Patent Grant
9873259
1. Technical Field
The present invention relates to a liquid consumption apparatus, etc.
2. Related Art
Inkjet printers are known as an example of liquid consumption apparatuses (liquid injection apparatuses). Inkjet printers can perform printing on printing media such as printing paper by ejecting ink, which is an example of a liquid, from a printing head onto the printing media. Also, inkjet printers are provided with an ink tank, which is an example of a liquid container for storing ink, and perform printing by supplying the stored ink to the printing head. Among inkjet printers of this type, some inkjet printers are known for being provided with a liquid detection unit as disclosed in JP-A-3-275360, which detects the amount of ink remaining in the ink tank, which is a kind of ink information.
In some cases, the liquid detection unit passes an electric current through the ink inside the ink tank in order to detect the amount of remaining ink. In such cases, there is the possibility of the ink being subjected to electrolysis due to the direct current passing through the ink, which leads to the occurrence of bubbles or the deposition of the ink components on the electrodes. Such a situation is problematic because the bubbles or the deposited ink components are mixed into the ink and conveyed to the printing head, clog up the nozzle of the printing head, and have a negative influence on ink ejection. The liquid detection unit according to JP-A-3-275360 is provided with a voltage limiting unit, and applies a pulse voltage also across a plurality of electrodes. Thus, JP-A-3-275360 suggests a means for detecting the amount of remaining ink while suppressing electrical energy to be applied and preventing electrolysis. However, JP-A-3-275360 does not disclose the technical concept of avoiding the negative influence of electrolysis by passing an alternating current through the ink, or any specific means for realizing the concept.
Note that an alternating current is a current with which the polarity of the voltage applied across two electrodes periodically changes with time, and the flow of the current passing between the two electrodes changes in direction along with the voltage changing. A representative example of this is a sine wave alternating current. In this specification, a sine wave alternating current and a non-sine wave alternating current are collectively referred to as an alternating current.
Regarding the case of detecting the amount of remaining ink by passing an electric current through the ink inside the ink tank, related art such as JP-A-3-275360 does not disclose a technique to appropriately position the circuit elements of a circuit substrate on which detection circuits are provided, or a technique to appropriately connect the circuit substrate to the ink tank. Note that a connection between the circuit substrate and the ink tank may be a physical connection in an appropriate relative positional relationship or an electrical connection between the circuit substrate and an electrically-conductive member (electrode rod) provided for the ink tank.
Some aspects of the invention can provide, for example, a liquid consumption apparatus that is applicable to the case of detecting a liquid surface level by using an alternating current, and in which a circuit substrate is appropriately positioned.
One aspect of the invention relates to a liquid consumption apparatus that detects a liquid surface level of a liquid inside a liquid container, comprising: a circuit substrate; a substrate holder that holds the circuit substrate; and a control unit that detects the liquid surface level. The liquid container is provided with a pair of electrically-conductive members consisting of a first electrically-conductive member and a second electrically-conductive member. The circuit substrate is provided with a pair of terminals corresponding to the pair of electrically-conductive members. The substrate holder is provided with an elastic contact for connecting the pair of electrically-conductive members and the pair of terminals with each other. The elastic contact is a contact that is elastic in a first direction, where the first direction is a longitudinal direction of the first electrically-conductive member and the second electrically-conductive member.
According to one aspect of the invention, the circuit substrate is held by using the substrate holder, and the substrate holder is provided with the elastic contact. With this configuration, the circuit substrate and the substrate holder can be fixed in an appropriate positional relationship, and the displacement of the circuit substrate in the first direction can be absorbed. Accordingly, this configuration makes it possible to improve the reliability of the electrical connections between the pair of terminals and the pair of electrically-conductive members, for example.
In one aspect of the invention, each of the pair of terminals may have a circular shape.
This configuration makes it possible to improve the reliability of the electrical connections between the pair of terminals and the pair of electrically-conductive members.
In one aspect of the invention, the substrate holder may be fixed to the liquid container with a fixing member.
This configuration makes it possible to fix the substrate holder and the liquid container in an appropriate positional relationship.
In one aspect of the invention, the circuit substrate may have a regulation part that regulates a movement thereof in a direction along a plane that intersects the first direction.
This configuration makes it possible to prevent the circuit substrate from being displaced in the direction intersecting the first direction, for example.
In one aspect of the invention, the elastic contact may be attached to a contact holder, and the contact holder may be attached to the substrate holder.
This configuration makes it possible to fix the elastic contact to the substrate holder in an appropriate positional relationship.
In one aspect of the invention, the liquid container may be provided as 1st to kth liquid containers, where k is an integer greater than or equal to 2. 1st to kth pairs of terminals corresponding to the 1st to kth liquid containers each having the pair of electrically-conductive members may be positioned on the circuit substrate. The substrate holder may be provided with 1st to kth pairs of elastic contacts corresponding to the 1st to kth pairs of terminals.
This configuration makes it possible to provide an appropriate number of elastic contacts corresponding to the number of pairs of electrically-conductive members and the number of pairs of terminals, for example.
In one aspect of the invention, the circuit substrate may be provided with a selection circuit for supplying an alternating current voltage to the pair of electrically-conductive members provided for a liquid container selected from among the 1st to kth liquid containers.
This configuration makes it possible to appropriately detect the liquid surface levels in the plurality of liquid containers, for example.
In one aspect of the invention, the circuit substrate may be provided with at least a portion of an alternating current generation circuit configured to be able to supply an alternating current voltage to the liquid inside the liquid container via the pair of electrically-conductive members provided for the liquid container.
This configuration makes it possible to provide an alternating current generation circuit and to position at least a portion of the alternating current generation circuit on the circuit substrate.
