JP2009269360A - Image recording method and image recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording device with an ink circulation passage, which is started when a user needs to output image recording first on the day, and is controlled not to start recording till ink reaches an appropriate temperature for recording, regardless of a job amount of image recording. <P>SOLUTION: In the image recording method and image recording device, when an image recording job having a small recording amount is provided, either the ink remaining within the ink liquid chamber of a recording head or the ink remaining within the ink warming circulation passage shorter than the ink circulation passage through a bypass communication passage provided in the ink circulation passage is warmed, thereby the ink is warmed up to an appropriate temperature for recording in a short period of time and image recording starts in a shorter standby time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image recording method and an image recording apparatus that are provided with a circulating ink flow path and eject an ink to record an image on a recording medium.

  In general, an inkjet image forming apparatus that records an image by driving an actuator such as a piezoelectric element or a heating element of a recording head to discharge ink onto a recording medium is known. When bubbles or foreign matter are mixed in the actuator of the recording head, or when the viscosity of the ink filled in the actuator increases due to evaporation of moisture from the nozzle of the recording head, ink clogging occurs in the actuator of the recording head. There is a problem in that normal ink ejection cannot be performed and image recording is hindered.

Therefore, for example, in Patent Document 1, in an ink supply path of an image recording apparatus, an ink supply path for supplying ink to a recording head and an ink return path for returning ink that has not been used for image formation to the ink supply path. And an ink circulation path for circulating ink is proposed. By performing such ink circulation, foreign matter flows out of the head by the ink flow and is removed by the filter, and further, the heat dissipation effect of the flowing ink is used to prevent the temperature of the recording head being driven from rising. . It also has the effect of removing bubbles generated in the recording head and preventing ink thickening.
JP 2006-88575 A

  The image forming apparatus having the ink circulation path described above has a larger amount of ink remaining in the ink supply path than the apparatus having no circulation path. Increasing the amount of ink increases the heat capacity of the ink as a whole and reduces the temperature fluctuation of the ink. On the other hand, the process of warming up the ink temperature until the ink can be recorded after the apparatus is started (warm-up). It takes time.

  The conventional image forming apparatus having the ink circulation path cannot start image recording unless the ink temperature reaches the proper recording temperature. When the image recording apparatus is used in winter or in a region where the temperature is low, the determination performed immediately after the main power is turned on has a low possibility that the ink temperature is low and recording cannot be started.

  The timing at which the image recording device is activated often requires the user to output an image for the first time of the day. However, unless the ink reaches the proper recording temperature, the recording operation will not be started, so it is necessary to wait until the warm-up is completed. It becomes. However, the waiting time is affected by the outside air temperature around the apparatus and is not related to the number of recording media (job amount) on which an image is recorded and output.

  Therefore, the user must wait for the same time, for example, when implementing a recording medium on which one image is recorded and outputting, or when implementing a large number of image recording sheets. Therefore, the user waits for a long time even in the case of a small amount of image recording job.

  Therefore, the present invention focuses on the above problems, and can start up and start image recording in a short time by switching to an ink circulation channel that heats a small amount of ink according to a small amount of image recording job. An object is to provide an image recording method and an image recording apparatus.

  To achieve the above object, an image recording method according to an embodiment of the present invention includes at least one recording head, an ink tank that stores ink, an ink supply path that connects the ink tank to the recording head, and the An image recording method in an image recording apparatus, comprising: an ink circulation path comprising an ink return path connecting a recording head to the ink tank; and an ink circulation means provided on the ink circulation path for circulating the ink. A determination step for determining whether or not the job amount to be image-recorded is less than a predetermined job amount when the temperature of the ink remaining in the recording head is lower than the proper recording temperature; and When it is determined that the job amount to be recorded is less than the predetermined amount, the ink circulation unit is controlled to A circulation stopping step that does not perform a ring, and a first heating step that heats only the ink remaining in the recording head while the circulation of the ink is stopped. An image recording step of performing image recording in a state where the ink circulation is stopped after the ink is heated and reaches the proper recording temperature;

  An image recording apparatus according to an embodiment of the present invention includes at least one recording head that discharges ink to record an image, an ink tank that stores ink, and an ink supply that connects the ink tank to the recording head. A first ink circulation path comprising an ink return path connecting the path and the recording head to the ink tank, a first ink circulation means for circulating the ink in the first ink circulation path, and the ink supply path. A second ink circulation for bypassing a short path between the ink return path and including the recording head on the path to circulate an ink amount smaller than the ink remaining in the first ink circulation path. A second ink circulating means for circulating the ink in the second ink circulation path, and the second ink circulation means. When the amount of ink that can be recorded with the amount of ink remaining in the ink circulation path is input, the ink is circulated in the second ink circulation path and the ink passing through the recording head is not ejected. Then, the recording head is driven to heat the ink passing through the recording head and reach an appropriate recording temperature, and then image recording is performed.

  According to the present invention, an image recording method and an image recording apparatus that can start up and start image recording in a short time by switching to an ink circulation channel that heats a small amount of ink according to a small amount of image recording job. Can be provided.

  First, the concept of the present invention will be described. According to the present invention, when an image recording job with a small recording amount (number of printed sheets) is given, the amount of ink remaining in the ink liquid chamber of the recording head or the ink circulation via the bypass communication path provided in the ink circulation path When it is determined that image recording is possible with the amount of ink remaining in the ink heating circulation path shorter than the path, only the ink remaining in the ink liquid chamber or only the ink remaining in the ink heating circulation path Is an image recording method and an image recording apparatus in which the temperature of the ink is raised to a proper recording temperature in a short time and image recording is started in a short standby time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically showing an ink circulation path for supplying ink to a recording head of an ink jet type image recording apparatus according to a first embodiment of the present invention. The image forming apparatus 1 of the present embodiment mainly includes a plurality of recording heads 10 provided with an upstream ink port 10b and a downstream ink port 10c, a transport mechanism 30 that transports the recording medium 31, and an ink circulation path to the recording head 10. 2 and a control unit 42 that controls ink supply, recording head drive (ink ejection), and overall control of the apparatus.

