The inner peripheral surface of the cylindrical body portion 32 has a lower end-side inner peripheral surface portion 37 and a tapered inner peripheral surface portion 3 which continuously protrudes inward from the upper peripheral portion 37.
8 and a small-diameter upper end side inner peripheral surface portion 39 continuous to the upper side.

The cup-shaped cap 31 of this shape is attached to the cylindrical protruding portion 26 formed in the ink chamber 30 in a capped state from the upper side. The outer peripheral surface of the projecting portion 26 has a slightly larger large diameter outer peripheral surface portion 41 on the lower end side, and a smaller diameter outer peripheral surface portion 42 on the upper end side, and an annular step surface 43 is formed therebetween. There is. As shown in FIG. 6, the small-diameter outer peripheral surface portion 4
Ribs 44 protruding outward are formed at 2 at predetermined angular intervals. In this example, four ribs 44 are formed at intervals of 90 degrees, and these ribs 44 have the same protrusion amount and have a predetermined length in the vertical direction. The amount of protrusion of these ribs 44 is such that they are cup-shaped caps 31.
It is set so as to fit exactly into the outer peripheral surface portion 39 of the upper end.

When the cup-shaped cap 31 is capped on the protruding portion 26, the cup-shaped cap 31 is positioned by the four ribs 44, and four cups are provided between the inner peripheral surface of the cup-shaped cap 31 and the outer peripheral surface of the protruding portion 26. A gap 45 having an arcuate cross section for ink suction is formed. Further, the height dimension from the lower surface of the protrusion 36 formed on the circular end surface 35 at the lower end of the cup-shaped cap 31 to the back surface of the top plate portion 33 is set to be larger than the height dimension of the protruding portion 26 by a predetermined amount. . Therefore, in the capping state, a gap 46 for ink passage is formed at a predetermined interval between the second filter 12 attached to the upper end of the protruding portion 26 and the back surface of the top plate portion 33 of the cup-shaped cap 31. The gap 46 communicates with the gap 45. Further, in the capping state, four gaps 47 having a constant width and having an arc-shaped cross section are formed between the four protrusions 36 formed at the lower end of the cup-shaped cap 31. This arcuate cross section gap 4
7 communicates with the above-mentioned gap 45 having an arcuate cross section.

Here, by setting the gaps 45, 46, and 47 to appropriate widths, ink is sucked up from the gap 47 through the gap 45 and passes through the gap 46 and the second filter 12. As a result, an ink suction passage reaching the communication port 29 at the upper end of the protruding portion can be formed. By doing so, even when the amount of ink accumulated in the sub ink chamber 30 is reduced and the liquid level thereof is lower than that of the second filter 12, the ink in the sub ink chamber 30 is kept in the second state.
Suck up to the position of the filter 12 of the ink passage 27
Can be supplied to the ink extraction hole 8a.

Further, in this example, the outer peripheral surface 32a of the cup-shaped cap 31 forms the sub-ink chamber 30, and the cylindrical frame 2 is formed.
The second inner side surface 22a is separated from the inner side surface 22a by a predetermined width. Outer peripheral surface 32a of cup-shaped cap 31
When the ink comes into contact with the inner side surface 22a of the cylindrical frame 22, the inside of the sub ink chamber 30 is divided into left and right with the contact position as a boundary, and the ink accumulated in the sub ink chamber 30 cannot be sucked up efficiently. There is a risk. In this example, the cup-shaped cap 31 can efficiently suck up the ink accumulated in the sub ink chamber 30.

(Detection Mechanism) Next, the ink tank 1 of this example
In the above, a detected portion 50 having a prism reflection surface 51 used for optically detecting whether or not the ink tank 1 is attached to the attachment portion of the inkjet printer is arranged. Further, a detected portion 60 having a prism reflection surface 61 used for optically detecting that the amount of ink remaining in the sub ink chamber 30 has fallen below a predetermined amount is arranged.

Referring to FIGS. 3, 5 and 6, a horizontally long rectangular plate 54 is adhesively fixed to the lower end portion of the side plate portion 53 of the container body 2, and the inner surface of the rectangular plate 54 is fixed. Prisms 52 and 62 are integrally formed at a constant interval. These prisms 52 and 62 are provided with prism reflecting surfaces 51 and 61, respectively, which are defined as described later.

