JPH022012A - Recording apparatus - Google Patents

Abstract

PURPOSE:To obtain a stable image without collapsing the balance of recording density by mounting a control means for controlling the temps. of a plurality of recording heads to a preset temp. range on the basis of the output results of temp. detection means. CONSTITUTION:A temp. detection means 4 and a heater 5 are arranged to each recording head 3 of a recording unit 1 and the output signal of the temp. detection means 4 of each recording head 3 is taken in a control unit 8 as the digital data of the present temp. of each recording head through a converting amplifier 6 and an A/D converter 9, and a drive signal is emitted to the heater 5 from the control unit 8 through a heater driving circuit 10 when the part of the recording head is low in temp. and requires heating but to a blowing means 7 when the recording head requires cooling because of its high temp. Further, prior to performing control operation, the temps. of recording heads 3a, 3b, 3c, 3d are preset corresponding to the recording density characteristics of respective ink colors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording device, and more particularly to a recording device having a plurality of recording heads that perform recording using thermal energy.

[Conventional technology]

A variety of recording devices have been known for a long time, and among them, recording devices that use heat as recording energy, such as bubble jet recording, thermal recording, and thermal transfer recording, are easy to configure and can be easily converted to color, so they are popular among others. Its future prospects are seen as more promising than other recording devices. Among such recording apparatuses that use heat as recording energy, a plurality of recording heads may be provided especially for purposes such as color recording and high-speed recording.

[Problem to be solved by the invention]

In a recording device that uses this kind of thermal energy as a recording source, for example, a plurality of recording heads filled with the same ink are installed, and an image recording signal is sent from a fall control device to the electrothermal converter of each recording head. When each recording head performs recording according to the recording head, the amount of heat generated by the electrothermal transducer may vary depending on the recording head.

This difference in the amount of heat generated by the electrothermal transducer of each recording head appears as a temperature difference between each recording head, and in the case of inkjet recording, the difference in head temperature results in a difference in the temperature of the recording ink. Differences in ink viscosity between each head cause differences in ink ejection amount between each head,
As a result, this becomes a factor that causes image fluctuations as density differences.

Particularly when full-color recording is performed using heads of different colors, the temperature of each color head fluctuates, and if there is a large temperature difference between the heads, not only density differences but also color balance fluctuations occur.
A problem arises in that a stable color image cannot be obtained, and in order to solve this problem, a method of keeping the recording head temperature constant has been proposed.

By the way, in the case of an inkgenic recording device that has multiple recording heads equipped with multiple colors of ink, even if the temperature of each recording head is the same, the type of dye contained in each ink and the degree of dissolution in the ink may vary. The recording density on the recording paper differs depending on the density of the dye used. Furthermore, since the amount of change in print density of each print head with respect to the amount of change in temperature of each print head is also different, even if the print heads of each color are controlled at the same set temperature, the print density balance between each print head will be disrupted. It was difficult to obtain stable images.

Therefore, it is an object of the present invention to provide a printing apparatus that eliminates the above-mentioned problems and can obtain stable images without losing the balance of the recording distance of 71 degrees by each printing head.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a plurality of recording heads with different recording colors, a temperature detection means for detecting the temperature of each of the plurality of recording heads, and a plurality of recording heads based on the output results of the temperature detection means. The present invention is characterized by comprising a control means for controlling the temperature of each of the recording heads within a preset temperature range.

(Function) According to the present invention, it is possible to provide a recording device with a simple configuration that can suppress image fluctuations caused by temperature differences between heads and easily obtain stable images.

〔Example〕

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

FIG. 1 is a block diagram showing the basic configuration of a recording apparatus according to the present invention. a is a recording head, b is a temperature detection means for detecting the temperature of the recording head, and C is a temperature detection means for controlling the temperature of each recording head within a preset temperature range based on the output result of the temperature detection means. It is a control means.

In the following, a case where the present invention is applied to an inkjet recording apparatus using a bubble jet method will be exemplified.

FIG. 2 shows an example of the configuration of the inkjet recording apparatus of the present invention. Here, 1 is a recording unit mounted on a carriage 2, in which a pulse voltage according to an image recording signal is applied to an electrothermal transducer, and the thermal energy generated from the electrothermal transducer causes foaming to eject ink. It has a plurality of recording heads 3 for printing.

