JP2006001272A - Ink tank and ink jet recording apparatus - Google Patents

Abstract

Provided is an ink tank that is capable of more reliably detecting the presence / absence of ink and the presence / absence of an ink tank, while having a simple configuration, and that is also effective against erroneous mounting due to multi-color ink.
An ink tank that stores ink to be supplied to a recording head includes a light emitting element that emits light from below to above in a direction of gravity and a light receiving element that receives light emitted from the light emitting element. It is detachably attached to the device. The ink tank 20 is a bottom in a state where it is mounted on the recording apparatus, and a housing 23 that is light transmissive at least at a portion that becomes a light input / output path, an ink supply port 22b that supplies ink to the recording head, An air communication port 21a that communicates with the outside and a light reflecting member 27 that is disposed in the ink storage chamber 25 and reflects light emitted from the light emitting element to the light receiving element are provided. A space between the light transmissive portion of the housing 23 and the light reflecting member 27 is a space where ink exists.
[Selection] Figure 3

Description

  The present invention relates to an ink tank that is used as an ink storage container in a recording apparatus that uses liquid ink for recording, and an ink jet recording apparatus that performs recording by ejecting ink supplied from the ink tank from a head. The present invention provides an improved structure that makes it possible to detect whether or not an ink tank is attached to the ink tank, detect the remaining amount of ink stored in the ink tank, and detect the type of ink stored in the ink tank. The present invention relates to an ink jet recording apparatus equipped with an ink tank and a mechanism capable of detecting the above items by mounting the ink tank.

  The ink jet recording apparatus performs desired recording by ejecting ink droplets from fine ejection ports provided in the ink jet recording head and attaching the ink droplets to a recording medium such as paper or a resin sheet. As an ink jet recording apparatus, for example, an energy generation element that generates energy for ejecting ink from an ejection port, an electromechanical conversion element such as a piezo element, or an electrothermal conversion element having a heating resistor is used. For example, a liquid that heats a liquid and discharges ink droplets is used.

  In this type of ink jet recording apparatus, an ink supply mechanism that supplies liquid ink to an ink jet recording head is provided, and an ink tank that contains ink is detachably connected to the ink supply mechanism. It has become. Therefore, the ink jet recording apparatus has a mounting portion (for example, a carriage that mounts the ink jet recording head and moves back and forth, a holder that holds the ink tank, and the like) to which the ink tank is detachably mounted. When the ink in the ink tank runs out, recording can be continued by replacing the ink tank with a new one.

  In recent years, ink jet recording apparatuses capable of recording in full color have become mainstream, and the number of inks used for recording is increasing. Accordingly, a plurality of ink tanks that store inks of different colors are mounted on the ink jet recording apparatus. In addition, when the ink in the ink tank becomes very small, the conventional ink jet recording is performed in order to prompt the user to replace the ink tank or to interrupt the recording operation of the ink jet recording apparatus as necessary. The apparatus has a system for detecting the remaining amount of ink in the ink tank.

  Conventionally, as a method of recognizing and identifying the remaining amount of ink contained and the type of ink tank classified by ink color, an electrical method based on ROM information, and the shape of the ink tank for each type of ink tank A mechanical method for incompatibility, an optical method using light reflection, an electrical method by arranging an electrode in an ink tank and changing electric resistance, and the like are known.

  Among these, as an optical method, as disclosed in Patent Document 1, an ink tank having a reflecting plate as an optical reflecting member in the ink chamber and detecting the presence or absence of ink, Patent Document 2 or Patent As disclosed in Document 3, a system is known in which a plurality of optical reflecting members are provided to detect the presence of an ink tank and the remaining ink level in the ink tank.

  Patent Document 4 discloses an ink jet recording apparatus that can detect the presence or absence of an ink tank and the presence or absence of ink with a single photosensor.

  Furthermore, as an electrical method based on ROM information, it is determined whether or not the ink is of an appropriate color by comparing the ROM data mounted in the ink tank with the optically measured data, A system for determining whether or not the remaining amount of ink is very small based on the measured data is disclosed in Patent Document 5.

  Below, the system disclosed by patent document 3 is demonstrated from the prior art mentioned above. FIG. 11 shows a conventional ink tank provided with optical detection means. 4A is an external perspective view, FIG. 4B is a bottom view, and FIG. 3C is a cross-sectional view taken along line AA ′ in FIG. FIG. 12 is a diagram for explaining the state of reflection at the bottom of the ink tank shown in FIG.

  The ink tank 107 is made of a translucent light-transmitting material and is detachably attached to a carriage (not shown) of the ink jet recording apparatus. As shown in FIG. 11A, a triangular notch 250 is formed in the lower portion of the side wall of the ink tank 107. Further, as shown in FIGS. 11B and 11C, a prism 180 and a concave curved reflecting portion 190 are provided on the bottom surface of the ink tank 107. The prism 180 is used for detecting the remaining amount of ink, and the concave curved reflection unit 190 is used for detecting the presence or absence of an ink tank.