One of the prisms 52 faces the side plate portion 53 of the container body 2 via an air layer 55 having a constant gap. That is, the side plate portion 53 is formed with a concave portion 56 having a shape corresponding to the prism 52, whereby the back surface of the prism reflection surface 51 faces the side plate portion 53 of the main ink chamber 5 via the air layer 55 having a constant gap. is doing.

On the other hand, the other prism 62 is directly exposed to the inside of the sub ink chamber 30 through the opening 22b formed in the tubular frame 22 forming the sub ink chamber 30. That is, the back surface of the prism reflection surface 61 is an ink interface. Therefore, when the ink surface of the sub ink chamber 30 is above the mounting position of the prism 62, the prism reflection surface 61 comes into contact with the ink and does not function as a reflection surface. However, when the ink surface drops downward,
The prism reflection surface 61 gradually regains its function as an original reflection surface.

Next, as shown in FIG. 6, the ink tank 1
Reflective optical sensors 70 and 80 are attached to the side of an ink jet printer (not shown) to which is attached. These optical sensors 70, 80 are mounted on a head carriage 220 for scanning an inkjet head (not shown) in the print width direction, and are mounted on an ink tank mounting portion to mount the prism reflection surface 51 of the ink tank 1.
61 is scanned in the print width direction A (arrow direction in FIG. 6) for detection.

These optical sensors 70, 80 include light emitting elements 71, 81 and light receiving elements 72, 82. The optical sensor 80 includes a light emitting element 81 and a light receiving element 8 thereof.
When the interval of 2 (optical axis interval) is D and the emitted light L emitted from the light emitting element 81 is reflected by the prism reflection surface 61 and returns to the light receiving element 82 as the returning light Lr, the received light amount of the light receiving element is Based on this, the ink end of the ink tank 1 is detected. The other reflection type optical sensor 70 has the same structure.

(Shape of Prism Reflecting Surface) Here, the prism reflecting surfaces 51 and 6 of the respective prisms 50 and 60 in this example.
A method of defining the shape of 1 will be described. Since the defining methods of both reflecting surfaces are the same, the defining method of the prism reflecting surface 61 for ink end detection will be described.

In the present example, the prism is formed so that the light L emitted from the light emitting element 81 is reflected by the prism reflection surface 61 and returned to the light receiving element 82 as return light at a plurality of locations in the sensor scanning direction A. It defines the shape of the reflective surface. In other words, the prism reflection surface shape is defined so that the detection points of the sensor are plural.

Referring to FIG. 8, in the case of a generally used right-angle prism, a pair of orthogonal prism reflection surfaces 201 and 202 are inclined by 45 degrees with respect to the light L emitted from the light emitting element 81. It is placed in the state where it was opened. In this case, the pair of prism reflection surfaces 201 and 202 detects that the light emitted from the light emitting element 81 returns to the light receiving element 82 that is away from the light emitting element 81 by a distance D in a return light Lr state parallel to the light emitted. The point is the prism reflection surface 20
The light emitting element 81 and the light receiving element 8 are provided on the center lines of 1, 202.
It is only when the center line 83 between the two optical axes coincides. In this state, the incident angle θ1 of the light emitted from the light emitting element 81 with respect to one prism reflecting surface 201 is 45 degrees, and the incident angle of the reflected light Lr1 reflected by the rectangular prism 201 into the other prism reflecting surface 202 is also. It is 45 degrees.

Here, each prism reflecting surface 201, 202
Is an arbitrary curved surface, a reflection portion (hereinafter, referred to as a first reflection portion) 110 of the outgoing light L on the prism reflection surface 201.
The incident angle θ1 with respect to is the angle formed by the normal line 111 standing on the first reflecting portion 110 and the emitted light L. Similarly, the incident angle θ2 of the reflected light Lr1 reflected by the prism reflection surface 201 with respect to the reflection portion (hereinafter referred to as the second reflection portion) 120 on the prism reflection surface 202 is also the second reflection portion 12.
It is an angle formed by the normal line 121 set to 0 and the reflected light Lr1.