FIG. 3 shows an enlarged view of the recording unit 1, in which each recording head 3 is provided with a temperature detecting means 4 and a heater 5. In this example, the recording unit 1 consists of four recording heads 3a, 3b, 3c, and 3d, each of which can correspond to, for example, yellow, magenta, cyan, and black.

As the temperature detection means 4, an IC temperature sensor thermistor, a thermal lightning pair, a varistor, etc. can be used. Further, as the heater 5, for example, a power transistor or a heating element can be used.

Referring again to FIG. 2, reference numeral 7 denotes an air blowing means, for example, in the form of a fan, provided for the recording heads 3a to 3d, and by driving this, the head unit 1 can be cooled. 11 is a paper feed motor;
The recording medium P such as paper is moved by the paper feed motor 11 according to the drive of the paper feed motor 11.
It is conveyed in the direction f in the figure by a roller 10 connected to the glaze. The roller 12 is a roller that cooperates with the roller 10 to flatten the recording medium P and form a recording surface for the recording unit 1.

14 is a belt for driving the carriage that fixes the carriage 2, and 16 is the belt 14 in the S direction in the figure! The motor moves by 1v, and 18 is a guide rail for the carriage 2. That is, the carriage 2 can move in the S direction in the figure along the guide rail 18 in accordance with the drive of the motor 16, and can perform recording on the recording surface.

Further, the detection signal of the temperature detection means 4 is manually inputted to the control device 8 shown in FIG. Make sure to keep the temperature within the appropriately set temperature range.

FIG. 4 shows an example of the configuration of a control system applicable to the apparatus shown in FIG. The output signal of the temperature detection means 4 of each recording head 3 is taken into the control device 8 via the conversion amplifier 6 and the D/D converter 9 as digital data of the current temperature of each recording head. On the other hand, the control device 8 issues a drive signal to the heater 5 via the heater drive circuit 10 when the recording head portion is at a low temperature and requires heating, and to the blower means 7 when the recording head portion is at a high temperature and requires cooling.

The control device 8 includes, for example, a CPU that performs control operations according to processing procedures described later with reference to FIGS. 7, 8, and 9.
, a microcomputer having a ROM storing programs and other fixed data corresponding to the processing procedure, a working RAM, and the like.

Before performing the control operation, the print heads 3a, 3b, 3c, and 3d are adjusted in advance according to the print density characteristics of each ink color.
Set the temperature. In the case of an inkjet recording device that uses thermal energy to eject ink droplets as in this example,
Using a recording head with a recording density of 400 dpi, the dye concentrations of cyan, magenta, yellow, and black were set to 2 wL%, 2 wt%, 2 wt%, and 3 wt, respectively.
When recording was performed using a recording ink with a printing ratio of %, temperature-density characteristics as shown in FIG. 5(A) were obtained.

From the results shown in Figure 5(A), it is clear that the recording head temperature is 2.
When printing at 5 degrees Celsius, the recording density of the black ink with the lowest temperature of 7 degrees Celsius (19 degrees) is 1.00, and the recording density of the yellow ink with the lowest temperature of i61 degrees is 1.15, resulting in an imbalance in recording density. . Therefore, both records t"J
=? In order to make the Q degree uniform, it is necessary to lower the set temperature of the yellow ink print head and increase the set temperature of the black ink print head.

FIG. 5(B) shows the cyan dye (
This is the temperature-density characteristic of the recording head when recording was performed at a printing ratio of 75% using recording ink set at 1 wt% and 3 wt%. From FIG. 5(B), the set temperature of the recording head equipped with recording ink with a cyan dye concentration of 1wt% is 35°C, and the cyan dye concentration is 3wt%.
The set temperature of the recording head equipped with % recording ink is 2.
By setting the temperature to 5° C., it becomes possible to perform good recording without any deviation in recording density.

Figure 5(B) shows the temperature-density characteristics of the recording head when changing the dye density of cyan, but is not limited to cyan, and when changing the dye density of magenta and black. Also, by changing the set temperature of the print head for each print head, it is possible to perform good printing without a deviation of 1 degree.