In one aspect of the invention, the alternating current generation circuit may include: a first resistor having one end that is connected to the first electrically-conductive member; a reference electric potential supply unit that includes at least one electrical element connected between the other end of the first resistor and a reference electric potential, and that connects the first electrically-conductive member to the reference electric potential via the first resistor; and at least one capacitor connected between the second electrically-conductive member and the reference electric potential. The circuit substrate may be provided with at least the first resistor, the reference electric potential supply unit, and the capacitor.
This configuration makes it possible to realize the alternating current generation circuit that includes at least the first resistor, the reference electric potential supply unit, and the capacitor, which are provided on the circuit substrate.
In one aspect of the invention, the alternating current generation circuit may include: a periodic signal generation unit that generates a predetermined periodic signal; and a predetermined-electric potential supply unit connected to the other end of the first resistor of the alternating current generation circuit, and the predetermined-electric potential supply unit may connect the first electrically-conductive member to a predetermined electric potential that is higher than the reference electric potential via at least the first resistor during a first interval within one cycle of the predetermined periodic signal, and may disconnect a connection between the first electrically-conductive member and the predetermined electric potential during a second interval within the one cycle of the predetermined periodic signal.
This configuration makes it possible to realize the alternating current generation circuit that includes the periodic signal generation unit and the predetermined-potential supply unit.
In one aspect of the invention, the circuit substrate may be provided with a determination voltage generation unit that generates a determination voltage used for detecting the liquid surface level based on a detection voltage that is based on an electric potential of the first electrically-conductive member.
This configuration makes it possible to generate the determination voltage used for detecting the liquid surface level.
In one aspect of the invention, the determination voltage generation unit may include: a smoothing circuit that smooths the detection voltage; and a switch circuit that switches an output of the detection voltage to the smoothing circuit ON and OFF.
This configuration makes it possible to realize the determination voltage generation unit with the smoothing circuit and the switch circuit.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, an embodiment will be described. Note that the embodiment described below is not intended to unreasonably limit the contents of the invention set forth in the claims. Also, not all constituent elements described in this embodiment are essential to the invention.
Hereinafter, a technique according to the present embodiment will be described. As mentioned above, great importance is attributed to the processing of liquid surface level (remaining liquid amount) detection in a liquid consumption apparatus, and more specifically, the processing of ink level detection in the ink tank of a printer. However, related art such as JP-A-3-275360 does not disclose the technical concept of avoiding the negative influence of electrolysis by passing an alternating current through the ink, or any specific means for realizing the concept.
The applicant of the invention proposes, with respect to a technique to detect the amount of remaining liquid by passing an alternating current through the liquid, a specific circuit configuration for realizing the generation of the alternating current, for example. For this purpose, the liquid consumption apparatus has a circuit substrate, on which an alternating current generation circuit is provided, for example. The liquid container is provided with, for example, an electrically-conductive member used for passing the alternating current through the liquid. The circuit substrate and the electrically-conductive member need to be electrically connected to each other.
For example, it is conceivable that a terminal is provided on the surface of the circuit substrate on the liquid container side, and the terminal and the electrically-conductive member are electrically connected. Therefore, in the liquid consumption apparatus, the circuit substrate needs to be fixed to the liquid container in a predetermined positional relationship. Otherwise, the terminal of the circuit substrate and the electrically-conductive member are not electrically connected, and there is the possibility that the detection of the amount of remaining ink (the detection of the liquid surface level) cannot be properly performed. Note that the terminal and the electrically-conductive member are not necessarily in direct contact, and may be connected via, for example, an elastic contact 273, which is described below with reference to
Considering the above, the applicant of the invention proposes, as described below with reference to
The liquid consumption apparatus according to the present embodiment has the substrate holder 27, and the circuit substrate 26 is held (fixed) by the substrate holder. Therefore, with the substrate holder 27, compared to the case where the circuit substrate 26 alone is to be fixed to the liquid container, it is possible to reliably fix the circuit substrate 26 to a desired position within the liquid consumption apparatus. This configuration can improve the reliability of the electrical connections between the pair of terminals of the circuit substrate 26 and the pair of electrically-conductive members provided for the liquid container, and consequently makes it possible to perform appropriate liquid surface level detection.
However, even if such fixing is performed, a tiny displacement cannot be prevented due to a mechanical tolerance for manufacturing or assembly. Then, when a gap occurs below the circuit substrate 26, that is, if the circuit substrate 26 (specifically, the pair of terminals 38 and 39) is located further in the positive Z axis direction of the ink tank 30 than envisioned, a possibility arises in which the pair of terminals and the pair of electrically-conductive members will not be electrically connected. Note that the setting of the coordinate system is described later with reference to
In this case, the first terminal 38 and the second terminal 39 are isolated from each other, and this situation is similar to the situation in which the resistance between the first electrically-conductive member 35 and the second electrically-conductive member 36 is very large. In this case, it is determined that the amount of remaining ink is small regardless of the actual amount of remaining ink (the details are described later with reference to Part G of
Therefore, according to the present embodiment, the pair of terminals and the pair of electrically-conductive members are respectively connected by using the elastic contact 273, and the elastic contact is elastic in the first direction (Z axis direction). With this configuration, even when a displacement in the Z axis direction occurs, the elastic contact 273 can absorb the displacement, and this makes it possible to further improve the reliability of the electrical connections between the pair of terminals and the pair of electrically-conductive members.
Hereinafter, a specific technique according to the present embodiment will be described. First, a description is given of an example of the outline of the configuration of the liquid consumption apparatus, and then a description is given of the details of the technique of detecting the liquid surface level. Note that the configuration of a liquid detection unit 60 that performs liquid surface level detection and an example of the positions of the circuit elements and the terminal of the circuit substrate 26 are described in the description of the technique of detecting the liquid surface level. Some modification examples are described at the end.
