JPH04151252A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To provide uniform precision for recording position throughout a wide temperature range by a method wherein a first temperature detecting means to detect temperature in the vicinity of a recording head and a second temperature detecting means to detect temperature in the vicinity of a transmission means are provided and the timing of a recording signal is changed according to a detecting result therefrom. CONSTITUTION:A first temperature detecting means 3 is a thermistor thermally densely arranged in an ink flow passage to detect the temperature of ink in an ink jet recording head. A second temperature detecting means 5 is a thermistor located to detect temperature in the vicinity of a transmission means comprising a drive pulley 17 and a timing belt 16. Outputs from the first and second temperature detecting means 3 and 5 are recognized by an CPU 1 through an A-D converter. The CPU 1 reads a correction amount, preset according to the detecting result, from an ROM 2 and outputs the correction amount as a delay amount to a delay circuit 11. This constitution changes the timing of a recording signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inkjet recording device that performs recording by ejecting ink droplets, and more specifically, performs bidirectional recording by reciprocating a carriage equipped with an inkjet recording head. The present invention relates to an inkjet recording device with improved recording position accuracy.

[Conventional technology]

FIG. 3 shows a general structure of an inkjet recording apparatus that performs bidirectional recording by reciprocating a carriage equipped with an inkjet recording head with respect to a recording medium. Here, 14 is an inkjet recording head, and 15 is a carriage. 7 is a motor for driving the carriage, 17 is a drive pulley, and 16 is a timing belt. 18 is a platen, 19 is a recording medium, and 8 is an encoder directly connected to a carriage drive motor. The rotational force of the motor 7 is transmitted to the carriage 15 via a drive pulley 17 and a timing belt 16.
The carriage 1 is rotated according to the forward and reverse rotation of the motor 7.
5 performs reciprocating motion with respect to the recording medium 9.

On the other hand, a recording signal generated in synchronization with the rotation angle of the motor 7 is applied to the inkjet recording head to perform a series of recordings at a predetermined position. Here, the recording signal is generated from the output signal of the encoder 8. Here, assuming that the flight speed of the ink droplets ejected by the inkjet recording head is Vl and the moving speed of the carriage is v2, the ink droplets on the recording medium when the carriage moves from left to right (outward path) The reached position is shifted to the right by an amount S from the ink droplet ejection position, as shown in FIG. 4(a). On the other hand, when moving from right to left (return trip), it shifts to the left by S as shown in FIG. 4(b). Therefore, when performing bidirectional recording, if a recording signal synchronized with the rotation angle of the carriage drive motor 7 is applied to the inkjet recording head, the recording position will shift by 25 degrees depending on the direction of carriage movement. Another reason for the deviation is the so-called backlash of the transmission means constituted by the drive pulley 17 and timing belt 16 shown in FIG. This transmission means transmits force by meshing tooth profiles, so the motor 7
A deviation corresponding to backlash occurs in the rotation angle and the position of the carriage 15 during forward rotation and reverse rotation.

Conventionally, a method of absorbing these deviations and correcting the arrival position of ink droplets in bidirectional printing is to advance the timing of the printing signal given to the inkjet printing head on the return trip by an amount corresponding to the deviation of the printing position. There is. In other words, as shown in FIG.
The position where the recording signal was generated is advanced by one position to position n+1, and then delayed by an appropriate time (tl) to correct the deviation of the recording position.

[Problem to be solved by the invention]

However, in general, the operating temperature of inkjet recording devices is 0°
The viscosity of the ink varies widely with temperature changes, affecting the flight speed of ejected ink droplets. Therefore, the amount of deviation in the recording position also changes depending on the operating temperature.

Furthermore, since the drive boom and timing belt that constitute the transmission means also expand and contract depending on the temperature, the amount of backlash also changes depending on the temperature. Further, the temperature distribution inside the inkjet recording apparatus with respect to the operating environment temperature is uneven, such that it is high near the motor or the like that generates heat, and low near the opening of the apparatus.

For this reason, the amount of deviation in the arrival position of the ink droplets varies widely depending on the operating environment temperature and usage conditions (driving state of the heating element) of the inkjet recording device, which has the disadvantage of deteriorating positional accuracy during bidirectional recording. .

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide an inkjet recording apparatus that has uniform recording position accuracy over a wide temperature range.

[Means to solve the problem]

The inkjet recording apparatus of the present invention includes an inkjet recording head that ejects ink whose viscosity changes depending on temperature, a carriage that carries the inkjet recording head and moves back and forth with respect to a recording medium, a motor that drives the carriage, and a motor that drives the carriage. In an inkjet recording apparatus having a transmission means for transmitting rotational force to a carriage and a recording signal output means for supplying a recording signal to an inkjet recording head, a first temperature detection means for detecting a temperature in the vicinity of the inkjet recording head; a second temperature detection means for detecting the temperature in the vicinity of the means; and a timing correction for changing the timing of a recording signal given to the inkjet recording head according to the detection results of the first temperature detection means and the second temperature detection means. It is characterized by providing means.

