Image Recording Device

Abstract

To provide a technique enabling improvement of accuracy in detection of residual quantity of liquid.SOLUTION: An image recording device is provided, comprising: a liquid ejection cartridge that forms an image on a recording material by ejecting ink droplets from a recording element substrate, wherein the liquid ejection cartridge comprises a liquid chamber that stores liquid for use in recording of an image and a first electrode pin and a second electrode pin that are inserted into the liquid chamber; applying means that applies voltages to a space between the first electrode pin and the second electrode pin; and detection means that comprises detection resistance to which voltages are applied from the applying means and detects voltage values or current values between the first electrode pin and the second electrode pin, wherein when the applying means applies voltages to the space between the first electrode pin and the second electrode pin, the detection means detects the voltage values or the current values to detect residuals of liquid in the liquid chamber. The image recording device sequentially sets at least one of a determination threshold for determining whether the residuals of liquid in the liquid chamber are smaller than a predetermined amount, an applied voltage value and a value of the detection resistance, on the basis of cumulative application times of voltages.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an image recording apparatus that records an image by ejecting a liquid such as ink onto a recording medium. [Background technology]

[0002] Conventionally, various recording methods using a liquid ejection cartridge unit have been proposed as a means for recording an image on a recording medium such as paper, and for example, a thermal transfer method, a wire dot method, a thermal method, an inkjet method, etc., have been put to practical use. Among them, the inkjet method has attracted attention as a recording method that has low running costs and suppresses recording noise, and is used in a wide range of fields.

[0003] The inkjet method is an image recording method in which ink droplets are ejected from ink ejection ports formed by nozzle members on the surface of a recording element substrate by driving the recording element substrate equipped in a liquid ejection cartridge unit, and an image is formed by landing the ink droplets at desired positions on a paper surface.

[0004] In many inkjet systems, signals and power for driving the recording element substrate are supplied to the liquid ejection cartridge unit from an image recording apparatus in which the liquid ejection cartridge unit is mounted, via an electrical connection portion.

[0005] There are various configurations for supplying liquid such as ink used for image formation to a liquid ejection cartridge unit. In one representative configuration, an ink tank having a liquid storage chamber separate from the liquid ejection cartridge unit is directly connected to the liquid ejection cartridge unit to supply liquid from the ink tank to the liquid ejection cartridge unit. A tube supply system has also been put to practical use, in which liquid is supplied from an ink tank set in an image recording device to a liquid ejection cartridge via an ink supply tube. In the case of the tube supply system, a sub-tank is provided in the liquid ejection cartridge unit, and liquid supplied from the ink supply tube is generally held in the sub-tank and supplied to a recording element substrate.

[0006] In any of the above methods, the liquid supplied from a liquid supply source is guided into the liquid ejection cartridge, and then guided to the recording element substrate through a liquid supply flow path formed in the housing of the liquid ejection cartridge unit.

[0007] Image recording devices require a function to grasp the remaining amount of liquid in the supply source. There are two typical purposes for this. The first purpose is to display a message to the user when the remaining amount of liquid in the supply source is low, and to encourage the user to replace the ink tank or refill liquid. The second purpose is to trigger print control such as divided printing in order to prevent damage to the nozzle member that may occur when a discharge operation is performed when the liquid has run out.

[0008] Various methods have been proposed for detecting the remaining amount of liquid, including the dot count method, which calculates the remaining amount of liquid from the number of liquid ejections, the prism method, which irradiates light onto the liquid storage chamber and obtains the reflected light level with a sensor to determine the remaining amount, and the pin remaining amount detection method, which inserts an electrode pin into the liquid storage chamber to obtain an electrical response. Of the above, the pin remaining amount detection method has been widely used because of its relatively low introduction cost and high detection accuracy.

[0009] The conventional method of detecting the remaining amount of pins is to insert two pins into the liquid chamber. In conventional ink cartridges, the remaining amount of liquid is detected by applying an electrical signal to the electrode pins. Most liquids, such as ink, are electrically conductive, so when there is liquid in the liquid chamber (when the two electrode pins are in contact with the liquid) and an electrical signal is applied to the electrode pins, a current flows between the electrode pins via the liquid. On the other hand, when there is no liquid (when the two electrode pins are not in contact with the ink), there is no electrical path between the electrode pins, so no current flows.