  The recording head 10 in the present embodiment is a short head in which the nozzle row length (the width at which an image is formed by nozzles arranged in a row) is less than the width of the recording medium 31, and a plurality of recording heads 10 are connected to the recording medium 31. The nozzle rows are alternately arranged in a staggered manner in the width direction so that the nozzle array length exceeds the width of the recording medium 31 and the areas where ink is ejected overlap. In the present embodiment, six short recording heads are arranged in a staggered manner to enable image formation that is greater than the width of the recording medium 31. Of course, one recording head having a length exceeding the width of the recording medium 31 may be used. The recording head 10 ejects ink supplied from the ink circulation path 2 through a plurality of nozzles 10a by driving an actuator constituted by a piezoelectric element. The nozzle 10a ejects ink in the vertical direction on the recording medium 31 that passes through a facing position separated by about 2 mm, based on an ejection signal synchronized with the transport speed, thereby forming an image.

  The ink supplied into the recording head 10 from the upstream ink port 10b is discharged from the nozzle 10a, and the ink that has not been discharged is discharged out of the recording head 10 from the downstream ink port 10c.

  The ink circulation path 2 includes an upstream ink supply path 2a for supplying ink to the recording head 10, and a downstream ink return path 2b for returning the ink discharged from the recording head 10 to the ink supply path (upstream sub tank 15) 2a. Consists of.

  The ink supply path 2a is provided above the nozzle 10a in the gravity direction, and connects the upstream sub tank 15 for supplying ink from the upstream ink port 10b to the recording head 10, and the recording head 10 (upstream ink port 10b) and the upstream sub tank 15. A tube 16a to be supplied, an ink bottle 19 for supplying ink to the upstream sub tank 15, a tube 18 connecting the upstream sub tank 15 and the ink bottle 19 via a valve 20b, and ink supply control for controlling opening and closing of the valve 20b. And a liquid level sensor 20 a provided in the upstream sub tank 15. The upstream air release valve 15 a opens the inside of the upstream sub tank 15 to the atmosphere.

  The ink return path 2b is provided below the nozzle 10a in the gravitational direction, and a downstream sub tank 11 that temporarily stores ink discharged from the downstream ink port 10c without being used by the recording head 10, and the recording head 10 (downstream). A tube 16b connecting the ink port 10c) and the downstream sub tank 11, a pressure regulator 17 and a downstream atmospheric release valve 11a provided in the downstream sub tank 11, a downstream atmospheric release valve 11a provided in the downstream sub tank 11, and the downstream sub tank 11 And the upstream sub-tank 15, a circulation pump 12 and a temperature regulator 13 provided on the path of the tube 16 c, and a filter 14 for removing foreign matters in the circulating ink.

Hereinafter, each component will be described in detail.
In the ink supply path 2a, the liquid level sensor 20a outputs a detection signal related to the detected liquid level to the ink supply control unit 20c. Based on the detection signal, the ink supply control unit 20c opens and closes the valve 20b to replenish ink from the ink bottle 19 so that the liquid level in the upstream sub tank tank 15 maintains a water head value at which proper ink discharge is possible. Always keep it at the right height. The valve 20b is closed except when the upstream sub tank 15 is replenished with ink from the ink bottle 19.

  Further, a filter (not shown) provided in the upstream atmosphere release valve 15a prevents foreign matter from entering the ink supply path 2a through the upstream atmosphere release valve 15a. The atmosphere communication pipe 19a keeps the inside of the ink bottle 19 at atmospheric pressure at all times. In addition, when the user has excessively filled the ink in the ink bottle 1, a configuration may be provided in which the ink bottle 1 is discharged to an ink pan (not shown) through the atmosphere communication pipe 19a.

  In the ink return path 2b, the pressure regulator 17 adjusts the atmospheric pressure inside the tank, and the downstream atmospheric release valve 11a is opened under the control of the control unit 42, and the internal space of the downstream sub tank 11 is released to the atmosphere. Further, the downstream sub-tank 11 can be sealed by closing the downstream atmosphere release valve 11a. When the downstream sub-tank 11 is maintained at atmospheric pressure, the height of the downstream sub-tank 11 is determined so as to obtain an appropriate pressure such that a meniscus is generated in the nozzle 10a due to a water head difference between the downstream sub-tank 11 and the nozzle 10a. It has been.

  When the downstream air release valve 11a is closed and the downstream sub-tank 11 is sealed, the pressure regulator 17 is provided in the downstream sub-tank 11 so that the pressure applied to the nozzle 10a becomes the proper recording pressure regardless of whether or not the ink is circulated. Adjust the air pressure.

  The liquid level adjuster 11b is provided at the end of the tube 16c in the downstream sub tank 11, and adjusts the amount of ink flowing from the downstream sub tank 11 toward the upstream sub tank tank 15 through the tube 16c. The downstream atmosphere release valve 11a is provided with a filter (not shown) to prevent foreign matters from entering the ink supply path 2 through the downstream atmosphere release valve 11a.

  The circulation pump 12 supplies pressure for circulating ink according to the control of the control unit 42. The temperature adjuster 13 detects the temperature of the ink flowing through the tube 16c, and adjusts the temperature by heating or cooling the ink so as to be in an appropriate temperature range.

The filter 14 removes foreign matters including paper dust in the circulating ink, ink lump, and the like.
When ink is circulating, the upstream atmosphere release valve 15a is opened and the downstream atmosphere release valve 11a is closed. At this time, the pressure adjuster 17 adjusts the atmospheric pressure in the downstream sub-tank 11 so that the ink liquid pressure in the nozzle 10a becomes the image recording proper pressure. On the other hand, when the ink is not circulating, the upstream atmosphere release valve 15 is closed and the downstream atmosphere release valve 11a is opened.

