JP5489569B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus that has a thermal head and prints on a recording material based on image information.

  Since the thermal transfer type printer device as an image recording device can easily change the amount of heat for controlling one pixel, the number of gradations for one pixel of an image to be recorded can be easily reduced to several hundreds. Is possible. In order to perform full-color printing with a thermal transfer type printer, it is necessary to transfer a plurality of colors of ink in a superimposed manner. Usually, three colors of yellow, magenta, and cyan are sequentially stacked and printed. Patent Document 1 discloses such a thermal transfer type printer device.

  In the printer device described in Patent Document 1, an ink sheet and a recording paper as a recording material are pressed against each other with a thermal head, and the thermal energy generated from the thermal head is used to thermally transfer the ink on the ink sheet onto the recording paper. Let Accordingly, the printer device conveys the recording paper and prints on the recording paper. After printing with the first color ink, printing with the second color ink is performed. For this purpose, the pressure contact between the ink sheet and the recording paper by the thermal head is released, and the recording paper is returned to the printing start position (during printing). The recording paper is conveyed in the opposite direction). Next, similarly to printing with the first color ink, printing with the second color ink is performed. Thereafter, in the same manner, a full color image can be printed on the recording paper by printing with the third color ink.

  Since the thermal head generates heat to thermally transfer the ink, the temperature of the thermal head rises during printing. In patent document 1, in order to suppress the temperature rise of a thermal head, the thermal head is cooled by a cooling fan. Further, in order to efficiently transfer the heat of the thermal head to the cooling fan, a heat pipe is used as a heat transport means. In addition, a metal member is provided between the thermal head and the heat pipe, and the metal member efficiently transfers the heat of the thermal head to the heat pipe. Furthermore, in order to increase the efficiency of cooling by the cooling fan, a heat radiating fin is provided at the end of the heat pipe.

JP 2007-216526 A

  It is necessary that the thermal head does not become uncontrollable beyond the guaranteed operating temperature of an electronic component (for example, a control integrated circuit) mounted on the thermal head during a printing operation. In addition, it is necessary to avoid that the temperature of the thermal head is too high so that a low-density image cannot be appropriately developed and the printing becomes low quality. Furthermore, it is necessary to avoid that the temperature of the thermal head is too low and the high density portion cannot properly develop color, and the printing is not low quality.

  Therefore, it is desirable that the temperature of the thermal head does not exceed the predetermined upper limit temperature during the printing operation and exceeds the predetermined lower limit temperature. For this reason, when printing is started, the thermal head waits for the temperature to exceed a predetermined lower limit temperature, and in order to perform printing quickly, the thermal head is set to the predetermined temperature immediately after the start of heat generation of the thermal head. It is desirable to exceed the lower limit temperature.

  Usually, the predetermined upper limit temperature is determined by either an operation guarantee temperature of an electronic component mounted on the thermal head or a limit temperature on the high temperature side at which an image printed by the thermal head cannot be properly developed. The predetermined lower limit temperature is usually the temperature resulting from the heating and color development characteristics of the thermal head, ink, and recording paper, and is determined by the lower temperature limit temperature at which the high-density part of the image printed by the thermal head cannot properly develop color. Is done.

  In order to prevent the temperature of the thermal head from exceeding a predetermined upper limit temperature during the printing operation, it is conceivable to increase the thermal capacity of the thermal head and moderate the temperature rise. Further, the heat capacity may be increased as a whole by connecting a heat sink to the thermal head. Further, it is conceivable to enhance the cooling by the cooling fan. However, in these cases, since the temperature rise of the thermal head is suppressed, the time from the start of heat generation of the thermal head until the thermal head exceeds the predetermined lower limit temperature becomes longer. That is, the print start timing is delayed.

  On the other hand, in order to quickly exceed the predetermined lower limit temperature after the start of the printing operation, the heat capacity of the thermal head and / or the heat storage unit is reduced to increase the temperature rapidly, or cooling by the cooling fan is weakened or It is possible to stop. However, in this case, the temperature of the thermal head increases rapidly and exceeds a predetermined upper limit temperature during printing.