[0010] In consideration of these characteristics, a configuration has been adopted in which the presence or absence of ink is determined by applying an electrical signal between electrode pins and obtaining an electrical response (Patent Document 1). [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2015-223830 A Summary of the Invention [Problem to be solved by the invention]

[0012] However, the configuration described in Patent Document 1 may cause the following problems.

[0013] Metallic stainless steel materials are mainly used for the electrode pins, but when two electrode pins are used, one as the anode and the other as the cathode, and current is repeatedly passed in one direction with liquid between them, oxidation and reduction reactions of the metal may occur on the surface of the electrode pins. In other words, oxidation progresses on the surface of the anode electrode pin, and reduction progresses on the surface of the cathode electrode pin. As the above reaction progresses, the electrical resistance increases due to the oxidation of the anode electrode pin, and the current value flowing between the electrode pins decreases even when liquid is present. In that case, the difference between the response when there is liquid and the response when there is no liquid becomes small, and there is a concern that the accuracy of detecting the remaining liquid level will decrease.

[0014] If the accuracy of detecting the remaining amount of liquid decreases, in one case, the user may be prompted to replace the ink tank even when there is liquid, or the printer may enter divided print mode, causing a decrease in print speed. In another case, even when there is no liquid, no indication of this may be displayed, causing blank printing (a state in which printing is performed without ejecting liquid), which may lead to damage to the nozzle member. In this way, a decrease in the accuracy of detecting the remaining amount of liquid is undesirable from the standpoint of usability and reliability.

[0015] An object of the present invention is to provide a technique capable of improving the accuracy of detecting the remaining amount of liquid. [Means for solving the problem]

[0016] In order to achieve the above object, the image recording apparatus of the present invention comprises: A liquid ejection cartridge unit that ejects ink droplets from a recording element substrate to form an image on a recording material, a liquid chamber for storing a liquid used for recording an image; a first electrode pin and a second electrode pin inserted into the liquid chamber; A liquid ejection cartridge unit including: an application means for applying a voltage between the first electrode pin and the second electrode pin; a detection means for detecting a voltage or a current value between the first electrode pin and the second electrode pin, the detection means comprising a detection resistor to which a voltage is applied by the application means; Equipped with an image recording device capable of performing a detection operation to detect a remaining amount of liquid in the liquid chamber by detecting a voltage value or a current value when the application means applies a voltage between the first electrode pin and the second electrode pin, At least one of a judgment threshold value for judging whether the amount of liquid in the liquid chamber is less than a predetermined amount, a voltage value applied by the application means, or a detected resistance value of the detection resistor is sequentially set based on a cumulative application time of the voltage.death, The frequency of updating the setting of the determination threshold, the applied voltage value, or the detected resistance value varies based on a cumulative application time of the voltage, and is high during a first period from the start of application of the voltage, and is low during a second period following the first period. It is characterized by: Effect of the Invention

[0017] According to the present invention, it is possible to improve the accuracy of detecting the remaining amount of liquid. [Brief description of the drawings]

[0018] [Figure 1] Schematic diagram of an image recording device [Diagram 2] FIG. 1 is a diagram illustrating the configuration of a liquid ejection cartridge unit; [Diagram 3] Circuit diagram of ink level detection system [Figure 4] FIG. 13 shows an example of input and output signals for detecting remaining ink level. [Diagram 5] A diagram showing an example of an output signal after the first electrode pin (anode side) is oxidized. [Figure 6] FIG. 1 shows the effect of electrode pin oxidation in Example 1. [Figure 7] FIG. 1 shows the effect of electrode pin oxidation in Example 2. [Figure 8] FIG. 13 shows the effect of electrode pin oxidation in Example 3. [Figure 9A] FIG. 13 shows the effect of electrode pin oxidation in Example 4. [Figure 9B] FIG. 13 shows the effect of electrode pin oxidation in Example 4. [Figure 9C] FIG. 13 shows the effect of electrode pin oxidation in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiment for carrying out the present invention will be described in detail by way of example. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiment should be appropriately changed depending on the configuration of the device to which the invention is applied and various conditions. In other words, it is not intended to limit the scope of the present invention to the following embodiment.