  As described above, the ink liquid pressure at the nozzle 10a at this time is an appropriate image recording pressure. The control unit 42 also acquires information on the presence / absence of a recording job and the recording amount. For example, the recording head 10 is provided with a temperature sensor 21 in a path through which ink circulates, and measures the temperature of the ink. As the temperature sensor 21, for example, a thermocouple is suitable.

Next, ink circulation in the ink circulation path 2 of the present embodiment will be described.
First, when the apparatus is activated, ink circulates from the upstream sub tank 15 through the tube 16a so as to be supplied from the upstream ink port 10b to the recording head 10.

  In response to an image recording instruction from the control unit 42, the recording medium 31 is fed, ink is ejected when passing in front of the nozzle 10a, and an image is recorded on the recording medium 31. Of the supplied ink, excess ink that has not been ejected by the nozzle 10a flows out of the downstream ink port 10c and is discharged to the downstream sub-tank 11 through the tube 16b.

  The ink flowing into the downstream sub tank 11 is sucked up by the circulation pump 12 and returns to the upstream sub tank 15 through the tube 16c. At this time, foreign matters are removed by the filter 14 in the process of flowing through the tube 16c, and the temperature adjuster 13 adjusts the ink to a temperature suitable for recording. Whether or not the ink is at a temperature suitable for image recording is determined based on the ink temperature measured by the temperature sensor 21.

  The liquid level height of the downstream sub-tank 11 is always maintained at an appropriate height by the liquid level adjuster 11b. In the liquid level adjuster 11b, for example, a pipe having an outlet opened on a side surface connected to the tube 16c is provided, and a floating member in which ink floats is fitted into the pipe.

  When the circulation pump 12 circulates ink at a constant pressure, if the ink level in the downstream sub-tank 11 falls below a predetermined position, the lowered floating member narrows the outlet and reduces the amount of flow out to the tube 16c. Limit or stop. Thereby, the flow path resistance when the circulation pump 12 sucks up ink from the downstream sub tank 11 increases. As a result, the amount of ink sucked from the downstream sub tank 11 per unit time decreases, and the ink level in the downstream sub tank 11 rises due to the ink flowing from the recording head 10 side. It becomes height. At this time, the floating member also rises to open the outlet, and the ink is sucked up by the circulation pump 12.

  As described above, the liquid level in the downstream sub-tank 11 varies within a certain width with respect to the position (height) of the outlet formed in the tube 16c, and the liquid level is maintained within the width.

  However, if image recording is performed, ink is ejected from the nozzles 10 a, so that the total amount of circulated ink also decreases, and the ink level also decreases in the upstream sub-tank 15. When the liquid level sensor 20a detects a decrease in the liquid level in the upstream sub tank 15, the liquid level sensor 20a sends the information of the ink supply control unit 20c. In the ink supply control unit 20, the valve 20 b is opened based on the liquid level drop information, and ink is supplied from the ink bottle 19 to the upstream sub tank 15 through the tube 18.

  Further, in the ink circulation path 2 as in the present embodiment, the ink circulates through the inside of the recording head 10. For this reason, the heat generated by driving the recording head 10 propagates to the ink, and the temperature rise of the recording head 10 is suppressed. Here, since the heat applied to the ink diffuses throughout the ink supply path 2, the temperature of the circulating ink is difficult to increase.

  Further, by circulating the ink, bubbles and foreign matters clogged in the recording head 10 are discharged from the downstream ink port 10c and removed.

  In this way, by suppressing the temperature rise of the recording head and eliminating foreign matter, the image forming apparatus 1 continuously performs a recording operation without degrading the quality of image recording (printing) for a long time. can do.

  On the other hand, when the ink temperature detected by the temperature sensor 21 is lower than the proper recording temperature, it is necessary to heat the ink in advance before starting the recording operation. However, as described above, the amount of ink circulating in the ink supply path 2 is large, and as described above, the role of preventing the temperature rise of the recording head is regarded as more important. It is difficult to raise.

  That is, since the ink supply path 2 is provided, the preparation time (or standby time) until the recording operation is started becomes long. In addition to being able to perform high-quality image recording over a long period of time, the user strongly demands that the ink temperature immediately reaches an appropriate recording temperature and that recording can be started in a short waiting time.

  With reference to the flowchart shown in FIG. 2, the ink temperature control method in the ink circulation path of the present embodiment will be described. FIG. 2 is a flowchart for explaining the procedure of the ink heating control in the first embodiment. In the following description, the term “ink circulation” indicates that the ink has already circulated in the ink supply path 2, and if the ink has not been circulated at that time, the ink circulation starts immediately. It means to do. It is assumed that the ink circulation is continued until the ink circulation is stopped.

  First, when the power is turned on, each component is activated and initialized so as to be in a predetermined standby state (step S1). Here, the control unit 42 acquires the ink temperature information from the detection value of the temperature sensor 21 at all times or at a predetermined timing, and determines whether or not the ink temperature is equal to or higher than the proper recording temperature (step S2).

  In this determination, if the ink temperature is equal to or higher than the proper recording temperature (YES), ink circulation is started (step S3), the ink temperature is adjusted, and the proper recording temperature is maintained (step S4). Next, it is determined whether or not there is an image recording job (step S5). If there is an image recording job (YES), image recording is started (step S6). After the end of the image recording (step S7), it is determined whether or not to stop the apparatus (step S8). If it is not stopped to perform another image recording (NO), the process returns to step S2 to check the ink temperature. On the other hand, if there is no image recording job in step S5 (NO), the process waits for a predetermined time (step S9), and then proceeds to step S8.

