JP3066924B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and, more particularly, to an ink jet recording apparatus for correcting the temperature of a recording head.

[0002]

2. Description of the Related Art Conventionally, a recording apparatus for performing recording on a recording medium (hereinafter, also referred to as recording paper or simply paper) such as paper or OHP sheets has been proposed in a form in which recording heads of various recording systems are mounted. I have. This recording head includes a wire dot type, a thermal type, a thermal transfer type, an ink jet type, and the like.

[0003] In particular, the ink jet system, which directly ejects ink onto recording paper, has attracted attention as a quiet recording method with low running cost. The recording density of this ink jet recording method has temperature dependency, and the relationship between the recording density and the ambient temperature generally decreases as the temperature decreases, as shown in FIG. This is because when the temperature becomes low, the viscosity of the ink increases, and the ejection amount of the ink decreases. Since a normal recording apparatus is set to have an appropriate density at normal temperature (for example, 20 ° C.), the recording density becomes lower than appropriate in a low-temperature environment.

Therefore, temperature correction of the recording density is performed so that an appropriate recording density can be obtained even in a low temperature environment. As one of the methods, there is a method of preventing the viscosity of the ink from increasing by warming the ink at a low temperature.

FIG. 2A is a schematic sectional view of a head cartridge in which a recording head and an ink tank are integrated. Reference numeral 21 denotes a heater board whose details are shown in FIG. 1B, and a discharge heater 21g is formed on a Si substrate. By applying a voltage to the discharge heater 21g, the ink in the common liquid chamber 23 formed by the heater board 21 and the top plate 22 obtains thermal energy and is discharged as droplets from the discharge ports 24 to perform recording. Is performed. An ink supply pipe 26 extends from the ink tank 25 to the common liquid chamber 23.
The ink is supplied through the.

At this time, by forming a heat retaining heater 21d together with the discharge heater 21g on the heater board 21 and appropriately controlling the heating of the heat retaining heater 21d, it is possible to heat and raise the temperature of the ink in the common liquid chamber. Reference numeral 21e denotes a temperature detecting sensor, and a hatched portion indicates a position of a top plate mounted to form the common liquid chamber 23.

FIG. 3 is a graph showing an example of the relationship between the energizing time and the amount of increase in the ink temperature when a pulse is applied to the heat retaining heater. As can be seen from the figure, the ink temperature can be temporarily raised to an appropriate temperature by selecting the pulse energizing time.

Therefore, by detecting the environmental temperature, determining the power supply time for raising the temperature of the ink by the temperature difference from the normal temperature (target temperature) from FIG. 3 and controlling the power supply to the heat retaining heater, the ink is temporarily supplied. It can be heated to room temperature.
At this time, since the viscosity of the ink becomes equal to that at normal temperature, by performing recording (ie, ink ejection) immediately, it is possible to obtain an appropriate recording density equivalent to that at normal temperature.

For example, when the proper recording density is 20 ° C.,
As shown in FIG. 3, if the environment temperature is 10 ° C., when the heater is energized for 50 ms, the ink temperature rises by 10 ° C. to 20 ° C., so that if printing is performed quickly, an appropriate recording density can be obtained.
In this manner, the energization time to the heat retaining heater at each environmental temperature can be determined as shown in FIG.

In the case of this control system, when the energization of the heat retaining heater is completed, the ink temperature decreases with time due to heat radiation, but when recording starts, the decrease in the ink temperature is suppressed to a small degree by the heat generated by the discharge heater. Therefore,
In general, the energization of the heater is performed only once at the beginning of each recording line in a serial scanning type recording apparatus. In order to simplify the control, the heater energization timing at the beginning of each line is such that the heater is energized while the carrier is stopped and the carrier is driven immediately after the energization ends, or the carrier energization start of the heater is controlled. Or syncing.

[0011]

In the prior art, the start timing of energization of the heat retaining heater is fixed to a certain time during acceleration / running of the carrier, and is controlled by a timing chart as shown in FIG. When the temperature at which the appropriate recording density is reached is 20 ° C., the energization time to the heat retaining heater is 50 ms in a 10 ° C. environment and 20 ms in a 14 ° C. environment as shown in FIG.
Becomes

In order to easily set the power supply start timing of the heat retaining heater in terms of control, it is preferable to synchronize with the start of driving of the carrier. However, for example, 50
FIG. 5 shows a change in the ink temperature when the power is supplied for ms, and the ink temperature rapidly decreases after the power supply is completed. Therefore, it is desirable to start recording as soon as possible after the power supply is completed.