[0020] <Example 1> Fig. 1 is a simplified schematic diagram of an image recording device 1 and a liquid ejection cartridge unit 2 according to an embodiment of the present invention. Fig. 1(a) and Fig. 1(b) show different ink supply methods to the liquid ejection cartridge unit 2, but the present invention can be embodied in either configuration.

[0021] FIG. 1(a) shows an on-carriage ink tank type configuration. An ink tank 3 that contains and stores ink as a liquid used in image recording is directly connected to a liquid ejection cartridge unit 2 that has an ink ejection function, and ink is supplied. The ink tank 3 has a structure that is detachable from the liquid ejection cartridge unit 2. On the other hand, FIG. 1(b) shows a tube supply type configuration, in which ink as a liquid is supplied (liquid supply) from the ink tank 3 arranged in the image recording device to the liquid ejection cartridge unit 2 via an ink supply tube 4 (liquid supply tube).

[0022] In both of the methods shown in FIG. 1, a detection operation is required when the ink supply to the liquid ejection cartridge unit 2 is cut off. The main purposes of detecting the remaining ink level are as follows: First, it is used to notify the user that the ink in the ink tank 3 has run out, and to encourage the user to replace the ink tank 3 or refill the ink. Second, it is used to detect in advance that the liquid ejection cartridge unit 2 will be ejected without any ink, and to trigger printing control such as stopping printing or dividing printing, thereby preventing damage to the nozzle member that may occur in the worst case scenario during empty ejection. In particular, in the configuration of the tube supply method shown in FIG. 1(b), even if there is ink remaining in the ink tank 3, air may penetrate the ink supply tube 4 and enter the ink supply flow path if the ink tank 3 is left unused for a long period of time, etc. In order to detect the empty discharge that occurs in this case, this embodiment is provided with a configuration for detecting the amount of ink remaining in the liquid discharge cartridge unit 2.

[0023] FIG. 2 shows a detailed configuration of the liquid ejection cartridge unit 2 having an internal ink remaining amount detection function. FIG. 2(a) is a perspective view of the liquid ejection cartridge unit, and FIG. 2(b) is a cross-sectional view of the liquid ejection cartridge unit. The liquid ejection cartridge unit 2 is a unit in which a head unit 5 and a subtank 6 are combined. Ink supplied from an ink tank 3 or an ink supply tube 4 flows into the liquid ejection cartridge unit 2 from a joint portion 7 provided in the subtank 6 independently for each color of ink. A subtank liquid chamber 8 is formed in the subtank 6, and the supplied ink is temporarily held and stored in the subtank liquid chamber 8, and then guided to a recording element substrate 9 through an ink supply flow path formed in a housing of the head unit 5. Then, ink droplets of the ink that have passed through the ink supply flow path are ejected from the recording element substrate 9, forming an image on a recording material.

[0024] In order to detect the presence or absence of ink in each sub-tank liquid chamber 8, two electrode pins 10, a first electrode pin corresponding to an anode and a second electrode pin corresponding to a cathode, are inserted into each sub-tank liquid chamber 8. In this embodiment, the material of the electrode pins 10 is SUS304 in consideration of cost and workability, but other metal materials such as SUS316 and SUS384 may also be used. The inserted electrode pins 10 make contact with an electrical connection member 11 at the end opposite to the one end protruding into the sub-tank liquid chamber 8, and are electrically connected to the image recording device 1 via the electrical connection member 11.

[0025] 3 shows a simplified system configuration for detecting the remaining amount of ink using electrode pins 10. A signal for detecting the remaining amount of ink is input from an input port 12 of the image recording device 1. The input signal is branched into the number of inks for which remaining amounts are to be detected, and each is connected to an anode electrode pin 10a provided in each sub-tank liquid chamber 8 of the liquid ejection cartridge unit 2 via a detection resistor 13. The cathode electrode pin 10b provided in each sub-tank liquid chamber 8 is shorted within the liquid ejection cartridge unit 2 and connected to the GND terminal of the image recording device 1. Meanwhile, an output port 14 for remaining amount detection output is connected between the detection resistor 13 and the anode electrode pin 10a, and is provided for the number of ink colors for which detection is to be performed.