  As described above, in order to cope with two contradictory matters, it is conceivable to temporarily weaken or stop the air cooling after enhancing the cooling by the cooling fan. However, in this case, there is a problem of an increase in power consumption. This is because the heat effect of the thermal head is forcibly taken away by strengthening the cooling effect during the printing operation, so that it is necessary to supply extra thermal energy to the thermal head during printing. In particular, during the pause period between the printing operation with the first color ink and the printing operation with the second color ink, the temperature of the thermal head rapidly decreases. It is necessary to input energy. Therefore, it is desirable to have a thermal head that can quickly exceed a predetermined lower limit temperature after heat generation of the thermal head, that does not exceed a predetermined upper limit temperature during printing, and that can suppress power consumption of the thermal head. It is.

  SUMMARY An advantage of some aspects of the invention is that it provides an image recording apparatus that can control a temperature change of a thermal head with low power consumption.

An image recording apparatus of the present invention includes a thermal head that generates thermal energy for recording an image on a recording material, and a heat storage unit that stores heat generated by the thermal head, and is separated from the thermal head. A heat accumulator provided at a position, and a heat transfer unit for transmitting heat transmitted from the thermal head directly or through a heat conducting member to the heat accumulator, and is outside the recording range of the thermal head. A heat transfer portion extending to the heat transfer portion, and the heat storage portion is provided so as to be connectable to the heat transfer portion at a portion extending outside the recording range of the heat transfer portion. And the connection state of the said heat-transfer part is comprised variably.

  Here, when the heat resistance of the heat transfer path is variable, it also includes that the heat transfer path is substantially cut off and the heat resistance becomes substantially infinite.

  The temperature change of the thermal head can be controlled with low power consumption.

1 is a schematic plan view of a printer device according to a first embodiment of the present invention. FIG. 2 is a schematic plan view of the printer device viewed from the 2A-2A direction in FIG. 1. It is the schematic which shows the structure of the connection part periphery of a heat pipe and a heat sink. It is a graph which shows the time dependence of the temperature and power consumption of a thermal head. FIG. 3 is a schematic diagram showing an example of the arrangement of temperature sensors in the printer apparatus and a control line by the control means. It is a flowchart for demonstrating an example of the control method by a control means. It is a flowchart for demonstrating an example of the control method by a control means. It is a flowchart for demonstrating an example of the control method by a control means. It is a flowchart for demonstrating an example of the control method by a control means. It is a schematic plan view of the printer apparatus which concerns on the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The image recording apparatus described in detail in the following embodiments is a thermal transfer type printer apparatus that transfers ink applied to a tape to a recording material. However, the image recording apparatus of the present invention is a thermal type printer apparatus. May be. Furthermore, the present invention is not limited to a printer apparatus, and can be applied to all image recording apparatuses having a thermal head.

[First Embodiment]
FIG. 1 is a schematic plan view of the printer apparatus according to the first embodiment of the present invention, and FIG. 2 is a schematic plan view of the printer apparatus viewed from the 2A-2A direction of FIG. The printer apparatus includes a thermal head 1 and a heat storage unit that stores heat generated by the thermal head 1. In the present embodiment, the heat sink 5 is used as the heat storage unit. Furthermore, the printer apparatus includes a heat pipe 2 and a heat transfer medium 3 for transferring the heat of the thermal head 1 to the heat storage unit. Further, the printer device may include the heat radiation fins 4 and the cooling fan 9 as heat radiation means for radiating the heat of the thermal head 1.

  The thermal head 1 generates thermal energy for recording an image on the recording material 10. Specifically, thermal energy is generated by a heater such as a thermal resistance element provided in the thermal head 1. The heating resistor elements are linearly arranged on a substrate made of ceramic, for example. The printer apparatus conveys the ink sheet 7 and the recording material 10 in a state where the ink sheet 7 and the recording material 10 are pressed against each other by the thermal head 1. Accordingly, the heating resistor element is selectively energized to generate thermal energy, and an image is recorded on the recording material 10 in a dot line shape. In this specification, an image includes characters and symbols.

  The thermal head 1 is held by a heat conducting medium 3, and the heat pipe 2 is in contact with the heat conducting medium 3. The heat conducting medium 3 may be a metal member, for example, and transfers heat of the thermal head 1 to the heat pipe 2.