The fact that both incident angles θ1 and θ2 are 45 degrees means that the normals 111 and 121 are orthogonal to each other, and therefore the tangents 113 and 123 drawn to the reflecting portions 110 and 120 form. The angles will intersect at right angles. Therefore, the first condition that the tangent lines are orthogonal to each other and the interval between the outgoing light L and the return light Lr becomes the constant value D is satisfied.
The reflecting portion and the second reflecting portion are plotted on a plane, and the positions of the plurality of pairs of the first and second reflecting portions 110 and 120 are obtained,
By obtaining a curve or polygon including these and adopting such a curve or polygon as the prism reflection surface shape, a prism reflection surface having a plurality of detection points can be obtained.

FIG. 9 shows a method of calculating the prism reflection surface shape in a more general case. When an arbitrary curve is assumed as the prism reflection surface shape, the light L emitted from the light emitting element 81 is incident on the first reflection section 110 at an arbitrary incident angle θ1, and the reflected light Lr1 therefrom is at an arbitrary incident angle θ2. Second
The light is incident on the reflecting section 120 and returns to the sensor 80 side to obtain the light Lr.
Return as. At this time, in order to return the return light Lr to the light receiving element 82 as a light beam parallel to the emitted light L, as in the case of FIG. 8, the tangent lines 113 and 123 drawn to the first and second reflecting portions 110 and 120 are used. Should cross at right angles. That is, the sum of the incident angles θ1 and θ2 may be 90 degrees.

Therefore, also in this case, the tangent line 11
3, 123 are orthogonal to each other, and the first reflection part and the second reflection part 110, 120 satisfying the condition that the distance between the emission light L and the return light Lr becomes a constant value D are plotted on a plane,
The positions of the plurality of pairs of the first and second reflecting portions 110 and 120 are obtained, and a curve or polygon including them is obtained,
By adopting such a curve or polygon as the prism reflection surface shape, a prism reflection surface having a plurality of detection points can be obtained.

Here, an elliptic curve can be mentioned as a specific curve that defines the shape of the prism reflecting surface having such a plurality of detection points. As shown in FIG. 10B, the ellipse E is defined by the following equation in the Cartesian coordinate system. x ² / a ² + y ² / b ² = 1 The inclination α (tangential inclination angle) of an arbitrary point (x1, y1) of the ellipse is obtained by differentiating the above equation once, and is as follows. α = (-2bx / a ² ) / 2√ {(1- (x ² /
a ² )} The value of the angle can be obtained by taking the arc tangent of α and changing the unit from radian to degree.

Here, the distance between the optical axes of the sensors, that is,
It was confirmed that the tangent lines intersect at right angles at two points on the ellipse E, where D is the distance between the optical axes of the light emitting element and the light receiving element, and appropriate values are selected as the coefficients a and b. Therefore, a part of the ellipse thus obtained is converted into the prism reflection surfaces 71, 81.
If adopted as the reflection surface shape of, a prism reflection surface having continuous detection points can be realized.

FIG. 10A shows an example of a concrete calculation result. In this calculation example, the coefficients a = 3.5 and b = 5.029 in the above elliptic formula are used, and the sensors 70, 8
It is calculated by calculating the inclination α and the inclination angle (degree) θ of the tangent line at each point on the elliptic curve E when the optical axis distance D of 0 is D = 4 mm.

As can be seen from this figure, the point A on the ellipse E is
The tangent lines 1 to A11 and the tangent lines B1 to B11 are
They intersect at a 90-degree intersection angle. Therefore, if a plurality of pairs are selected from these 11 pairs and a curve or a polygon including the points of each pair is adopted as the reflecting surface of the prism reflecting surfaces 71 and 81, the prism having a plurality of detection points. A reflective surface can be realized. Of course, if the elliptic curve portion from the point A1 to the point A11 and the elliptic curve portion from the points B1 to B11 are adopted as the reflecting surface shapes of the prism reflecting surfaces 71 and 81, a prism reflecting surface having continuous detection points is realized. it can.

In this example, for example, as shown in FIG.
A polygonal prism reflection surface shape with three detection points is adopted. Here, the three pairs of first and second reflecting portions that define the detection points are respectively the points 110.
(1) and 120 (1), points 110 (2) and 12
0 (2), points 110 (3) and 120 (3).
The prism reflection surfaces 51 and 61 are defined by a polygonal shape including six symmetrical planes including these points.