  If it is determined in step S2 that the ink temperature is equal to or lower than the proper recording temperature (NO), the control unit 42 determines the presence or absence of an image recording job (step S10). If there is no image recording job in this determination (NO), the ink is circulated (step S11) and heated (step S12). At this time, the method for heating the ink is to drive the recording head 10 using a drive waveform that does not cause ink ejection from the nozzle (hereinafter referred to as “non-ejection drive waveform”) and to use the temperature regulator 13. is there. After heating the ink over a predetermined time, the process returns to step S2 to check the ink temperature by the control unit 42.

  On the other hand, if there is an image recording job in step S10 (YES), the control unit 42 determines whether or not the recording amount of the image recording job is equal to or less than a predetermined recording amount (step S13). In this determination, the recording amount information (printing amount information) of the image recording job is a calculated value calculated from, for example, the number of recordings, the number of recordings (or the number of printings), and the recording rate (or printing rate). The predetermined recording amount is, for example, a recording amount that can be recorded using ink heated to an appropriate recording temperature by ink heating in a state where ink circulation is stopped (or recording on a recording medium is possible). Number).

  If it is determined in step S13 that the recording amount of the image recording job exceeds a predetermined recording amount (NO), since the required amount of ink is large, the ink is heated while circulating the ink (step S14). (Step S15). At this time, for the ink heating, the control unit 42 acquires ink temperature information from the detection value of the temperature sensor 21, and determines whether or not the ink temperature is equal to or higher than the proper recording temperature (step S16). If it is determined that the ink temperature has reached the appropriate recording temperature (YES), ink is ejected onto the recording medium 31 to start image recording (step S17). After the image recording is completed (step S18), the process proceeds to step S8 to determine whether or not to stop the apparatus. On the other hand, if it is determined in step S16 that the ink temperature is equal to or lower than the proper recording temperature (NO), the ink heating is continued.

  If it is determined in step S13 that the recording amount in the image recording job is equal to or smaller than the predetermined recording amount (YES), the control unit 42 determines whether or not ink is being circulated at this time (step S19). ). If the ink is circulated in this determination (YES), the ink circulation is stopped (step S20), and the recording head 10 is driven to heat the ink (step S21). On the other hand, if the ink is not circulated in this determination (NO), the process proceeds to step S21 as it is to heat the ink. The heating at this time mainly drives the recording head 10 with a non-ejection driving waveform to heat the ink remaining in the recording head 10.

  Next, it is determined whether or not the temperature of the ink remaining in the ink liquid chamber in the recording head 10 is equal to or higher than the proper recording temperature (step S22). If the ink temperature is equal to or higher than the proper recording temperature (YES), The control unit 42 starts image recording (step S23), and after the image recording ends (step S24), the control unit 42 proceeds to step S8 described above.

  If image recording by a separate image recording job is performed after the image recording job with a small amount of recording is completed, ink circulation is performed according to a user instruction or setting and ink is added by the temperature regulator 13. The temperature may be started. Further, if the recording is finished with this image recording job, it is not necessary to drive the temperature regulator 13.

  In this embodiment, when a job with a small recording amount for completing an image recording job is given by the amount of ink remaining in the ink liquid chamber of the recording head 10, the ink liquid is simply driven by the head without performing ink circulation. Warm up ink in the room. In this heating, only the ink in the ink chamber of the recording head 10 is heated and the ink is not circulated, so that the heat applied to the ink is not diffused throughout the ink circulation path. Therefore, with this ink heating method, since the amount of ink to be heated is very small, the recording proper temperature is reached in a short time, and image recording can be started in a short standby time.

  Therefore, by using the ink heating method of the present embodiment, an image recording apparatus that has not been activated can start image recording in a short standby time if the image recording job has a small recording amount, and can also record a large amount of recording amount. Since an image recording job can be handled in a normal standby time, it is possible to perform image recording that is efficient for the user and easy to use for the user.

  In the present embodiment, the temperature sensor 21 is provided inside the recording head 10, but is not limited thereto. For example, if there is no significant temperature difference between the ink temperature detected by the temperature sensor 21 and the ink flowing into the recording head 10 at a position upstream of the recording head 10 in the ink supply path, For example, the temperature sensor 21 may be provided in the upstream ink port 10b and does not need to be inside the recording head 10. Also, in this embodiment, when an image recording job with a small recording amount is executed, ink is heated without circulating ink, and whether or not the ink has reached an appropriate recording temperature based on the detection value of the temperature sensor 21. However, the detection value of the temperature sensor 21 is not necessarily used. For example, since the temperature rise characteristic when ink is heated without ejecting ink is determined by the design specifications of the apparatus, the start of the job is determined by assuming the ink temperature based on the driving time of the recording head 10. May be. Further, before starting the ink heating, the drive time of the recording head 10 for heating the ink may be set from the difference between the ink temperature acquired by the temperature sensor 21 and the appropriate recording temperature.

  Next, an ink heating method in the image recording apparatus according to the second embodiment will be described. Here, FIG. 3 is a diagram showing a concept of an ink circulation path for supplying ink to the recording head of the ink jet type image recording apparatus according to the second embodiment. FIG. 4 is a diagram illustrating an ink heating communication path that connects an ink supply path and an ink return path provided in the recording head. FIGS. 5A and 5B are diagrams for explaining the flow of ink at the branch of the ink heating communication path. FIG. 6 is a flowchart for explaining the procedure of the ink heating control in the second embodiment.

  As shown in FIGS. 3 and 4, the image forming apparatus according to the present embodiment has ink connected to the upstream ink port 10 b and the downstream ink port 10 c of the recording head 10 in addition to the configuration of the first embodiment described above. The ink heating circulation path 40 including a bypass communication path 40c that communicates between the tube 16a of the supply path 2a and the tube 16b of the ink return path 2b is provided.