  The carriage has an opening formed in a region facing the prism 180 and the concave curved reflecting portion 190 when the ink tank 107 is mounted. In the ink jet recording apparatus, an optical unit 140 having a light emitting element 150 and a light receiving element 160 is disposed at a position facing the prism 180 and the concave curved surface reflecting section 190 through the opening of the carriage. The light emitting element and the light receiving element are arranged side by side in a direction perpendicular to the moving direction of the carriage (the F direction in FIG. 11B). The concave curved reflecting portion 190 has a curvature with respect to the two directions of the carriage moving direction and the F direction in FIG. 11B, and a curved surface is formed in the entire region of the concave curved reflecting portion 190. As shown in FIG. 12, the optical unit 140 has a light emitting part of the light emitting element 150 and a light receiving part of the light receiving element 160 approximately when the concave curved reflection part 190 of the ink tank 107 is positioned directly above the optical unit 140. It is attached so as to be located at the center of curvature C of the concave curved reflection portion 190. As a result, the central axis of the light emitted from the light emitting element 150 is parallel to a line passing through the center of curvature C and perpendicular to the bottom surface of the ink tank 107.

  In the above-described detection system, light is emitted from the light emitting element 150 of the optical unit 140 while moving the carriage. Here, when the ink tank 107 is not attached to the carriage, the light emitted from the light emitting element 150 does not return to the light receiving element 160 and is not detected by the light receiving element 160. When the ink tank 107 is mounted on the carriage, the light emitted from the light emitting element 150 first enters the prism 180. The light incident on the prism 180 is transmitted through the prism 180 when ink is present in the ink tank 107, and is reflected by the surface constituting the outer shape of the prism 180 and returned to the light receiving element 160 when there is no ink. Therefore, the presence or absence of ink in the ink tank 107 can be detected from the intensity of light detected by the light receiving element 160. With the movement of the carriage, the light emitted from the light emitting element 150 is then applied to the concave curved reflecting portion 190. Due to the shape of the concave curved surface reflection unit 190 and the arrangement of the optical unit 140 described above, the light emitted from the light emitting element 150 is reflected by the concave curved surface reflection unit 190 and returns to the light receiving device 160 and detected by the light receiving device 160.

From the above, when the change in the intensity of the light detected by the light receiving element 160 is observed, the ink tank 107 is not installed unless there is a peak value. If the peak value is 1, the ink tank 107 is installed. However, if there is no ink and there are two peak values, it can be determined that the ink tank 107 is installed and ink is present.
JP-A-8-183183 JP-A-9-174877 Japanese Patent Laid-Open No. 10-323993 JP-A-9-29989 JP 2001-328273 A

  However, the above-described conventional detection system can handle only a specific request as described below, and is not configured to simultaneously satisfy another request.

  That is, in the configuration described above, the presence or absence of the ink tank and the presence or absence of the contained ink can be detected, but the color of the ink contained in the ink tank cannot be identified. For this reason, in an ink jet recording apparatus in which a plurality of ink tanks each having different ink colors are mounted, this is not detected even if the mounting position is wrong. The color of the ink to be produced is completely different. For example, it is possible to cope with erroneous mounting of the ink tank using the optical detection means by changing the position of the reflecting member for each ink color. However, in recent ink jet recording apparatuses, the number of colors has been increasing, and making the ink tank corresponding to each color causes an increase in production cost and each within a limited space of the ink tank. It is very difficult to place the reflecting member at different positions depending on the ink color.

  In addition, when detecting the presence / absence of an ink tank and the presence / absence of ink using corresponding optical elements (prisms and reflecting portions), in order to detect with one set of light emitting element and light receiving element, that is, one optical unit, 2 It is conceivable to arrange two optical elements parallel to the direction of movement of the carriage. At this time, in order to enable reliable detection by each optical element, it is necessary to obtain a sufficient amount of reflected light, and therefore the positional relationship between the optical element and the optical unit is important. Therefore, in consideration of the dimensional accuracy and mounting accuracy of each component or unit, the optical element needs to have a certain size, leading to an increase in the size of the ink tank.

  The above-described problems are desired to be solved at an early stage from the viewpoint of increasing the number of colors of ink, reducing the size of the ink jet recording apparatus, and reducing the production cost.

  The present invention has been made in view of the above-described problems, and its object is to perform more reliable ink presence / absence detection and ink tank presence / absence detection with a simple configuration using a set of optical elements and a photosensor. It is also possible to provide an ink tank and an ink jet recording apparatus that are possible and that are effective against erroneous mounting accompanying the increase in color of ink.

In order to achieve the above object, an ink tank of the present invention includes a holding unit for detachably holding an ink tank that stores ink supplied to a recording head that performs recording on a recording medium using ink. A light emitting element that emits light from below to above in the direction of gravity toward the ink tank held by the holding unit, and a light receiving element that has light receiving sensitivity in a wavelength region of light emitted from the light emitting element. In an ink tank to be mounted on a recording device provided,
A casing constituting the ink tank;
A supply unit for supplying the ink to the recording head;
An atmospheric communication portion communicating with the ink tank and the outside;
A light reflecting member that is disposed in an ink chamber as an ink storage space constituted by the casing and reflects the light emitted by the light emitting element to the light receiving element;
With
The casing is a portion that becomes the bottom when the ink tank is attached to the holding portion, and at least a portion that becomes an entrance / exit path portion of the light is light transmissive,
The space between the light transmissive portion of the casing and the light reflecting member is a space where the ink exists.

  As described above, according to the present invention, by irradiating the light reflecting member provided in the ink tank with light and detecting the reflected light of the light, the presence or absence of the ink tank and the presence or absence of the ink in the ink tank are detected. As well as the color of the ink. This is possible even when the ink tank structure is common to each color, and in particular, by applying the present invention to an ink jet recording apparatus equipped with a plurality of ink tanks having different ink colors, With only the above-described configuration, it is possible to detect erroneous mounting of the ink tank.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing a partial schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is an external perspective view of an example of an ink cartridge mounted on the carriage shown in FIG.

