JP2012011643A - Ink supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink supply device, capable of stably discharging ink by suppressing negative pressure fluctuation in a recording head.SOLUTION: The speed of a supply pump 72 for supplying ink is changed according to the consumption of ink in a head unit 22K.

Description

  The present invention relates to an ink supply device used in a recording apparatus that performs recording by discharging ink onto a recording medium.

  2. Description of the Related Art Conventionally, ink jet recording apparatuses that perform recording by discharging ink from a recording head onto a recording medium are known. In such an ink jet recording apparatus, high-definition recording is generally performed using a small recording head in which a plurality of nozzles from which ink is ejected are formed at high density. In addition, by arranging a plurality of small recording heads and supplying different color inks to the respective recording heads, color recording can be performed on a recording medium with a relatively inexpensive and small configuration. For this reason, ink jet recording apparatuses are used in various recording apparatuses such as printers, facsimiles, and copying machines regardless of whether they are for business use or home use.

  In such an ink jet recording apparatus, in order to stabilize the ink ejection operation from the recording head, the ink in the recording head is maintained at a predetermined negative pressure (the pressure acting on the ink in the recording head is set to a predetermined negative pressure). Is important). For this reason, a general ink jet recording apparatus includes a negative pressure generating means in an ink supply system that supplies ink to the recording head, and supplies ink to which the negative pressure has been applied by the negative pressure generating means to the recording head. Yes.

  As a negative pressure generating means, Patent Document 1 discloses a configuration in which a negative pressure is generated using the capillary action of a sponge-like ink absorber housed in an ink tank. As another negative pressure generating means, Patent Document 2 discloses a configuration including a flexible ink bag and a bow spring. As another negative pressure generating means, Patent Document 3 discloses a configuration in which an ink tank is disposed below the recording head and a negative pressure is applied to the ink by utilizing a water head difference between the recording head and the ink tank. ing.

  In an ink supply system having negative pressure generating means as in Patent Document 1 to Patent Document 3, the negative pressure in the recording head increases as ink is ejected from the recording head. Using this increasing negative pressure, ink is supplied from the ink tank to the recording head. For this reason, when the amount of ink ejected from the recording head per unit time is large, the ink supply from the ink tank to the recording head cannot catch up, and the negative pressure in the recording head may become larger than a predetermined negative pressure. .

  With respect to such a problem, in Patent Document 4, ink is supplied to the recording head by a pump, and negative pressure in the recording head is controlled by a fan as a negative pressure generating unit. A configuration for performing the control separately has been proposed.

JP 2002-001988 A Japanese Patent Application Laid-Open No. 06-198904 JP 2003-011380 A JP 2006-326855 A

  However, even if the ink supply to the recording head and the negative pressure control in the recording head are separately performed as in Patent Document 4, the fan that performs the negative pressure control rotates at a constant speed, so that the recording that occurs when the ink is supplied Negative pressure fluctuation in the head is inevitable. As a result, ink ejection may become unstable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink supply apparatus that can suppress negative pressure fluctuation in a recording head and can stably eject ink.

  An ink supply device according to the present invention includes a head unit capable of discharging ink stored therein, a supply pump capable of supplying the ink to the inside of the head unit, and negative pressure generation capable of adjusting the pressure in the head unit And a detecting means for detecting the amount of the ink in the head unit, wherein the detecting means detects that the amount of the ink in the head unit is less than a predetermined amount. In this case, the supply pump starts driving, and when the consumption amount of the ink in the head unit per unit time after the supply pump driving starts is larger than a predetermined amount, the supply pump It is characterized by increasing the supply amount.

  According to the present invention, in the ink supply device, when the detection unit detects that the ink amount in the head unit is less than the predetermined amount, the supply pump starts driving. When the consumption amount of ink in the head unit per unit time after the start of driving is larger than a predetermined amount, the supply pump increases the supply amount of ink. Accordingly, it is possible to realize an ink supply device that can suppress negative pressure fluctuation in the recording head and stably eject ink.

