JPH058106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording device that can control print density based on humidity.

[Prior art]

An inkjet recording device is a device that ejects ink based on data signals from multiple ink ejection ports formed in a print head, and records by depositing ink droplets on paper, and is used in printers, facsimile machines, etc. ing.

There are two types of inkjet recording devices: a line print type in which ink ejection ports for one line are arranged on the print head and scan in the paper feeding direction, and a line print type in which the print head is mounted on a carriage that moves along the paper. There is also a serial print type that scans in the paper width direction. Furthermore, various arrangements of ink ejection orifices for line printing have been proposed, such as a straight line arrangement and a staggered arrangement.

Further, in the case of color printing, a plurality of print heads of different colors such as yellow, magenta, cyan, and black are installed.

In such an inkjet recording device, the print head portion including the print head and head drive circuit is generally formed into a unit, and the structure is such that each unit can be replaced.

However, in this type of inkjet recording apparatus, properties such as ink viscosity change depending on the temperature of the apparatus, particularly the temperature of the print head, and the amount of ink ejected changes.

For example, when the temperature becomes low (for example, 5° C. or lower), the viscosity of the ink increases, making it difficult to eject, reducing the flying speed and reducing the amount of ink ejected. Also,
When the temperature is high (for example, 50° C. or higher), the viscosity of the ink decreases and the amount of ink ejected increases.

By the way, when increasing humidity makes it difficult for ink to dry, when controlling print density by reducing the amount of ink ejected, the conventional temperature control of the print head is You can increase or decrease the drive time during the cycle, that is, the time for energizing the heating element that is the ejection energy generator (heater), or change the energization of the heat generator (heater) for heating the head based on the detected temperature of the print head. This was done intermittently.

However, with these conventional methods, it takes time to preheat and cool down, which reduces the actual printing speed, makes it difficult to maintain the optimum ejection temperature, and makes it difficult to control the amount of ink ejection due to changes in humidity. The problem was that it was difficult.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording apparatus which can solve the problems of the prior art described above and which can change the amount of ink ejected according to changes in humidity.

〔overview〕

In the present invention, a printing head unit is provided with a heater and a temperature detecting means, and a blower and a humidity detecting means are provided in the apparatus, and the heater is The above object is achieved by controlling the amount of ink ejected from printing by controlling the drive of the blower.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings, taking as an example a case in which the present invention is applied to a line print type color inkjet recording apparatus.

FIG. 1 shows the internal structure of a color inkjet recording apparatus according to one embodiment, in which a print head assembly 2 is provided at the front of a case 1, that is, on the paper (not shown) side. This print head assembly consists of a plurality of (four in the illustrated example) print head units 3A, 3B, 3C, and 3D that are arranged in the vertical direction (paper feeding direction) and installed in a replaceable manner. The printer is equipped with a plurality of print head elements 4 and is configured to print one line (in terms of bit number) at a time. The four print head units 3A...3D print different colors, for example, cyan, magenta, yellow, and black.

For example, one line is formed of 1792 bits (dots), and each print head unit has a structure in which 128 bits, that is, 14 print head elements each having 128 ink ejection ports are mounted in a staggered manner above and below the base plate 5. have.

At the rear of the case 1, ink containers 6A...6D for supplying ink to the print head units 3A...3D are replaceably installed.

Thus, each print head unit 3A...3D is provided with a heater 7 and a temperature detection means 8, respectively. Furthermore, a blower 9 is provided in the apparatus for cooling each print head unit 3A...3D.

2 and 3 show the temperature control system of any one of the print head units 3A...3D.

In FIG. 2, the desired position of the base plate 5 of the print head unit 3, that is, each print head element 4
The heater 7 and the temperature detecting means 8 are provided at a position close to the temperature or a position showing a temperature corresponding to the temperature. This printing head unit can be cooled by the common blower 9 provided within the device. As the heater 7, for example, a power transistor or a heating element can be used.

The detection signal of the temperature detection means 8 is input to the control section (microcomputer) of the device, and the control section controls the heater 7 and the blower 9 based on this temperature signal.
The temperature of the print head is controlled appropriately.

