Liquid dispensing device

Abstract

To detect existence / non-existence of an ink in an ink tank and an ink cartridge with one detection means.SOLUTION: A liquid discharge device includes: an ink cartridge 41 having a first ink storage part in which an ink is stored; an ink tank 31 which is connected to the ink cartridge and has a second ink storage part; and detection means having a floodlight part 52 which projects detection light and a light receiving part 53 which receives the detection light. The ink cartridge 41 has a first projection 42. The ink tank 31 has a recessed part 31a and a second projection 32. The floodlight part 52 and the light receiving part 53 are disposed at the recessed part 31a. The first projection 42 and the second projection 32 are arranged between the floodlight part 52 and the light receiving part 43.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device that ejects liquid. [Background technology]

[0002] A known liquid ejection device includes an ink cartridge containing a liquid such as ink, an ink tank connected to the ink cartridge and supplied with ink from the ink cartridge, and an ink ejection head that ejects the ink in the ink tank. The ink tank is connected to the ink ejection head via a tube. An inkjet device is one example of a liquid ejection device. In this liquid ejection device, if the liquid in the ink tank runs out, the liquid can no longer be ejected. Therefore, a detection means is required to detect the presence or absence of liquid in the ink cartridge or ink tank.

[0003] Patent Document 1 describes a recording device in which a recording head and an ink tank that supplies ink to the recording head are mounted on a carriage. An optical prism for detecting the presence or absence of ink is provided on the bottom surface of the ink tank. An optical unit (detection means for detecting the presence or absence of liquid) equipped with a light-emitting means and a light-receiving means is disposed in a position facing the bottom surface of the ink tank on the path along which the carriage passes. When the carriage passes over the optical unit, the light-emitting means irradiates light onto the optical prism. The light-receiving means receives light reflected from the optical prism. The presence or absence of ink can be detected based on the light-receiving result. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3530727 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the recording device described in Patent Document 1, a single detection means can only detect the presence or absence of ink in an ink tank. In other words, if it is also desired to detect the presence or absence of ink in an ink cartridge, a separate detection means must be provided for the ink cartridge, which increases the cost of the liquid ejection device. Furthermore, providing a detection means for the ink cartridge would increase the size of the liquid ejection device.

[0006] In view of the above problems, an object of the present invention is to detect the presence or absence of ink in both an ink tank and an ink cartridge using a single detection means. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a liquid ejection device having an ink cartridge having a first ink storage section for storing ink, an ink tank having a second ink storage section connected to the ink cartridge and to which ink from the ink cartridge is supplied, and detection means having a light-emitting section for emitting detection light and a light-receiving section for receiving the detection light, wherein the ink cartridge 1st a first protrusion communicating with an ink storage section, the ink tank having a recess and a second protrusion communicating with the second ink storage section, the recess having: the detecting means is arranged, and the first protrusion and the second protrusion are arranged between the light emitting portion and the light receiving portion. [Effects of the Invention]

[0008] According to the present invention, the presence or absence of ink in both the ink tank and the ink cartridge can be detected by a single detection means, thereby preventing increases in cost and size of the liquid ejection device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating the appearance of a liquid ejection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the main structure of the recording portion of the liquid ejection device shown in FIG. [Figure 3] FIG. 2 is a perspective view schematically illustrating a general configuration of a liquid storage section. [Figure 4] FIG. 2 is a perspective view schematically illustrating the configuration of an ink cartridge. [Figure 5] FIG. 2 is a perspective view schematically illustrating a configuration of an optical sensor. [Figure 6] FIG. 2 is a perspective view schematically illustrating the configuration of an ink tank. [Figure 7] 3A and 3B are schematic diagrams for explaining the state of passage and blocking of detection light in the optical sensor. [Figure 8] FIG. 2 is a block diagram showing the configuration of a portion related to control of the liquid detection operation. [Figure 9] 10 is a flowchart showing the flow of a recording operation of the liquid ejection device. [Figure 10] FIG. 10 is a perspective view schematically illustrating the configuration of an ink tank used in a liquid ejection device according to a second embodiment of the present invention. [Figure 11] FIG. 2 is a schematic diagram for explaining a float plate. [Figure 12] FIG. 2 is a schematic diagram for explaining a light-shielding plate. [Figure 13] 3A and 3B are schematic diagrams for explaining the state of passage and blocking of detection light in the optical sensor. [Figure 14] 10 is a flowchart showing the flow of a recording operation of the liquid ejection device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions, and the scope of the present invention is not limited to the following embodiments.