  The ink heating circulation path 40 includes a downstream branch point 40b provided in the ink return path 2b on the downstream side of the recording head 10, and an upstream branch point 40a provided in the ink supply path 2a on the upstream side of the recording head 10. A bypass communication path 40c that communicates with each other, a bypass circulation pump (ink heating circulation means) 40d that circulates in the bypass communication path 40c so that ink flows from the downstream branch point 40b to the upstream branch point 40a, and the recording head 10 It consists of. In the following description, the downstream and upstream of the downstream branch point 40b and the upstream branch point 40a are based on the ink flow in the ink circulation path including the ink supply path 2a and the ink feedback path 2b. Accordingly, in the bypass communication path 40c of the ink heating circulation path 40, ink flows from the downstream branch point 40b toward the upstream branch point 40a.

  As shown in FIG. 4, in the ink heating circulation path 40, the ink discharged from the downstream ink port 10b branches at the downstream branch point 40b, flows into the bypass communication path 40c, passes through the bypass circulation pump 40d, A circulation path is constructed that flows into the ink supply path 2a from the upstream branch point 40a and feeds back into the recording head 10 again.

  The amount of ink contained in the ink heating circulation path 40 is sufficiently smaller than the total amount of ink contained in the ink circulation path composed of the ink supply path 2a and the ink return path 2b, while the ink amount in the ink liquid chamber of the recording head. More than the remaining ink amount.

  In the bypass circulation pump 40d, for example, the flow resistance at the time of stopping is greater than the flow resistance in the recording head 10, that is, between the flow resistance from the upstream ink port 10b through the recording head 10 to the downstream ink port 10c. high.

  As an example of the upstream branch point 40a in the present embodiment, as shown in FIG. 5A, it has a branch shape that branches into a V shape, and the structure of the downstream branch point 40b is also as shown in FIG. 5B. , A branch shape intersecting the V-shape. By forming these branched shapes, the ink flow is smoothly branched without interfering with the flow, and smoothly merged. When performing ink heating circulation, the bypass circulation pump 40d is driven in a state where the circulation pump 12 is stopped, and the ink in the bypass communication path 40c is caused to flow from the downstream branch point 40a toward the upstream branch point 40b. . The ink flowing out of the bypass communication path 40c at the upstream branch point 40b is directed to the recording head 10 due to inertia, and the ink flowing out of the recording head 10 flows into the bypass communication path 40c at the downstream branch point 40a. During this circulation, the recording head 10 is driven with a non-ejection driving waveform to heat the ink.

  Next, an ink heating control method according to this embodiment will be described with reference to a flowchart shown in FIG. In the following description, the normal ink circulation indicates a state in which the ink circulates in the ink circulation path 2 including the ink supply path 2a and the ink return path 2b, and the ink heating circulation indicates that the ink discharged from the recording head 10 is discharged. This suggests a circulating state in which the ink returns from the ink return path 16b, passes through the bypass communication path 40c, joins the ink supply path 16a again, and feeds back into the recording head 10. Further, the normal ink circulation means that the circulation is continued when the circulation is already performed in the ink circulation path, and the normal ink circulation is started when the ink circulation is not performed. Means that. Further, the normal ink circulation continues the ink circulation until the stop operation is performed.

  First, when the power is turned on, each component is activated and initialized so as to enter a predetermined standby state (step S41). Here, the control unit 42 acquires the ink temperature information from the detection value of the temperature sensor 21 at all times or at a predetermined timing, and determines whether or not the ink temperature is equal to or higher than the proper recording temperature (step S42).

  In this determination, if the ink temperature is equal to or higher than the proper recording temperature (YES), the control unit 42 drives the circulation pump 12 in a normal ink circulation state in which the ink circulates the ink circulation path 2 (step In step S43, the ink temperature is adjusted (step S44).

  Next, it is determined whether or not there is an image recording job (step S45). If there is an image recording job (YES), image recording is started (step S46). After the end of the image recording (step S47), it is determined whether or not to stop the apparatus (step S58). If it is not stopped to perform another image recording (NO), the process returns to step S42 to check the ink temperature. On the other hand, if there is no image recording job in step S45 (NO), a predetermined time is waited (step S48), and then the process returns to step S42.

  If it is determined in step S42 that the ink temperature does not reach the proper recording temperature (NO), the control unit 42 determines whether there is an image recording job (step S49). If there is no image recording job in this determination (NO), the ink is normally circulated (step S50) and the ink is heated (step S51). At this time, the method of heating the ink is performed using the drive of the recording head 10 based on the non-ejection drive waveform and the temperature regulator 13. After heating the ink for a predetermined time, the process returns to step S42 and the ink temperature by the control unit 42 is confirmed.

  On the other hand, if there is an image recording job in step S49 (YES), the control unit 42 determines whether or not the recording amount of the image recording job is equal to or less than a predetermined recording amount (step S52). In this determination, the recording amount information (printing amount information) of the image recording job is a calculated value calculated from, for example, the number of recordings, the number of recordings (or the number of printings), and the recording rate (or printing rate).

The predetermined recording amount in the present embodiment is the amount of ink contained in the ink heating circulation path 40, and can be recorded using ink that is heated to an appropriate recording temperature by the ink heating circulation. This is the amount (or the number of recordable recording media). Specifically, the amount of ink contained in the ink heating circulation path 40 is the ink path connecting the recording head 10, the downstream ink port 10 b, the downstream branch point 40 b, the bypass communication path 40 c, the upstream branch point 40 a, and the recording head 10. This is the amount of ink remaining inside.

  If it is determined in step S52 that the recording amount of the image recording job exceeds the predetermined recording amount (NO), since the required amount of ink is large, the ink is heated while performing normal ink circulation (step S53). (Step S54).

  At this time, for the ink heating, the control unit 42 acquires ink temperature information from the detection value of the temperature sensor 21, and determines whether or not the ink temperature is equal to or higher than the proper recording temperature (step S55). If it is determined that the ink temperature has reached the proper recording temperature (YES), image recording is started (step S56). After the image recording is completed (step S57), the process proceeds to step S58 to determine whether or not to stop the apparatus. On the other hand, if it is determined in step S55 that the ink temperature is equal to or lower than the proper recording temperature (NO), the ink heating is continued.