(Detection Operation) Detection of whether or not the ink tank 1 of this example is mounted in the mounting portion of the ink jet printer and detection of ink end of the ink tank 1 are performed as follows.

When the ink tank 1 is mounted on the mounting portion of the ink jet printer, as shown in FIG. 4 (b), the tip portion of the ink supply needle 61 arranged on the ink jet printer side causes the ink to be taken out of the ink tank 1. Hole 8
The valve 9 located in the ink passage 27 is pushed up by penetrating a.

As a result, since the ink take-out hole 8a is opened, the ink absorbed and held in the foam 6 in the main ink chamber 5 of the ink tank 1 flows through the first filter 11 and the sub ink chamber 30. The ink flows into the ink passage 27 through the ink supply needle 61 and can be supplied to the inkjet head on the inkjet printer side. Since such an ink supply mechanism is known, further description will be omitted.

When the ink tank 1 is mounted in this way, the prism 52 formed on the side surface of the ink tank 1 comes to a position where it can face the optical sensor 70 on the ink jet printer side. When the power of the inkjet printer is turned on, the optical sensor 70 mounted on the head carriage is moved by the initial operation to detect whether or not the ink tank is mounted. When the optical sensor 70 reaches the position facing the prism reflection surface 51, the light L emitted from the light emitting element is reflected by the prism reflection surface 51 and the return light Lr is detected on the light receiving element 72 side (FIG. 6).

In this example, as shown in FIG. 11A, three positions in the carriage scanning direction are the detection points. Therefore, at these positions, the amount of the return light Lr received by the light receiving element 72 is detected. Is the maximum. Therefore, by comparing the amount of light received at each of these points with a preset threshold value, it is possible to detect whether or not the ink tank is mounted.

Since there are three detection points, at any one of the detection points, dirt is attached to the first and second reflecting portions that define the optical path of the return light Lr, and the amount of received return light is reduced. Even if it does, the attachment of the ink tank can be reliably detected at other detection points. Therefore, erroneous detection can be prevented.

Next, when the ink jet head is driven and ink is ejected, an ink suction force acts on the ink ejection hole 8a by the ink ejection pressure, and ink is supplied toward the ink jet head. When the ink is supplied and the amount of the ink retained in the foam 6 is reduced, air is introduced into the main ink chamber 5 through the atmosphere communication port 13 accordingly. As shown by the chain double-dashed line in FIG. 4A, the ink impregnated in the foam 6 gradually decreases as the ink is consumed, and instead, bubbles enter the foam 6. When the amount of ink remaining in the foam 6 becomes small, air enters the sub ink chamber 30 through the first filter 11 to generate bubbles in the sub ink chamber 30. Since the second filter 12 partitioning between the sub ink chamber 30 and the side of the ink outlet 8a does not allow air bubbles to pass through,
Bubbles gradually accumulate inside the sub ink chamber 30.

When the remaining amount of ink is further reduced, the liquid level of the ink stored in the main ink chamber 5 and the sub ink chamber 30 is gradually lowered, and the prism reflection surface 61 of the prism 62 exposed in the sub ink chamber 30 is gradually decreased. Is gradually exposed from the ink surface. As a result, the prism reflection surface 61 gradually starts to function as a reflection surface. When the ink liquid surface of the sub ink chamber 30 falls below a predetermined liquid surface position (for example, the position P shown in FIG. 5), the light receiving amount of the light receiving element 82 of the optical sensor 80 exceeds the predetermined light receiving amount.

That is, when the optical sensor 80 mounted on the head carriage and scanning the prism reflection surface 61 of the ink tank passes three detection points for the prism reflection surface 61, the light receiving element 82 receives light. The amount exceeds a predetermined threshold. Based on this, the ink in the ink tank 1 has run out (ink end)
Is detected.