It is the front view which showed typically the inkjet recording device which can apply 1st Embodiment. FIG. 2 is a block diagram illustrating a control system of the recording apparatus in FIG. 1. FIG. 4 is a diagram illustrating a path through which ink passes from an ink tank to a head unit. It is the flowchart which showed the procedure at the time of cleaning an ejection port surface. (A) to (c) is a schematic diagram showing a procedure for wiping ink from a discharge surface with a wiper. It is the figure which expanded and showed the head unit and its circumference | surroundings. It is the figure which showed the table of the speed of the supply pump in 1st Embodiment. 5 is a flowchart showing a flow of recording processing in the first embodiment. It is the figure which showed the table of the speed of the fan in 2nd Embodiment. 10 is a flowchart showing a flow of recording processing in the second embodiment. (A), (b) shows the pump stop sequence of step S714 of FIG. It is the figure which showed the head unit of 3rd Embodiment, and its periphery.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a front view schematically showing an ink jet recording apparatus (hereinafter also simply referred to as a recording apparatus) to which the present embodiment can be applied. The recording apparatus 10 is connected to the host PC 12, and based on the recording information transmitted from the host PC 12, ink is applied from four head units 22K, 22C, 22M, 22Y to a recording medium (hereinafter also referred to as roll paper) P. Recording is performed by discharging. The four head units 22K, 22C, 22M, and 22Y are arranged along the conveyance direction (arrow A direction) of the recording medium P. Each head unit is arranged in the order of black ink head unit 22K, cyan ink head unit 22C, magenta ink unit head 22M, and yellow ink head unit 22Y in the transport direction. The head units 22K, 22C, 22M, and 22Y are so-called line heads, and are provided in a state where the head units 22K, 22C, 22M, and 22Y are arranged in parallel over the entire recording width in the recording medium conveyance direction. When the recording apparatus performs recording, the recording is performed by ejecting ink from the nozzles by driving a heater provided in the head unit without moving each head unit.

  The head unit changes the ejection state due to foreign matters such as dust and ink droplets adhering to the surfaces having nozzles (hereinafter also referred to as ink ejection port surfaces) 22Ks, 22Cs, 22Ms, and 22Ys during recording, which affects recording. May give. Therefore, the recovery unit 40 is incorporated in the recording apparatus 10 so that ink can be stably ejected from the head units 22K, 22C, 22M, and 22Y. By periodically cleaning the ink discharge port surface by the recovery unit 40, the ink discharge state from the nozzles of the head units 22K, 22C, 22M, and 22Y can be recovered to the initial good ink discharge state. The recovery unit 40 includes a cap 50 that removes ink from the ink discharge port surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four head units 22K, 22C, 22M, and 22Y during the cleaning operation. The cap 50 is provided independently for each head unit 22K, 22C, 22M, 22Y, and includes a blade, an ink removing member, a blade holding member, a cap, and the like.

  The roll paper P is supplied from the roll paper supply unit 24 and is transported in the direction of arrow A by the transport mechanism 26 incorporated in the recording apparatus 10. The transport mechanism 26 includes a transport belt 26a for loading and transporting the roll paper P, a transport motor 26b for rotating the transport belt 26a, and a roller 26c for applying tension to the transport belt 26a.

  When recording, when the roll paper P being conveyed reaches below the black head unit 22K, black ink is ejected from the head unit 22K based on the recording information sent from the host PC 12. Similarly, ink of each color is ejected in the order of the head unit 22C, the head unit 22M, and the head unit 22Y, and color recording on the roll paper P is completed.

  Further, the recording apparatus 10 has main tanks 28K, 28C, 28M, 28Y for storing ink supplied to each head unit, a pump capable of supplying ink to each head unit, and a pump for performing a cleaning operation described later. (Refer to FIG. 3 etc.).

  FIG. 2 is a block diagram showing a control system of the recording apparatus 10 of FIG. Recording information and commands transmitted from the host PC (host device) 12 are received by the CPU 100 via the interface controller 102.