[0011] (First embodiment) FIG. 1 is a schematic diagram showing the appearance of a liquid ejection device according to a first embodiment of the present invention. The liquid ejection device 10 shown in FIG. 1 has an input unit 11, an output unit 12, a liquid storage unit 13, and an operation panel unit 14. The input unit 11 is used to input print media such as paper. The output unit 12 is used to eject printed matter. The liquid storage unit 13 stores liquid such as ink. The operation panel unit 14 accepts input operations such as printing operations. This liquid ejection device 10 can be called a so-called inkjet recording device.

[0012] Next, we will explain the structure of the recording portion of the liquid ejection device 10. Figure 2 is a schematic diagram showing the main structure of the recording portion of the liquid ejection device 10. The liquid ejection device 10 has a cassette 24, a paper feed roller 25, a paper discharge roller 26, a positioning roller 27, a recording head 23, a liquid tube 22, and a liquid storage unit 13.

[0013] The cassette 24 is a box-shaped container that can store multiple sheets of recording paper as printing media in a stacked state. The cassette 24 is equipped with a slide mechanism that allows it to be moved horizontally in and out of the main body of the liquid ejection device 10. The cassette 24 is pulled out and paper is loaded. After loading the paper, the cassette 24 is pushed back in. Movable guides are installed in two locations inside the cassette 24, one in the width direction and one in the depth direction. Even when storing paper of different sizes, such as A4 size or postcard size, the guides make it possible to store the paper aligned based on the center.

[0014] A paper feed roller 25 is provided in each of the input section 11 and the cassette 24. The rotation of the paper feed roller 25 allows it to pick up the recording paper stored in the cassette 24 one sheet at a time. Similarly, the rotation of the paper feed roller 25 in the input section 11 allows it to pick up the recording paper one sheet at a time. The rotation speed of the paper feed roller 25 is adjustable. The surface of the paper feed roller 25 that comes into contact with the paper is wrapped with rubber that has a wave pattern known as elephant skin. The recording paper picked up by the paper feed roller 25 is directed toward the positioning roller 27.

[0015] The positioning roller 27 transports the recording paper transported from the paper feed roller 25 toward the recording head 23. Two rollers, one above the other, sandwich the recording paper between them. One roller is rotated by a motor, and the other roller rotates accordingly. The recording paper is sandwiched between the upper and lower rollers and transported with high precision so that the distance between the recording head 23 and the recording paper is maintained within a certain range. To achieve high-precision transportation, friction between the surface of each roller and the recording paper is important. The roller surfaces are covered with paint containing ceramic particles, for example.

[0016] The recording head 23 prints on the recording paper by ejecting droplets while moving in a direction perpendicular to the conveyance direction of the recording paper. For example, it is possible to record an image on the recording paper based on a document or image data provided from a personal computer (not shown). The recording paper that has passed the recording head 23 heads toward the paper ejection roller 26. The paper ejection roller 26 ejects the recording paper that has passed the recording head 23 out of the liquid ejection device 10. The liquid storage unit 13 supplies the liquid to the recording head 23 via the liquid tubes 22. When liquids of multiple colors are supplied to the recording head 23, a liquid tube 22 is provided for each color of liquid. The liquid tubes 22 have a sufficient length so as not to limit the movable range of the recording head 23.

[0017] The configuration of the liquid storage unit 13 will be described below with reference to the drawings. FIG. 3 shows a schematic configuration of the liquid storage unit 13. The liquid storage unit 13 has an ink cartridge 41 that stores liquid such as ink, an ink tank 31 that is connected to the ink cartridge 41 and to which liquid is supplied from the ink cartridge 41, and an optical sensor 51. The optical sensor 51 can detect the presence or absence of liquid in the ink tank 31 and the ink cartridge 41. The ink tank 31, ink cartridge 41, and optical sensor 51 are provided for each color of liquid. Liquid of each color has the property of absorbing or reflecting detection light (hereinafter referred to as detection light) used by the optical sensor 51. Hereinafter, the liquid may be referred to as ink.

[0018] Figure 4 shows the configuration of the ink cartridge 41. The ink cartridge 41 has a first ink storage section 44 that stores ink, a first protrusion 42, and a liquid discharge section 43. When the ink cartridge 41 is connected to the ink tank 31, the liquid stored in the ink cartridge 41 is supplied to the ink tank 31 via the liquid discharge section 43. The first protrusion 42 is inserted into a recess on the ink tank 31 side. Because the first protrusion 42 communicates with the first ink storage section 44, when the ink cartridge 41 is filled with ink, ink is also stored in the first protrusion 42. The first protrusion 42 is made of a material that is transparent to the detection light used in the optical sensor 51. The first protrusion 42 has a space that is in communication with the space that contains the liquid inside the ink cartridge 41. The height from the bottom of the ink cartridge 41 to the top end of the first protrusion 42 is h1. If the liquid level inside the ink cartridge 41 exceeds height h1, the first protrusion 42 will be filled with liquid. The liquid level inside the first protrusion 42 will match the liquid level inside the ink cartridge 41.