  The recording head 1 is an ink jet recording head that performs recording on a recording medium (not shown) by discharging ink, and is detachably connected to an ink tank 20 that stores ink to be supplied to the recording head 1. The The recording head 1 and the ink tank 20 constitute an ink cartridge. In this embodiment, the recording head 1 and the ink tank 20 are separable ink cartridges, but they may be integrated so as not to be separable. In either case, the ink cartridge is detachably held on the carriage 2 that is a holding portion. The recording head 1 is provided with means (for example, an electrothermal converter or a laser beam) that generates thermal energy as energy used for ejecting ink, and is in an ink state by the thermal energy. It uses a system that causes changes, thereby achieving higher recording density and higher definition. The ink ejection method is not limited to this, and an ink ejection method using an electromechanical conversion element such as a piezo element is also applicable to the present invention. Further, the recording head 1 may be integrated with the carriage 2 and only the ink tank 20 may be detached from the carriage 2.

  The recording head 1 is detachably mounted on the carriage 2 so as to eject ink downward in FIG. The carriage 2 is slidably provided on a guide shaft 3 supported by the frame of the ink jet recording apparatus. Further, a portion of a timing belt (not shown) driven by rotation of a carriage motor (not shown) is fixed to the carriage 2, and the carriage 2 is rotated forward and backward so that the carriage 2 is guided by the guide shaft 3. Along the direction of arrow E.

  A recording medium on which recording is performed by the recording head 1 is stacked on an automatic paper feeder (not shown). By driving the automatic paper feeder, the recording media loaded on the automatic paper feeder are sent out one by one. The recording medium sent out from the automatic paper feeder is placed on a platen (not shown) disposed in a region facing the recording head 1 by a transport mechanism including transport rollers, paper discharge rollers, and the like (both not shown). Is conveyed in a direction intersecting with the moving direction of the carriage 2. The operation of the automatic paper feeder and the operation of the transport mechanism are performed by a feed motor (not shown).

  Recording is performed on the recording medium by ejecting ink droplets from the recording head 1 while reciprocating the carriage 2. At this time, recording can be performed on the entire recording medium by intermittently feeding the recording medium at a predetermined pitch each time the carriage 2 is moved in one direction or one reciprocating movement.

  A head recovery mechanism (not shown) is provided at a portion facing the recording head 1 when the carriage 2 is positioned at a home position that is one end of the carriage 2 reciprocating movement range. The head recovery mechanism is a mechanism for maintaining a good discharge state of the recording head 1, and includes a cap (not shown) for capping the recording head 1, a wiper (not shown) for wiping the ink discharge surface of the recording head 1, and a recording head. A suction pump (not shown) for forcibly sucking ink from one ink discharge nozzle is provided.

  An optical unit 14 is installed adjacent to the head recovery mechanism. The optical unit 14 is an optical sensor used to detect whether or not the ink tank 20 is mounted on the carriage 2 and the remaining amount of ink in the ink tank 20 and to determine the color of the ink. The light emitting element 15 that emits light and the light receiving element 16 that has light receiving sensitivity in the wavelength region of the light emitted from the light emitting element 15 are included. In the optical unit 14, when the carriage 2 moves directly above, the light emitting element 15 irradiates light, which will be described later, of the ink tank 20 mounted on the carriage 2 (see also FIG. 3). The direction is fixed. That is, the light emitting element 15 emits light from the lower side to the upper side in the direction of gravity. For example, an LED can be used as the light emitting element 15, and a phototransistor can be used as the light receiving element 16, for example. Here, the light emitting element 15 and the light receiving element 16 are installed as one unit, but may be installed separately.

  In this configuration example, the ink tank 20 is detachably mounted on the tank holder 7 in which the recording head 1 is integrally provided. The tank holder 7 and the ink tank 20 constitute an ink cartridge. Accordingly, the ink tank 20 can be detached from the carriage 2 (see FIG. 1) alone or as an ink cartridge.

  In this example, the ink tank 20 mounted on the tank holder 7 includes three types of ink tanks 20C: an ink tank 20C that stores cyan ink, an ink tank 20Y that stores yellow ink, and an ink tank 20M that stores magenta ink. , 20Y, 20M, which are detachable independently of each other. The ink tanks 20C, 20Y, and 20M can be attached to and detached from the tank holder 7 by using a lever 22e provided on the outer wall of the ink tanks 20C, 20Y, and 20M.

  When detecting the presence / absence of the ink tanks 20C, 20Y, and 20M, detecting the presence / absence of ink in the ink tanks 20C, 20Y, and 20M, and determining the color of the ink, these ink tanks 20C, 20Y, and 20M are connected to the optical unit 14 (FIG. 1), the carriage 2 (see FIG. 1) is moved so as to pass sequentially. As long as the carriage 2 and the optical unit 14 move relatively in the arrangement direction of the ink tanks 20C, 20Y, and 20M, the optical unit 14 may be moved while the carriage 2 is stopped. Both may be moved.

  In the following description, the ink tanks 20C, 20Y, and 20 are not particularly distinguished, and are simply referred to as “ink tank 20”. Here, a case where the number of ink tanks 20 to be mounted is three is described as an example, but the number of ink tanks to be mounted is not limited to this, and may be one or two. It is possible to mount as many ink tanks as necessary to achieve the required recording even if there are more than two.