[0026] In the above-mentioned configuration, the voltage division ratio of the detection resistor 13 and the electrical resistance R of the ink is detected as an output by the current detection unit 15 of the image recording device 1 and transmitted to the control unit 17 that controls the operation of the image recording device 1. The control unit 17 controls a power supply circuit that uses the commercial power 16 to which the image recording device 1 is connected as a voltage application means, and can arbitrarily control the magnitude and polarity of the voltage applied as an electrical signal between the electrode pins 10a, 10b. The control unit 17 obtains the voltage between the electrode pins 10a, 10b from the current value detected by the current detection unit 15 as a current detection means connected to the power supply circuit, and can detect the remaining amount of ink in each sub-tank liquid chamber 8 from the magnitude of the voltage. The above-mentioned configuration constitutes the liquid remaining amount detection mechanism in the image recording device 1 of this embodiment.

[0027] When there is no ink in the subtank liquid chamber 8, the anode and cathode electrode pins 10 are electrically open, so no current flows to the liquid ejection cartridge unit 2. Therefore, a voltage close to the input signal is detected at the output port 14. On the other hand, when ink is present in the subtank liquid chamber 8, the anode and cathode electrode pins 10 are electrically connected via the ink, so that a current also flows to the liquid ejection cartridge unit 2. Therefore, the signal detected at the output port 14 is an output with a lower voltage level than the input signal. Note that, although the voltage value of the input signal is detected and judged in the embodiment of the present invention, a current value may also be detected and judged.

[0028] FIG. 4 shows the above-mentioned output levels in an example of a conventional detection system. In the remaining amount detection configuration described above, as shown in Fig. 4(a), two 3.3V rectangular pulses are used for the remaining amount detection signal input from the input port 12. On the output port 14 side, the output "Val(Min)" immediately before the input of the second pulse and the output "Val(Max)" immediately before the falling edge of the second pulse are acquired, and detection is performed as the remaining amount detection output (OutputVal) = "Val(Max) - Val(Min)".

[0029] When there is ink, the remaining amount detection output will be a low output of, for example, about 0.2V to 0.6V, as shown in Figure 4(b), whereas when there is no ink, the output will be about 2.0V to 3.3V, as shown in Figure 4(c).

[0030] Figure 4(d) illustrates the remaining ink amount (liquid amount) in the subtank liquid chamber 8 and the transition of the remaining amount detection output. As ink is consumed at a water level where the ink contacts the electrode pin 10 (water level h(A) → h(B) → h(C)), the remaining amount detection output changes with a gentle gradient from a1 → b1 → c1. Then, when the ink level leaves the electrode pin 10, the gradient of the output change in the remaining amount detection output becomes larger. However, even if the ink level leaves the electrode pin 10, due to ink and bubbles remaining at the meniscus between the electrode pins 10, the output does not transition digitally but transitions with a steep gradient.

[0031] In detecting the remaining amount of ink, a common method is to provide a judgment threshold Vth between the ink levels h(C) and h(Emp), i.e., between c1 and V_Emp, to determine whether the amount of ink liquid is less than a predetermined amount. By doing so, the remaining amount detection output value exceeds the judgment threshold between the time when the ink level falls below the tip of the electrode pin 10 and when the ink becomes empty, making it possible to detect the time to replenish the ink.

[0032] If the output value of the remaining ink detection output does not change with respect to the remaining ink amount, it is possible to detect the remaining ink amount accurately by setting the threshold value as described above. However, if the electrode pins 10 are made of metal material such as SUS material (SUS304) and the operation of passing a current in one direction between the electrode pins 10 through the ink is repeated, an oxidation-reduction reaction of the metal may occur on the surface of the electrode pins 10. The oxidation-reduction reaction is a phenomenon in which the surface of the electrode pin 10a on the anode side is oxidized and the surface of the electrode pin 10b on the cathode side is reduced. As the above reaction progresses, the electrical resistance increases due to the oxidation of the electrode pin 10a on the anode side, so the current value flowing between the electrode pins 10 decreases even though there is ink, and the remaining ink detection output increases.