If the volume of the sub ink chamber 30 is made sufficiently small, the ink end is detected when the remaining ink amount becomes small, so the ink end is detected when the remaining ink amount is as small as possible. It is possible to suppress waste of ink. If this state is regarded as near end and the following processing is performed, waste of ink can be further eliminated. That is, after the near end of the ink is detected by the optical sensor 80, the amount of ink used thereafter is counted, and when the value reaches the amount corresponding to the amount of ink accumulated in the sub ink chamber 30, the real end is set. If confirmed, the ink can be used until the time when the remaining amount of ink is substantially exhausted.

Here, since there are three detection points by the prism reflection surface 61 as described above, the ink tank 1
The ink end of can be reliably detected.

That is, when air enters the sub ink chamber 30 and bubbles are generated as the ink remaining amount decreases, the space above the ink surface in the sub ink chamber 30 is filled with bubbles. The ink liquid level drops in this state. For this reason, in a state where the ink liquid surface gradually lowers from the upper end of the prism reflection surface 61, bubbles float near the portion of the prism reflection surface 61 exposed from the ink liquid surface. Therefore, even if the ink surface becomes lower than the prism reflection surface 61, the back surface of the prism reflection surface 61 remains partially covered by the ink held between the air bubbles floating in the vicinity thereof. There is a risk of falling into a state.

The conventional prism reflection surface is shown in FIG.
As shown in (b), it is a pair of orthogonal prism reflecting surfaces that generally form a right-angled prism, and this detection point is one place. Therefore, if bubbles adhere to the back surface of either the first reflecting portion or the second reflecting portion that defines this detection point, this portion does not function as a reflecting surface. As a result, the ink end cannot be detected.

However, in this example, as shown in FIG. 11A, there are three detection points, 80 (1), 80 (2), and 80 (3), so ink is detected at any one of the detection points. The end can be detected. Therefore, even if the bubble B adheres to or floats on the back surface of the prism reflection surface 61, it is possible to prevent the problem that the bubble B is not detected despite the ink end.

(Other Embodiments) In the above-described example, the optical detection device using the prism according to the present invention is used to determine whether or not an ink tank is attached to an ink jet printer using a foam type ink tank as an ink supply source, It is applied for end detection.

However, the present invention can be applied as it is as a detection mechanism other than the detection of the presence / absence of attachment of the ink tank and the ink end.

In the above example, the prism reflecting surface is scanned by the detecting section. Instead of this
It goes without saying that the detection device may be configured such that both are fixed at a fixed position. In this case, by using the prism reflecting surface on which continuous detection points are formed, it is possible to obtain an effect that the detection accuracy can be prevented from being lowered even if the mounting accuracy of both members is poor.

[0083]

As described above, in the optical detection device using the prism of the present invention, the shape of the prism reflection surface is set so that there are a plurality of detection points by the prism reflection surface. According to this configuration, the detection accuracy can be improved as compared with the conventional optical detection device using a right-angle prism or the like, which has a single detection point. Particularly, in the case of a movable type in which a detected portion having a prism reflection surface is scanned in a predetermined direction by the detection portion, erroneous detection due to dirt on the prism reflection surface can be prevented, which is preferable.

Further, when the prism reflection surface is formed into a curved surface shape that adopts a part of an elliptic curve, there is an advantage that a prism reflection surface having continuous detection points can be realized.

Therefore, according to the optical detecting device for an ink tank to which the present invention is applied, it is possible to accurately and surely detect whether or not the ink tank is mounted and the ink end.

Particularly, when the present invention is applied to the ink end detection of the foam type ink tank, there is a problem that the ink end cannot be detected due to the air bubbles adhering to or floating on the back surface of the prism reflection surface as the detected portion. Can be avoided.

Therefore, in the ink jet printer which uses the foam type ink tank having the detected portion having such a structure as the ink supply source, the ink end of the ink tank can always be detected accurately.

[Brief description of drawings]

1A and 1B are a plan view and a front view showing a foam type ink tank according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the ink tank of FIG. 1 when viewed from the bottom side.

FIG. 3 is an exploded perspective view of the ink tank of FIG.

4A is a cross-sectional view of the ink tank when cut along line IV-IV in FIG. 1, and FIG. 4B is a partial cross-sectional view showing a state in which an ink supply needle is inserted.

5 is a cross-sectional view of the ink tank when cut along the line VV in FIG.