  In the present invention, ink means all liquid ejected from an ink jet recording head and attached to a recording medium at the time of recording. In addition to colored ink, for example, recording is performed to prevent ink bleeding. It also includes a processing liquid that is attached to the recording medium before or after the ink is attached to the medium. Therefore, in the case of ink color, the color includes colorlessness.

  Next, the configuration of the ink tank will be described with reference to FIG. FIG. 3 is a cross-sectional view of the ink tank 20 shown in FIG.

  The ink tank 20 has a cup portion 22 and a lid portion 21 and stores ink using a space formed in a casing 23 constituted by these as an ink chamber. The inside of the housing 23 is partitioned into two spaces by a partition wall 22a formed in the cup portion 22 having a communication portion 22c in the lower portion. One space is an ink storage chamber 25 that is sealed except for the communication portion 22c and directly stores ink. The other space is a negative pressure generating member storage chamber 24 that stores a negative pressure generating member 26 that absorbs and holds ink. In order to supply ink to the recording head 1 (see FIG. 2), the ink tank 20 is attached to the tank holder 7 (see FIG. 2) to record on the wall surface forming the negative pressure generating member storage chamber 24. An ink supply port 22b connected to the head 1 and an air communication port 21a for communicating the inside and the outside of the ink tank 20 for introducing the air into the ink tank 20 from the outside as the ink is consumed are formed. Has been. In the posture when the ink tank 20 is used (posture in a state where the ink tank 20 is installed so as to be capable of recording operation), the atmosphere communication port 21a is positioned above and the ink supply port 22b is positioned below. The air communication port 21 a is formed in the lid portion 21, and the ink supply port 22 b is formed in the bottom wall of the cup portion 22.

  On the wall surface of the partition wall 22a on the negative pressure generating member storage chamber 24 side, the air is quickly introduced from the negative pressure generating member storage chamber 24 to the ink storage chamber 25, and the ink level in the negative pressure generating member is specified. As a structure for stabilizing the position, a gas introduction groove 22d extending upward from the communication portion 22c is formed. Although air introduction is possible without providing the gas introduction groove 22d, more stable ink supply can be performed. Further, in the interior of the negative pressure generating member storage chamber 24, the space around the atmosphere communication port 21a is a space (buffer portion) where the negative pressure generating member 26 does not exist. Between the negative pressure generating member 26 and the ink supply port 22b, an ink lead-out member (hereinafter referred to as a recording head supply pipe) for facilitating guiding the ink absorbed by the negative pressure generating member 26 to the ink supply port 22b. (This is also referred to as a pressure contact body because the connection state is a pressure contact state.) 28 is provided.

  When ink from the negative pressure generating member 26 is consumed by the ink ejection from the recording head 1 and the gas-liquid interface 26a in the negative pressure generating member storage chamber 24 reaches the upper end of the gas introduction groove 22d, the ink is consumed thereafter. Air is introduced into the negative pressure generating member storage chamber 24 from the atmosphere communication port 21a, and the introduced air enters the ink storage chamber 25 through the communication portion 22c. Instead, the ink in the ink storage chamber 25 enters the negative pressure generation member storage chamber 24 through the communication portion 22 c and is filled in the negative pressure generation member 26. This operation is called gas-liquid exchange operation.

  Therefore, even if the ink in the negative pressure generating member storage chamber 24 is consumed by the recording head 1, the ink corresponding to the consumed amount is filled from the ink storage chamber 25 into the negative pressure generating member 26, and the negative pressure generating member storage. The gas-liquid interface 26a in the chamber 24 is maintained at a substantially constant height. That is, the negative pressure generating member 26 holds a substantially constant amount of ink, whereby the negative pressure with respect to the recording head 1 is maintained substantially constant, and the ink supply to the recording head 1 is stabilized.

  A light reflecting member 27 is installed inside the ink containing chamber 25 at the bottom. The light reflecting member 27 has two reflecting surfaces 27a and 27b which are not parallel to each other. As shown in FIG. 4, the two reflecting surfaces 27a and 27b and the bottom wall surface 22f of the ink tank 20 (cup portion 22). It is a structure configured to form a triangular prism-shaped space with both ends open. The light reflecting member 27 may be formed integrally with the cup part 22, or may be configured as a member different from the cup part 22.

  The reflection surfaces 27a and 27b reflect light that has entered the ink storage chamber 25 from the outside of the ink tank 20 through the bottom wall surface 22f of the ink tank 20 and emit the light to the outside of the ink tank 20 again. For this purpose, the housing 23 of the ink tank 20 is formed with a member that transmits light at least in a region where light enters and exits the light reflecting member 27. The light here is light emitted from the optical unit 14 (see FIG. 1) of the ink jet recording apparatus to which the ink tank 20 is mounted. An example of the member that transmits light is polypropylene.

  In addition, when the light reflecting member 27 is positioned right above the optical unit 14 so that the light reflecting member 27 can be irradiated with light from the optical unit 14 through the bottom wall surface 22f of the ink tank 20. Further, a member (for example, the carriage 2 (see FIG. 1) or the tank holder 7 (see FIG. 2)) existing between the light reflecting member 27 and the optical unit 14 is formed with an opening for allowing light to pass through. Yes.