[0033] In order to explain the effect of the oxidation-reduction reaction of the electrode pin 10 on the residual ink detection output, Fig. 5 shows the change in output between the initial state (ini) before oxidation-reduction and the state after oxidation-reduction of the electrode pin 10 (used). In the initial state (ini), if the judgment threshold is set between c1 and V_Emp, which is the residual ink detection output between the ink level at the pin tip h(C) and the empty state h(Emp), it is possible to detect the residual ink at the desired residual ink level. If the cumulative application time, which is the cumulative total time that the voltage is applied, increases, oxidation occurs in the anode side electrode pin 10a, and the output value of the residual ink detection output increases significantly. If the judgment threshold is set to a constant value, the output value of the residual ink detection output may exceed the judgment threshold and be detected earlier than the time when ink refilling is actually required. This phenomenon indicates that the output value of the residual ink detection output may exceed the judgment threshold and be detected even when the ink is fully immersed in the pin and it is not the recommended time to refill the ink. If the output value of the remaining amount detection output is detected as exceeding the judgment threshold too early, even though there is still plenty of ink remaining, it may cause problems such as prompting the user to replace the ink tank 3 or frequently slowing down the printing speed. It is possible to vary the judgment threshold according to the number of pulses given to the electrode pin 10, but since there is variation in the output fluctuation due to oxidation due to individual differences in the electrode pin 10, it becomes difficult to obtain high detection accuracy.

[0034] Considering the above situation, a configuration for detecting the remaining ink amount with high accuracy when the electrode pin 10 is oxidized / reduced by the application of a pulse will be described with reference to FIG. 6. As described above, when the electrode pin 10 is oxidized / reduced by the application of a pulse to the electrode pin 10, the remaining ink amount detection output increases in value from "ini" to "used" for a certain remaining ink amount. In this situation, if the judgment threshold of the remaining ink amount detection output is kept constant at the initial value "Vth(Ini)", the output "used" after the oxidation / reduction of the electrode pin 10 will exceed the judgment threshold "Vth(Ini)" even when there is still a sufficient amount of ink remaining. To avoid this, this embodiment employs a configuration in which the judgment threshold is changed from "Vth(Ini)" to "Vth(used)" as shown in FIG. 6(a). For example, by having the feature of offsetting the judgment threshold "Vth(used)" by an expected increase in the remaining amount detection output according to the number of applied pulses and the cumulative application time, it becomes possible to set an appropriate judgment threshold according to the progress of oxidation / reduction of the electrode pin 10. In other words, it is possible to perform highly accurate remaining amount detection by canceling the influence of oxidation / reduction.

[0035] Since the degree of oxidation / reduction of the electrode pin 10 differs depending on the type of ink, the offset amount of the determination threshold of the remaining amount detection output can be set for each type of ink, thereby enabling detection with higher accuracy.

[0036] Furthermore, when the liquid ejection cartridge unit is used for the first time, when the liquid chamber is filled with ink (when there is a predetermined amount or more), such as when the liquid chamber is refilled with ink, the remaining amount detection output may be acquired for the first time. By doing so, it becomes possible to set the difference value of the remaining amount detection output from the start of use as the amount of the oxidation effect of the electrode pin 10 and use it as the offset amount of the judgment threshold.

[0037] In this embodiment, the above-mentioned judgment threshold is set and updated every fixed number of applications of the input signal from the input port 12 or every fixed period. That is, the judgment threshold is set and updated sequentially. Here, the setting and updating of the judgment threshold will be described with reference to FIG. 6(b). In FIG. 6(b), the horizontal axis shows the cumulative number of applications of the remaining amount detection signal, and the vertical axis shows the change in the remaining amount detection output due to the effect of oxidation of the electrode pin 10. Note that as the cumulative number of applications increases, the cumulative application time also increases. As shown in FIG. 6(b), the remaining amount detection output increases significantly in the initial period T1 (first period) after the start of voltage application, and then gradually changes gradually in the subsequent period T2 (second period). This is because the oxidation saturates when the surface of the electrode pin 10 is oxidized to a certain amount. In this way, since the oxidation of the electrode pin 10 progresses differently in the T1 period and the T2 period, it is effective to change the judgment threshold according to the cumulative number of applications. That is, the setting update frequency for changing the above-mentioned judgment threshold may be variable, high frequency in the oxidation progression period (T1) and low frequency in the oxidation stability period (T2). For example, the judgment threshold for the remaining amount detection output may be changed so as to be successively updated every 0.1E+05 pulses in the oxidation progression period (T1) and every 1E+05 pulses in the oxidation stability period (T2).

