JPS61237652A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To absorb dispersion of recording head characteristics by making high-quantity recording even under any temperature condition all the time by converting density data into optimal drive voltage of a head according to temperatures. CONSTITUTION:An ink jet recording means (a) to make recording by discharging ink liquid droplets onto a recording medium, a temperature sensor (b) to detect ambient temperatures, and a discharge amount data output unit (c) to send out corresponding optimal discharge amount data by receiving detected temperature data of the sensor (b) and recording density data are provided. A driver (d) serves to drive the recording means (a) on the basis of optimal discharge amount data obtained from the output unit (c). The drive voltage of the ink jet recording means (a) can thus be optimized even under any temperature condition, permitting high-quality recording to be performed all the time.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an inkjet recording device that records characters, images, etc. by ejecting ink liquid onto a recording medium, and particularly relates to an inkjet recording device that has a temperature compensation function. The present invention relates to an inkjet recording device.

[Summary of the Disclosure] This specification and drawings describe an inkjet recording device that converts density data into an optimal head drive voltage according to temperature, thereby optimizing the recording head drive voltage under any temperature condition. The present invention discloses a technology that allows high-quality recording to be obtained at all times and absorbs variations in characteristics due to the temperature of the recording head.

[Prior Art] Conventionally, inkjet recording has been used to express halftones by changing the drive voltage of the inkjet head to change the amount of ink ejected, thereby changing the diameter of the recording dots on the recording paper. A recording device has been proposed.

[Problems to be Solved by the Invention] However, in this type of device, the physical properties of the ink that is the recording liquid, that is, the viscosity index surface tension, change greatly depending on the temperature, and the ejection of the head itself also changes depending on the temperature. It has the following temperature characteristics. Therefore, in general, the relationship between the optical density on the recording paper after recording and the voltage applied to the electrode changes depending on the temperature as shown in FIG. 2. That is,
The higher the temperature, the higher the optical density even with the same head applied voltage.

Therefore, if printing is performed at 10°C using density-voltage data at 25°C as in the past, for example, the printed density will be low, and ink may not be ejected in the low voltage range. Similarly, if printing is performed at 40°C using density-voltage data at 25°C, the amount of ink ejected will be too large and the ink will be too dark, or the recording paper will not be able to absorb the ink. This causes various inconveniences, including not only density changes in the image reproduction range, such as disappearance and protrusion.

On the other hand, conventional temperature compensation methods include a method of keeping the physical properties of the ink constant using a heater or the like, and a method of changing the voltage applied to the head depending on the temperature. but,
The former method of keeping physical property values constant increases the size of the device, the increase in power supply capacity, and the resulting increase in manufacturing costs, as well as printing defects due to the generation of dissolved gas in the ink due to rapid heating. There are drawbacks.

Furthermore, the latter method of changing the applied voltage is effective only for binary images, and if this method is used to express halftones by changing the amount of ink ejection, it will be difficult to deal with nonlinear changes in various characteristics. The drawback is that the circuit configuration becomes extremely complicated, resulting in high costs and making it difficult to put it into practical use.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to eliminate the above-mentioned drawbacks and provide a simple device.

[Means for Solving the Problems] In order to achieve this object, an inkjet recording means that performs recording by ejecting ink droplets onto a recording medium;
Temperature detection means for detecting ambient temperature; Discharge amount data output means for inputting the detected temperature data and recording density data of the temperature detection means and outputting the corresponding optimum discharge amount data; The present invention is characterized by comprising a driving means for driving the inkjet recording means based on optimum ejection amount data.

[Function] Since the inkjet recording means is driven by the optimum ejection amount data obtained by inputting it to the data output means, the driving voltage of the inkjet recording means is optimal under any temperature condition, and as a result, the drive voltage of the inkjet recording means is always high. A record of quality can be made.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the basic configuration of the embodiment.

Here, a is an ejection amount data output means that inputs an inkjet recording device that performs printing by ejecting ink droplets onto a recording medium, and outputs corresponding optimum ejection amount data. Further, d is a drive means for driving the above-mentioned inkjet recording means a based on the optimum ejection amount data obtained from the above-mentioned ejection amount data output means C.

FIG. 3 shows an example of the circuit configuration of the embodiment device.

In this figure, reference numeral 1 denotes a sequence controller, which controls the entire apparatus based on a control procedure as shown in FIG. 7, which is stored in advance in an internal memory. 2 is a temperature sensor as an ambient temperature detection means consisting of a thermistor, etc., and a temperature detection signal 3 outputted from this temperature sensor
is converted into a 2-bit temperature signal 5 by an A/D (analog/digital) converter 4 and sent to the system controller l.

Further, 8 is an image processing unit which performs predetermined image processing on the image input signal 6 and converts it into density data 8. After storing this density data 8 in the internal memory, the system controller 1 also outputs the data. The signals are sequentially output from this internal memory in response to the command signal 7.