  In the present embodiment, the reflecting surfaces 27 a and 27 b are disposed so as to be inclined with respect to the bottom wall surface 22 f of the ink tank 20 at an angle of 45 ° and face each other. As a result, light incident perpendicularly to the bottom wall surface 22f of the ink tank 20 is sequentially reflected by the two reflecting surfaces 27a and 27b, and then follows an optical path that exits perpendicularly to the bottom wall surface 22f of the ink tank 20. . That is, the light reflecting member 27 reflects light incident from a direction perpendicular to the bottom wall surface 22f of the ink tank 20 by the reflecting surfaces 27a and 27b, and emits the light in parallel and opposite to the incident light. To do. The optical unit 14 is installed so that the optical axis of the light emitted from the light emitting element 15 is perpendicular to the bottom wall surface 22 f of the ink tank 20. The reason will be described later.

  The reflecting surfaces 27a and 27b may be made of the light reflecting member 27 (a housing material when integrally molded with the housing, or a suitable material when formed separately), but the reflecting surfaces 27a and 27b It is preferable that a reflection film having a higher reflectance is attached to or formed in the region to be 27b. When the reflective surfaces 27a and 27b are formed of a reflective film, examples of the reflective film include a reflective film attached by adhesion or mechanical bonding, a reflective tape, or a metal film formed by vapor deposition. When the reflecting surfaces 27a and 27b are made of the light reflecting member 27 itself, the light reflecting member 27 is made of a metal material such as aluminum or chrome, and when the reflecting surfaces 27a and 27b are formed by mirror finishing, light reflection is performed. Efficiency is improved. The light reflecting member 27 is a member that comes into contact with the ink in the ink containing chamber 25. If the physical properties or appearance of the light reflecting member 27 changes, the light reflecting member 27 may greatly affect the detection performance such as the remaining amount of ink described later. In particular, it is preferable that the reflecting surfaces 27a and 27b are made of an ink-resistant member whose physical properties and appearance hardly change even when in contact with ink. Even when the light reflecting member 27 is formed of the same material as that of the housing, it is expected that the reflected light amount is reflected but the reflected light amount is significantly reduced. It is necessary to take measures such as raising

  The space formed between the bottom wall surface 22f of the ink tank 20 and the reflecting surfaces 27a and 27b by the light reflecting member 27 is open at both ends and communicates with the ink containing chamber 25. Accordingly, the ink freely flows between this space and the ink storage chamber 25, and the ink exists in this space at the same height as the ink liquid level in the ink storage chamber 25.

  Next, with reference to FIGS. 5A to 5C, the detection of the presence or absence of the ink tank 20, the detection of the presence or absence of ink, and the determination of the color of the ink by the optical unit 14 and the light reflecting member 27 described above will be described. explain.

(A) No tank:
When the ink tank 20 is not attached, as shown in FIG. 5A, the light emitted from the light emitting element 15 of the optical unit 14 proceeds as it is, and the light does not return to the light receiving element 16. Therefore, no output is obtained from the optical unit 14, and the control unit of the ink jet recording apparatus determines that there is no tank, that is, the ink tank 20 is not installed.

(B) With tank / With ink:
As shown in FIG. 5B, when the ink tank 20 is mounted and ink is present therein, more precisely, when ink is present at least around the light reflecting member 27. In addition, the light emitted from the light emitting element 15 passes through the housing 23 of the ink tank 20 and enters the light reflecting member 27. In the light reflecting member 27, the incident light is sequentially reflected by the two reflecting surfaces 27 a and 27 b, travels in a direction opposite to the incident direction, passes through the housing 23 again, and enters the light receiving element 16. Therefore, an output corresponding to the intensity of the light incident on the light receiving element 16 is obtained from the optical unit 14. Here, if ink is present in the ink tank 20, ink is also present in the space between the two reflecting surfaces 27 a and 27 b and the housing 23, so that the light emitted from the light emitting element 15 is In the ink tank 20, the ink advances.

(C) With tank / without ink:
When the ink tank 20 is mounted but no ink is present therein, more precisely, when no ink is present around the light reflecting member 27, the ink tank 20 is shown in FIG. As described above, the light emitted from the light emitting element 15 travels on the same optical path as that in the case where ink is present and enters the light receiving element 16. However, in this case, since no ink is present in the space between the two reflecting surfaces 27 a and 27 b and the housing 23, the light emitted from the light emitting element 15 travels in the air in the ink tank 20. .

As described above, when the ink tank 20 is mounted, the light emitted from the light emitting element 15 is reflected by the light reflecting member 27 regardless of the presence or absence of ink in the ink tank 20 and is received by the light receiving element 16. Will be detected. Here, it is assumed that the intensity of light detected by the light receiving element 16 when ink is not present is A, and the intensity of light detected by the light receiving element 16 when ink is present is B. When the intensity of light detected by the light receiving element 16 in each case is compared,
A> B
It becomes.

This is because the degree of light attenuation is higher when traveling in ink than when traveling in air. Further, when the ink tank 20 is not attached, the intensity of light detected by the light receiving element 16 is C (≈0: the influence of direct light from an adjacent light emitting element cannot be denied, but may be considered to be substantially zero. Not). In this case, since the light emitted from the light emitting element 15 is not detected by the light receiving element 16, the intensity of the light detected by the light receiving element 16 is the smallest among the above three cases (a) to (c). As a result, between these light intensities,
A>B> C
There is a relationship.

  An output signal corresponding to the intensity of incident light is obtained from the optical unit 14. That is, different output signals are obtained from the optical unit 14 in each case of FIGS. If the relationship between each state of FIGS. 5A to 5C and the output signal from the optical unit 14 is associated in advance, one light reflecting member 27 provided in the ink tank 20 and the ink jet recording apparatus are provided. The presence or absence of the ink tank 20 and the presence or absence of ink can be detected by one optical unit 14 provided on the main body side. It should be noted that by increasing the detection accuracy, it is also possible to detect the amount of light attenuation and detect the amount of ink below the light reflecting member 27 linearly.