  Moreover, the connection part of the heat pipe 2 and the heat sink 5 is comprised so that connection and division | segmentation are possible. The heat pipe 2 may be a heat transport means having a heat transport action in which a volatile liquid is enclosed in a sealed space and the liquid evaporation and condensation cycle is repeated.

  Further, the printer device includes a roller 8 that conveys the ink sheet 7 and the recording material 10, and the function thereof may be the same as that of a known technique. In addition, the printing operation by causing the thermal head 1 to generate heat while the ink sheet 7 and the recording material 10 are in pressure contact can be performed using any known technique. A heat pipe 2 is attached to the thermal head 1 via a heat conducting medium 3, and heat generated by the thermal head 1 is transported toward the heat sink 5 via the heat pipe 2. Thus, the thermal head 1, the heat transfer medium 3, the heat pipe 2, and the heat sink 5 constitute a heat transfer path that transfers the heat of the thermal head to the heat sink 5 as a heat storage unit. It is a transmission path part which comprises a heat transfer path. The printer apparatus includes means for changing the connection state (connection, division, and connection strength state) between the heat sink 5 and the heat pipe 2. In this way, the heat resistance of the heat transfer path is configured to be variable.

  Next, the configuration around the connecting portion between the heat pipe 2 and the heat sink 5 will be described. 3A and 3B are schematic views of the heat sink 5 viewed from the same direction as FIG. The heat sink 5 is formed by connecting a first member 31 and a second member 32 as shown in the figure. Specifically, the first member 31 and the second member 32 are connected so as to be rotatable about the same rotation shaft 33. The first member 31 and the second member 32 can be rotated only by an angle within a certain range when the first and second members 31 and 32 collide with each other. A compression spring 34 is provided between the first member 31 and the second member 32, and the first and second members 31 and 32 are stable in a certain state when there is no external force. (See FIG. 3 (a)). The first member 31 and the second member 32 are rotated by an external force applied by the cam 35 (see FIG. 3B). The printing apparatus has driving means 6 for driving the cam 35.

  Concave grooves are formed in the first member 31 and the second member 32, and these grooves are aligned to form a cylindrical cavity. The heat pipe 2 is passed through this cavity. As shown in FIGS. 3A and 3B, when the first and second members 31 and 32 are rotated, the pressure of the connection between the heat pipe 2 and the heat sink 5 becomes stronger or weaker. To do. Moreover, the heat pipe 2 and the heat sink 5 may be divided. In this way, the magnitude of the thermal resistance of the heat transfer path is variable.

  In the state shown in FIG. 3A, the heat sink 5 and the heat pipe 2 are strongly pressed by the load of the compression spring 34. Therefore, the heat transfer efficiency of the heat transfer path is high, that is, the heat resistance of the heat transfer path is low. On the other hand, FIG. 3B shows a state in which the cam 35 rotates against the elastic force of the compression spring 34 and the first member 31 and the second member 32 of the heat sink 5 rotate with respect to each other. At this time, the heat sink 5 and the heat pipe 2 are separated from each other, and the heat resistance of the heat transfer path is high. In this specification, the change in the heat resistance of the heat transfer path includes that the heat transfer path is substantially divided and the heat resistance becomes substantially infinite.

  The driving means 6 for driving the cam 35 includes at least an actuator (not shown) such as a motor plunger (not shown) and a piezoelectric element, and is a general part such as a gear (not shown) or a lever (not shown). It may be configured. For example, when the cam 35 is rotated by the operation of the actuator, the heat pipe 2 and the heat sink 5 can be switched between a pressed state and a separated state. Of course, the heat pipe 2 and the heat sink 5 may not be completely separated from each other, but only weaken or strengthen the connection pressure.

  As described above, the connection state of a series of heat transfer paths from the thermal head 1 through the heat transfer medium 3 and the heat pipe 2 to the heat sink 5 is configured to be variable, so that the heat transfer path It is possible to change the thermal resistance. In this embodiment, the connection part of the heat transfer path is in the connection part between the heat pipe 2 and the heat sink 5. However, the connection part of the heat transfer path is not limited to the position of this embodiment, and may be anywhere.