  The CPU 100 is an arithmetic processing unit that performs overall control such as reception of recording information of the recording apparatus 10, recording operation, handling of the roll paper P, and the like. After analyzing the received command, the CPU 100 renders the image data of each color component of the recording data by developing a bitmap on the image memory 106. In the operation process performed before recording, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor driving unit 116, and the head units 22K, 22C, 22M, 22Y are separated from the cap 50 to the recording position. Move to. Further, as will be described later, the CPU 100 determines the rotation of the fan motor of the fan as a negative pressure generating means capable of adjusting the pressure in the head units 22K, 22C, 22M, and 22Y to an appropriate value by the pressure sensor. Based on the information, control is performed as necessary. Further, the CPU 100 drives the roll motor 126 that feeds the roll paper P through the output port 114 and the motor driving unit 116, the transport motor 120 that transports the roll paper P, and the like to transport the roll paper P to the recording position. Control.

  When performing recording, the leading end detection sensor 109 detects the leading end position of the roll paper P in order to determine the timing (recording timing) at which ink is ejected onto the rolled paper P conveyed at a constant speed. Thereafter, in synchronism with the conveyance of the roll paper P, the CPU 100 sequentially reads the recording information from the image memory 106, and the read recording information is transferred to the head units 22K, 22C, 22M, and 22Y via the head unit control circuit 112. And transfer.

  The operation of the CPU 100 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores processing programs and tables corresponding to the control flow. The CPU 100 uses a work RAM 108 as a working memory. Further, the CPU 100 drives the pump motor 124 via the output port 114 and the motor driving unit 116 during the cleaning and recovery operations of the head units 22K, 22C, 22M, and 22Y, and controls ink pressurization and suction. .

  FIG. 3 is a diagram schematically showing a path through which ink passes from the ink tank 28K to the head unit 22K in the recording apparatus of the present embodiment. Since each head unit has the same structure, only the black ink head unit 22K will be described below as an example.

  The recording apparatus 10 incorporates an ink supply device 60 that supplies ink to the head unit 22K, and the head unit 22K can discharge ink with a storage portion 22Kr as a liquid chamber that supplies ink to the discharge portion 22KSi. And a discharge unit 22KSi. The ink supply device 60 includes an ink tank 28K that can be attached to and detached from the main body of the recording apparatus 10, and an ink supply pump 72 that is disposed in the middle of an ink supply path 62 that connects the ink tank 28K and the head unit 22K. Yes. The supply pump 72 is responsible for supplying ink to the reservoir 22Kr via the ink filter 90.

  A liquid level detection sensor 86 for detecting the level of the liquid level 22Krs of the stored ink (hereinafter also referred to as stored ink) is attached to the storage unit 22Kr. Further, below the reservoir 22Kr, a nozzle 22Kn of the head unit 22K and an ejection unit 22KSi in which an ink supply port to the nozzle 22Kn is formed are connected.

  An air flow path 64 is connected to a space 66 (hereinafter referred to as an air chamber) 66 filled with air via an air filter 95 above the reservoir 22Kr. The air flow path 64 includes an atmospheric valve 84 and A pressure detection sensor 81 capable of measuring pressure is provided. The pressure detection sensor 81 can detect the pressure in the air chamber 66. The other end of the air channel 64 opposite to the one end where the air filter 95 is provided is connected to the decompression channel 65 in a T-shape, and the decompression channel 65 has one end. The atmosphere is released and the other end is connected to the fan 68.

  A detection sensor (not shown) for detecting the presence or absence of ink in the ink tank 28K is attached to the ink tank 28K. The ink tank 28K is provided with an air release valve 74 for setting the internal pressure of the ink tank 28K to atmospheric pressure.

  When it is determined from the measurement result of the liquid level detection sensor 86 in the reservoir 22Kr that the ink amount is equal to or less than the predetermined amount, the air release valve 74 of the ink tank 28K is opened, and the supply pump 72 is operated to remove the ink from the ink tank 28K. Aspirate the ink. Then, the sucked ink is supplied into the storage portion 22Kr. On the other hand, when the liquid level detection sensor 86 detects the ink level 22Krs above a certain level, the supply pump 72 is stopped, the air release valve 74 of the ink tank 28K is sealed, and the ink supply is stopped.

  Incidentally, a tube pump is used as the supply pump 72, and the ink supply path 62 is blocked when the supply pump 72 is not in operation (the flow path between the ink tank 28K and the storage portion 22Kr is blocked).