[0019] 5 shows the configuration of the optical sensor 51. The optical sensor 51 includes a light-projecting unit 52 that projects detection light and a light-receiving unit 53 that is disposed opposite the light-projecting unit 52 and receives the detection light, and outputs a signal indicating whether or not the detection light is received. The optical sensor 51 is a concave member that includes a first side surface 52a on which the light-projecting unit 52 is disposed and a second side surface 53a that faces the first side surface 52a and on which the light-receiving unit 53 is disposed. The light-projecting unit 52 and the light-receiving unit 53 are disposed within the recess of the ink tank 31. The detection light emitted by light-emitting unit 52 travels along optical path 54 and reaches light-receiving unit 53. The output signal of optical sensor 51 has a first signal level when light-receiving unit 53 is receiving the detection light, and a second signal level when light-receiving unit 53 is not receiving the detection light. A state in which light-receiving unit 53 is not receiving the detection light refers, for example, to a state in which the detection light traveling along optical path 54 is blocked by some means. Here, the first signal level indicates an ON state, and the second signal level indicates an OFF state.

[0020] Figure 6 is a diagram for explaining the configuration of the ink tank 31. Figure 6(a) is a perspective view of the ink tank 31. Figure 6(b) is a front view of the ink tank 31. As shown in Figures 6(a) and 6(b), the ink tank 31 has a second ink storage section 37 that stores ink, a recess 31a, a second protrusion 32, and a flow path 33. The ink tank 31 is connected to the ink cartridge 41 with the first protrusion 42 of the ink cartridge 41 inserted into the recess 31a. When the ink cartridge 41 and the ink tank 31 are connected, the liquid discharge section 43 of the ink cartridge 41 abuts against the flow path 33 of the ink tank 31, and liquid in the ink cartridge 41 flows into the ink tank 31. The recess 31a can accommodate an optical sensor 51 made of a concave member. The second protrusion 32 is part of the ink tank 31. In other words, the second protrusion 32 communicates with the second ink storage section 37, and when the ink tank 31 is filled with ink, ink is also stored in the second protrusion 32.

[0021] The second protrusion 32 is made of a material that is transparent to the detection light used in the optical sensor 51. The second protrusion 32 protrudes from the inner surface of the recess 31a so as to intersect with the optical path 54 of the optical sensor 51. As described above, the second protrusion 32 and the space (second ink storage section 37) that stores the liquid in the ink tank 31 are in communication. Therefore, the liquid in the ink tank 31 flows into the space inside the second protrusion 32. The height of the liquid surface inside the second protrusion 32 is the same as the height of the liquid surface inside the ink tank 31. The height from the bottom of the ink tank 31 to the top of the second protrusion 32 is h2. If the height of the liquid surface inside the ink tank 31 is equal to or greater than h2, the second protrusion 32 is filled with liquid.

[0022] The height from the bottom of the ink tank 31 to the optical path 54 is h3. Liquid has the property of absorbing or reflecting the detection light emitted by the light-emitting unit 52. Therefore, when the height of the liquid surface in the ink tank 31 is equal to or greater than h3, the detection light is blocked by the liquid in the second protrusion 32. When the height of the liquid surface in the ink tank 31 is less than h3, the detection light passes through the second protrusion 32. Here, height h3 is an example of a predetermined height. When the ink cartridge 41 and ink tank 31 are connected, the first protrusion 42 and the second protrusion 32 are arranged in parallel on the optical path 54 of the optical sensor 51. The first protrusion 42 and the second protrusion 32 are arranged in parallel in a direction perpendicular to the insertion direction of the ink cartridge 41 and perpendicular to the vertical direction. The first protrusion 42 is arranged closer to the light-emitting unit 52 than the second protrusion 32.

[0023] When the liquid level in the second protrusion 32 is located above the optical path 54, the detection light emitted by the light-emitting unit 52 is blocked by the liquid in the second protrusion 32. When the liquid level in the second protrusion 32 is located below the optical path 54, the detection light emitted by the light-emitting unit 52 passes through the second protrusion 32 and enters the light-receiving unit 53. Similarly, when the liquid level in the first protrusion 42 is located above the optical path 54, the detection light emitted by the light-emitting unit 52 is blocked by the liquid in the first protrusion 42. When the liquid level in the first protrusion 42 is located below the optical path 54, the detection light emitted by the light-emitting unit 52 passes through the first protrusion 42.