Reference numeral 11 denotes a data conversion table section serving as a discharge amount data output means, which inputs density data 9 from the image processing section 8 and temperature data lO from the system controller 1 and converts them into 6-bit voltage value data 12. do. Reference numeral 14 denotes a D/A converter that latches this voltage value data 12 in synchronization with a latch pulse 13 from the system controller 1 and performs D/A (digital/analog) conversion, and outputs converted analog data 15.

Reference numeral 17 denotes a motor driver that drives a head scanning motor 18 that reciprocates a recording head (described later) in the scanning direction via a carriage (not shown), and a sequence controller l.
It is controlled by a control signal 16 from. An encoder section 18 detects the position of the recording head and outputs a position signal 20, which will be described later, and is composed of a known optical sensor, a slit, and the like.

A head driver 22 serves as a driving means for driving the recording head 23, and receives the analog voltage data 15 from the D/A converter 14 and the position signal 20 from the encoder 19.
As will be described later, the sequence controller 1 is equipped with a configuration for defining the minimum time interval, that is, the maximum frequency, of the ejection command pulses 21 in accordance with the temperature signal 5, as will be described later.

Furthermore, 24 is a paper feed pulse motor 2 for feeding the recording paper.
This is a pulse motor driver that drives the controller 5, and is controlled by a control signal from the sequence controller l.

(not shown).

FIG. 4 shows an example of the configuration of the table section 11 shown in FIG. As shown in this figure, this table section 11 includes, for example, one ROM (
By inputting temperature data (temperature signal) 10 from the person 1 and inputting density data (density signal) 9 from the image processing section 8 to the lower 6 bits of the input port, , determines a search address (reference address), and outputs 6-bit voltage value data (Do-D,) 12 from its output port.

FIG. 5 shows an example of the contents of the table section 11 mentioned above. As shown in the figure, the contents are set in advance so that as the temperature data (Ab + A7) changes, different voltage value data (Do to Os) are output for the same concentration data (Ao''As). ing.

FIG. 6 shows a time chart regarding the regulation of the driving frequency of the recording head 23. Here, the timer 31 is an internal timer of the sequence controller 1, and the motor voltage 32 is the drive voltage of the head scanning motor 18.

Next, the operation of the device with the above configuration is shown in FIG. 7(A).
This will be explained with reference to the flowchart of CB).

When the printing process is started (step Sl), the output signal 3 of the temperature sensor 2 is first converted into a 2-bit temperature signal 5 by the A/D converter 4, and then the output signal 3 of the temperature sensor 2 is converted into a 2-bit temperature signal 5.
(step S2).Next, in accordance with the 2-bit temperature signal 5, a time constant Tref for determining the drive frequency 1/Tref of the recording head 23 is prepared in advance in the sequence controller 1. A certain constant Tr
For example, Trefl is selected from ef...Tref4 (step S3). Furthermore, a 2-bit temperature signal 5 is sent from the sequence controller 1 to the A/T converter 4.
The temperature data 10 corresponding to the temperature data 10 is output to the upper two bits (A7, A6) of the input port of the table section 11, and this temperature data is latched throughout the recording of one screen (one page) (step S4). This latch is used to eliminate instability near the temperature switching point, and also because the temperature of ejected ink changes relatively rapidly even if the ambient temperature changes rapidly, so the voltage supplied to the recording head 23 is This is because there is no need to change.

Next, when the image input signal 6 is input to the image processing section 8,
This input signal 6 is stored as an image in the image processing section 8 (step S5). When the preparation for printing is completed, the sequence controller 1 outputs the data output command signal 7 to the image processing section 8, and the density data 9 for one pixel (first pixel) is stored in the table from the internal memory of the image processing section 8. It is output to section 11 (Stella 7' SS). Next, the sequence controller 1 sets the count value N in the internal counter (step S7), and the motor driver 1
Activate 7. As a result, the motor 18 is activated and scanning of the recording head 23 is started (step S8).

At the same time, the timer (Fig. 6, 31) in the sequence controller 1 is started (step S9-1), and the set value of the timer at this time is the constant TrefI selected according to the temperature signal 5 in the above-mentioned step S3. .

Next, the rise of the output signal 20 of the encoder section 1θ is detected (steps 59-2, 5I3-3), and the rise of the encoder output signal 20 is detected after the timer ends (step 5I
3-4), it indicates that the moving speed of the recording head 23 is slow, so the sequence controller 1
accelerates the head scanning motor 18 in step S8-5.
), and if the rise of the encoder output signal 20 described above indicates that the timer is operating, it indicates that the moving speed of the recording head 23 is fast, so the sequence controller l decelerates the head scanning motor 18 (steps 5a-e). ).