Before explaining an example of the operation of the control system shown in FIG. 4, the above-mentioned set temperature will be explained.

6A and 81 are algorithms showing the temperature control operation of the cyan ink recording head.

Figure 6 (A) shows that a blower fan is provided to cool the recording head, and recording is performed by turning the blower fan on or off, or turning the heater on or off. This is an algorithm for controlling the head temperature within a predetermined set temperature range.

In FIG. 6(A), Tlc is a set temperature at which the blower fan is turned on when the temperature of the recording head rises and exceeds this value. T2C is a set temperature that turns off the blower fan when the (rA degrees) of the recording head decreases to below this value.In other words, as the temperature of the recording head increases, the temperature above Tic turns off the blower fan. When the temperature of the print head drops, the blower fan is in the on range until T2C.In this way, when the temperature of the print head rises and falls, the temperature of the print head remains the same. However, the on/off status of the blower fan is different.

Further, T4C is a set temperature at which the heater is turned on when the temperature of the recording head decreases to below this value. T3
C is a set temperature at which the heater is turned off when the temperature of the recording head increases and exceeds this value. That is, when the temperature of the print head is decreasing, the heater is on in the region below T4C, and when the temperature of the print head is increasing, the heater is on in the region up to T3C. In this way, even when the temperature of the print head is the same, the on state and off state of the heater are different when the temperature of the print head rises and when it falls.

FIG. 6(8) shows another algorithm for the recording head in the control system of the present invention. In Figure 6(B),
In order to improve the cooling efficiency of the recording head, the first O.
The temperature of the recording head can be adjusted by installing a pressure pump as shown in the figure and turning on or off the pressure and pressure of the recording ink, or by turning the heater on or off. Control within a predetermined set temperature range. T
ic is a set temperature at which the pressure pump is turned on when the temperature of the recording head rises and exceeds this value.

T6C is a set temperature at which the pressure pump is turned off when the temperature of the recording head decreases to below this value. That is, when the temperature of the recording head increases, TSc
The above is the on-region of the pressure pump, and when the temperature of the recording head decreases, the on-region of the pressure pump is up to Tic. In this way, when the temperature of the recording head increases and when it decreases, even if the temperature of the recording head is the same, the on state and the off state of the pressure pump are different. Note that T3C and T4C have been explained in FIG. 6(A), so their explanation will be omitted here.

In this way, when the temperature of the recording head increases and when the temperature of the recording head decreases, the blower fan or pressure pump is on or off, and the heater is on or off. This fact can be used to prevent overshoot and undershoot of the recording head.

In the present invention, as shown in FIG. 3, each of the recording heads is provided with a temperature detection means, and based on the output result of the temperature detection means, the control device determines the temperature of each of the recording heads by the heater, air blower, or The pressure pump was controlled to keep the temperature within a certain set temperature range. For example, the temperature of each of the four recording heads (cyan, macenda, yellow, and black) is detected, and if the temperature of even one of the four recording heads is higher than the set temperature to turn on the blower fan when the power is turned on or during printing. If so, turn on the blower fan to start cooling the recording head.

Since the control for each color print head is the same, in the following embodiment, an example of the operation of the cyan ink print head will be described.

Embodiment 1 FIG. 7 is a flowchart of an example of the operation of the control system of the recording apparatus according to the present invention.

First, in step S1, the temperature of the recording head is detected and compared with a set temperature Tlc for turning on the blower fan.

If the temperature of the print head is higher than TIc, the process proceeds to step S2, and if the temperature of the print head is below Tlc, the process proceeds to step S5.

In step S2, the blower fan is turned on to turn off the recording head, and the process proceeds to step S3.

In step S3, the temperature of the recording head is compared with a set temperature T2c for turning on the blower fan, and if the temperature of the recording head is higher than T2C, the blowing of air is continued and the process is on standby. When the recording head temperature becomes 72c or lower, the process proceeds to step S4, where the blower fan is turned off, and the process proceeds to step S5.

In step S5, the recording head temperature is compared with a set temperature T4C for turning on the heater, and if the recording head temperature is T4C or higher, the recording operation is continued without turning on the heater. If the temperature of the recording head is lower than T4c, the process advances to step S6.