  The member which comprises a heat transfer path is not limited to this embodiment, A various change is possible. For example, the heat conduction medium 3 may be removed and the thermal head 1 and the heat pipe 2 may be connected, and further, the heat pipe 2 may be removed and the thermal head 1 and the heat sink 5 may be connected.

  In the present embodiment, as shown in FIG. 1, a heat transfer path connecting portion is provided outside the printing range P, sufficiently separated from the printing range P of the thermal head 1. In order to obtain a uniform and good image, the thermal head 1 needs to be set so as to be adjusted with high accuracy and uniform pressurization. For this reason, if there is a connecting portion of the heat transfer path inside the printing range, the print image during the printing operation is particularly affected by the vibration accompanying the change in the state of the connecting portion. However, as shown in FIG. 1, the influence on the printed image can be reduced by providing the connecting portion of the heat transfer path at a position away from the printing range P of the thermal head 1.

  In the present embodiment, an example in which the connecting portion between the heat pipe 2 and the heat sink 5 is outside the printing range P has been described. However, if the operation of the connecting portion does not affect printing even if the operation is performed inside the printing range P, for example, if the thermal head 1 and the heat transfer medium 3 have sufficient rigidity, or the connecting portion has a sufficient connecting pressure. In the case where the heat transfer path is weak, the connecting portion of the heat transfer path may be inside the printing range P. In this case, if it is not necessary to use the heat pipe 2, the heat pipe 2 can be omitted.

  Next, advantages of the printer apparatus of this embodiment will be described below. FIG. 4A is a graph showing the time change of the temperature of the thermal head during the printing operation, and FIG. 4B is a graph showing the time change of the total power consumption consumed by the thermal head. is there. In the graph, the printer device of this embodiment is indicated by a solid line, the printer device of Comparative Example 1 described below is indicated by a one-dot chain line, and the printer device of Comparative Example 2 described below is indicated by a dotted line.

  The printer device of Comparative Example 1 does not have a function of changing the thermal resistance of the heat transfer path, and other configurations are the same as those in FIG. Moreover, in the comparative example 2, it does not have the function to change the thermal resistance of a heat transfer path, has a configuration in which the heat sink 5 shown in FIG. 1 is removed, and is similar to the configuration described in Patent Document 1. In addition, the cooling by the cooling fan included in the printer device is enhanced as compared with the cooling fan of the present embodiment.

  A timing A in the graph is a timing at which energization of the heating resistor element of the thermal head 1 starts in response to a print start command. Timing B is a timing at which printing with the first color ink is started, and the thermal head 1 must reach a predetermined lower limit temperature LT by this time. Timing C is timing when printing with the first color ink is completed. Timing D is a timing at which printing with the second color ink is started. Between timing C and timing D, the printer device returns the recording material 10 in the reverse direction and prepares for printing with the second color ink. Timing E is timing when printing with the second color ink is completed. Actually, the printing with the third color ink is performed after the printing with the second color ink. However, in order to simplify the explanation and illustration, the graph shows the time until the printing with the second color ink is completed. Show. Further, although the temperature and power consumption of the thermal head 1 change depending on the density of the image to be printed, the graph prints the image with the highest density where the temperature rise is most remarkable in order to explain the temperature rise and power consumption. The case of printing over the entire range is illustrated.

  First, the temperature change of the thermal head will be described with reference to the graph of FIG. In the printer device of the present embodiment, a series of printing operations is started in a state where the heat pipe 2 and the heat sink 5 are separated (see FIG. 3A). At the timing A when the energization of the thermal head 1 starts to be started, the temperature of the thermal head 1 rapidly increases because the temperature of the thermal head 1 is low. Since the heat sink 5 is divided, the temperature change of the thermal head 1 is almost the same as that of the comparative example 2. The temperature of the thermal head 1 reaches the predetermined lower limit temperature LT until timing B when the color development starts. On the other hand, in the printer device of Comparative Example 1, the heat transfer path from the thermal head to the heat sink is connected and the overall heat capacity is large, so the temperature rise of the thermal head is slow. Therefore, the thermal head does not reach the predetermined lower limit temperature LT by the above-described timing B, and the printing start (coloring start) timing must be delayed.