The following describes an inkjet printer 1 (hereinafter referred to as “the printer”), which is an example of a liquid consumption apparatus to which the present embodiment has been applied. The printer 1 performs printing on printing media such as paper 12 by ejecting ink 34, which is stored in an ink tank 30, from a printing head 17 onto the printing media (see
2.1 Example of Overall Configuration
First, a description is given of the overall configuration of the printer 1 with reference to
As shown in
The ink tank unit 20 includes an ink tank unit covering 21 and an ink tank unit bottom part 22, and is installed outside the casing 14. The ink tank unit 20 can house a plurality of ink tanks 30. The ink tanks 30 store ink 34 used for printing, and when the printer 1 performs printing, the ink 34 is supplied from the ink tanks 30 to the printing head 17 (see
At least a portion of each ink tank 30 is formed from light-transmissive material, so that the ink 34 stored therein can been seen from the outside. The ink tank unit covering 21 has light-transmissive windows parts 24, which are respectively located in positions facing the light-transmissive portions of the ink tanks 30 housed therein. Therefore, the user can visually check the amount of the ink 34 in each ink tank 30 from the outside of the printer 1 via the corresponding window part 24.
The operation unit 13 and the paper discharge unit 11 are positioned on the front surface of the printer 1. The operation unit 13 is provided with a power button, a setting button, a display panel, etc. The printer 1 includes a control unit 16, which is mounted on a control substrate 15 (see
2.2 Example of Configuration of Ink Tank Unit
Next, a description is given of a configuration of the ink tank unit 20 with reference to
As shown in
A plurality of ink tanks 30 can be attached to the ink tank unit 20 so as to face the ink tank unit bottom part 22. In the present embodiment, four ink tanks 30 are attached. Each of the four ink tanks 30 stores a different type of the ink 34 (with a different color, material, etc.). One of the four ink tanks 30 is greater in size than the rest, and can store a larger amount of the ink 34. Considering the above, for example it is possible to use the ink tank 30 having a large size to store the ink 34 of the color black, which is frequently used, and use the other ink tanks 30 to separately store the inks 34 of the color yellow, magenta, and cyan.
The substrate holder 27 in the vertical upward direction of the ink tank unit bottom part 22 is positioned to come into contact with the ink tanks 30 when the ink tanks 30 are positioned and attached to the ink tank unit 20. The ink tanks 30 are thus positioned in the ink tank unit 20 so as to be sandwiched between the ink tank unit bottom part 22 and the substrate holder 27.
The ink tanks 30 are fixed to the substrate holder 27 with screws 28. The substrate holder 27 has a circuit substrate 26, on which circuitry including an alternating current generation circuit 40 (see
2.3 Example of Configuration of Ink Tank
Next, a description is given of a configuration of each ink tank 30 and its connection to the printer 1 with reference to
As shown in
Each ink tank 30 is defined by an outer wall, which is at least partially light-transmissive. In the present embodiment, a portion of the outer wall in the +X axis direction is light-transmissive. This outer wall surface has a mark 31 (see
The ink tank 30 also has an ink supply part 33, which sends the ink 34 stored therein to the printing head 17.
The ink tank 30 also has a pair of electrically-conductive members (electrodes, electrode rods) consisting of the first electrically-conductive member 35 and the second electrically-conductive member 36. The first electrically-conductive member 35 and the second electrically-conductive member 36 project to the outside of the ink tank 30, and are positioned in a region that is in contact with the substrate holder 27, particularly a region that is in contact with the circuit substrate 26.
The first electrically-conductive member 35 and the second electrically-conductive member 36 are each manufactured from a stainless material having the shape of a flattened rod extending from the outside of the ink tank 30 into the hollow part. The length of the first electrically-conductive member 35 is shorter than the length of the second electrically-conductive member 36. The second electrically-conductive member 36 extends further than the end of the first electrically-conductive member 35, reaching the vicinity of the bottom of the hollow part. Thus, at least when the ink 34 fills the hollow part, both of the electrodes, namely the first electrically-conductive member 35 and the second electrically-conductive member 36, are immersed in the ink 34. Then, after printing is performed, the ink 34 is consumed, and the amount of ink decreases, the first electrically-conductive member 35 is exposed to the outside of the ink 34, and only the second electrically-conductive member 36 is immersed in the ink 34.
As described above, the ink tanks 30 are positioned in the ink tank unit 20 so as to be sandwiched between the ink tank unit bottom part 22 and the substrate holder 27. The circuit substrate 26 is positioned on the substrate holder 27 so as to face, and so as to be contactable with, the first electrically-conductive member 35 and the second electrically-conductive member 36 of the ink tank 30. A pair of terminals consisting of a first terminal 38 and a second terminal 39 are formed at positions of the circuit substrate 26 that face the first electrically-conductive member 35 and the second electrically-conductive member 36. Thus, when the ink tank 30 is positioned in the ink tank unit 20, the first electrically-conductive member 35 and the first terminal 38 are brought into contact and electrically connected, and the second electrically-conductive member 36 and the second terminal 39 are brought into contact and electrically connected.
Also, due to the substrate holder 27 and the ink tank 30 being fixed to each other with a screw 28, the first electrically-conductive member 35 is joined to the first terminal 38 by pressure, and the second electrically-conductive member 36 is joined to the second terminal 39 by pressure. The electrical connections of the electrically-conductive members 35 and 36 and the terminals 38 and 39 are thus reliably established.
Furthermore, the circuitry mounted on the circuit substrate 26 and the circuitry mounted on the control substrate 15 of the printer 1 are connected to each other via the signal wiring FFC 19. The circuitry mounted on the control substrate 15 includes the control unit 16, and accordingly the circuitry on the circuit substrate 26 can perform mutual communication with the control unit 16.