  FIG. 4 is a flowchart showing a procedure for cleaning the discharge port surface 22Ks of the head unit 22K. FIG. 5 is a schematic diagram showing a procedure for wiping ink from the ejection surface 22Ks with the wiper 52, (a) showing before the start of wiping, (b) showing immediately after wiping is completed, and (c) showing completion of wiping. It is a figure which shows the waiting state after. The term “cleaning” as used herein refers to an operation performed in order to continuously maintain the ink ejection of the head unit 22K in a good state. When conditions such as elapsed time and ejection conditions are satisfied, or there is an abnormality in recording quality. This is an operation that is performed automatically or arbitrarily when viewed. Hereinafter, the cleaning operation will be described in order.

  When the cleaning command is received in step S401, the atmosphere release valve 84 is released in step S402. Thereafter, in step S403, the cleaning pump 92 is driven in a direction to depressurize the inside of the cap 50, and the ink in the reservoir 22Kr is drawn into the cap 50 from the nozzle 22Kn and discharged. By discharging the ink, it is possible to remove foreign matters such as fine bubbles accumulated around the nozzles 22Kn during the recording operation and the like, and dust attached to the ejection port surface 22Ks of the head unit. Then, after a certain period of time has elapsed, the driving of the cleaning pump 92 is stopped at step 404 and the atmospheric valve 84 is closed at step 405.

  In this state, ink may still adhere to the ejection port surface 22Ks including the opening of each nozzle 22Kn of the head unit 22K. Therefore, in order to remove the dirt, the discharge port surface 22Ks is wiped with a wiper 52 provided together with the cap 50, as will be described later. At that time, first, in step S406, the head unit 22K is moved above the recovery cap 50 as shown in FIG. Thereafter, the cap 50 is moved in the direction of arrow B in step S407, so that the dirt such as ink adhering to the face surface 22Ks is wiped off by the wiper 52 as shown in FIG. This operation is called a wiping operation. After the wiping operation is completed, as shown in FIG. 5C, the head unit 22K is capped again and enters a standby state in step S408. The head unit 22K in the standby state has the face surface 22Ks capped (closed) by the cap contact portion 54, so that there is almost no air convection in the cap 50, and the ink in the nozzles 22Kn does not flow. It is possible to prevent thickening. The head unit 22K enters a standby state, and the cleaning operation ends.

  The ink (waste ink) discharged from the nozzle 22Kn is received by the cap 50 and sucked by the suction pump 92 (see FIG. 3). The absorbed waste ink is pumped to a waste ink tank 71 (see FIG. 3). The waste ink tank 71 is provided with a minute air opening 75 and plays a role of releasing the pressure in the waste ink tank 71 that changes with the inflow of waste ink (and bubbles) to the atmosphere.

  FIG. 6 is an enlarged view of the head unit 22K and its surroundings. At the time of recording, it is necessary to apply an appropriate negative pressure to the head unit 22K in order to form a meniscus on the nozzle 22Kn. Therefore, during recording, the air valve 66 in the head unit 22K is decompressed by opening the atmospheric valve 84 and operating the fan 68 to create an air flow in the C direction. As a result, the pressure in the nozzle 22Kn is similarly reduced through the reservoir 22Kr.

  In the present embodiment, the reservoir 22Kr communicating with the atmosphere is disposed above the discharge unit 22Ks. Therefore, when the atmosphere valve 84 is opened, the opening at the tip of the nozzle 22Kn has a positive head pressure H from the liquid level 22Krs. The pressure acts on the nozzle 22Kn opening. Therefore, the amount of pressure reduction by the fan 68 into the air chamber 66 is set to be equal to or higher than the water head pressure H. Thereby, a negative pressure is applied to the nozzle 22Kn of the head unit 22K. As a result, an ink meniscus is formed in the opening of the nozzle 22Kn.