FIG. 6 is a cross-sectional view of the ink tank when cut along line VI-VI in FIG.

FIG. 7 is a diagram showing a cup-shaped cap in the ink tank of FIG.

FIG. 8 is an explanatory diagram showing a method for determining the shape of a prism reflection surface having a plurality of detection points.

FIG. 9 is an explanatory diagram showing a general method for determining the shape of a prism reflection surface having a plurality of detection points.

FIG. 10 is an explanatory diagram showing that an example of a prism reflection surface shape having a plurality of detection points is an elliptic curve.

11A is an explanatory diagram showing an example of a prism reflection surface shape adopted in the ink tank of FIG.
(B) is an explanatory view showing a reflection surface shape of a conventional rectangular prism.

[Explanation of symbols]

1 ink tank 2 container body 3 Upper opening of container body 4 container lid 5 Main ink chamber 6 forms 7 Ink removal section 8 rubber packing 8a Ink removal hole 9 valves 10 coil spring 11 First filter 12 Second filter 13 atmosphere communication hole 21 Bottom plate of container body 27 ink passage 30 Sub ink chamber 31 cap 32 torso 50, 60 Detected part 51, 61 prism reflection surface 52, 62 prism 70, 80 Optical sensor 71, 81 Light emitting element 72, 82 Light receiving element 80 (1) to 80 (3) Detection points 110, 110 (1) to 110 (3) First reflector 120, 120 (1) to 120 (3) Second reflector 111, 121 Normal 113, 123 tangent θ1 Angle of incidence on the first reflector θ2 Incident angle on the second reflection part Light emitted from L light emitting element Lr1 Light reflected from the first reflecting portion Lr Return light to photo detector D Distance between optical axes of light emitting element and light receiving element

Claims (9)

[Claims] 1. A detection unit having a prism reflection surface, and a detection unit for irradiating the prism reflection surface with light and receiving reflected light from the reflection surface, wherein the detection unit is a light emitting element and A light receiving element is provided, the light receiving element is capable of receiving detection light that is incident in parallel with the emitted light emitted from the light emitting element at a constant interval, and the prism reflection surface includes a first reflection portion and a first reflection portion. A plurality of pairs of two reflecting portions are included, and the first reflecting portion in each pair reflects the light emitted from the light emitting element toward the corresponding second reflecting portion, and the first reflecting portion. Let θ1 be the incident angle of the light emitted from the light emitting element with respect to, and θ2 be the incident angle of the reflected light reflected by the first reflecting portion and incident on the corresponding second reflecting portion. The sum of angles (= θ1 + θ2) is 90
An optical detection device characterized by a degree. 2. The optical detection device according to claim 1, wherein the first and second reflecting portions of each pair are points on an elliptic curve. 3. The optical detection device according to claim 1, wherein the prism reflection surface is defined by a curve or a polygon. 4. The optical detection device according to claim 1, wherein the detection unit and the detection target unit move relative to each other. 5. The optical detection device according to claim 1, further comprising an ink tank storing ink, wherein the prism reflection surface is formed in the ink tank. An optical detection device for an ink tank, which is characterized in that 6. The optical detection device for an ink tank according to claim 5, wherein the rear surface of the prism reflection surface is an air interface. 7. The ink according to claim 5, wherein the back surface of the prism reflection surface is an ink interface,
An optical detection device for an ink tank, which is gradually exposed to the air from the liquid surface of the ink as the remaining amount of ink in the ink tank decreases. 8. A foam in which ink is absorbed and held, a main ink chamber in which the foam is stored, which is open to the atmosphere, an ink take-out hole, and formed between the main ink chamber and the ink take-out hole. In addition, an ink suction force acting on the ink outlet hole allows ink and bubbles to be introduced from the main ink chamber side, and an ink based on the amount of air that has entered the sub ink chamber from the main ink chamber. And a detected portion capable of optically detecting whether or not there is no ink. An ink tank comprising the prism reflection surface used in the optical device according to any one of claims 1 to 4. 9. An inkjet printer using the ink tank according to claim 8 as an ink supply source, wherein the detection unit for detecting the ink end of the ink tank based on the amount of reflected light from the detection target unit is used. An inkjet printer characterized by being provided.