Therefore, the energization start timing is set so that energization ends at the first character position when the maximum energization time (in this case, 50 ms at 10 ° C.). When the energization time changes at another environmental temperature, the start of energization is set to the same. That is, as shown in FIG. 11, assuming that the time from the start of driving of the carrier to the recording area, that is, the position of the first character, is Tms, control is performed by setting the energization start time to be T-50 ms after the start of driving of the carrier. .

However, in this conventional method, if the energization time changes depending on the environmental temperature, printing cannot be performed immediately after the energization is completed. Was. Also, when the ambient temperature is 10 ° C. and the time is 50 ms, the termination of energization is 1
Even if it is at the character position, if the recording start position in one line is not at the first character position, the ink temperature will also drop by the start of recording, and the recording density will be lower than appropriate by that much. .

For example, assuming that the recording speed is 100 characters / second,
Consider the case where 50 ms of current is supplied. Recording start position is 1
If it is at the character position, the printing is started immediately after the end of the energization, so that the ink temperature at the start of the printing is the target 20 ° C. as shown by A in FIG. However, assuming that the recording head position is at the sixth character, 50 m is required from the end of energization to the start of recording.
Therefore, the ink temperature at the start of recording drops to 16 ° C. as shown in FIG. 5B.

Accordingly, the present invention has been made to solve the above-mentioned problems, and provides an ink jet recording apparatus capable of obtaining an appropriate recording density irrespective of a recording start position, an environmental temperature or an ink temperature. The purpose is to:

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to an ink jet recording apparatus for performing recording using a recording head which discharges ink, and a drive signal supplied with ink in the recording head. Heating means for heating and maintaining the temperature by the energy of the recording head, detecting means for detecting a recording start timing corresponding to a recording position at which ink is ejected by the recording head, and timing corresponding to the recording start timing detected by the detecting means And a supply unit for starting supply of the drive signal to the heating unit prior to the start of recording by the recording head. The present invention also relates to an ink jet recording apparatus that performs recording using a recording head that discharges ink, wherein a heating unit that heats the ink in the recording head by the energy of a supplied drive signal to maintain the temperature is provided. Determining means for determining the signal width of the drive signal in accordance with the temperature; and at a timing corresponding to the signal width of the drive signal determined by the determiner, the heating means is provided to the heating means prior to the start of recording by the recording head. Supply means for starting supply of the drive signal. According to the above configuration, an appropriate recording density can be obtained regardless of the recording start position, the environmental temperature, or the ink temperature.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) In this embodiment, the energization of the heater is terminated at the recording start position of the heater.
By controlling the energization of the heat retaining heater, the ink temperature from the end of energization to the start of printing is not reduced, and the ink temperature at the start of printing is set to a target appropriate temperature.

First, the control configuration of this embodiment will be described with reference to the block diagram of FIG. Reference numeral 10 denotes a CPU for controlling the energization based on a program stored in the ROM 11. The ROM 11 also stores the table and the like shown in FIG. Reference numeral 12 denotes a timer for obtaining various timings, and reference numeral 13 denotes a control circuit 13 for controlling the heat retaining heater 21d and a temperature sensor 14 for detecting an environmental temperature.
It is.

The recording head used in this embodiment discharges ink by using thermal energy from a discharge heater in the same manner as described above with reference to FIG. Set the resistance of heater 21d to 144
Since Ω ± 20Ω and the drive voltage for heating are set to 24V, about 4W of power can be output.

Next, the energization control of this embodiment will be described with reference to FIG.
And the timing chart of FIG. First, for the sake of simplicity, a case where the recording head position in one line is the first character (case A in the figure) will be described.
An energization start reference is set for each temperature so that the energization control at each environmental temperature satisfies the condition. This includes step S
1, the energizing time Xms is determined from FIG. 4 in step S2, and T-Xms after the start of carrier driving may be set as the energizing start reference in step S3. For example, in a 10 ° C. environment as shown in FIG.
So T-50ms, 20ms in 14 ℃ environment, so T
Set each to -20 ms. Thus, when the recording start position in one line is the first character, the end of energization of the heat retaining heater can be matched with the recording start.

Next, consider the case where the recording start position is the Nth character. Assuming that the recording speed is S characters / second, the recording time per character is 1000 / Sms, so that the recording start of the Nth character is delayed by 1000 · (N−1) / Sms from the first character. . Accordingly, the recording position is set to the N-th character in step S4, and the energization start reference is set to a time delayed by 1000 · (N−1) / Sms in step S5. For example, the end of energization can be coincident with the start of recording. For example, assuming that the recording speed is 100 characters / second, when the recording start position is the sixth character as shown in FIG. 12, the energization start may be set 50 ms later than the reference.