  In the present embodiment, the negative pressure generated by operating the fan 68 is not directly applied to the air chamber 66, but is provided with the suction port 61 (air introduction portion) through which the atmosphere can be introduced, thereby providing the negative pressure. Is indirectly applied to the air chamber 66. Further, in the present embodiment, by operating the fan 68, a flow of air taken in from the suction port 61 is generated in the decompression channel 65, and the air in the air channel 64 connected to the decompression channel 65 is It is drawn into the flow of air in the decompression flow path 65 mainly by the ejector principle. As a result, a negative pressure is generated in the air chamber 66.

  The storage unit 22Kr disposed in the head unit 22K is a buffer for supplying ink used for recording to the nozzles 22Kn, and an ink upper limit level and an ink lower limit level are set for the amount of ink in the storage unit 22Kr. . In the head unit 22K, the liquid level upper limit level detection sensor 86a and the liquid level lower limit level detection sensor 86b are monitored so as to always maintain the ink amount in the range from the upper limit level to the lower limit level. The supply pump 72 can adjust the flow rate of ink supplied to the head unit 22K by operating at a five-stage speed. The first speed and the second speed are set from the slowest speed, and the maximum speed is the fifth speed. It has become. The supply pump 72 can operate independently for each color of KCMY, and each pump is operated as necessary.

  FIG. 7 is a diagram showing a speed table of the supply pump 72 in the present embodiment. In the present embodiment, the supply pump 72 operates at a five-stage speed Np, but the number of stages may be increased or decreased as necessary. By discharging ink from the head unit 22K, the ink in the reservoir 22Kr is consumed, and when the lowering of the liquid level 22Krs is detected by the liquid level lower limit level detection sensor 86b, the supply pump 72 is first turned to the first speed (Np = 1) The ink is supplied from the ink tank 28K to the liquid chamber. After operating the supply pump 72 to start supplying ink to the reservoir 22Kr, after waiting for a predetermined time, the state of the liquid level lower limit level detection sensor 86b is confirmed again. When the liquid level lower limit level detection sensor 86b confirms that the amount of ink in the reservoir 22Kr exceeds the ink lower limit level of the liquid chamber, the supply pump 72 continues to supply ink at the current speed. When the liquid level upper limit detection sensor 86a detects that the ink in the reservoir 22Kr has reached the ink upper limit level, the supply pump 72 is stopped.

  When the state of the liquid level lower limit level detection sensor 86b is confirmed again, if the ink amount in the liquid chamber does not exceed the ink lower limit level, it is determined that the ink supply amount is smaller than the ink consumption amount, and the speed Np of the supply pump 72 is determined. Is increased by one step (Np = 2) to increase the ink supply amount. After the speed of the supply pump 72 is increased by one step, the state of the liquid level lower limit level detection sensor 86b is confirmed again after a predetermined time, and it is confirmed whether the ink amount exceeds the ink lower limit level. That is, it is determined whether the amount of ink consumed in the head unit consumed for a predetermined time is large or small. When the amount of ink consumed in the predetermined time is large and the ink lower limit level is not exceeded, processing for increasing the speed Np of the supply pump 72 is performed again. That is, the speed of the supply pump 72 is increased until the ink supply amount at the speed Np of the supply pump 72 exceeds the ink consumption amount (ink decrease amount in the storage unit 22Kr) accompanying the recording process. Therefore, the ink supply amount (maximum supply amount) of the supply pump 72 at Np = 5, which is the speed for supplying the largest amount per unit time in FIG. 7, is the maximum ink consumption amount per unit time in the head unit 22K. The value is higher.

  As described above, in the present embodiment, by changing the speed of the supply pump 72 that supplies ink as the ink in the head unit 22K is consumed, it is possible to suppress the occurrence of large fluctuations in the negative pressure in the head unit 22K. ing.

  The ink flow rate at the fifth speed is set to be larger than the consumption amount when all the nozzles 22Kn of the recording head discharge simultaneously, so that the ink supply amount can exceed the ink consumption amount. Thereafter, the ink level in the storage unit 22Kr is continuously monitored until the end of recording, and the ink level in the storage unit 22Kr is kept in a certain range.

  In the present embodiment, the ink amount in the storage unit 22Kr is monitored by the liquid level upper limit level detection sensor 86a and the liquid level lower limit level detection sensor 86b. You may control the flow rate at any time.