Also, the ink 34 has electrical conductivity with an ink resistance value Ri (see
The ink supply part 33 is provided in a position corresponding to the lower part of the ink tank 30 when the ink tank 30 is in use. The ink 34 injected from the ink injection port 32 to the ink tank 30 is stored in the hollow part, and is sent to the outside from the ink supply part 33. A tube 18, which serves as an ink transport passage, is positioned by being fixed to the printer 1. One end of the tube 18 is connected to the ink supply part 33, and the other end of the tube 18 is connected to the printing head 17. Thus, the ink 34 in the ink tank 30 is transported to the printing head 17 via the tube 18 and is used for printing.
The ink tank unit 20 is configured such that the ink supply part 33 joins to the tube 18 when the ink tank 30 is positioned.
As described above, when the ink tank 30 is attached to the ink tank unit 20, the ink supply part 33 is joined to the tube 18, and the first electrically-conductive member 35 and the second electrically-conductive member 36 are electrically connected to the first terminal 38 and the second terminal 39 on the circuit substrate 26. Thus, the ink 34 stored in the ink tank 30 is brought into the state of being able to be used in the printer 1.
2.4 Substrate Holder and Elastic Contact
As described above, the liquid consumption apparatus includes the substrate holder 27 as shown in
The outline of the substrate holder 27 is as shown in
Specific external perspective views of the substrate holder 27 are shown in
The circuit substrate 26 also has a regulation part that regulates its movement in the direction along the plane (the XY plane) intersecting a first direction (the Z axis direction). The regulation part may be embodied in various forms, and for example, may be a recessed part 261 (a cutaway part) as shown in
A projection part 2711 is provided on the main body part 271 of the substrate holder 27, and the recessed part 261 and the projection part 2711 engage with each other in the state where the circuit substrate 26 is fixed to the substrate holder 27. In other words, during assembly, first, the recessed part 261 and the projection part 2711 are engaged with each other, and then the circuit substrate 26 is fitted into holder-side first regulation parts 2712 (2712a to 2712d) and holder-side second regulation parts 2713 (2713a to 2713d), which are provided on the main body part 271 of the substrate holder 27 and regulate the movement of the circuit substrate 26 at least in the first direction (the Z axis direction), and thus the circuit substrate 26 is fixed to the substrate holder 27. The holder-side first regulation parts 2712 and the holder-side second regulation parts 2713 are engaging claws that regulate the movement of the circuit substrate 26 by engaging with the outer periphery of the circuit substrate 26.
Note that in the example shown in
The substrate holder 27 is fixed to the liquid containers (ink tanks 30) with the fixing members. The fixing members are the screws 28. In this way, the circuit substrate 26 and the substrate holder 27 are fixed by using the regulation parts and so on, and the substrate holder 27 and the ink tanks 30 are fixed with the fixing members. As a result, it is possible to fix the circuit substrate 26 to the ink tanks 30 (more specifically, the pairs of electrically-conductive members) in an appropriate positional relationship.
Also, as described above, in the liquid consumption apparatus according to the present embodiment, the elastic contacts 273 are provided so that the pairs of terminals and the pairs of electrically-conductive members are electrically connected even when a displacement in the Z axis direction occurs with respect to the circuit substrate 26 and any of the ink tanks 30.
For example, in the case where 1st to kth liquid containers (k is an integer greater than or equal to 2) are provided in the liquid consumption apparatus according to the present embodiment, 1st to kth pairs of terminals that respectively correspond to the 1st to kth liquid containers each having a pair of electrically-conductive members are positioned on the circuit substrate 26, and 1st to kth pairs of elastic contacts that respectively correspond to the 1st to kth pairs of terminals are provided on the substrate holder 27.
With this configuration, it is possible to provide an appropriate number of elastic contacts 273 according to the number of liquid containers, thereby improving the reliability of the electrical connections between the electrically-conductive members provided for each liquid container and the circuit substrate 26.
A specific example of the elastic contact 273 is shown in
The plate-shaped electrically-conductive member 2733 of the elastic contact 273 is configured to be elastically deformable in the Z axis direction by bending like a leaf spring, as shown in
Note that although
With this configuration, even when the positional relationship in the Z axis direction is changed to some extent due to, for example, a gap occurring below the circuit substrate 26, a high degree of contact between the pair of terminals and the pair of electrically-conductive members is maintained, and the reliability of the electrical connections can be thus improved. When the distance in the Z axis direction between the circuit substrate 26 and the ink tank 30 is shorter than envisioned, an excessive pressing force is applied to the circuit substrate 26, which leads to the problem of the circuit substrate 26 deforming. However, the above-described configuration can also prevent the circuit substrate 26 from deforming.
Note that the 1st to kth pairs of elastic contacts are provided on the substrate holder 27. For example, each pair of elastic contacts is attached to the contact holder 272, and the contact holder 272 is attached to the substrate holder 27 (more specifically, the main body part 271 of the substrate holder 27). A plan view (a view from the Z axis direction) and a cross-sectional view (a view from the X axis direction) of the contact holder 272 in the state of being attached to the main body part 271 are respectively shown in
As shown in
A plurality of protection wall parts 2716 (four protection wall parts 2716a to 2716d in the examples in
Although the displacement in the Z axis direction is considered above as the displacement due to a mechanical tolerance, the displacement due to a mechanical tolerance may occur in the direction along the XY plane. Therefore, it is preferable that a configuration is adopted in which the reliability of the electrical connections between the pairs of terminals and the pairs of the electrically-conductive members can be improved, even if this displacement occurs.