(Embodiment 2) As in the first embodiment, a second method for controlling the energization of the thermal insulation heater so that the energization of the thermal insulation heater ends at the recording start position of each row will be considered. In the first embodiment, the energization start reference determined from FIG. 4 is set for each environmental temperature.

In the second embodiment, as shown in the flowchart of FIG. 8 and the timing chart of FIG. 13, in each row, the energization start timing is directly determined based on the information of the recording start position. Assuming that the recording speed is S characters / sec, it takes 1000 · (N−1) / Sms from the first character to the Nth character. That is, T + 1000 from the start of carrier driving to the Nth character
-It will take (N-1) / Sms. Therefore, to end the energization of Xms at the Nth character, energization of the heat retention heater should be started at T + 1000 · (N−1) / S−Xms from the start of carrier driving. Therefore, if the recording head position is set to the N-th character in step S14, the direct energization start time is set to T + 1 in step S15.
000 · (N−1) / S−X, and step S1
In step 6, the heater is pulsed with electricity.

(Embodiment 3) According to the method of Embodiments 1 and 2,
The ink temperature at the print start position of each row can always be set to the target temperature regardless of the print position. Also, during recording, the ink temperature is less likely to decrease due to the heat generated by the discharge heater. Therefore, all the recordings in one line can be set to almost the proper density. However, in actuality, the recording data in one line is not necessarily all continuous, and recording may start again once with a space for several characters in the middle. In this case, the decrease in the ink temperature cannot be ignored in the space portion, and particularly when the space portion is long, the recording density after that becomes lower than appropriate.

Therefore, in the present embodiment, in order to obtain an appropriate temperature even in the above case, the power supply to the heat-retaining heater is not only performed before the recording start position in each row but also in the recording start position after a space in one row. This is performed at the same timing before.

The amount of space in which the ink temperature returns before the temperature rise depends on the amount of temperature rise of the ink, for example, 50 ms.
In the case where the temperature is raised by 10 degrees by energizing, the temperature drops to the original temperature about 300 ms after the end of energizing according to FIG. Assuming that the recording speed is 100 characters / second, 300 ms is equivalent to 30 characters. In this case, if the space portion in one line accumulates and reaches 30 characters, the correction effect is completely lost.

Therefore, in this case, before starting the recording of one line,
When a space character in one line is counted, and there is a recording character after a portion that cumulatively exceeds 30 characters, the head recording position is treated in the same manner as the head recording position in one line.
At that position, the energization of the insulated heater is controlled so that the energization of the insulated heater is terminated. Here, FIG. 9 shows the above-described accumulated space amount for each environmental temperature, that is, each energizing time.

Next, the flowchart of this embodiment is shown in FIG.
The control operation will be described with reference to FIG. 8, the same steps as those in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted. In step S27, the accumulated space amount Y characters are determined from FIG. 9 based on the environmental temperature detected in step S21. Then, the first recording start position after the accumulated space amount exceeds Y characters in one line is determined in step S28.
To set the Mth character. Then, the energization start time is set to T + 1000 · (M−1) · SX in step S29, and pulse energization to the heat retaining heater is started in step S26.

As described above, recording can be performed with an appropriate density even when a space exists in one line.

In the first to third embodiments, in order to set the ink temperature at the start of printing to 20 ° C., which is the target, the end of energization of the heat retaining heater and the start of printing are matched. However, this is because FIG. 4 was used as a correspondence table between each environmental temperature and the energization time of the heat retaining heater. That is, since all the tables in FIG. 4 set the ink temperature at the end of energization to 20 ° C., it was necessary to record before the ink temperature dropped.

Therefore, when a correspondence table between the environmental temperature which becomes the target temperature and the energization time which becomes the target temperature after a certain period of time from the energization end and the energization time is used, the energization end is performed in the same manner as in the first to third embodiments. If the control is performed such that the printing is started after the predetermined time, the ink temperature at the time of starting printing is set to the target 2
It can be 0 ° C.

In the above embodiment, the appropriate recording density is 2
Although described as 0 ° C., this can be applied in any number of times. Further, the lower limit of the correction temperature range is set to 10 ° C., but this may be any number of times. In addition, although the change in the temperature rise of the ink is described by the energizing time of a single pulse in FIG. 3, even when a plurality of pulses are used, the temperature rise change similar to that in FIG. Can be controlled.