  In the present embodiment, during printing, when the temperature of the thermal head 1 exceeds a preset reference temperature BT, control is performed to reduce the thermal resistance of the heat transfer path. Specifically, the heat pipe 2 and the heat sink 5 are connected. The timing of this control is indicated by timing F in the graph. After that, the heat capacity of the heat transfer path is as large as that of the printer device of Comparative Example 1, and the temperature change of the thermal head 1 is the same as in Comparative Example 1, whether the temperature is rising or falling. It changes slowly. Therefore, it is possible to control the temperature of the thermal head 1 so as not to exceed the predetermined upper limit temperature UT during printing without enhancing the cooling of the cooling fan 9 and the like.

  It is not necessary to energize the heat generating resistance element of the thermal head from timing C when printing with the first color ink is completed until timing D when the recording material 10 is returned and printing with the second color ink is started. Therefore, the temperature of the thermal head decreases monotonously. Even in this temperature decrease process, the thermal head 1 in the present embodiment gradually changes in temperature as in the first comparative example. On the other hand, the temperature of the thermal head in Comparative Example 2 is drastically lowered because the cooling by the cooling fan is enhanced. Therefore, in this embodiment, the temperature of the thermal head at the timing D when printing with the second color ink is started is higher than the temperature of the thermal head in Comparative Example 2. The temperature of the thermal head rises again monotonously until timing E when printing with the second color ink is completed. In the process of this temperature increase, as in Comparative Example 1, the temperature gradually changes, and therefore the temperature of the thermal head can be suppressed to a predetermined upper limit temperature UT or less without enhancing forced cooling by a cooling fan or the like.

  As described above, in the printer apparatus of the present embodiment, the thermal head 1 is thermally separated from the heat sink 5 before the start of printing with the first color ink, so that the temperature of the thermal head 1 quickly rises. Further, by connecting the thermal head 1 and the heat sink 5 during printing and reducing the thermal resistance of the heat transfer path, the subsequent temperature change of the thermal head 1 can be moderated. In this way, when the temperature of the thermal head 1 during image recording exceeds a preset temperature, the thermal resistance of the heat transfer path is made smaller than the thermal resistance of the heat transfer path before the start of image recording. Control. As a result, after the thermal energy is input to the thermal head 1, the temperature of the thermal head 1 quickly exceeds the predetermined lower limit temperature LT, and during printing, the temperature of the thermal head 1 exceeds the predetermined upper limit temperature UT. It can be controlled so that there is no.

  Next, the total power consumption of the thermal head will be described with reference to the graph of FIG. During printing with the first color ink and the second color ink (between timing A and timing C and between timing D and timing E), the heating head heating element is energized, so the power consumption is monotonous. To increase. On the other hand, during the period when printing is not performed and the recording material 10 is returned (between timing C and timing D), it is not necessary to energize, so the power consumption does not increase. The higher the temperature of the thermal head, the smaller the rate of increase in power consumption. This is because less energy is required to make the heating resistor element of the thermal head reach a predetermined temperature.

  In the thermal head 1 of the present embodiment, the total power consumption until the timing E when the printing with the second color ink is completed is approximately the same as that of the printer device in the comparative example 1, and is higher than that of the printer device in the comparative example 2. However, the total power consumption is suppressed. This is because in Comparative Example 2, it is necessary to add extra heat energy to the heating resistance element of the thermal head in order to enhance the cooling by the cooling fan and forcibly remove the heat of the thermal head. In particular, at the timing D when printing with the second color ink is started, the temperature of the thermal head of Comparative Example 1 is drastically decreased, and thus extra power is consumed during the printing of the second color. On the other hand, in the thermal head in the present embodiment and Comparative Example 2, the temperature drop is moderate, and the thermal head does not take heat as in Comparative Example 1. Therefore, it is not necessary to supply extra thermal energy to the thermal head. Therefore, the total power consumption can be suppressed.

  As described above, in the present embodiment, the period from the start timing A of energization to the heating resistor element to the start timing B of printing with the first color ink is shortened and the power consumption of the thermal head is suppressed. Can do.