  FIG. 8 is a flowchart showing the flow of recording processing in the present embodiment. Normally, when the recording apparatus is not used, the atmospheric valve 84 is closed for the purpose of preventing ink leakage from the nozzle Kn. When starting recording, the CPU 100 first operates the fan 68 with the atmospheric valve 84 closed to depressurize the decompression flow path 65 and the air flow path 64, and then turns the atmospheric valve 84 on. open. The recording process of this embodiment will be described below along this flowchart.

  When the recording apparatus 10 receives a recording signal in step S701, the CPU 100 proceeds to step S702 and activates the fan 68. Next, in step S <b> 703, the CPU 100 confirms the pressure in the air flow path 64 with the pressure detection sensor 81 in order to confirm whether or not the pressure reduction by the fan 68 is normally performed. If the predetermined pressure is not obtained, the CPU 100 proceeds to step S704 and corrects the rotational speed of the fan 68. If the predetermined pressure is obtained in step S703, the CPU 100 proceeds to step S705 and releases the atmospheric valve 84. When the atmospheric valve 84 is released, the air chamber 66 is depressurized, and a negative pressure acts on the nozzle 22Kn. A meniscus is formed in an optimal state at the opening (discharge port) of the nozzle Kn.

  Next, the CPU 100 moves the head unit 22K to the wiping position in step S706, and performs wiping of the discharge port surface 22Ks of the head unit 22K in step S707. Thereafter, the CPU 100 lowers the head unit 22K and moves it to the recording position in order to perform recording in step S708. In step S709, recording is performed on the recording medium P. Then, by recording on the recording medium P, the ink in the reservoir 22Kr is consumed, and when the liquid level lower limit level detection sensor 86b detects the lower limit level of the liquid level 22Krs in step S710, the CPU 100 in step S720. Increase the speed of the supply pump 72 by one step. At this time, when the supply pump is in the stop state Np = 0, the speed of the supply pump 72 becomes the first speed Np = 1. Then, the CPU 100 drives the supply pump 72 in step S711. After starting the supply pump 72, the CPU 100 waits for a predetermined time in step S721, returns to step S710 again, and confirms whether the ink in the reservoir 22Kr is equal to or lower than the lower limit. If the liquid level is still below the lower limit, the CPU 100 increases the speed of the supply pump 72 by repeating steps S720 to S721 until the ink exceeds the lower limit level.

  When the CPU 100 confirms that the ink in the reservoir 22Kr exceeds the lower limit level in step S710, the CPU 100 confirms whether the supply pump 72 is operating in step S712. When the supply pump 72 is in operation, the CPU 100 checks the liquid level upper limit level detection sensor 86a in step S713. If the upper limit is not reached, the CPU 100 waits for a predetermined time in step S719 and the liquid level again in step S713. Check if it is at the upper limit. When the liquid level reaches the upper limit, the CPU 100 stops the supply pump 72 in step S714. When the supply pump 72 is stopped, the CPU 100 proceeds from step S712 to step S715, confirms the end of the recording operation, and if the recording is not completed, repeats steps S710 to S715 until the recording is completed. After the end of the recording operation, the CPU 100 raises the head unit 22K in step S716, moves to the standby position, and is capped by the cap 50 again. Thereafter, the CPU 100 closes the atmospheric valve 84 in step S717, stops the operation of the fan 68 in step S718, enters the standby mode again, and ends this flowchart.

  The number of ink ejection dots of the head unit 22K is counted, and the ink consumption per unit time (ink reduction amount in the storage unit 22Kr) is calculated from the number of ink ejection dots per unit time to determine the supply pump operating speed. It doesn't matter. Even in this case, the ink supply amount (maximum supply amount) of the supply pump 72 at Np = 5, which is the speed at which the largest amount is supplied per unit time, is the maximum ink consumption amount per unit time in the head unit 22K. It is assumed to exceed the value. Here, a method in which the ink supply amount of the supply pump 72 is set to a value exceeding the maximum consumption amount of ink per unit time in the head unit 22K and the operation speed of the supply pump 72 is operated at a constant speed is also conceivable. However, when the operation speed of the supply pump 72 is operated at a constant speed as described above, if the ink consumption per unit time is small, the ink suddenly flows into the storage portion 22Kr, so the negative pressure in the air chamber 66 is reduced. There is a possibility that the pressure will suddenly become smaller than the predetermined negative pressure. However, the problem as described above can be suppressed by controlling the ink supply amount by the supply pump 72 in accordance with the ink consumption amount as in the present embodiment.