[0024] 7 is a schematic diagram showing the state of passing and blocking of detection light in the optical sensor 51. The operation of the optical sensor 51 will be described in detail below with reference to FIG. FIG. 7(a) shows a state in which the ink cartridge 41 is not connected to the ink tank 31. Only the second protrusion 32 of the ink tank 31 is arranged in the optical path 54, and the first protrusion 42 of the ink cartridge 41 is not arranged. No liquid is present in the second protrusion 32. In this case, the detection light emitted by the light-emitting unit 52 passes through the second protrusion 32 and enters the light-receiving unit 53. The optical sensor 51 outputs a signal indicating an ON state.

[0025] FIG. 7(b) shows a state in which the ink cartridge 41 is connected to the ink tank 31, and the second protrusion 32 of the ink tank 31 and the first protrusion 42 of the ink cartridge 41 are arranged in the optical path 54. No liquid is present in the second protrusion 32. Similarly, no liquid is present in the first protrusion 42. In this case, the detection light emitted by the light-emitting unit 52 passes through the first protrusion 42 and the second protrusion 32 in this order and enters the light-receiving unit 53. The optical sensor 51 outputs a signal indicating an ON state.

[0026] FIG. 7(c) shows a state in which the ink cartridge 41 is connected to the ink tank 31, and the second protrusion 32 of the ink tank 31 and the first protrusion 42 of the ink cartridge 41 are arranged in the optical path 54. Liquid is present in the second protrusion 32, but no liquid is present in the first protrusion 42. In this case, the detection light emitted by the light-emitting unit 52 passes through the first protrusion 42 and is then blocked by the liquid in the second protrusion 32. The optical sensor 51 outputs a signal indicating an OFF state.

[0027] FIG. 7(d) shows a state in which the ink cartridge 41 is connected to the ink tank 31, and the second protrusion 32 of the ink tank 31 and the first protrusion 42 of the ink cartridge 41 are arranged in the optical path 54. Liquid is present in the second protrusion 32. Similarly, liquid is present in the first protrusion 42. In this case, the detection light emitted by the light-emitting unit 52 is blocked by the liquid in the first protrusion 42. The optical sensor 51 outputs a signal indicating an OFF state.

[0028] Next, the liquid detection operation of the liquid ejection device of this embodiment will be described. FIG. 8 shows the configuration related to the control of the liquid detection operation. The control unit 1 is composed of a CPU (Central Processing Unit) and the like. The control unit 1 receives an output signal from the optical sensor 51. The control unit 1 determines the storage state of the liquid in the ink tank 31 based on the output signal from the optical sensor 51. The output unit 60 outputs a signal such as a warning, for example, a signal requesting replacement of the ink cartridge 41. For example, the output unit 60 may display a message requesting replacement of the ink cartridge 41. The output unit 60 may also include a light-emitting element such as an LED (light emitting diode), which may display a light-emitting pattern to request replacement of the ink cartridge 41.

[0029] The control unit 1 controls the operation of the output unit 60 depending on the liquid storage state. Specifically, when the output signal of the optical sensor 51 is in the ON state, the control unit 1 determines that the liquid in the ink tank 31 is low, and causes the output unit 60 to output a signal requesting replacement of the ink cartridge 41. Hereinafter, the state in which the signal requesting replacement of the ink cartridge 41 is output will be referred to as "ink cartridge replacement request ON." Furthermore, the state in which the signal requesting replacement of the ink cartridge 41 is not output will be referred to as "ink cartridge replacement request OFF."

[0030] The control unit 1 also controls the recording operation of the recording head 23. When the control unit 1 detects that the output signal of the optical sensor 51 is in the ON state, it determines whether the amount of liquid used in the ink tank 31 has exceeded a specified amount. For example, the control unit 1 counts the number of times the recording head 23 ejects droplets from the time the output signal of the optical sensor 51 turns ON. Here, the amount of droplets used in one ejection is known. Therefore, the amount of liquid used can be calculated based on the count value.

[0031] If the amount of liquid remaining in the ink tank 31 becomes small, it may cause problems with the ejection operation of the recording head 23. To prevent this, a minimum remaining amount of liquid is determined in advance. The specified amount specifies how much liquid can be used until the amount of liquid at the time the output signal of the optical sensor 51 turns ON reaches the minimum remaining amount. For example, the specified amount is given by subtracting the minimum remaining amount from the amount of liquid at the time the output signal of the optical sensor 51 turns ON.

[0032] 9 shows the flow of the recording operation of the liquid ejection device 10 of this embodiment. In S101, the power supply to the liquid ejection device 10 is turned on. After the power supply is turned on, in S102, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S102 is "ON", then in S103 the control unit 1 sets the ink cartridge replacement request ON for the output unit 60. Next, in S104 the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S104 is "ON", the process of S103 is executed again. If the determination result in S104 is "OFF", then in S105 the control unit 1 sets the ink cartridge replacement request OFF for the output unit 60.