In step S6, the heater is turned on, and step S6
In step 7, the recording head temperature is compared with a set temperature T3c for turning off the heater. If the temperature of the recording head is lower than T3c, heating by the heater is continued and the recording head is on standby. If the temperature of the recording head is equal to or higher than T3e, the heater is turned off in step S8 and the process returns to step St.

The control operation of this embodiment is such that gradually during continuous printing,
Alternatively, even if the temperature of the print head suddenly increases, the temperature of the print head can be controlled.

In this way, based on the recording head temperature -/μ degree characteristic for each recording ink, the set temperature of each recording head is changed to maintain each recording head within the set temperature range of each ink and print. By doing so, it becomes possible to perform good recording without deviation in recording In degree.

FIG. 8 is a flowchart showing another example of the operation of the recording apparatus according to the present invention, which is configured to prevent such problems and simplify control by the control device.

First, in step 511, the temperature of the print head is detected and compared with Tlc. Recording head temperature 1)) TI
If the temperature of the recording head is higher than Tlc, the process advances to step 512, and if the temperature of the recording head is below Tlc, the process advances to step 517.

In step 512, the blower fan is turned on to cool the recording head, and the process proceeds to step S13.

In step 513, a timer is set to a predetermined time and the process proceeds to step 514.

In step 514, the temperature of the print head is compared with T2c, and if the print head temperature is 72c or less, the blower fan is turned off in step 515, and the process proceeds to 517.

In step 514, detecting the temperature of the recording head;
Compare the print head temperature and T2c, and if the print head temperature is higher than T2c, proceed to step 516;
Determine whether the time set by the timer has elapsed.

In step 516, when a predetermined set time has elapsed, the flow advances to step 517 with the blower fan turned on, and the temperature of the recording head and T4C are compared. In step 51B, if the timer set time has not elapsed, the process returns to step 514.

In step 517, the print head temperature is compared with a set temperature T4C for turning on the heater, and if the print head temperature is T4e or higher, the heater is not turned on and the printing operation continues. If the temperature of the recording head is lower than 74C, the process advances to step 518.

In step 518, the heater is turned on, and in step 519, the recording head temperature is compared with a set temperature T3e for turning off the heater. The temperature of the recording head is T3
If the temperature is lower than c, the heater continues heating and waits. If the temperature of the recording head is T3c or higher, step S2
At 0, the heater is turned off and the process returns to step Sll.

By providing a timer set in step S13 as in the present embodiment, it is possible to stop the recording head for a long time in the first embodiment due to reasons such as the temperature of the recording head being extremely high or the cooling capacity of the blower fan being low. , the problem of taking a long time to move on to the next operation is solved.

Instead of providing a timer set as in this example,
By calculating the print lines (number of scans) in the main scanning direction using a counter set, the same effect can be obtained even if the operation is performed after a certain predetermined number of print lines has elapsed.

Example 3 In Examples 1 and 2, the recording head was cooled by a blower fan.

In this embodiment, in order to improve the cooling efficiency, a pressure pump as shown in Figure 1O is provided for each recording head to pressurize and forcefully feed the recording ink. It performs cooling.

If the temperature of one of the four recording heads is higher than the temperature set to turn on the pressure pump, one of the recording heads will be turned on.
After printing the line, move the carriage 2 with the recording head li fftu to the home position H (see Figure 2).
After the non-discharge recovery device 20 (see FIG. 2) is brought into close contact with each recording head, the recording ink is pressurized and fed under pressure.

That is, as shown in FIG. 1θ, by circulating ink from the ink tank 18 in the T direction through the ink supply pipe 15 using the ink pressure feeding means 17, the heated ink in the recording head is The recording ink that is removed from the nozzles and has a low temperature is supplied to the recording head, thereby realizing cooling of the recording head.

FIG. 9 is a flowchart illustrating an example of the operation of controlling the temperature of the recording head by force feeding ink.

First, in step 521, the temperature of the recording head is detected and the set temperature T2 is set to turn on the ink pressure feeding means 17.
Compare with. If the temperature of the print head is higher than Tic, the process proceeds to step S22, and if the temperature of the print head is less than vse, the process proceeds to step S525.