At the same time, the value of the timer is reset and the above-mentioned count value N is subtracted by 1 (step 510), and if the value of N is not zero (step 5ll), the process returns to the timer start process of step 58-1 again, and the above-mentioned count value N is subtracted by 1 (step 510). Steps 58-1 to 58 of
Repeat the process up to -8. By sequentially repeating this operation, the moving speed of the recording head 23 becomes constant, and the recording head 23 adjusts the output pitch of the encoder section 1B over time Tr.
Move with efl. Therefore, by matching the output pitch of the encoder 19 and the output pitch of the image, it is possible to keep the driving frequency of the recording head 23 constant and change the temperature driving frequency.

Next, the recording head 23, which has reached a constant speed in this way,
Since the value of the count value N of the encoder output signal 20 is set in advance so that the above-mentioned count value N becomes zero when the output signal reaches the initial discharge position, step Sl
When N=0 is reached at 1, the process moves to the next step S12 and discharge is started. At this time, the 6-bit density data 9 corresponding to the first pixel has already been sent from the image processing section 8 through the processing in step S6 to the input ports A5 to A of the table section 11.
0, and the temperature data IO is also sent to the input capo A7 + A6 of the table section 11 through the process in step S4. As described above, the table section 11 outputs the 6-bit voltage value data 12 extracted from the input ports D5 to D by using the data 9 and 10 inputted to the input ports A7 to Ao as addresses, and outputs this data 12 from its output ports D5 to D.
is converted into an analog voltage value 15 by the D/A converter 14 and input to the head driver 22. At this time, when the encoder output 20 is input to the sequence controller 0-l, the ejection command pulse 21 is output from the sequence controller l to the head driver 22 (step 512), and in synchronization with the ejection command pulse 21, the analog voltage value 15 is output. The recording head 23 is driven and a predetermined amount of ink is ejected.

Next, the data output command signal 7 is sent again from the controller 1 to the image processing section 8, and the density data corresponding to the next pixel is sent from the image processing section 8 to the table section 11 (step! 313). Subsequently, steps 58-1 to 58 described above
-6 is performed (step 514), and the processing operations of steps S12 to S14 described above are repeated until one line is printed (step 515). Thereafter, an image is recorded on the recording paper by repeating the above-described operation for one screen.

In this example, the case where there is one recording head has been described, but the present invention is not limited to this, and of course can be applied to a plurality of recording heads for color recording or a line head. In this case, it is also possible to change the address of the table section (ROM) 11 so as to correspond to the temperature data of each recording head. Furthermore, it is also possible to obtain more detailed temperature compensation by further increasing the number of bits of the temperature data IO. Further, the method of controlling the moving speed of the recording head is not limited to the one in this example, and it is of course possible to use other known methods.

[Effects of the Invention] As explained above, according to the present invention, since the head drive voltage value for the density data is selected and output according to the temperature data, the recording head can be operated under any temperature conditions that occur during use. It is possible to provide an inkjet recording apparatus in which the driving voltage is optimized, and thus it is possible to always perform high-quality recording, and it is also possible to completely absorb variations in characteristics due to the temperature of the recording head.

Furthermore, according to the present invention, compared to the conventional technology that uses a heater or the like for temperature compensation, it is much more energy efficient and inexpensive, and also has great benefits such as downsizing, simplifying equipment, and improving reliability. It will be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the basic configuration of an embodiment of the present invention. FIG. 2 is a characteristic diagram showing the relationship between head applied voltage and optical density with respect to temperature. FIG. 3 is a diagram showing the configuration of an embodiment of the apparatus. Figure 4 is a circuit diagram showing an example of the configuration of the table section in Figure 3, Figure 5 is an explanatory diagram showing the contents of the table in Figure 4, Figure 6 is the operation of the device in Figure 3. Timing chart of signals showing example FIGS. 7(A) and 7(B) are flowcharts showing an example of control operation by the sequence controller of FIG. 3. DESCRIPTION OF SYMBOLS 1... Sequence control roller, 2... Temperature sensor, 4... A/D conversion section, 8... Image processing section, 11... Table section, 14... D/A conversion section, 17... Motor driver, 18... Head scanning motor, 18... Encoder section, 22... Head driver, 23... Recording head, 24... Pulse motor driver, 25... Pulse motor. JP-A-6L-237Ei52 (8) (A) (B) Sequence controller I: '#+1' Self f)
-D-T-Y-T Fig. 7

Claims (1)

[Scope of Claims] a) an inkjet recording device that performs recording by ejecting ink droplets onto a recording medium; b) a temperature detection device that detects ambient temperature; and c) a temperature detected by the temperature detection device. ejection amount data output means for inputting data and recording density data and outputting corresponding optimum ejection amount data; d) driving the inkjet recording means with the optimum ejection amount data obtained from the ejection amount data output means; An inkjet recording device comprising a driving means.