[0033] If the determination result in S102 is "OFF", or after the process of S105 is executed, the control unit 1 performs normal operation in S106. The normal operation includes the printing operation and the like described above. During normal operation, in S107, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S107 is "OFF," normal operation is maintained as is. If the determination result in S107 is "ON," in S108, the control unit 1 sets an ink cartridge replacement request ON to the output unit 60. Subsequently, in S109, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51.

[0034] If the determination result in S109 is "OFF", then in S110 the control unit 1 sets the ink cartridge replacement request OFF for the output unit 60. After that, the process returns to normal operation. If the determination result in S109 is "ON", then in S111 the control unit 1 determines whether the amount of liquid used since the output signal of the optical sensor 51 turned ON has exceeded a specified amount. If the determination result in S111 is "NO", the process returns to the determination in S109. If the determination result in S111 is "YES", then in S112 the control unit 1 stops the operation of the recording head 23.

[0035] The liquid ejection device of the present embodiment described above provides the following advantageous effects. The first protrusion 42 of the ink cartridge 41 and the second protrusion 32 of the ink tank 31 are disposed between the light-emitting unit and the light-receiving unit. Therefore, the first protrusion 42 and the second protrusion 32 are disposed on the optical path 54 of the light emitted from the light-emitting unit. This makes it possible to detect the presence or absence of ink in the ink cartridge 41 and the ink tank 31 with a single detection means (optical sensor 51). Furthermore, being able to detect the presence or absence of ink in the ink cartridge 41 and the ink tank 31 with a single detection means makes it possible to prevent the liquid ejection device from becoming too costly and too large. Generally, to prevent the ink cartridge 41 from being inserted incorrectly, the ink tank 31 is provided with a recess 31a into which the first protrusion 42 of the ink cartridge 41 is inserted. In this embodiment, the space of this recess 31a is used to place the optical sensor 51, thereby reducing costs. In particular, as shown in FIG. 5, the optical sensor 51 is made of a concave member, so it can be easily accommodated in the recess 31a.

[0036] Additionally, when the optical sensor 51 is housed in the recess 31a of the ink tank 31, due to spatial constraints, it is appropriate to insert the first protrusion 42 of the ink cartridge 41 into the optical path 54 of the optical sensor 51. In this embodiment, by inserting the first protrusion 42 into the optical path 54 of the optical sensor 51, the space of the recess 31a can be made the minimum necessary.

[0037] Furthermore, in a configuration in which the first protrusion 42 of the ink cartridge 41 is inserted into the optical path 54 of the optical sensor 51, it is necessary to detect the presence or absence of liquid in the ink tank 31, regardless of the presence or absence of the ink cartridge 41 or the state of the liquid in the ink cartridge 41. According to this embodiment, it is possible to detect the presence or absence of liquid in the ink tank 31 with a single optical sensor 51, regardless of whether the ink cartridge 41 is connected to the ink tank 31 or not, and regardless of the amount of liquid remaining in the ink cartridge 41. If spatial constraints do not need to be taken into consideration, the first protrusion 42 of the ink cartridge 41 may be out of the optical path 54 of the optical sensor 51. In this case, when the ink cartridge 41 and the ink tank 31 are connected, only the second protrusion 32 of the ink tank 31 is positioned on the optical path 54 of the optical sensor 51. In the above description, an example has been shown in which the detection light is blocked by ink when ink is present in either the first protrusion 42 or the second protrusion 32, but this embodiment is not limited to this. That is, the amount of detection light may be increased so that the detection light passes through the first protrusion 42 and reaches the light receiving unit even if ink is present in the first protrusion 42. Furthermore, the detection light may be blocked by ink and not reach the light receiving unit only when ink is present in both the first protrusion 42 and the second protrusion 32. This allows the optical sensor 51 to output three levels of output results depending on the presence or absence of ink. For example, if there is no ink in either the first protrusion 42 or the second protrusion 32, the light receiving unit receives the greatest amount of light, and therefore outputs a high-level signal. If there is ink in either the first protrusion 42 or the second protrusion 32, the amount of light reaching the light receiving unit is somewhat reduced, and therefore outputs a mid-level signal. If there is ink in both the first protrusion 42 and the second protrusion 32, no light reaches the light receiving unit, and therefore outputs a low-level signal. In this way, a three-level output may be provided depending on the presence or absence of ink. This allows for more detailed identification of the ink presence or absence state. That is, if a high signal is output, it is determined that there is no ink in either the first protrusion 42 or the second protrusion 32. If a mid signal is output, it is determined that there is no ink in either the first protrusion 42 or the second protrusion 32. If a low signal is output, it is determined that there is no ink in either the first protrusion 42 or the second protrusion 32.