  Since the operation from the end of printing with the second color ink to the completion of printing with the third color ink is performed in the same manner, the description thereof is omitted. In addition, after obtaining a full-color image by superimposing the three colors of ink, a transparent overcoat layer may be printed to improve image storage stability.

  In the above example, the temperature drop of the thermal head is suppressed during the non-printing period before the start of printing with the second color ink, and printing with the second color ink is started with the temperature of the thermal head being high. However, for example, when the temperature of the thermal head is very close to a predetermined upper limit temperature and it is necessary to cool rapidly during the non-printing period, the thermal head is controlled to increase the thermal resistance of the heat transfer path. The temperature may be lowered rapidly.

  As described above, in the printer device according to the first embodiment, the temperature change of the thermal head 1 can be controlled by changing the thermal resistance of the heat transfer path during the printing operation. When a rapid temperature change is required, the thermal resistance can be increased, and when it is desired to moderate the temperature change, the thermal resistance can be decreased. As a result of the temperature control as described above, it is not necessary to enhance the cooling by the cooling fan 9, so that power consumption can be suppressed.

  Furthermore, it is desirable to control the thermal resistance of the heat transfer path by comprehensively considering not only the temperature of the thermal head 1 but also the room temperature, the temperature inside the printer device, and the density of the image to be printed. Of course, the thermal resistance may be controlled in consideration of the rate of change in temperature and whether the temperature is increasing or decreasing, thereby enabling more optimal control.

  FIG. 5 schematically shows an example of the arrangement of temperature sensors provided in the printer apparatus and a block diagram relating to temperature control. In FIG. 5, a temperature sensor 51 that detects the temperature of the thermal head 1, a temperature sensor 52 that detects the temperature inside the housing in which the thermal head 1 and the like are housed, and a temperature sensor 53 that detects the temperature of the heat sink 5. , Are shown. As these temperature sensors 51-53, a thermistor can be used, for example. The CPU as the control means 56 calculates the temperature value detected by the temperature sensors 51 to 53 and the print image data. The drive means 6 for changing the connection state between the thermal head 1 and the heat sink 5 and the control means 56 are connected by signal lines 54 and 55 for energization control.

  Further, for example, even if the temperature of the thermal head 1 approaches the predetermined upper limit temperature UT during printing, if the density of the printed image thereafter is low, the subsequent temperature rise of the thermal head is small, so that heat transfer Printing may be continued without controlling the path. Thus, the thermal resistance of the heat transfer path may be controlled according to the image data to be printed.

  Next, an example in which the control of the thermal resistance of the heat transfer path is determined by comprehensively considering not only the temperature of the thermal head 1 but also the image data to be printed will be described with reference to FIGS.

  FIG. 6 is an example of a flowchart performed when the thermal resistance of the heat transfer path is high during printing. When the temperature of the thermal head 1 is measured by the temperature sensor 51 and the temperature of the thermal head 1 is equal to or higher than a threshold value T1, the density of image data thereafter is calculated. If the calculated value of the concentration is equal to or greater than a certain threshold value X1, control is performed to reduce the thermal resistance of the heat transfer path. However, if the calculated value of the concentration is smaller than a certain threshold value X, the thermal head 1 does not reach the upper limit temperature even if the heat transfer path is not controlled, so it is not necessary to control the heat transfer path. The calculated value of the density of the image data may be a value calculated by comprehensively combining the amount and density of images to be recorded thereafter.

  FIG. 7 is an example of a flowchart performed when the thermal resistance of the heat transfer path is low during printing. The current temperature of the temperature sensor 51 is acquired, and when the temperature of the thermal head 1 is equal to or lower than a certain threshold T2, it is determined whether to increase the thermal resistance of the heat transfer path in order to quickly increase the temperature. Specifically, the density of subsequent image data is calculated, and if the calculated value is greater than or equal to a certain threshold value X2, the thermal resistance of the heat transfer path is increased. However, if the density of the subsequent print image data is smaller than a certain threshold value X2, image recording is continued without changing the thermal resistance of the heat transfer path. This is because it is expected that sufficient color development is possible even at a low temperature, and it is not necessary to increase the thermal resistance of the heat transfer path.