  If it is determined in step S52 that the recording amount in the image recording job is equal to or smaller than the predetermined recording amount (YES), the control unit 42 determines whether or not normal ink circulation is performed at this time (step S52). Step S59). If the ink is circulated at this time (YES), the circulation pump 12 is stopped to stop the normal ink circulation (step S60). Next, the bypass circulation pump 40d is driven to start the ink heating circulation described above (step S61). By this ink heating circulation, the ink discharged from the recording head 10 branches from the ink return path 2b, passes through the bypass communication path 40c, joins the ink supply path 2a, and feeds back into the recording head 10. At this time, the recording head 10 is driven with the non-ejection driving waveform, and the ink flowing in the ink heating circulation in the recording head 10 is heated (step S62).

  Next, the temperature sensor 21 detects the temperature of the ink remaining in the ink liquid chamber in the recording head 10, and determines whether or not the detection result is equal to or higher than the proper recording temperature (step S63). In this determination, if the ink temperature is equal to or higher than the proper recording temperature (YES), the control unit 42 starts image recording (step S64), and after the image recording is completed (step S65), the ink heating is performed. Circulation is stopped (step S66), and normal ink circulation is performed. Further, the process proceeds to step S58 described above.

  As described above, according to the present embodiment, when the amount of ink to be used is estimated to be small when an image is recorded on a recording medium, the ink heating circulation path 40 which is a bypass circulation path is selected. . By selecting the ink heating circulation, the ink is heated while flowing in the recording head 10. For this reason, the temperature of only the ink remaining in the ink chamber of the recording head 10 does not increase as in the first embodiment described above, but all of the ink in the bypass communication path 40c is heated, so that the recording is performed. The amount of image recording (or recording area) on the medium increases. In addition, since the temperature difference between the heat generating portion in the recording head 10 and the ink can be kept large compared to the case where the ink heating circulation is not performed when the ink is heated, the ink heating efficiency is improved.

  In the ink heating circulation path 40 of the present embodiment, the ink flowing out from the recording head 10 branches through the ink return path 16b during the ink heating circulation due to the branch shape of the upstream branch point 40b and the downstream branch point 40a. The configuration is such that the control is performed such that the ink supply path 16a is joined again via the bypass communication path 40c and returned to the recording head 10, but this is not necessarily limited. For example, a three-way solenoid valve is provided at two branch points or both, and a normal ink circulation path in which ink flowing out from the recording head 10 returns to the recording head 10 via the downstream sub-tank 11 and the upstream sub-tank 15, and ink heating The structure which switches between the circulation paths 40 may be sufficient.

  With such a configuration, even if the torque of the bypass circulation pump 40d is increased, ink is taken in from the normal ink circulation path and ink is supplied to the normal ink circulation path at the upstream branch point 4b and the downstream branch point 40a. There is no fear of escape. For this reason, the flow rate of the ink heating circulation can be increased, and the ink heating efficiency can be improved.

  Further, the ink heating circulation according to the present embodiment has been described in the case of an image recording job with a small recording amount. However, the configuration including the ink heating circulation is not necessarily limited thereto. When the recording amount of the image recording job is particularly small and falls below a predetermined recording amount standard, it is possible to switch to the ink heating according to the first embodiment and heat only the ink in the recording head. In this case, the time required for ink heating can be further reduced as compared with the case where ink heating circulation is performed.

  Next, an ink heating method in the image recording apparatus according to the third embodiment will be described. FIG. 7 is a diagram showing a concept of an ink circulation path for supplying ink to the recording head of the ink jet type image recording apparatus according to the third embodiment.

 In the ink circulation path, the ink discharged from the recording head 10 branches from the tube 16b of the ink return path 2b, passes through the bypass communication path 40f, and again returns to the ink supply path, as in the second embodiment. An ink heating circulation path 40 that joins the tube 2a of 2a and feeds back into the recording head 10 is provided. However, the upstream branch point 40a is provided at a position higher than the downstream branch point 4b, and the bypass communication path 40f is provided in the vertical direction. In the present embodiment, instead of the bypass circulation pump 40d of the second embodiment, for example, an ink heating unit 40e including a heater is provided.

  With such a configuration, the ink heated by the ink heating unit 40e moves vertically upward in the bypass communication path 40f. The ink that flows through the bypass communication path 40f and reaches the upstream branch point 40b joins the ink supply path 16 again and flows into the recording head 10 due to inertia.

  That is, the downstream branch point 40b serving as the inlet of the bypass communication path 40f has a weaker negative pressure than the upstream branch point 40a due to the ink flow generated by the ink heating unit 40e toward the upstream branch point 40a. Yes. Due to this pressure difference, the ink flowing out from the recording head 10 flows again into the bypass communication path 40f at the downstream branch point 40b.

  By repeating this convection, the temperature of the ink in the ink heating circulation path 40 rises. At this time, the ink heating efficiency can also be improved by driving the recording head 10 with a non-ejection driving waveform.

With reference to the flowchart shown in FIG. 8, the ink heating circulation of the present embodiment will be described.
In the present embodiment, as described above, the ink is heated by the ink heating unit 40e to generate the ink flow, but the ink heating circulation of the second embodiment described in FIG. 6 is a bypass. The difference is that the ink flow is generated by the circulation pump 40d and the ink is heated by driving only the recording head. In the present embodiment, the same operations or actions as those in the flowchart shown in FIG. 6 are given the same reference numerals to simplify the description, and the ink heating and flow by the ink heating unit 40e will be described in detail.