[0038] (Second embodiment) Next, a liquid ejection device according to a second embodiment of the present invention will be described. The liquid ejection device of this embodiment has basically the same configuration as the liquid ejection device of the first embodiment, except for the configuration of the liquid storage section 13. To avoid duplication of explanation, only the configuration that differs from the liquid ejection device of the first embodiment will be described in detail. In this embodiment, the liquid has the property of transmitting the detection light used in the optical sensor 51.

[0039] 10 is a schematic diagram showing the configuration of an ink tank 31 used in the liquid ejection device of this embodiment. The ink tank 31 has a recess 31a, a second protrusion 32, a flow path 33, a float plate 34, and a light blocking plate 35. The recess 31a, the second protrusion 32, and the flow path 33 are the same as those described in the first embodiment. An optical sensor 51 is housed in the recess 31a. Figure 11 is a schematic diagram for explaining the float plate 34. Figure 11(a) shows a state in which the float plate 34 is out of the optical path 54 of the optical sensor 51. Figure 11(b) shows a state in which the float plate 34 is inserted into the optical path 54 of the optical sensor 51.

[0040] As shown in Figures 11(a) and 11(b), the float plate 34 has a rotation center 341, an arm 343 extending from the rotation center 341, and a floating portion 342 provided at a position away from the rotation center 341 of the arm 343. The floating portion 342 is housed in the space of the second protrusion 32. The float plate 34 rotates around the rotation center 341. When liquid is present in the second protrusion 32, the floating portion 342 maintains a floating state above the liquid surface in the second protrusion 32 due to buoyancy. When there is no liquid in the second protrusion 32, the floating portion 342 is fixed in contact with the bottom inside the second protrusion 32 due to its own weight. As shown in Figure 11(a), when the liquid level in the ink tank 31 is equal to or higher than height h3, the floating portion 342 is positioned above the optical path 54 of the optical sensor 51. In other words, the float plate 34 is tilted up to the left. As a result, the floating portion 342 is out of the optical path 54 of the optical sensor 51. In this case, the detection light passes through the second protrusion 32 and enters the light receiving portion 53. The output signal of the optical sensor 51 is in the ON state.

[0041] On the other hand, as shown in Figure 11(b), when the height of the liquid surface in the ink tank 31 is less than height h3, the floating portion 342 is at the same height as the optical path 54 of the optical sensor 51. In other words, the float plate 34 is in a horizontal state. Therefore, the floating portion 342 is inserted into the optical path 54 of the optical sensor 51. In this case, the detection light is blocked by the floating portion 342 and does not enter the light receiving portion 53. The output signal of the optical sensor 51 is in the OFF state. The float plate 34 and the second protrusion 32 are an example of a light-blocking means that can switch between a light-blocking state in which the detection light emitted by the light-emitting unit 52 is blocked and a light-transmitting state in which the detection light is transmitted. Here, the light-blocking means switches between the light-blocking state and the light-transmitting state depending on the height of the liquid level in the ink tank 31.

[0042] 12 is a diagram illustrating the light shielding plate 35. FIG. 12(a) shows a state in which the light shielding plate 35 is not subjected to an external force. FIG. 12(b) shows a state in which the light shielding plate 35 is subjected to an external force and has moved toward the inner surface of the recess 31a. Here, the external force is generated when the first protrusion 42 presses the light shielding plate 35 when the ink cartridge 41 is connected to the ink tank 31. 12(a) and 12(b), an elastic body 36 is provided on an opposing portion 31b of the inner surface of the recess 31a, facing the first protrusion 42. The elastic body 36 is, for example, a spring member. The light blocking plate 35 is supported by the elastic body 36 so as to block the detection light traveling through the optical path 54 of the detection sensor 51.

[0043] 12(a), when no external force is applied, the elastic body 36 is in an extended state, and the light blocking plate 35 is disposed on the optical path 54 of the detection sensor 51. In this case, the detection light is blocked by the light blocking plate 35. 12(b), when the elastic body 36 contracts due to an external force, the light shielding plate 35 moves out of the optical path 54 of the detection sensor 51. For example, with the ink cartridge 41 connected to the ink tank 31, the first protrusion 42 pushes the light shielding plate 35 toward the opposing portion 31b. As a result, the light shielding plate 35 moves out of the optical path 54 of the detection light. In this case, the detection light passes through the first protrusion 42.

[0044] 13 is a schematic diagram showing the state of passage and blocking of detection light in the optical sensor 51. The operation of the optical sensor 51 will be described in detail below with reference to FIG. FIG. 13(a) shows a state in which the ink cartridge 41 is not connected to the ink tank 31. Only the light-shielding plate 35 and the second protrusion 32 are arranged in the optical path 54, and the first protrusion 42 of the ink cartridge 41 is not arranged. Because the liquid level in the ink tank 31 is less than h3, the floating portion 342 of the float plate 34 is arranged within the second protrusion 32 so as to block the detection light. In this case, the detection light emitted by the light-emitting portion 52 is blocked by the floating portion 35. Because the detection light does not enter the light-receiving portion 53, the optical sensor 51 outputs a signal indicating an OFF state.