  The light is attenuated by passing through the ink, but the wavelength of the attenuated light differs depending on the type (color) of the ink. Therefore, when the light emitted from the light emitting element 15 is transmitted through the ink, the intensity of the light incident on the light receiving element 16 varies depending on the color of the transmitted ink. Therefore, the ink color can also be determined from the output signal of the optical unit 14. In order to improve the discrimination accuracy of the ink color, the wavelength included in the light emitted from the light emitting element 15 is appropriately set so that the difference between the output signals obtained according to the color of the ink to be detected becomes as large as possible. It is preferable to select.

  By determining the color of the ink, it can be determined whether or not the mounted ink tank 20 is mounted at an appropriate position, thereby preventing erroneous mounting of the ink tank 20. Further, since the light reflecting member 27, which is a structure for discriminating the color of ink, is common to the ink tanks 20 of each color, it is not necessary to prepare the casing 23 of the ink tank 20 for each color of ink, and is common to each color. And greatly contributes to reduction in manufacturing cost and size reduction of the ink tank 20.

  In the detection system using the conventional prism, the optical path length passing through the solid is long, and the light is easily attenuated accordingly. On the other hand, in the present embodiment, most of the detection light passes through the gas or liquid except when it passes through the casing 23 of the ink tank 20. Therefore, there is little useless attenuation of light, and the light emitted from the light emitting element 15 can be used efficiently.

  In the embodiment described above, the light reflecting member 27 forms a triangular prism-like space communicating with the ink storage chamber 25 in the rectangular parallelepiped structure as shown in FIG. Therefore, the light reflecting member 27 has a thick portion and a thin portion. When the light reflecting member 27 is molded from resin, especially polypropylene having a high heat shrinkage rate, sink marks are generated in the reflecting surfaces 27a and 27b in the thick portion, and the reflection efficiency of incident light may be lowered. . Therefore, as shown in FIGS. 6A and 6B, it is preferable to make the thickness of the light reflecting members 37 and 38 substantially uniform to obtain the reflecting surfaces 37a and 38a having desired flatness. . The light reflecting member 37 shown in FIG. 6A is an example in which the outer surface is also a flat surface, and the light reflecting member 38 shown in FIG. 6B is an example in which the outer ridge lines are connected by a curved surface. . In this manner, the outer shape of the light reflecting members 37 and 38 is arbitrary as long as the reflecting surfaces 37a and 38a are formed in a desired shape.

  Referring to FIG. 3, in the present embodiment, the case where the ink reflecting chamber 27 is set as the position where the light reflecting member 27 is installed has been described as an example, but it may be in the negative pressure generating member storing chamber 24. . In this case, since the negative pressure generating member 26 covers the light reflecting member 27 and is inserted into the negative pressure generating member storage chamber 24, the negative pressure generating member 26 hardly exists in the space inside the light reflecting member 27. Instead, only ink is present. Therefore, even if the light reflecting member 27 is installed in the negative pressure generating member storage chamber 24, the negative pressure generating member 26 hardly affects the above-described presence / absence of the tank, detection of the remaining ink amount, and discrimination of the ink color. Therefore, the light reflecting member 27 can be applied to both an ink tank having only an ink storage chamber as an ink chamber and an ink tank having only a negative pressure generating member storage chamber. However, in the case where the light reflection member 27 is used to form a space where ink is present in the negative pressure generating member, it is in the space when the gas-liquid interface in the negative pressure generating member reaches the space due to ink consumption. Since the ink is absorbed by the negative pressure generating member, it is necessary to devise the arrangement location, the volume of the space, and the like when adopting this configuration.

  In the above-described embodiment, the light reflecting member 27 repeats the reflection in the prism-shaped space twice, and emits the light incident from the outside of the ink tank 20 to the outside of the ink tank 20 again. A configuration of a simple plate-like light reflecting member 47 as shown in FIG. 7 is also conceivable.

  The light reflecting member 47 shown in FIG. 7 is a flat plate disposed in the ink chamber of the ink tank 40 so as to face the wall surface of the housing 43 of the ink tank 40 and to be parallel to the wall surface of the housing 43. The surface facing the wall surface is a reflecting surface 47a. The wall surface of the housing 43 facing the light reflecting member 47 may be a bottom wall surface or a side wall surface. In the space between the reflecting surface 47 a of the light reflecting member 47 and the housing 43, ink freely circulates between the ink chamber in which the light reflecting member 47 is disposed.

  The light emitted from the light emitting element 15 of the optical unit 14 passes through the housing 43 of the ink tank 40, travels into the ink chamber, and is reflected by the reflecting surface 47 a of the light reflecting member 47. The reflected light passes through the housing 43 again and enters the light receiving element 16. At this time, as described above, the presence or absence of ink in the ink tank 40 and the color of the ink can be determined from the intensity of light detected by the light receiving element 16. The presence or absence of the ink tank 40 can also be detected based on whether or not the reflected light from the reflecting surface 47a is detected.