In order to change the temperature of the ink, it is also possible to change the energizing voltage by applying a pulse with an appropriate pulse width. Available by guiding. Also, although the embodiments have been described in connection with the serial recording apparatus,
Also in the line type recording apparatus, the control method of the heat retention heater in each row of the above embodiment can be applied as it is to the transport direction of the recording medium. For example, it is also possible to virtually divide the line head into a plurality of parts, provide a heat retaining heater for each part, and apply the present control to each part.

In each of the above embodiments, the present invention is applicable to all ink jets having an ink ejection amount having a temperature dependency, such as an on-demand type using a thermal energy or mechanical energy, and a continuous type ink jet. Not only the system but also a solid ink system in which solids are melted and ejected at the time of recording by the recording head unit may be used.

Further, the heat retaining heater may directly or indirectly heat the ink, and the type and location of the ink are not specified.

Further, the printing means is not limited to the ink jet type, but can be applied to other general recording heads such as a thermal head.

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus using thermal energy among ink jet recording methods.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 47407.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 96. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and the film is heated on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal, which is effective. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble,
Form at least one drop. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. Examples of the drive signal in the form of a pulse include U.S. Pat. Nos. 4,463,359 and 4,345.
No. 262 are suitable. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface described above are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,558,333 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 459600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication (Kokai) No. 123670/1984 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing pressure waves of thermal energy. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

[0042]

As described above, according to the present invention, the ink temperature at the start of printing can be set to the target temperature irrespective of the printing start position or the environmental temperature or the ink temperature. An appropriate recording density can be obtained regardless of the position, the environmental temperature, or the ink temperature.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an environmental temperature and a recording density.

FIG. 2 is a diagram illustrating details of a head cartridge.

FIG. 3 is a graph showing a relationship between an energizing time and an ink heating amount when energizing a heat retaining heater.

FIG. 4 is a table showing a correspondence between an environmental temperature and an energizing time.

FIG. 5 is a diagram illustrating the principle of the first embodiment.
6 is a graph showing a change in the ink heating amount at the time.

FIG. 6 is a control block diagram according to the first embodiment.

FIG. 7 is a control flowchart of the first embodiment.

FIG. 8 is a control flowchart of the second embodiment.

FIG. 9 is a correspondence table of an environmental temperature and an accumulated space amount according to the third embodiment.

FIG. 10 is a control flowchart of the third embodiment.

FIG. 11 is a timing chart showing a conventional energization timing.

FIG. 12 is a timing chart showing the energization timing of the first embodiment.

FIG. 13 is a timing chart showing the energization timing of the second embodiment.

[Explanation of symbols]

 10 CPU 11 ROM 12 Timer 14 Temperature sensor 21d Heat insulation heater

Claims (6)

(57) [Claims] 1. An ink jet recording apparatus that performs recording using a recording head that discharges ink, comprising: a heating unit that heats ink in the recording head by energy of a supplied driving signal to maintain the temperature; Detecting means for detecting a recording start timing corresponding to a recording position at which ink is ejected; and at a timing corresponding to the recording start timing detected by the detecting means, the heating means is provided to the heating means prior to the start of recording by the recording head. A supply unit for starting supply of a driving signal. 2. The ink jet recording apparatus according to claim 1, wherein the supply unit controls the supply timing of the drive signal so that the time from the supply end timing of the drive signal to the recording start timing is constant. apparatus. 3. The ink jet recording apparatus according to claim 1, wherein a signal width of the drive signal changes according to an environmental temperature or an ink temperature. 4. An ink jet recording apparatus for performing recording using a recording head for discharging ink, a heating means for heating the ink in the recording head by the energy of a drive signal supplied thereto to maintain the temperature, Determining means for determining the signal width of the drive signal in accordance with the temperature; and at a timing corresponding to the signal width of the drive signal determined by the determination means, An ink jet recording apparatus, comprising: a supply unit that starts supplying a drive signal. 5. The ink jet recording apparatus according to claim 1, wherein said recording head is of a serial scanning type. 6. The recording head is provided for each of a plurality of ejection ports for ejecting ink and a corresponding ejection port, and causes a state change due to heat in the ink to cause the ink to flow from the ejection port based on the state change. 6. An ink jet recording apparatus according to claim 1, further comprising a thermal energy generating means for ejecting and forming flying droplets.