Specifically, each terminal out of the pairs of terminals provided on the circuit substrate 26 according to the present embodiment may have a circular shape as shown in
Each terminal can establish an electrical connection with the elastic contact 273 by coming into contact with the elastic contact 273 at any point (surface) inside the circular shape. In other words, the terminal can appropriately connect to the elastic contact 273 insofar as displacement is within the range of the circular shape.
With the pairs of terminals each configured to have a shape that has an equal size (distance) in any direction within the XY plane from a given point serving as a reference point, it is possible to realize terminals that can efficiently address displacement in any direction within the XY plane. Each terminal has the shape of a true circle when the distance from the reference point is exactly equal in any direction. However, even if the distance is slightly different in any direction, the effect of efficiently addressing displacement in the XY directions remains unchanged. In other words, it is advantageous that the pairs of terminals each have a substantially circular shape, and preferably have the shape of a true circle.
Next, a description is given of the technique to detect the liquid surface level. Specifically, a description is first given of an example of the configuration of a liquid detection unit 60. Note that the liquid detection unit 60 includes a component provided on the control substrate 15, a component provided on the circuit substrate 26 for detection, and a component provided on other portions (e.g., the pairs of electrically-conductive members). Therefore, a description is first given of the overall configuration of the liquid detection unit 60, and then a description is given of specific components provided on the circuit substrate 26 for detection. A description is also given of the details of the detection operation, with reference to Parts A to G of
3.1 Example of Configuration of Liquid Detection Unit
The following describes the liquid detection unit 60 with reference to
As shown in
In the example shown in
The alternating current generation circuit 40 also includes a periodic signal generation unit 41 that generates a predetermined periodic signal, and a predetermined-electric potential supply unit that is connected to the other end of the first resistor R1 in the alternating current generation circuit (the end differing from the end connected to the first electrically-conductive member 35). In the example shown in
Also, as shown in
The determination voltage generation unit 55 includes a smoothing circuit 54 that smooths detection voltage, and a switch circuit 53 that switches the output of the detection voltage to the smoothing circuit 54 ON and OFF. The smoothing circuit 54 includes a resistor R54 and a capacitor C54. The switch circuit 53 has a control terminal S, and switches to ON and OFF according to the state of the control terminal S.
The liquid detection unit 60 includes: the first electrically-conductive member 35 and the second electrically-conductive member 36; the first terminal 38 that connects the first electrically-conductive member 35 and the first resistor R1; and the second terminal 39 that connects the second electrically-conductive member 36 and the capacitor C1. The first electrically-conductive member 35 and the second electrically-conductive member 36 are provided in the ink tank 30. The first terminal 38 and the second terminal 39 are provided on the circuit substrate 26. The specific positions, etc., of the first terminal 38 and the second terminal 39 on the circuit substrate 26 is described below.
In the liquid detection unit 60, the alternating current generation circuit 40 generates a detection voltage V1, the determination voltage generation unit 55 generates a determination voltage by shaping the waveform of the detection voltage V1, and a detection unit 50 detects the presence or absence of the liquid between the pair of electrically-conductive members based on the determination voltage. The amount of the ink 34 is thus detected.
The above-described elements of the alternating current generation circuit 40 constitute the alternating current generation circuit 40 by being connected by wiring as shown in
Note that the periodic signal generation unit 41 is constituted by a signal generator that can generate a periodic signal with various timings according to the control of the control unit 16 of the printer 1.
The determination voltage generation unit 55 transmits the detection voltage V1, which is generated by the alternating current generation circuit 40, to the smoothing circuit 54 with particular timing by using the switch circuit 53, and smooths the detection voltage V1 by using the smoothing circuit 54. The smoothed output from the smoothing circuit 54 serves as a detection output (determination voltage) 57 that is output by the detection unit 50. As shown in
Although the description above is given of an example of the case where a single liquid container (ink tank 30) is provided, the present embodiment is also applicable to a liquid consumption apparatus that has a plurality of liquid containers (the 1st to kth liquid containers). In this case, the circuit substrate 26 is provided with a selection circuit 49 for supplying an alternating current voltage to the pair of electrically-conductive members provided for the liquid container selected from among the 1st to kth liquid containers.
In other words, the alternating current generation circuit 40A includes the 1st to kth capacitors C1 (C1a, C1b, . . . , C1x) each connected between the second electrically-conductive member side terminal (the second terminal 39) out of the corresponding pair among the 1st to kth pairs of terminals, and the reference electric potential VSS.
Therefore, when the first electrically-conductive member 35a is selected by the selection circuit 49, the detection voltage V1 that can be used for detecting the ink information of the ink tank 30a can be generated by the same operation as the operation of the alternating current generation circuit 40 described above. As a result, the liquid detection unit 60 can detect the ink information of the ink tank 30a.
Similarly, when another first electrically-conductive member 35 (35b, . . . , 35x) is selected by the selection circuit 49, the ink information of the ink 34 stored in the ink tank 30 (30b, . . . , 30x) that corresponds to the selected first electrically-conductive member 35 (35b, . . . , 35x) can be detected.
With the configuration shown in
Furthermore, the capacitors C1 are separately connected to the respective second electrically-conductive members 36 of the plurality of ink tanks 30. Therefore, it is possible to position a capacitor C1 in the vicinity of each ink tank 30. As a result, wiring between the second electrically-conductive member 36 and the capacitor C1 can be easily installed, and the electrical properties can be stabilized.
3.2 Example of Positions of Circuit Elements of Circuit Substrate
Next, a description is given of a specific example of the positions of the circuit elements and so on of the circuit substrate 26, with reference to
It is not necessary that all the elements of the alternating current generation circuit 40 be provided on the circuit substrate 26, and, as shown in
The circuit substrate 26 is also provided with a connector CN1 for connecting a flexible flat cable (the FFC 19). In this case, the determination voltage generation unit 55 is connected to the control unit 16 via the flexible flat cable, and the control unit 16 detects the liquid surface level based on the determination voltage (detection output 57) acquired via the flexible flat cable.