  As described above, the ink supply device of this embodiment changes the speed of the supply pump 72 that supplies ink as the ink in the head unit 22K decreases. As a result, it was possible to realize an ink supply device capable of suppressing large fluctuations in the negative pressure in the head unit 22K and stably ejecting ink.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIG. 9 is a diagram showing a speed table of the fan 68 in the present embodiment. The fan 68 in the present embodiment can operate at a rotation speed Nf at six stages as shown in FIG. 9, and the first speed and the second speed are determined from the slowest speed, and the maximum speed is the sixth speed. It has become. In the present embodiment, the rotational speed Nf of the fan 68 is a six-stage speed, but is not limited to this, and may be adjusted as necessary. In the present embodiment, when ink in the reservoir 22Kr is consumed by ejecting ink from the head unit 22K, the liquid level lower limit level sensor 86b detects that the ink in the reservoir 22Kr has fallen below a predetermined ink amount. To do. When it is detected that the liquid level lower limit level sensor 86b has fallen below, the supply pump 72 is operated at the first speed to start supplying ink from the ink tank 28K to the liquid chamber. At that time, the fan 68 increases the rotation speed by one step with the change in the operation speed of the supply pump 72 as a trigger to increase the negative pressure. Similarly, every time the speed of the supply pump 72 increases by one step, the rotational speed of the fan 68 also increases by one step. It is desirable to control the speed of the supply pump 72 and the rotational speed of the fan 68 in such a relationship that the negative pressure of the reservoir 22Kr is always constant.

  FIG. 10 is a flowchart showing the flow of recording processing in the present embodiment. Normally, when the recording apparatus is not used, the atmospheric valve 84 is closed for the purpose of preventing ink leakage from the nozzle Kn. When recording is started, the CPU 100 first operates the fan 68 with the atmospheric valve 84 closed to depressurize the decompression flow path 65 and the air flow path 64, and then activate the atmospheric valve 84. open. The recording process of this embodiment will be described below along this flowchart. Steps S701 to S709 are the same as those in the first embodiment, and therefore, the processing after step S710 will be described.

  Due to the recording operation in step S709, the ink in the reservoir 22Kr is reduced. In step S710, when the liquid level lower limit level detection sensor 86b in the reservoir 22Kr detects the lower limit level of the liquid level, the CPU 100 increases the speed of the supply pump 72 by one level in step S720 (the supply pump is in a stopped state Np = 0). In this case, the first speed Np = 1). Then, the CPU 100 drives the supply pump 72 in step S711. The CPU 100 then increases the rotational speed Nf of the fan 68 by one step in step S722, and drives the fan 68 in step S723. In the initial stage, the speed of the supply pump 72 is Np = 0, and the rotational speed of the fan 68 is Nf = 1. After driving the fan 68 in step S723, the CPU 100 waits for a predetermined time in step S721, returns to step S710 again, and checks whether the ink in the reservoir 22Kr is equal to or lower than the lower limit. If the liquid level is still below the lower limit, the CPU 100 repeats Step S720 to Step S721 until the ink exceeds the lower limit level, and increases the speed Np of the supply pump 72 and the rotational speed Nf of the fan 68.

  When the CPU 100 confirms that the ink in the reservoir 22Kr exceeds the lower limit level in step S710, the CPU 100 confirms whether the supply pump 72 is operating in step S712. When the supply pump 72 is in operation, the CPU 100 checks the liquid level upper limit level detection sensor 86a in step S713. If the upper limit is not reached, the CPU 100 waits for a predetermined time in step S719 and again in step S713. Check if is at the upper limit. When the liquid level reaches the upper limit, the CPU 100 stops the supply pump 72 in step S714. When the supply pump 72 is stopped, the CPU 100 proceeds from step S712 to step S715, confirms the end of the recording operation, and if the recording is not completed, repeats steps S710 to S715 until the recording is completed. After the end of the recording operation, the CPU 100 raises the head unit 22K in step S716, moves to the standby position, and is capped by the cap 50 again. Thereafter, the CPU 100 closes the atmospheric valve 84 in step S717, stops the operation of the fan 68 in step S718, enters the standby mode again, and ends this flowchart.