[0038] There are various types of ink for which the remaining amount is to be detected, but in this embodiment, ink using carboxylic acid type self-dispersed CB (self-dispersed carbon black) among self-dispersed pigments is adopted, taking into consideration image performance and material costs. The above ink has a tendency that the remaining amount detection output value increases significantly due to the oxidation phenomenon of the electrode pin 10a when a voltage is applied from the input port 12. In such a case, the effect of implementing the present invention is great, and the accuracy of remaining amount detection can be obtained regardless of the type of ink. On the other hand, since the oxidation phenomenon occurs in the case of other inks as well, the effect of improving the accuracy of remaining amount detection can be obtained by applying the configuration of the present invention.

[0039] As described above, according to the first embodiment, the electrode pin 10 is made of a metal material (SUS304, SUS384, SUS316, etc.) that is easily oxidized, and the ink that is easily oxidized is used. Even in such a case, the amount of remaining ink can be detected with high accuracy.

[0040] In addition, in a configuration in which ink is supplied by a tube supply method, if the device is left unused for a long period of time, air may permeate the tube and get in, or irregular air may be present in the supply path, which may affect the ejection, etc. The configuration of the present invention, which can detect the remaining ink amount with high accuracy, is effective in detecting the above-mentioned effects on ejection and suppressing empty ejection.

[0041] In this embodiment, the present invention is applied to detecting the amount of remaining ink in the liquid ejection cartridge unit 2, but it can also be applied to detecting the amount of remaining ink in the ink tank 3 or other ink supply paths. In particular, when detecting the amount of remaining ink in a narrow space such as the ink supply tube 4 or subtank 6, it is not possible to provide a distance between the ink liquid surface and the tip of the electrode pin 10, and higher detection accuracy is required. In other words, if oxidation of the electrode pin 10 causes fluctuations in the remaining ink detection output, it becomes difficult to accurately determine the amount of remaining ink, so implementing the present invention is more effective.

[0042] <Example 2> 7 shows the configuration and remaining amount detection output in the second embodiment. Here, only the differences from the first embodiment will be explained. The purpose of the following remaining amount detection output is to perform highly accurate detection of the remaining amount of ink when the anode electrode pin 10a is oxidized by application of a voltage from the input port 12, as described in the first embodiment.

[0043] In this embodiment, the detection resistance value of the detection resistor 13 is changed as shown in FIG. 7. The output value Val [V] of the remaining amount detection output is detected by the voltage division ratio of the detection resistor 13 and the electrical resistance R of the ink. Therefore, by changing the detection resistance value of the detection resistor 13, it is possible to adjust the remaining amount detection output with respect to the change in the electrical resistance R of the ink. By utilizing this, the detection resistance value of the detection resistor 13 is changed according to the progress of oxidation of the electrode pin 10, and the detection sensitivity of the electrode pin 10 is increased, thereby making it possible to suppress the influence of the change in the remaining amount detection output due to oxidation. For example, if the detection resistance value of the detection resistor 13 is increased according to the progress of oxidation of the electrode pin 10, the output value Val [V] of the remaining amount detection output will decrease due to the voltage division ratio of the resistors, and the influence of oxidation of the electrode pin 10a on the anode side can be adjusted. In this embodiment, as shown in FIG. 6(b), the setting update frequency of the detection resistance value of the detection resistor 13 may be changed to a high frequency during the oxidation progress period (T1) and a low frequency during the oxidation stability period (T2).

[0044] <Example 3> FIG. 8 shows the configuration and remaining amount detection output in the third embodiment. In the first embodiment, the configuration was shown in which the judgment threshold Vth is changed according to the progress of oxidation of the electrode pin 10a. This configuration suppresses erroneous detection caused by the remaining amount detection output fluctuating due to the oxidation of the electrode pin 10 by changing the judgment threshold Vth. However, on the other hand, after the oxidation of the electrode pin 10, the difference in the output value of the remaining amount detection output when there is ink and when there is no ink becomes small, and it becomes difficult to detect whether the value of the remaining amount detection output exceeds the judgment threshold Vth. In particular, the difference in the output value of the remaining amount detection output when changing from the water level C on the horizontal axis in FIG. 8 to the water level 0 is small when the electrode pin 10a is in the oxidized state, and it is difficult to detect whether the value exceeds the judgment threshold Vth.