[0045] FIG. 13(b) shows a state in which the ink cartridge 41 is connected to the ink tank 31, and the second protrusion 32 of the ink tank 31 and the first protrusion 42 of the ink cartridge 41 are arranged in the optical path 54. Because the liquid level in the ink tank 31 is less than h3, the floating portion 342 of the float plate 34 is arranged within the second protrusion 32 so as to block the detection light. In this case, the detection light emitted by the light-emitting portion 52 passes through the first protrusion 42 and is then blocked by the floating portion 342. Because the detection light does not enter the light-receiving portion 53, the optical sensor 51 outputs a signal indicating an OFF state.

[0046] FIG. 13(c) shows a state in which the ink cartridge 41 is connected to the ink tank 31, and the second protrusion 32 of the ink tank 31 and the first protrusion 42 of the ink cartridge 41 are arranged in the optical path 54. Because the liquid level in the ink tank 31 is equal to or higher than h3, the floating portion 342 of the float plate 34 is out of the optical path 54 within the second protrusion 32. In this case, the detection light emitted by the light-emitting unit 52 passes through the first protrusion 42 and the second protrusion 32 in that order. Because the detection light is incident on the light-receiving unit 53, the optical sensor 51 outputs a signal indicating an ON state.

[0047] Next, the liquid detection operation of the liquid ejection device of this embodiment will be described. In the first embodiment, when the liquid level in the ink tank 31 is equal to or greater than h3, the output signal of the optical sensor 51 is OFF, and when the liquid level is less than h3, the output signal of the optical sensor 51 is ON. In contrast, in this embodiment, when the liquid level in the ink tank 31 is equal to or greater than h3, the output signal of the optical sensor 51 is ON, and when the liquid level is less than h3, the output signal of the optical sensor 51 is OFF. Furthermore, when the light-shielding plate 35 is inserted into the optical path 54 while the liquid level in the ink tank 31 is equal to or greater than h3, the output signal of the optical sensor 51 is OFF. Conversely, when the light-shielding plate 35 is removed from the optical path 54, the output signal of the optical sensor 51 is ON. Therefore, in this embodiment, the ON / OFF determination of the output signal of the optical sensor 51 differs from that in the first embodiment.

[0048] 14 shows the flow of the recording operation of the liquid ejection device 10 of this embodiment. In S201, the power supply to the liquid ejection device 10 is turned on. After the power supply is turned on, in S202, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S102 is "OFF", then in S203 the control unit 1 sets the ink cartridge replacement request ON for the output unit 60. Next, in S204 the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S204 is "OFF", the process of S203 is executed again. If the determination result in S204 is "ON", then in S205 the control unit 1 sets the ink cartridge replacement request OFF for the output unit 60.

[0049] If the determination result in S202 is "ON", or after the process of S205 is executed, the control unit 1 performs normal operation in S206. The normal operation includes the above-mentioned recording operation. During normal operation, in S207, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51. If the determination result in S207 is "ON", normal operation is maintained as is. If the determination result in S207 is "OFF", in S208, the control unit 1 sets an ink cartridge replacement request ON to the output unit 60. Subsequently, in S209, the control unit 1 determines the ON / OFF state of the output signal of the optical sensor 51.

[0050] If the determination result in S209 is "ON", in S210 the control unit 1 sets the ink cartridge replacement request OFF for the output unit 60. After that, the process returns to normal operation. If the determination result in S209 is "OFF", in S211 the control unit 1 determines whether the amount of liquid used since the output signal of the optical sensor 51 turned OFF has exceeded a specified amount. If the determination result in S211 is "NO", the process returns to the determination in S209. If the determination result in S211 is "YES", in S212 the control unit 1 stops the operation of the recording head 23.

[0051] The liquid ejection device of this embodiment described above also provides the same effects as those of the first embodiment. Additionally, when the ink cartridge 41 is not connected to the ink tank 31, the detection light emitted by the light-emitting unit 52 is blocked by the light-shielding plate 35 (see FIG. 13(a)), so the output signal of the optical sensor 51 is always in the OFF state. As a result, a request to replace the ink cartridge 41 is always output from the output unit 60. In this way, by providing the light-shielding plate 35, it is possible to output a request to replace the ink cartridge 41 when the ink cartridge 41 is not present.