  First, when the power is turned on, the ink temperature is initialized and the ink temperature is measured. If the ink temperature is equal to or higher than the proper recording temperature, the ink temperature is adjusted by normal ink circulation through the ink circulation path 2 (steps S41 to S44). Next, the presence / absence of an image recording job is confirmed (step S45). If there is a job (YES), image recording is started (step S46). After image recording is completed (step S47), the image recording apparatus is stopped. If it does not stop (NO), it returns to step S42. If there is no job (NO), it waits for a predetermined time set in advance for job input (step S48), and determines whether or not to stop the image recording apparatus. If not (NO), the process goes to step S42. Return.

  On the other hand, if it is determined in step S42 that the ink temperature does not reach the proper recording temperature (NO), it is determined whether there is an image recording job (step S49). If there is no image recording job (NO), normal ink circulation is performed. (Step S50), the nozzle is driven without ink ejection as described above, and the ink is heated using the temperature regulator 13 (step S51). On the other hand, if there is an image recording job (YES), it is determined whether or not the image recording job is equal to or less than a predetermined amount (step S52). Ink heating is continued (steps S53 and S54). When the ink temperature is equal to or higher than the proper recording temperature, image recording is started, and when the recording is completed, the process proceeds to step S58 (steps S55, S56, S57). If it is determined in step S52 that the image recording job is equal to or smaller than the predetermined amount (YES), the normal ink circulation is stopped (steps S58 and S59), and the ink heating unit 40e switches to ink heating (step S71).

  As described above, the ink heated by the ink heating unit 40e is divided into the bypass communication path 40f, the upstream branch point 40a, the ink supply path 16a, the recording head 10, the ink return path 16b, the downstream branch point 40b, and the ink warming. By convection through the path of the member 40e, the temperature rises in the ink heating circulation path 40.

  If the temperature of the ink in the heating circulation path 40 reaches the proper recording temperature (YES), image recording is started (steps S62 and S63), and after the recording is completed (step S64), the process proceeds to step S58. It is then determined whether to stop the apparatus.

  According to the present embodiment, since a small amount of ink is heated as compared with the normally heated ink heating, the ink temperature can quickly reach the proper recording temperature. With this image recording, it is possible to provide a user-friendly image recording apparatus with a shorter waiting time for the user.

  Further, when the ink is heated and circulated using the bypass communication path 40f, the circulation is performed by the convection generated by the ink heating without using the ink moving means such as a pump as in the second embodiment. Therefore, it can be realized at a low cost. Furthermore, since no moving parts such as a pump are used, the generated noise is at a low level.

  In the present embodiment, the bypass communication path 40f in which the ink heating unit 40e is disposed is disposed in the vertical direction, but is not limited to this, and has a certain degree of inclination so that ink can convect. If so, ink heating circulation can be performed.

  In the present embodiment, it is possible to use both the ink heating unit 40e and the ink heating by the non-ejection nozzle driving in combination with the ink heating, thereby realizing efficient ink heating.

  In each of the above-described embodiments, the line recording method for performing image recording by passing the recording medium in the vicinity of the fixed recording head has been described. However, the recording medium is not limited to the fixed recording head. A serial recording method may be used in which an image is formed by recording an image while moving the recording head in the width direction. You may combine suitably several embodiment mentioned above.

  The image recording method of the image recording apparatus of the present invention includes the following gist.

(1) An image recording method for an image forming apparatus having an ink circulation path,
The ink circulation is stopped when the ink is heated, and only the ink remaining in the recording head is heated to perform image recording.

(2) The image recording method according to (1),
Ink in the ink circulation path when the temperature of the ink in the ink circulation path is equal to or lower than the proper recording temperature and an image recording job for completing image recording with the amount of heated ink remaining in the recording head is input. The circulation is stopped, the ink in the recording head is heated, the image recording is executed after the ink temperature reaches the proper recording temperature, and after completion of the image recording, the ink is circulated in the ink circulation path, The ink is heated by the recording head.

  (3) An image forming apparatus having two or more ink circulation paths with different ink amounts in the path is characterized in that the ink is heated in a state where circulation of the circulation path with a large amount of ink is stopped.

  (4) In the image forming apparatus described in (3), the ink is heated while circulating through a circulation path with a small amount of ink in a state where circulation of a circulation path with a large amount of ink is stopped. And

  (5) In the image forming apparatus described in item (3), the means for circulating ink through a circulation path with a small amount of ink also serves as a heating means for heating the ink to generate convection to circulate. Features.

FIG. 1 is a diagram schematically illustrating an ink circulation path for supplying ink to a recording head of an ink jet image recording apparatus according to the first embodiment. FIG. 2 is a flowchart for explaining the ink temperature control method in the ink circulation path of the first embodiment. FIG. 3 is a diagram showing a concept of an ink circulation path for supplying ink to the recording head of the ink jet type image recording apparatus according to the second embodiment. FIG. 4 is a diagram illustrating an ink heating communication path that connects an ink supply path and an ink return path provided in the recording head according to the second embodiment. FIGS. 5A and 5B are diagrams for explaining the flow of ink at the branch of the ink heating communication path. FIG. 6 is a flowchart for explaining the procedure of the ink heating control in the second embodiment. FIG. 7 is a diagram illustrating an ink heating communication path that connects an ink supply path and an ink return path provided in the recording head according to the third embodiment. FIG. 8 is a flowchart for explaining the procedure of the ink heating control in the third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Ink circulation path, 2a ... Ink supply path, 2b ... Ink return path, 10 ... Recording head, 10a ... Nozzle, 10b ... Upstream ink port, 10c ... Downstream ink port, 11 ... Downstream sub tank, 11a ... Downstream atmospheric release valve, 11b ... Liquid level regulator, 12 ... Circulating pump, 13 ... Temperature regulator, 14 ... Filter, 15 ... Upstream sub tank, 15a ... Upstream atmospheric release valve, 16a, 16b, 16c, 18 ... Tube , 17 ... Pressure regulator, 19 ... Ink bottle, 19a ... Atmospheric communication pipe, 20a ... Liquid level sensor, 20b ... Valve, 20c ... Ink supply controller, 21 ... Temperature sensor, 30 ... Conveying mechanism, 31 ... Recording medium, 40 ... Ink heating circulation path, 40a ... Upstream branch point, 40b ... Downstream branch point, 40c ... Bypass communication path, 40d ... Bypass circulation pump (ink heating) Ring means), 42 ... control unit.