The selection circuit 49 is connected to the control unit 16 via the flexible flat cable, and the selection circuit 49 supplies the pair of electrically-conductive members, which are provided for the liquid container selected from among the plurality of liquid containers, with an alternating current voltage based on the selection signal received from the control unit 16 via the flexible flat cable. Specific control performed by the control unit 16 is described later with reference to Parts A to G of
Also, as shown in
Note that from among the elements of the liquid detection unit 60, the elements not shown in
3.3 Details of Liquid Surface Level Detection Operation
Next, a description is given of the details of the liquid surface level detection operation, with reference to
Both the PWM output 42 shown in Part A of
The periodic signal generation unit 41 is controlled by the control signal from the control unit 16, with respect to the start and the stop of the oscillation of the periodic signal. During a period for which the periodic signal generation unit 41 receives an oscillation instruction from the control unit 16, the periodic signal generation unit 41 outputs, as the PWM output 42, a signal in which a first interval T1 (VSS level) and a second interval T2 (VDD level) are periodically repeated. In Part A of
Upon receiving an oscillation stop signal from the control unit 16, the periodic signal generation unit 41 stops the oscillation and outputs a signal at the VDD level as the output 42 (during the period from t2 to t3).
In the alternating current generation circuit 40 shown in
During the first interval T1, the second resistor R2 is also connected to VDD, and accordingly an electric current flows from VDD to VSS via the second resistor R2. Since this electric current increases the power consumed by the alternating current generation circuit 40, it is preferable to increase the value of the second resistor R2 as much as possible in order to prevent the increase in power consumption.
As described above, in a situation where the pair of electrically-conductive members, namely the first electrically-conductive member 35 and the second electrically-conductive member 36, are immersed in the ink 34, the pair of electrically-conductive members are electrically connected via the ink 34 having the ink resistance value Ri as shown in
Accordingly, during the first interval T1, an electric current flows through the following passage: VDD→the p-channel type FET 43→the first resistor R1→the first terminal 38→the first electrically-conductive member 35→the ink→the second electrically-conductive member 36→the second terminal 39→the capacitor C1→VSS. When an electric current flows through this passage, the capacitor C1 is charged. Therefore, the electric potential of the capacitor C1 gradually approaches the VDD level, and during the first interval T1, as shown in Part C of
Subsequently, during the second interval T2, the p-channel type FET 43 is turned off. Therefore, no electric current flows from VDD, and the capacitor C1, which has been charged, has the highest electric potential within the circuit system. As a result, an electric current flows through the following passage: the capacitor C1→the second terminal 39→the second electrically-conductive member 36→the ink 34→the first electrically-conductive member 35→the first terminal 38→the first resistor R1→the second resistor R2→VSS. Electricity charged to the capacitor C1 is discharged during the first interval T1. Therefore, the second resistor R2 functions as the reference electric potential supply unit that connects the first electrically-conductive member 35 to VSS via the first resistor R1. At this time, the electric potential of the capacitor C1 gradually decreases along with electrical discharge. Therefore, as shown in Part C of
As is clear from the above description, the direction in which the electric current passes through the ink 34 during the first interval T1 and the direction in which the electric current passes through the ink 34 during the second interval T2 are opposite. In other words, an alternating current passes through the ink 34 during the periodic signal section for which the first interval T1 and the second interval T2 of the PWM output 42 are periodically repeated.
Next, a description is given of the operation of the determination voltage generation unit 55 shown in
Therefore, during the second interval T2, in which the electric potential V2 approaches the VSS level, the detection voltage V1 is transmitted to the output 56 of the switch circuit 53. On the other hand, during the first interval T1, in which the electric potential V2 is at the VDD level, the transmission of the detection voltage V1 is blocked, and the output 56 comes into the undefined state. Part F of
Here, in Part E of
As described above, a portion of the detection voltage V1 is cut out based on changes in the electric potential V2, and serves as the output 56 from the switch circuit 53 (Part F of
Therefore, due to the detection output 57 being detected by the detection unit 50 in the subsequent stage, it is possible to detect the presence of the ink 34 between the first electrically-conductive member 35 and the second electrically-conductive member 36. Furthermore, since the detection output 57 varies its electric potential level according to the type of the ink 34, it is also possible to detect the type of the ink 34 by, for example, providing the detection unit 50 with an A/D converter to grasp the difference in electric potential levels.
When the ink 34 has been consumed and the ink 34 is absent between the second electrically-conductive member 36 and the first electrically-conductive member 35, the first electrically-conductive member 35 and the second electrically-conductive member 36 are electrically disconnected and are brought into an isolated state. Therefore, during the first interval T1 for which the p-channel type FET 43 is ON, the detection voltage V1 is connected to VDD via the first resistor R1. On the other hand, during the second interval T2 for which the p-channel type FET 43 is OFF, the detection voltage V1 is connected to VSS via the first resistor R1 and the second resistor R2. As a result, as indicated by the broken line in Parts C and E of
Next, a more detailed description is given of the operation of the alternating current generation circuit 40 with reference to
In the case where both electrodes, namely the first electrically-conductive member 35 and the second electrically-conductive member 36, are immersed in the ink 34, when SW is turned ON, C1 is connected to VDD via R1 and Ri, and an electric current flows. The detection voltage V1 in this case can be expressed by equation (1) below.
V1=VDD−(R1/(R1+Ri))×(VDD−Vc(t)) (1)
Note that Vc(t) denotes the electric potential of C1. (t) denotes a parameter, and indicates that Vc(t) changes along with the progress of time t.