  As yet another example, the temperature of the heat sink 5 may be detected by the temperature sensor 53 that measures the temperature of the heat sink 5 and may be considered as one factor for determining the control of the thermal resistance of the heat transfer path. Further, for example, if the connecting force (pressure contact force) between the heat pipe 2 and the heat sink 5 can be controlled in stages, the thermal resistance of the heat transfer path can be controlled in multiple stages. Thus, more appropriate temperature control becomes possible by controlling the thermal resistance of the heat transfer path in multiple stages. Hereinafter, an example of controlling the thermal resistance of the heat transfer path in consideration of not only the temperature of the thermal head but also the temperature of the heat sink will be described with reference to FIGS.

  FIG. 8 is an example of a flowchart performed when the thermal resistance of the heat transfer path is high during printing. When the current temperature of the temperature sensor 51 is acquired and the temperature of the thermal head 1 is equal to or higher than a certain threshold T3, in order to prevent reaching the predetermined upper limit temperature UT, is the thermal resistance of the heat transfer path reduced? Judge whether. Specifically, if the temperature of the heat sink 5 at that time is equal to or lower than a certain threshold value Z1, control is performed to reduce the thermal resistance of the heat transfer path. However, if the temperature of the heat sink 5 at that time is greater than a certain threshold value Z1, if the heat resistance of the heat transfer path is reduced, the temperature of the thermal head 1 may increase, so the heat resistance of the heat transfer path. It is possible to judge that the change is not made.

  FIG. 9 is an example of a flowchart performed when the thermal resistance of the heat transfer path is low during printing. When the temperature of the current temperature sensor 51 is acquired and the temperature of the thermal head 1 is equal to or lower than a certain threshold value T4, it is determined whether to increase the thermal resistance of the heat transfer path in order to increase the temperature as soon as possible. Specifically, if the temperature of the heat sink 5 at that time is equal to or higher than a certain threshold value Z2, control is performed to increase the thermal resistance of the heat transfer path. However, if the temperature of the heat sink 5 at that time is smaller than a certain threshold value Z2, if the heat resistance of the heat transfer path is increased, the temperature rise may be hindered. Therefore, it is judged that the heat resistance of the heat transfer path is not changed. It becomes possible.

  As described above, it is possible to provide a printer device with higher reliability by controlling the thermal resistance of the heat transfer path in consideration of not only the temperature of the thermal head 1 but also the temperature of the heat sink 5 and image data. Can do. Of course, the present invention is not limited to the flowcharts shown in FIGS. 6 to 9, and for example, a flowchart in which these are combined may be used.

  The printer device according to the present embodiment includes a cooling fan 9 and heat radiating fins 4. However, if the heat capacity of the heat sink 5 can be set sufficiently large and the surface area of the heat sink 5 and the conditions of heat convection in the apparatus can be set so that the efficiency of natural cooling is sufficiently high, the cooling fan 9 and the heat radiation fins 4 are unnecessary. is there. In this case, since the cooling fan 9 and the radiating fin 4 are not required, there are advantages in terms of downsizing the device, reducing the weight of the device, reducing the operation noise, and the manufacturing cost of the device.

  In the present embodiment, an example in which the thermal head 1 is attached to the heat pipe 2 via the heat conducting medium 3 has been shown. However, the thermal head 1 and the heat pipe 2 are inseparably integrated by a method such as press fitting, for example. Even if it becomes, the same effect is acquired.

  The configuration of the heat sink 5 described in the present embodiment is an example. If the connection state between the heat sink 5 and the heat pipe 2 is variably configured so that the thermal resistance of the heat transfer path is variable, these specific examples are possible. The general configuration is arbitrary.

  Further, the connecting portion where the heat transfer path is connected and divided is not limited between the heat sink and the heat pipe. Specifically, the heat transfer path is composed of at least two transfer path portions, and it is only necessary that the state of the connecting portion where the transfer path portions are connected is variable. Moreover, in the connection part of a heat transfer path, when a transfer path part is connected, the area of contact is comprised variably, and thermal resistance may be variable.