  In the conventional ink jet recording apparatus, the optical reflecting member provided inside the ink tank is used only for detecting the remaining amount of ink in the ink tank, and regarding the presence or absence of the ink tank, the electrical connection between the ink tank and the ink jet recording apparatus It was detected using. On the other hand, in the present invention, the ink jet recording apparatus can detect not only the remaining amount of ink in the ink tank 40 but also the presence or absence of the ink tank 40 from the presence and intensity of light detected by the light receiving element 16, and as a result, The configuration of the ink tank 40 and the ink jet recording apparatus can be simplified.

  As described above, when light is incident on the plate-like light reflecting member 47 from the optical unit 14, the light from the optical unit 14 is used to reduce the size of the optical unit 14 and the size of the inkjet recording apparatus. The incident angle to the reflecting surface 47a is preferably small. If the incident angle is small, the light reflecting member 47 is formed of a transparent member, and if the reflecting surface 47a is formed of the light reflecting member 47 itself, light is not reflected but is transmitted. Therefore, in such a case, it is preferable that the light reflecting member 47 is made of metal as described above, or that a processing such as providing a reflecting film on the light reflecting surface 47a is performed.

  In the example shown in FIG. 7, light emitted from the light emitting element 15 in an oblique direction with respect to the wall surface of the housing 43 is used. For this, the direction of the optical axis of the light emitting element 15 is adjusted. Alternatively, the intensity of light is slightly reduced, but this can be dealt with by using a light component that has not been condensed when emitted from the light emitting element 15. 7 shows an example in which the light reflecting member 47 is arranged in parallel to the wall surface of the housing 43. However, the light reflecting member 47 is not necessarily parallel if it can reflect the light emitted from the light emitting element 15 and return it to the light receiving element 16. Good.

  Here, the detection sensitivities of the configuration shown in FIG. 5 and the configuration shown in FIG. 7 are compared.

  As shown in FIG. 7, the distance from the light emitting element 15 and the light receiving element 16 to the reflection position of the light from the light emitting element 15 on the reflection surface 47a in the direction perpendicular to the wall surface of the casing 43 is L1, The distance between the centers of the light emitting element 15 and the light receiving element 16 in the direction parallel to the wall surface 43 is L2. Also, as shown in FIG. 8, the distances L1 and L2 are also defined for the prism-type light reflecting member 27 shown in FIG.

First, the optical path length La until the light emitted from the light emitting element 15 enters the light receiving element 16 in the prism type light reflecting member 27 is obtained. The two reflecting surfaces 27a and 27b are arranged as described above, and the traveling direction of the light from the light emitting element 15 to the reflecting surface 27a and the traveling direction of the light reflected by the reflecting surface 27b are perpendicular to the wall surface of the housing 23. And the traveling direction of the light reflected by the reflecting surface 27a is parallel to the wall surface of the housing 23.
Optical path length La = 2L1 + L2 (1)
It is represented by

  On the other hand, the optical path length Lb from the light emitting element 15 to the light receiving element 16 in the flat light reflecting member 47 shown in FIG.

It is represented by

  From equations (1) and (2), it can be seen that La> Lb. Therefore, the prism type configuration having a longer optical path length has a greater intensity difference between the light emitted from the light emitting element 15 and the light incident on the light receiving element 16 than the Lambert-Beer law. Presence / absence detection and ink color discrimination are possible.

  The ink tank to which the present invention is applied is detachable from the inkjet recording apparatus, and the optical unit is installed in the inkjet recording apparatus. Therefore, variations in the distance between the optical unit and the light reflecting member due to dimensional tolerances and assembly tolerances of each part are unavoidable. Therefore, the change in the optical path when this distance changes will be described with reference to FIG.

  First, in the prism-type light reflecting member 27 shown in FIG. 9A, the light incident perpendicularly to the wall surface of the casing 23 of the ink tank 20 from the optical unit 14 is again emitted perpendicularly to the wall surface of the casing 23. Therefore, even if the distance between the optical unit 14 and the light reflecting member 27 in the direction perpendicular to the wall surface of the housing 23 is X, the light is incident from the light emitting element 15 and is reflected by the reflecting surfaces 27a and 27b. The reflected light is incident on the light receiving element 16. The same applies when the distance between the optical unit 14 and the light reflecting member 27 is close.

  On the other hand, in the flat light reflecting member 47 shown in FIG. 9B, light obliquely incident on the wall surface of the housing 43 is used, so that the distance between the optical unit 14 and the light reflecting member 47 is X. The light reflected by the reflecting surface 47a does not enter the light receiving element 16 when the distance is away from the light receiving element 16. The same applies when the distance between the optical unit 14 and the light reflecting member 47 is close. For this, the reflecting surface is adjusted so that the emission direction changes depending on the incident position of the light by adjusting the irradiation angle of the light emitting element 15 or changing the incident position on the reflecting surface 47a when the distance X changes. This can be dealt with by devising the shape of 47a or by managing the component dimensional tolerance and assembly tolerance more accurately. However, when compared with the prism-type light reflecting member 27, the prism-type light reflecting member 27 which does not require such adjustment is more preferable.

  FIG. 10 shows another example of a prism type light reflecting member. The light reflecting member 57 shown in FIG. 10 is a structure that is installed on the inner wall surface of the casing 53 by forming a prism-shaped space between the inner wall surface of the casing 53 of the ink tank 50 and has three reflections. Surfaces 57a, 57b, and 57c are provided. The space formed between the wall surface of the casing 53 and the reflecting surfaces 57a, 57b, 57c of the light reflecting member 57 has a trapezoidal cross section, and the ink in the ink chamber in which the light reflecting member 57 is provided is this space. This space communicates with the ink chamber so that it can freely flow between the ink chamber and the ink chamber. In each of the reflecting surfaces 57a, 57b, and 57c, the light incident perpendicularly to the wall surface of the housing 53 is sequentially reflected by the reflecting surfaces 57a, 57b, and 57c, and again to the outside of the housing 53, the wall surface of the housing 53. The angle with respect to the inner wall surface of the casing 53 is set so that the light is emitted in a direction perpendicular to the inner wall. The wall surface of the housing 53 on which the light reflecting member 47 is provided may be a bottom wall surface or a side wall surface.