During the first interval T1, C1 is charged by VDD, and Vc(t) gradually increases along with the progress of time. As a result, “(VDD−Vc(t))”, which is the third term on the right-hand side of equation (1), gradually decreases, and accordingly the value subtracted from “VDD”, which is the first term on the right-hand side, decreases. Thus, as indicated by the detection voltage V1 in Part C of
Here, if C1 has been sufficiently charged and Vc(t1)=0 at time t1, which is the starting time of the first interval T1, equation (2) below can be obtained by substituting this value into equation (1) above.
V1=(Ri/(R1+Ri))×VDD (2)
That is, the detection voltage V1 gradually increases from the initial value, which is the value expressed by equation (2), and approaches the VDD level, and accordingly the electric potential difference Vd gradually decrease.
Also, as can be seen from equation (2) above, the initial value of the detection voltage V1 is greater for a greater Ri. Therefore, at time t1, as shown in Part E of
During the second interval T2, electric charge is discharged from C1, which has been charged during the first interval T1, to VSS, via Ri, R1, and R2. Therefore, Vc(t) gradually decreases, and as shown in Parts C and E of
As described above, the liquid detection unit 60 can generate a different detection output 57 according to the type of the ink 34, and can detect the ink information such as the presence or absence of the ink 34 and the type of the ink 34.
Also, as can be seen from
If the first interval T1 increases, or the value of the first resistor R1 decreases, or the value of the capacitor C1 decreases, the electric potential of the capacitor C1 gets more closer to the VDD level during the first interval T1. As a result, no current flows from the VDD to the capacitor C1. The state in which no current flows is the same as the state in which the ink 34 is absent, and it is difficult to detect the presence or absence of the ink 34. For this reason, it is preferable that the length of the first interval T1 (in other words, the periods of the first interval T1 and the second interval T2 of the PWM output 42), the value of the first resistor R1, and the value of the capacitor C1 are determined such that when both electrodes, namely the first electrically-conductive member 35 and the second electrically-conductive member 36, are immersed in the ink 34, a current always flows from the VDD to the capacitor C1 and there is an electric potential difference Vd during the first interval T1.
As described above, according to the present embodiment, the alternating current generation circuit 40 of the liquid detection unit 60 can apply an alternating current to the ink 34. Therefore, it is possible to realize the liquid detection unit 60 that does not allows bubbles or the deposition of ink components on the first electrically-conductive member 35 or the second electrically-conductive member 36 to occur due to electrolysis when detecting the ink information.
Furthermore, it is possible to realize the alternating current generation circuit 40 that generates the detection voltage V1 that, when the ink 34 is present, always has the electric potential difference Vd from the VDD level during the first interval, and when the ink 34 is absent, has the electric potential difference Vd that is 0 during the first interval. Also, it is possible to realize the determination voltage generation unit 55 that generates the detection output 57 used for detecting the presence or absence and the type of the ink 34 based on the detection voltage V1. Therefore, with the liquid detection unit 60 that is configured to include the alternating current generation circuit 40, the determination voltage generation unit 55, and the detection unit 50 that detects the detection output 57, the printer 1 can detect the ink information without allowing bubbles or the deposition of ink components on the electrodes to occur due to electrolysis.
Furthermore, in the alternating current generation circuit 40 of the liquid detection unit 60, the first electrically-conductive member 35 is connected to the first resistor R1 via the first terminal 38, and the second electrically-conductive member 36 is connected to the capacitor C1 via the second terminal 39, and accordingly it is easy to disconnect each terminal part from the corresponding electrode. Therefore, it is possible to adopt a configuration in which, when the ink tank 30 is connected to the ink tank unit 20 and to the printer 1 accordingly, the first electrically-conductive member 35 is connected to the first terminal 38 and the second electrically-conductive member 36 is connected to the second terminal 39. As a result, it is possible to realize the liquid detection unit 60 with which the ink tank 30 can be attached to and detached from the printer 1 and that can establish a reliable connection when the ink tank 30 is attached, and to realize the printer 1 provided with the liquid detection unit 60.
Furthermore, as shown in
Furthermore, by appropriately determining the period of the periodic signal of the PWM output 42, the value of the first resistor R1, and the value of the capacitor C1, it is possible to set the alternating current generation circuit 40 of the liquid detection unit 60 such that when both electrodes, namely the first electrically-conductive member 35 and the second electrically-conductive member 36, are immersed in the ink 34, an electric current always flows from the VDD to the capacitor C1 via the first resistor R1 and the ink 34 during the first interval T1. As a result, the detection voltage V1 can be set to always have the electric potential difference Vd from the VDD level. Therefore, due to the detection unit 50 detecting the detection output 57 generated by the determination voltage generation unit 55 based on the detection voltage V1, it is possible to detect the ink information such as the presence Or absence and the type of the ink 34.
Furthermore, as the PWM output 42, it is possible to use a signal that intermittently has a periodic signal in which the first interval T1 and the second interval T2 are periodically repeated, and that is at the same electric potential level as that in the second interval T2 during intervals in which the periodic signal is present. Therefore, the capacitor C1, which is charged or discharges during intervals in which the periodic signal is present, can satisfactorily discharge during intervals in which the periodic signal is absent. As a result, it is possible to set the electric potential of the capacitor C1 to be a constant value at the time when the periodic signal starts, and accordingly it is possible to realize the alternating current generation circuit 40 that generates the detection voltage V1 that is stable, and furthermore, it is possible to realize the liquid detection unit 60 that performs stable operations.
Also, the determination voltage generation unit 55 of the liquid detection unit 60 can be configured with the switch circuit 53 and the smoothing circuit 54. Therefore, the detection voltage V1, which is generated during the first interval T1 and the second interval T2, can be selected by the switch circuit 53 with time division. Furthermore, the detection output 57 having a stable electric potential level is generated by the smoothing circuit 54 from the selected detection voltage V1. As a result, the detection output 57 can be detected at any time, and it is possible to improve the flexibility in designing the products.