  Further, the printer apparatus according to the present embodiment has a configuration for controlling the thermal resistance of the heat transfer path. For example, a connecting portion between the heat sink 5 and the heat pipe 2 and a driving unit for changing the state of the connecting portion. 6 is provided. Therefore, the thermal head 1 is more stable when it is fixed to the printer device without moving, and the reliability of image recording is increased. Therefore, when the recording material 10 and the ink sheet are pressed against each other during the printing operation and the recording material 10 is returned after the printing is finished, the thermal head 1 is fixed when the pressure contact is released. It is desirable for the platen roller to move.

[Second Embodiment]
FIG. 10 is a schematic plan view of a printer apparatus according to the second embodiment of the present invention. The heat sink 5 described in the first embodiment is mainly intended for heat storage. However, if the heat capacity of the heat sink 5 cannot be secured sufficiently, or the temperature inside the housing of the printer apparatus becomes very high, the heat sink 5 may be provided with a heat radiating portion 5a. The heat radiating area of the heat radiating part 5a is set so that heat exchange by the cooling fan 9 is possible, for example. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Even with such a configuration, it is possible to change the thermal resistance of the heat transfer path in which the thermal head 1, the heat pipe 2, and the heat sink 5 are integrated, so that the same effect as in the first embodiment can be obtained. Can be obtained.

  Although the preferred embodiments of the present invention have been presented and described in detail above, the present invention is not limited to the above-described embodiments, and it is understood that various changes and modifications can be made without departing from the gist. I want to be.

DESCRIPTION OF SYMBOLS 1 Thermal head 2 Heat pipe 3 Thermal conduction medium 4 Radiation fin 5 Heat sink 56 Control means

Claims (12)

A thermal head that generates thermal energy for recording an image on a recording material;
Said a heat storage unit for the thermal head to the thermal storage heat generated, said provided at a position apart from the thermal head heat storage unit,
A heat transfer portion for transferring heat transferred from the thermal head directly or via a heat conducting member to the heat storage portion, and a heat transfer portion extending outside a recording range by the thermal head; Have
The heat storage unit is provided so as to be connectable to the heat transfer unit at a portion extending outside the recording range of the heat transfer unit, and a connection state of the heat storage unit and the heat transfer unit is configured to be variable. An image recording apparatus. A heat dissipating means for dissipating heat generated by the thermal head;
The image recording apparatus according to claim 1, wherein the heat radiating unit is provided between the thermal head and the heat storage unit . The image recording apparatus according to claim 2, wherein the heat storage unit and the heat transfer unit are configured to be connected to each other and can be divided. The image recording apparatus according to claim 2 , wherein a pressure contact force when the heat storage unit and the heat transfer unit are connected to each other is configured to be variable. 5. The image recording apparatus according to claim 2, wherein an area of contact when the heat storage unit and the heat transfer unit are connected to each other is variably configured. 6. . The image recording apparatus according to claim 1, further comprising a control unit that controls a connection state between the heat storage unit and the heat transfer unit . A temperature sensor for detecting the temperature of the thermal head;
The image recording apparatus according to claim 6, wherein the control unit controls a connection state of the heat storage unit and the heat transfer unit according to a temperature of the thermal head. A temperature sensor for detecting the temperature of the heat storage unit;
The image recording apparatus according to claim 6, wherein the control unit controls a connection state between the heat storage unit and the heat transfer unit according to a temperature of the heat storage unit . A housing that houses at least the thermal head; and a temperature sensor that detects a temperature inside the housing;
The said control means controls the connection state of the said heat storage part and the said heat transfer part according to the temperature inside the said housing | casing, The any one of Claim 6 to 8 characterized by the above-mentioned. Image recording device. 10. The image recording according to claim 6, wherein the control unit controls a connection state of the heat storage unit and the heat transfer unit according to a density of an image to be recorded. apparatus. When the temperature of the thermal head during image recording exceeds a preset temperature, the control means determines the heat resistance of the heat transfer path from the thermal head to the heat storage section before the start of image recording. 11. The image recording apparatus according to claim 6 , wherein a connection state between the heat storage unit and the heat transfer unit is controlled so as to be smaller than a thermal resistance of the transmission path.   The image recording apparatus according to claim 1, wherein the thermal head is fixed to the image recording apparatus.

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