  FIGS. 11A and 11B show the pump stop sequence in step S714. As shown in (a), the supply pump 72 decelerates at a constant speed and stops. Accordingly, the fan 68 is also decelerated at a constant speed and stopped. Moreover, you may stop in steps on a rectangular table at regular intervals as shown in FIG.

  In the present embodiment, as in the first embodiment, the number of ink ejection dots of the head unit 22K is counted, and the ink consumption per unit time is calculated from the number of ink ejection dots per unit time to operate the supply pump 72. You can decide the speed. Even in this case, the ink supply amount (maximum supply amount) of the supply pump 72 at Np = 5, which is the speed at which the largest amount is supplied per unit time, is the maximum ink consumption amount per unit time in the head unit 22K. It is assumed to exceed the value.

  In this way, the speed of the supply pump 72 that supplies ink and the rotational speed of the fan 68 are changed as the ink in the head unit 22K is consumed. As a result, it was possible to realize an ink supply device capable of suppressing large fluctuations in the negative pressure in the head unit 22K and stably ejecting ink.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIG. 12 is a view showing the head unit of the present embodiment and its periphery. The negative pressure control means by the fan 68 may be connected to the plurality of head units 22Y, 22M, 22C, and 22K as in the present embodiment.

  Note that “recording” (also referred to as image formation) in the present specification is not limited to forming significant information such as characters and graphics. In other words, recording means that an image, a pattern, a pattern, etc. are widely formed on a recording medium regardless of whether it is significant involuntary, or whether it is manifested so that humans can perceive it visually, or This includes cases where media are processed.

  The “recording medium” (also referred to as roll paper) includes not only paper used in general recording apparatuses but also a wide range of materials such as cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. Including acceptable ones.

  Further, the term “ink” should be broadly interpreted in the same way as the definition of “recording”. In other words, the ink is applied onto the recording medium to form an image, pattern, pattern, or the like, process the recording medium, or process the ink (for example, solidify or insolubilize the colorant in the ink applied to the recording medium). ) Shall be included.

  In each of the above embodiments, the propeller type fan is used as the negative pressure generating means. However, the present invention is not limited to this, and the negative pressure generating means using a flexible ink bag and a bow spring, A mold pump or the like may be used. It goes without saying that liquids other than ink may be used in the apparatus of the present invention.

22K head unit 60 ink supply device 68 fan 72 supply pump 74 atmosphere release valve 84 atmosphere valve 86 liquid level detection sensor 86a liquid level upper limit level detection sensor 86b liquid level lower limit level detection sensor

Claims (5)

A discharge section capable of discharging ink stored therein, a liquid chamber for supplying ink to the discharge section, a supply pump for supplying ink to the liquid chamber, and a negative pressure generating means capable of adjusting the pressure in the liquid chamber And an ink supply device comprising: a detecting means for detecting the amount of ink in the liquid chamber;
When the detection unit detects that the amount of ink in the head unit is less than a predetermined amount, the supply pump starts operation, and the liquid chamber per unit time after the supply pump starts operating. The ink supply device, wherein the supply pump increases the amount of ink supplied to the liquid chamber when the amount of ink decrease is greater than a predetermined amount.   The ink supply device according to claim 1, wherein the supply pump gradually increases the amount of ink supplied to the liquid chamber.   The ink supply apparatus according to claim 1, wherein the supply amount to the liquid chamber by the supply pump is determined based on an ink consumption amount per unit time of ink in the liquid chamber.   4. The ink according to claim 1, wherein a maximum supply amount per unit time by the supply pump is larger than a maximum consumption amount that the discharge unit discharges per unit time. 5. Feeding device.   5. The ink supply device according to claim 1, wherein the negative pressure generating unit increases the negative pressure as the amount of ink supplied by the supply pump increases. 6.