[0045] Therefore, as a countermeasure, in this embodiment, not only is the judgment threshold value Vth variable as shown in FIG. 8, but the applied voltage value Vin applied from the input port 12 is also configured to be changeable according to the progress of oxidation of the electrode pin 10. With this configuration, even if the remaining amount detection output increases due to oxidation of the electrode pin 10, the applied voltage value Vin can be increased to increase the difference in output value between when there is ink and when there is no ink. This makes it possible to maintain high-precision detection even after the electrode pin 10 has been oxidized. Note that in this embodiment as well, the voltage Vin shown in FIG. 6(b) is applied to the remaining amount detection output. In this way, the frequency of updating the determination threshold value Vth and the applied voltage value Vin may be varied to be high frequency during the oxidation progressing period (T1) and low frequency during the oxidation stable period (T2).

[0046] In this embodiment, both the judgment threshold value Vth and the applied voltage value Vin are changed, but it is also possible to change only the applied voltage value Vin without changing the judgment threshold value Vth. This is because, even if the judgment threshold value Vth is not changed, highly accurate detection can be performed by increasing the difference in the output value of the remaining amount detection output when there is ink and when there is no ink from the oxidized electrode pin 10.

[0047] <Example 4> 9A, 9B, and 9C show a configuration and remaining amount detection output according to a fourth embodiment of the present invention. FIG. 9A shows a configuration in which not only the determination threshold Vth is variable, but also the detection resistance value of the detection resistor 13 can be changed. In this configuration, the detection resistance value of the detection resistor 13 can be changed according to the oxidation state of the electrode pin 10, the value of the remaining amount detection output can be adjusted, and the determination threshold Vth can be set to an appropriate value. This configuration makes it possible to suppress a decrease in the detection sensitivity of the electrode pin 10, and by suppressing an increase in the value of the remaining amount detection output, the adjustment amount (offset amount) of the determination threshold Vth can be kept small, and high-precision detection can be maintained.

[0048] Next, Fig. 9B shows a configuration in which the detection resistance value of the detection resistor 13 and the applied voltage value Vin can be changed. In this configuration, the detection resistance value of the detection resistor 13 is adjusted according to the degree of oxidation of the electrode pin 10, and the applied voltage value Vin is increased to increase the difference in the remaining amount detection output value of the oxidized electrode pin 10 when there is ink and when there is no ink. This suppresses fluctuations in the remaining amount detection output value due to oxidation of the electrode pin 10, suppresses increases in the remaining amount detection output value, and maintains high accuracy in detecting the remaining ink amount even in a state in which it is difficult to detect the remaining ink amount.

[0049] FIG. 9C shows a configuration in which the detection resistance value and applied voltage value Vin of the detection resistor 13 can be changed for each ink type. The degree of oxidation when a voltage is applied to the electrode pin 10 has different characteristics depending on the ink type. Therefore, as shown in the configuration of FIG. 9C, if the applied voltage value Vin applied from the input port 12 and the detection resistance value of the detection resistor 13 can be set individually for each ink type, highly accurate detection can be obtained regardless of the ink characteristics. Note that, in this embodiment as well, as shown in FIG. 6(b), the setting update frequency of the judgment threshold value Vth, the applied voltage value Vin, and the detection resistance value of the detection resistor 13 may be changed to a high frequency during the oxidation progression period (T1) and a low frequency during the oxidation stability period (T2). [Explanation of symbols]

[0050] 1: image recording device, 2: liquid ejection cartridge unit, 3: ink tank, 4: ink supply tube, 5: head unit, 6: subtank, 7: joint portion, 8: subtank liquid chamber, 9: recording element substrate, 10: electrode pin, 11: electrical connection member, 12: input port

Claims

1. A liquid ejection cartridge unit that ejects ink droplets from a recording element substrate to form an image on a recording material, a liquid chamber for storing a liquid used for recording an image; a first electrode pin and a second electrode pin inserted into the liquid chamber; A liquid ejection cartridge unit including: an application means for applying a voltage between the first electrode pin and the second electrode pin; a detection means for detecting a voltage or a current value between the first electrode pin and the second electrode pin, the detection means including a detection resistor to which a voltage is applied by the application means; Equipped with an image recording apparatus capable of detecting an amount of liquid remaining in the liquid chamber by detecting a voltage value or a current value when the application means applies a voltage between the first electrode pin and the second electrode pin, sequentially setting at least one of a judgment threshold value for judging whether or not the amount of liquid in the liquid chamber is less than a predetermined amount, a voltage value applied by the application means, or a detected resistance value of the detection resistor, based on a cumulative application time of the voltage; an update frequency of the judgment threshold, the applied voltage value, or the detected resistance value varies based on a cumulative application time of the voltage, the update frequency being high during an initial first period from the start of application of the voltage, and the update frequency of the setting being low during a second period following the first period.