[0052] When the user connects the ink cartridge 41 to the ink tank 31 in response to a replacement request, the light shielding plate 35 moves out of the optical path 54 (see FIG. 13(b)), and liquid is supplied from the ink cartridge 41 to the ink tank 31. As a result, the floating portion 342 in the second protrusion 32 moves out of the optical path 54, and as shown in FIG. 13(c), the detection light enters the light receiving portion 53, and the output signal of the optical sensor 51 switches from the OFF state to the ON state. However, this embodiment is not limited to the above. As described in the first embodiment, it is also possible to configure the optical sensor to output a plurality of output results. The amount of light from the light-emitting unit 52 is appropriately set so that the detection light reaches the light-receiving unit 53 even when, for example, ink is present in both the first protrusion 42 and the second protrusion 32. Then, the detection light can be prevented from reaching the light-receiving unit 53 only when the floating portion 342 of the float plate 34 blocks the detection light. In this way, it is possible to determine the following four stages (states): The first stage is when there is no ink in both the first protrusion 42 and the second protrusion 32. The second stage is when there is no ink only in the first protrusion 42. The third stage is when there is no ink in at least the second protrusion 32. The fourth stage is when there is ink in both the first protrusion 42 and the second protrusion 32. The float plate 34 may also be provided inside the first protrusion 42. Alternatively, the float plate 34 may be provided inside both the first protrusion 42 and the second protrusion 32. This allows the things that can be determined (determinable conditions and states) to be changed as needed, making it possible to detect the presence or absence of ink in more detail. [Explanation of symbols]

[0053] 31 Ink tank 31a Recess 32 Second protrusion 37 Second ink storage section 41 Ink cartridges 42 First protrusion 44 First ink storage section 51 Optical sensor (detection means) 52 Light projector 53 Light receiving part

Claims

1. an ink cartridge having a first ink containing section for containing ink; an ink tank connected to the ink cartridge and having a second ink storage section to which ink from the ink cartridge is supplied; A liquid ejection device having a detection means including a light projecting section that projects detection light and a light receiving section that receives the detection light, the ink cartridge has a first protrusion communicating with the first ink containing section, the ink tank has a recess and a second protrusion communicating with the second ink storage section; The detecting means is disposed in the recess, The liquid ejection device, wherein the first protrusion and the second protrusion are disposed between the light projecting portion and the light receiving portion.

2. 2. The liquid ejection device according to claim 1, characterized in that the detection light does not reach the light receiving unit when the height of the ink liquid surface inside the first protrusion is equal to or greater than a predetermined height or when the height of the ink liquid surface inside the second protrusion is equal to or greater than the predetermined height, and reaches the light receiving unit when the height of the ink liquid surface inside the first protrusion is less than the predetermined height and when the height of the ink liquid surface inside the second protrusion is less than the predetermined height.

3. 3. The liquid ejection device according to claim 1, wherein the first protrusion is a part of the ink cartridge.

4. 4. The liquid ejection device according to claim 1, wherein the second protrusion is a part of the ink tank.

5. the ink tank has a rotation center, an arm extending from the rotation center, and a float plate having a floating portion provided on the arm at a position away from the rotation center, the floating portion is disposed inside the second protrusion, 5. The liquid ejection device according to claim 1, wherein the float plate rotates around the center of rotation in accordance with the height of the ink surface.

6. The ink tank has a float plate having a rotation center, an arm extending from the rotation center, and a floating portion provided on the arm at a position away from the rotation center, the floating portion is disposed inside the second protrusion, The float plate rotates around the rotation center in accordance with the height of the ink surface, 3. The liquid ejection device according to claim 2, wherein the floating portion blocks the detection light when the height of the ink liquid surface inside the second protrusion is less than the predetermined height, and the floating portion moves out of the optical path of the detection light when the height of the ink liquid surface inside the second protrusion is equal to or greater than the predetermined height.

7. an elastic body provided on an inner surface of the recess at a position facing the first protrusion; a light blocking plate supported by the elastic body so as to block the optical path of the detection light, 7. The liquid ejection device according to claim 1, wherein when the ink cartridge and the ink tank are connected, the first protrusion pushes the light-shielding plate toward the opposing portion, causing the light-shielding plate to move out of the optical path of the detection light.

8. 8. The liquid ejection device according to claim 1, wherein the first protrusion is made of a material that is transparent to the detection light and is inserted into an optical path of the detection light.

9. 9. The liquid ejection device according to claim 1, wherein the second protrusion is made of a material that is transparent to the detection light and is inserted into an optical path of the detection light.

10. 10. The liquid ejection device according to claim 1, wherein the detection means comprises a concave member having a first side on which the light-emitting portion is provided and a second side facing the first side on which the light-receiving portion is provided, and the concave member is housed in the recess of the ink tank.

11. A liquid ejection device described in any one of claims 1 to 10, wherein the light-emitting unit and the light-receiving unit are arranged in the recess.

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