FIG. 3 shows this control system, in which the humidity detection means 11
A detected high humidity signal Si ₁ and a detected low humidity signal Si ₂ from a humidity sensor (for example, a humidity sensor having characteristics as shown in FIG. The control unit 10 issues a drive signal DH to the heater 7 when the print head is at a low temperature and requires heating, and to the blower 9 when the print head is at a high temperature and requires cooling. A drive signal DF is generated.

For example, if the humidity is high (relative humidity 95% or more), the head temperature should be lowered to reduce the amount of ink ejected to allow for better ink drying, and if the humidity is low (relative humidity 5% or less), the head temperature should be set to a higher temperature to reduce the amount of ink ejected. The discharge amount is increased to make the boundary between adjacent dots less noticeable.

FIG. 5 shows the control procedure. First, humidity detection means 1
If the control signal Si from 1 is in the "high humidity" state (high humidity signal Si is ON) in step 71, the control signal Si from step 72 is
Set the temperature to low temperature L (e.g. 30℃) and proceed to step 73.
When the temperature is low (low temperature signal Si ₂ is ON), set the temperature to high temperature H (for example, 40°C) in step 74.
If not, in step 75, set the temperature to room temperature M (for example, 35
℃), turn on the fan at step 76, and turn on the fan at step 76.
77 controls the heater, and step 78 prints.

Next, an example of the control operation will be explained with reference to FIGS. 5 to 7.

FIG. 6 shows the procedure for controlling the heater 7,
In step 102, the timer is activated for 1 second, and after confirming that 1 second has elapsed in step 103, the temperature data Tn from the temperature detection means 8 is detected in step 104.
(n=0 to 3).

From this temperature data Tn, it is determined in step 105 whether or not the temperature of the printing head portion is lower than the set temperature. If it is lower, the process proceeds to step 106, where the heater 7 is turned on and heated.

If it is determined in step 105 that the temperature is not lower than the set temperature, the process proceeds to step 107 to determine whether or not the temperature is higher than the set temperature. .

FIG. 7 shows the procedure for controlling the blower 9. At step 102, temperature data from the temperature detection means 8 is read. In step 103, it is determined whether the temperature data is higher than the set temperature, and if it is, the step
At step 104, the blower 9 is turned on. If the temperature is not higher than the set temperature, the process advances to step 105 and it is determined whether the temperature is lower than the set temperature. If the temperature is lower than the set temperature, the blower 9 is stopped in step 106, and if it is not lower than the set temperature, it is left as it is.

According to the embodiment described above, when the temperature of the print head becomes low or high, the heater 7 or the blower 9 is operated based on the detection signal to actively heat or cool the print head. The temperature of the area could be controlled quickly and accurately, and the print density could be controlled by controlling the amount of ink discharged.

In the illustrated embodiment, the printing head unit 3
Although one heater 7 and one temperature detecting means 8 are provided in each section, a plurality of heaters 7 and temperature detecting means 8 may be provided as required, and the temperature may be controlled for each divided area.

Further, the present invention can be similarly applied regardless of the number or structure of print head units, and can be similarly applied to a serial print type in which print heads are mounted on a carriage.

〔effect〕

As is clear from the above description, according to the present invention, the humidity detecting means, the heater, and the blower are provided, and these are electrically controlled based on the detected temperature value of the print head.
Temperature control for controlling the amount of ink ejected from the print head can be performed quickly and accurately, print density can be controlled by changes in humidity, and ink drying can be controlled.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the inside of an embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is an explanatory view showing the temperature control means of the print head unit in FIG. 1, and FIG. Fig. 4 is a schematic block diagram showing the control system of the temperature control means in Fig. 4, Fig. 4 is a graph showing the characteristics of the humidity sensor, and Figs. 3 is a flowchart illustrating a control operation procedure. 3, 3A...3D: Print head unit, 4:
Print head element, 7: Heater, 8: Temperature detection means, 9: Blower, 10: Control unit (CPU),
11: Temperature detection means.

Claims (1)

[Scope of Claims] 1. An ink heating heater provided in a recording head that discharges ink, a temperature detection means for detecting head temperature, an air blower for cooling the recording head, and a humidity detection means; Based on the detection signal of the detection means and the detection signal of the humidity detection means, the ink is heated by the heater and the recording head is cooled by the blower to control the temperature of the ink, so that the ink is ejected from the recording head. An inkjet recording device characterized by controlling the amount of ink used.