2. 2. The image recording apparatus according to claim 1, wherein the determination threshold value is successively set to be larger as the cumulative application time of the voltage becomes longer.

3. 3. The image recording apparatus according to claim 1, wherein the detected resistance value is successively set to be larger as the cumulative application time of the voltage becomes longer.

4. 4. The image recording apparatus according to claim 1, wherein the applied voltage value is successively set to be larger as the cumulative application time of the voltage becomes longer.

5. 5. An image recording device according to claim 1, wherein the judgment threshold value, the applied voltage value, or the detection resistance value that is initially set is set based on the voltage value or the current value detected by the detection means when the amount of liquid in the liquid chamber is greater than a predetermined amount.

6. 6. The image recording apparatus according to claim 5, wherein the state in which the amount of liquid in the liquid chamber is greater than the predetermined amount occurs either when the liquid ejection cartridge unit is used for the first time, or when the liquid chamber is refilled with liquid.

7. 7. The image recording apparatus according to claim 1, wherein the determination threshold value, the applied voltage value, or the detected resistance value is set based on the type of liquid.

8. A liquid ejection cartridge unit that ejects ink droplets from a recording element substrate to form an image on a recording material, a liquid chamber for storing a liquid used for recording an image; a first electrode pin and a second electrode pin inserted into the liquid chamber; A liquid ejection cartridge unit including: an application means for applying a voltage between the first electrode pin and the second electrode pin; a detection means for detecting a voltage or a current value between the first electrode pin and the second electrode pin, the detection means including a detection resistor to which a voltage is applied by the application means; Equipped with an image recording apparatus capable of detecting an amount of liquid remaining in the liquid chamber by detecting a voltage value or a current value when the application means applies a voltage between the first electrode pin and the second electrode pin, an image recording device characterized in that at least one of a judgment threshold for determining whether the amount of liquid in the liquid chamber has become less than a predetermined amount, an applied voltage value by the application means, or a detected resistance value of the detection resistor is successively set so that the detected resistance value becomes larger as the cumulative application time of the voltage becomes longer.

9. A liquid ejection cartridge unit that ejects ink droplets from a recording element substrate to form an image on a recording material, a liquid chamber for storing a liquid used for recording an image; a first electrode pin and a second electrode pin inserted into the liquid chamber; A liquid ejection cartridge unit including: an application means for applying a voltage between the first electrode pin and the second electrode pin; a detection means for detecting a voltage or a current value between the first electrode pin and the second electrode pin, the detection means including a detection resistor to which a voltage is applied by the application means; Equipped with an image recording apparatus capable of detecting an amount of liquid remaining in the liquid chamber by detecting a voltage value or a current value when the application means applies a voltage between the first electrode pin and the second electrode pin, an image recording device characterized in that at least one of a judgment threshold for determining whether the amount of liquid in the liquid chamber has become less than a predetermined amount, an applied voltage value by the application means, or a detected resistance value of the detection resistor is successively set so that the applied voltage value becomes larger as the cumulative application time of the voltage becomes longer.

10. 10. The image recording device according to claim 1, wherein the first electrode pin and the second electrode pin are made of SUS304, SUS384, or SUS316.

11. an ink tank for storing a liquid used for recording an image; a liquid supply tube for supplying liquid from the ink tank to the liquid chamber; Further equipped with 11. The image recording apparatus according to claim 1, wherein the liquid chamber is a sub-tank that temporarily holds the liquid supplied from the liquid supply tube and supplies the liquid to the recording element substrate.

12. The liquid ejection cartridge unit further includes an ink tank that stores a liquid used for recording an image and is configured to be detachable from the liquid ejection cartridge unit.

12. The image recording apparatus according to claim 1, wherein the liquid chamber is a sub-tank that temporarily holds the liquid supplied from the ink tank and supplies the liquid to the recording element substrate.

13. 13. The image recording apparatus according to claim 1, wherein the liquid in the liquid chamber is self-dispersing carbon black.

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