In step S22, the ink pressure feeding means is turned on to cool the recording head, and the process proceeds to step S523.

In step 523, the temperature of the recording head is compared with a set temperature T6c for turning off the ink pressure feeding means, and if the recording head temperature is higher than T6c, the ink pressure feeding is continued and the process waits. When the recording head temperature becomes equal to or lower than Tic, the process proceeds to step S24, where the ink pressure feeding means 17 is turned off, and the process proceeds to step S25.

In step S25, the recording head temperature is compared with a set temperature T4c for turning on the heater, and if the recording head temperature is T4C or higher, the recording operation is continued without turning on the heater. If the temperature of the recording head is lower than T2C, the process advances to step 526.

In step 526, the heater is turned on, and in step S27, the recording head temperature is compared with a set temperature T3c for turning off the heater. The temperature of the recording head is T3
If the temperature is lower than c, the heater continues heating and waits. If the recording head temperature is 73c or higher, step 52
At step S8, the heater is turned off and the process returns to step S21.

By controlling the temperature of the recording head in this way, recording 3/3
This can be achieved by maintaining a uniform agricultural balance and keeping good records.

In this example, as in Example 2, even when the temperature of the print head is extremely high, the timer is set and the ink pressure feeding means is kept on to keep the temperature of the print head within a certain temperature range. It is possible to set it to .

In the present invention, it is most desirable that control during recording be performed constantly in real time, but if the purpose is sufficiently achieved, an appropriate timer may be provided to simplify control by the CPU. It is also possible to control fl[I every predetermined number of scans.

Further, the present invention is applicable to an inkjet recording apparatus having a plurality of recording heads, even if the plurality of recording heads are provided corresponding to predetermined ink colors to perform multicolor recording, or gradation It goes without saying that it is also applicable to a system in which a plurality of recording heads are provided corresponding to predetermined densities for expression.

In addition, the format of the recording unit is not limited to the serial printer type shown above, but also the line printer type, which has multiple stages of recording heads with ink ejection orifices aligned across the entire width of the recording medium, corresponding to the ink color and density. Of course, it may also be one of the following.

Further, in the upper part, the ink temperature is controlled by the control device 8 having a CPU, but it goes without saying that it can be controlled by hardware by combining a comparator or other appropriate logic circuit.

In addition, the present invention is of course applicable to any recording method such as bubble jet recording, thermal recording, thermal transfer recording, etc.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a recording device with a simple configuration that can suppress image fluctuations caused by temperature differences between heads and easily obtain stable images.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a recording device according to the present invention, FIG. 2 is a perspective view showing an example of the configuration of an inkjet recording device as an example of a recording device to which the present invention can be applied, and FIG. FIG. 4 is a block diagram showing an example of the configuration of a control system applicable to the recording device shown in FIG. 2; FIGS. 5(A) and (B) are , a characteristic diagram showing the relationship between the set temperature of the recording head and the dye concentration; FIGS. 6(A) and 6(B) show the temperature control of the recording head by the control system of the recording apparatus according to the present invention shown in FIG. An explanatory diagram for explaining the algorithm, FIG. 7 is a flowchart showing an example of the temperature control procedure of the control system of the recording apparatus according to the present invention shown in FIG. 4, and FIG. FIG. 9 is a flowchart showing another embodiment of the temperature control procedure of the control system of the recording apparatus according to the present invention shown in FIG. Flow Chart Showing Other Embodiments FIG. 10 is an explanatory diagram illustrating a temperature control procedure using ink pressure feeding in a third embodiment of the recording apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Recording unit, 2... Carriage, 3, 3a, 3b, 3c, 3d --- Recording head, 4... Temperature detection means, 5... Heater, 6... Conversion amplifier, 7 ...Air blowing means. 8...Control device, 9...-A/D converter. 4. The amount of urine contained in the 5th and 1st month of 44 months is 1;
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Claims (1)

[Scope of Claims] 1) a plurality of recording heads with different recording colors; a temperature detection means for detecting the temperature of each of the plurality of recording heads; 1. A printing apparatus comprising: control means for controlling the temperature of each of the printing heads within a preset temperature range.