  As described above, even when the three reflection surfaces 57a, 57b, and 7c are provided, the relationship of A> B> C described above does not change, and the ink tank 50 can be determined from the intensity of light detected by the light receiving element 16. The presence / absence and presence / absence of ink can be detected, and the color of the ink can be further determined.

  Regarding the discrimination of the color of the ink, in the above-described example, the wavelength of the light emitted from the light emitting element 15 is set to a wavelength that is easily attenuated (is easily absorbed) when passing through the ink to be discriminated. However, in this case, it is necessary to find light of an appropriate wavelength having a difference in the degree of attenuation for each color ink. Therefore, the light emitting element 15 has a variable wavelength of emitted light so that light of a wavelength in a region where the absorbance in each ink color reaches a peak can be irradiated for each ink tank. The difference in the intensity of incident light becomes larger for each ink color, and the ink color can be easily determined.

1 is a plan view showing a partial schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is an external perspective view of an example of an ink cartridge mounted on a carriage illustrated in FIG. 1. It is sectional drawing of the ink tank shown in FIG. It is a perspective view of the light reflection member shown in FIG. It is a figure explaining the mode of detection in various cases by an optical unit and a light reflection member in one embodiment of the present invention. (A) (b) is a perspective view which shows the other example of a light reflection member, respectively. It is a figure which shows the other structural example of a light reflection member, and is a figure which shows the example of the light reflection member which has one reflective surface. It is a figure explaining the optical path length of the light radiate | emitted from the optical unit in the example shown in FIG. (A) is a figure explaining the difference in an optical path when the distance of the optical unit and light reflection member in the example shown in FIG. 5 changes. (B) is a figure explaining the difference in an optical path when the distance of the optical unit and light reflection member in the example shown in FIG. 7 changes. (A) is a perspective view which shows the other example of a multi-surface type light reflection member, (b) is a figure which shows the optical path of the said light reflection member. (A) (b) (c) is a figure which shows the structure of the optical detection means of the conventional ink tank, respectively. It is a figure explaining the mode of reflection of the optical detection means of the conventional ink tank shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording head 2 Carriage 14 Optical unit 15 Light emitting element 16 Light receiving element 20 Ink tank 23 Case 21a Atmospheric communication port 22b Ink supply port 25 Ink storage chamber 27, 37, 38, 47, 57 Light reflecting member 27a, 27b, 47a, 57a, 57b, 57c Reflective surface

Claims (7)

A holding unit for detachably holding an ink tank for storing ink supplied to a recording head for recording on a recording medium using ink; and toward the ink tank held by the holding unit In an ink tank mounted on a recording apparatus comprising: a light emitting element that emits light from below to above in the direction of gravity; and a light receiving element that has light receiving sensitivity in a wavelength region of light emitted from the light emitting element. ,
A casing constituting the ink tank;
A supply unit for supplying the ink to the recording head;
An atmospheric communication portion communicating with the ink tank and the outside;
A light reflecting member that is disposed in an ink chamber as an ink storage space constituted by the casing and reflects the light emitted by the light emitting element to the light receiving element;
With
The casing is a portion that becomes the bottom when the ink tank is attached to the holding portion, and at least a portion that becomes an entrance / exit path portion of the light is light transmissive,
An ink tank, wherein a space between the light transmissive portion of the casing and the light reflecting member is a space where the ink exists.   The ink tank according to claim 1, wherein the light reflecting member is configured by a flat plate that returns light from the light emitting element to the light receiving element by one reflection.   2. The ink tank according to claim 1, wherein the light reflecting member is a polyhedron configured to return light from the light emitting element to the light receiving element by a plurality of reflections.   The light reflecting member has two reflecting surfaces that sequentially reflect light incident on the ink chamber, and the prism-shaped space is formed between the two reflecting surfaces and the inner wall surface of the housing. The ink tank according to claim 3, wherein the ink tank is a structure provided integrally with the casing.   The angle of the plurality of reflecting surfaces is set so that light incident into the ink chamber perpendicular to the wall surface constituting the housing is emitted out of the ink chamber perpendicular to the wall surface. The ink tank according to 3 or 4.   The ink tank according to claim 1, wherein ink is contained in the ink chamber. In an inkjet recording apparatus that performs recording by ejecting ink from a recording head onto a recording medium,
An ink tank for storing ink to be supplied to the recording head, the light reflecting member disposed in the ink chamber constituting the ink storage space of the ink tank, and the bottom portion when the ink tank is used A light transmissive housing, and an ink tank configured as a space in which the ink exists is detachable between the light transmissive portion of the housing and the light reflecting member. A holding part for holding;
A light emitting element that emits light upward from below in the direction of gravity toward the ink tank held by the holding unit;
A light receiving element that has light receiving sensitivity in a wavelength region of light emitted from the light emitting element, and that receives light emitted from the light emitting element and reflected by the light reflecting member;
An inkjet recording apparatus, wherein the light emitting element has a variable wavelength of emitted light.

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