Also, the determination voltage generation unit 55 can be configured with the switch circuit 53 and the smoothing circuit 54 that is configured with passive elements. Therefore, compared to the case where the determination voltage generation unit 55 is configured with a single MOSFET or a bipolar transistor, a stable detection output 57 can be generated without the influence of variations in the threshold value (Vth) of the MOSFET or variations in the direct current amplification rate (hfe) of the bipolar transistor.
Also, with the determination voltage generation unit 55 configured to generate the detection output 57 during the second interval T2, it is possible to generate the detection output 57 according to the type of ink when the ink 34 is present, and to set the detection output 57 to be at the VSS level when the ink 34 is absent. Therefore, it is possible to make a distinction from a failure mode in which the detection output 57 is at the VSS level despite the presence of the ink 34.
Furthermore, the printer 1 is provided with the liquid detection unit 60 according to the present embodiment. Since the ink tank 30 with which the liquid detection unit 60 is configured is provided with the ink injection port 32, the printer 1 can be refilled with the ink 34.
Therefore, it is possible to generate the detection voltage V1 from which the ink information of the ink 34 can be detected, in the same manner as the operation of the alternating current generation circuit 40 described above.
Thus, the predetermined-potential supply unit can be configured with a single p-channel type FET 43, and the reference electric potential supply unit can be configured with a single n-channel FET 44. Thus, the alternating current generation circuit 40 (40B) can be configured with a small number of electrical elements, and the cost and the size of the liquid detection unit 60 (60B) can be reduced.
Although a description is given of the case where the first electrically-conductive member 35 and the second electrically-conductive member 36 are made from a stainless material having the shape of a flattened rod, the material of the first electrically-conductive member 35 and the second electrically-conductive member 36 are not limited to this. Any electrically-conductive materials can be adopted, and materials that will be not subject to corrosion and will not cause rust to mix into the ink 34 are preferable. For example, a carbon material may be used. Also, the shape is not limited to the shape of a flattened rod, and may be the shape of a round rod, a rectangular rod, a coil, and so on.
Also, in the embodiment above, although a description is given of the case where the duty ratio of the first interval T1 and the second interval T2 of the PWM output 42 is 50%, the duty ratio may be varied, and the second interval T2 may be set to be longer than the first interval T1. Thus, the period during which the capacitor C1 is charged can be set to be longer than the period during which the capacitor C1 discharges. Thus, the electric charge stored in the capacitor C1 during the first interval T1 can be satisfactorily discharged during the second interval T2, and accordingly the electric potential of the capacitor C1 at the time when the second interval T2 ends and the first interval T1 starts can be maintained at a constant value.
In the above-described embodiment, the ink information is detected by detecting the detection output 57 during the second interval T2. Meanwhile, during the first interval T1, the value of the detection voltage V1 varies according to the presence or absence and the type of the ink 34 between the first electrically-conductive member 35 and the second electrically-conductive member 36. Therefore, the detection output 57 may be detected during the first interval T1. Furthermore, the ink information may be detected from the value of difference between the detection output 57 detected during the first interval T1 and the detection output 57 detected during the second interval T2.
In the embodiment and modification example above, the ink 34 stored in the ink tanks 30 is described as an example of the liquid stored in the liquid containers, and the inkjet printer 1 is described as an example of the liquid consumption apparatus. However, the applicable scope of the present embodiment is not limited to this, and the present embodiment is applicable to a liquid consumption apparatus that can detect the liquid information of an electrically-conductive liquid stored in a liquid container and that can inject the liquid.
While the present embodiment has been described above in detail, a person skilled in the art should easily understand that many modifications are possible without substantially departing from new matters and effects of the invention. Therefore; all examples of such modifications are to be embraced within the scope of the invention. For example, terms that are used at least once in the description or the drawings in conjunction with different terms having broader or similar meanings can be replaced with different terms in any portion of the description or the drawings. Furthermore, the configurations and operations of the liquid consumption apparatus are not limited to those described in the present embodiment, and can be implemented with various modifications.
According to the description of the present embodiment, the ink tanks 30 (liquid containers) housed in the ink tank unit 20 are attached to the printer 1 by the printer vendor, and when the ink 34 is absent in an ink tank 30, the user of the printer 1 refills the ink tank 30 with ink from the ink injection port 32 without replacing the ink tank 30. The application of the present invention is not limited to this, and the ink tanks 30 may be configured to be able to be attached to or detached from the printer 1 by the user of the printer 1, and when the ink 34 in an ink tank 30 has been consumed, it may be replaced with a new ink tank 30. If this is the case, the ink tank 30 does not have the ink injection port 32, and the ink supply part 33 may have a valve that is configured to be able to be opened and closed. Then, the first electrically-conductive member 35 and the second electrically-conductive member 36 of the ink tank 30 may be connected to the terminals 38 and 39 of the circuit substrate 26 when the ink tank 30 is attached to the printer 1.
In the embodiment above, although a description is given of the case where the control unit 16 detects the liquid surface level inside the liquid container that has a single hollow part, liquid surface level detection is not limited to this. For example, when the liquid container has a plurality of chambers that are connected to each other with flow channels, liquid surface level detection is to detect the presence or absence of the liquid in the area where the pair of electrically-conductive members are positioned. In other words, liquid surface detection is to detect whether the amount of remaining liquid in the liquid container is equal to a predetermined amount or smaller.
The entire disclosure of Japanese Patent Application No. 2015-057512, filed on Mar. 20, 2015 is expressly incorporated herein by reference.
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