Claims (10)

An ink circulation path comprising at least one recording head, an ink tank for storing ink, an ink supply path connecting the ink tank to the recording head, and an ink return path connecting the recording head to the ink tank; An image recording method in an image recording apparatus comprising: an ink circulation means provided on the ink circulation path for circulating the ink;
A determination step of determining whether or not the job amount to be image-recorded is less than a predetermined job amount when the temperature of the ink remaining in the recording head is lower than the proper recording temperature;
A circulation stop step for controlling the ink circulation means and not performing ink circulation when it is determined in the determination step that the job amount to be image-recorded is less than the predetermined amount;
A first heating step for heating only the ink remaining in the recording head while the circulation of the ink is stopped, and
Performing the image recording in a state where the ink circulation is stopped after the ink in the recording head is heated and reaches the proper recording temperature; and
An image recording method for an image recording apparatus, comprising: A circulation step of controlling the ink circulation means to circulate the ink in the ink circulation path when it is determined in the determination step that the job amount to be recorded is equal to or more than the predetermined job amount; ,
A second heating step for heating the entire ink while circulating the ink in the ink circulation path,
The image recording apparatus according to claim 1, wherein image recording is performed while maintaining circulation of the ink after the temperature of the ink heated in the recording head reaches an appropriate recording temperature. Image recording method.   2. The image recording according to claim 1, wherein the first heating step heats only the ink remaining in the recording head by driving the recording head in a non-ejection state of the ink. Image recording method of apparatus.   3. The image recording apparatus according to claim 2, wherein in the second heating step, the whole of the circulating ink is heated by controlling an ink temperature adjusting means provided in the ink circulation path. Image recording method. In the second heating step, the ink is heated by an ink temperature adjusting means provided in the ink circulation path, and
3. An image recording method for an image recording apparatus according to claim 2, wherein the ink passing through the recording head is heated by driving the recording head in a state where the ink is not ejected. At least one recording head that discharges ink and records an image, an ink tank that stores ink, an ink supply path that connects the ink tank to the recording head, and a connection from the recording head to the ink tank A first ink circulation path including an ink return path, a first ink circulation means for circulating the ink in the first ink circulation path, and a bypass connection between the ink supply path and the ink feedback path; A second ink circulation path that includes the recording head on the path and circulates an ink having a smaller amount of ink than the ink remaining in the first ink circulation path; and the ink in the second ink circulation path. An image recording method in an image recording apparatus comprising: a second ink circulating means for circulating
The temperature of the ink remaining in the recording head is measured, and if the obtained ink temperature is less than the proper recording temperature, it is determined whether or not the job amount of the input image recording job is less than a predetermined amount. A determination step;
In the determination step, when it is determined that the job amount of the job to be image-recorded is less than a predetermined amount, the first ink circulation unit is controlled, and the circulation is not performed in the first ink circulation path. A first circulation step for controlling the second ink circulation means to circulate ink in the second ink circulation path;
A first heating step for heating ink remaining in the recording head while ink circulation is performed in the second ink circulation path;
An image recording step of performing image recording while circulating the ink in the second ink circulation path after the ink in the recording head has been heated and the ink temperature has reached the proper recording temperature;
An image recording method for an image recording apparatus, comprising: When it is determined in the determination step that the job amount of the job to be recorded is equal to or greater than the predetermined amount, the first ink circulation unit is driven to circulate the ink in the first ink circulation path. A second circulation step to be performed;
A second heating step for heating the ink in the first ink circulation path while the ink is circulating in the first ink circulation path;
The image recording is performed while circulating the ink in the first ink circulation path after the ink in the recording head is heated and the ink temperature reaches a proper recording temperature. Item 7. The image recording method of the image recording apparatus according to Item 6. At least one recording head for discharging ink and recording an image;
An ink tank for storing ink;
A first ink circulation path comprising an ink supply path connecting the ink tank to the recording head and an ink feedback path connecting the recording head to the ink tank;
First ink circulation means for circulating the ink in the first ink circulation path;
To bypass the ink supply path and the ink return path with a short path, and to circulate ink having a smaller amount than the ink remaining in the first ink circulation path, including the recording head on the path. A second ink circulation path of
Second ink circulation means for circulating the ink in the second ink circulation path;
Comprising
Ink that circulates the ink in the second ink circulation path and passes through the recording head when a job amount that can be recorded by the amount of ink remaining in the second ink circulation path is input. The image recording apparatus is characterized in that the recording head is driven in a non-ejection state, the ink passing through the recording head is heated to reach an appropriate recording temperature, and image recording is performed. At least one recording head for discharging ink and recording an image;
An ink tank for storing ink;
A first ink circulation path comprising an ink supply path connecting the ink tank to the recording head and an ink feedback path connecting the recording head to the ink tank;
First ink circulation means for circulating the ink in the first ink circulation path;
To bypass the ink supply path and the ink return path with a short path, and to circulate ink having a smaller amount than the ink remaining in the first ink circulation path, including the recording head on the path. A second ink circulation path of
Second ink circulation means for generating convection for heating and circulating the ink in the second ink circulation path;
Comprising
When a job amount that can be recorded with the amount of ink remaining in the second ink circulation path is input, the ink is heated in the second ink circulation path and circulated by convection, An image recording apparatus that performs image recording after the ink that has been reached has reached an appropriate recording temperature. In addition to the heating of the ink by the second ink circulation means,
The image recording apparatus according to claim 9, wherein the recording head is driven in a state where the ink is not ejected to heat the ink passing through the recording head.

Images