[Effect]

According to the present invention, the temperature states of two factors, the inkjet recording head and the transmission means, which determine the recording position accuracy of the inkjet recording apparatus, can be independently detected by the first and second temperature detection means. And these first,
Since the timing of the recording signal is changed by the timing correction means according to the detection result of the second temperature detection means, the timing is optimal for recording at any operating environment temperature or usage condition (that is, the temperature distribution inside the inkjet recording apparatus). This makes it possible to provide signals and provides an inkjet recording device with excellent recording position accuracy during bidirectional recording.

〔Example〕

The embodiments shown in the drawings will be described below.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, 3 is a first temperature detection means, 5 is a second temperature detection means, and 4 and 6 are AD converters. 7 is a carriage drive motor, 8 is a rotary encoder, and 9 is a position counter. l is CPU, 2 is ROM,
10 is a recording signal generator, 11 is a delay circuit, 12 is a head driver, and 13 is a data bus. The timing correction means in this embodiment is composed of a CPUI, a ROM 2, and a delay circuit 11.

FIG. 2 is a structural diagram showing the same embodiment. In the same figure, 1
4 is an inkjet recording head, and 15 is a carriage. 7 is a carriage drive motor 17 is a drive pulley; 1
6 is a timing belt. 18 is a platen, 19 is a recording medium, and 20 is a plate for mounting a motor. 3 is a first temperature detection means installed in the inkjet recording head;
Reference numeral 5 designates a second temperature detection means mounted on the motor plate, and reference numeral 8 designates a rotary encoder directly connected to the rotating shaft of the motor 7. The operation will be explained using FIGS. 1 and 2. First, the operation of each part will be explained. The first temperature detection means 3 is a thermistor that is thermally closely installed in the ink flow path to detect the temperature of the ink within the inkjet recording head.

FIG. 6 shows its characteristics, and FIG. 7 shows its circuit. The flight speed of ink droplets ejected by an inkjet recording head changes depending on the viscosity of the ink, and the viscosity of the ink changes depending on the environmental temperature. Therefore, the flight speed of ink droplets changes depending on the operating temperature of the inkjet recording apparatus. Changes in the flight speed of the ink droplets cause shifts in the positions at which the ink droplets arrive. In this example, the platen gap is 1.21, and the carriage movement speed is 0.28 m/s.
, the flight speed of the ink droplet is 5 m/s at 0 °C,
Since it is 8 m/s at 20°C and 11 m/s at 40°C, the amount of deviation with respect to temperature is as shown in FIG.

By detecting the temperature of the ink, the first temperature detection means 9 changes the timing of the recording signal via the delay circuit 11 so as to correct the shift in the arrival position of the ink droplet as shown in FIG. It is something. For example, if the temperature changes in a direction that increases the deviation of the reached position, the timing of the recording signal given to the head driver is advanced to prevent the deviation of the reached position.

The second temperature detection means 5 is a thermistor installed to detect the temperature near the transmission means constituted by the drive pulley 17 and the timing belt 16. In this embodiment, the same thermistor as the first temperature detection means 3 is used. Backlash between the drive pulley 17 and the timing belt 16 is caused by expansion and contraction of the component parts due to temperature.
Change as shown in the figure. This change in backlash results in a deviation between the rotation angle of the motor 7 and the relative position of the carriage 15, and in other words, it causes a deviation in the arrival position of the ink droplets depending on the temperature during the reciprocating movement of the carriage 15. It is.

Therefore, the delay circuit 1 detects the temperature near the transmission means and corrects the deviation in the arrival position of the ink droplet on the return path.
By changing the timing of the recording signal via 1, it is possible to secure an accurate recording position.

The outputs of the first temperature detection means 3 and the second temperature detection means 5 are recognized by the CPU via the A-D converter, and the CPU
1 reads a preset correction amount from the ROM 2 according to the detection result (detected value) and supplies it to the delay circuit 11 as a delay amount. This changes the timing of the recording signal.

The delay circuit 11 can be composed of a presettable counter as shown in FIG. 10, for example. In this embodiment, the circuit is capable of delaying up to 255 μsec in lμsec units.

Now, let me explain the overall operation. First, a case where the detected temperature is room temperature (20° C.) will be explained. The response frequency of the inkjet recording head is 2kHz (recording cycle 500μ
5ec). During recording on the outward path, after the carriage 15 moves from the standby position to the recording start position (managed by the position counter 9), the recording signal generator 10 generates a recording signal. Here, the recording signal is generated from the output signal of the rotary encoder 8. This recording signal is passed through the delay circuit 11 to the head driver 1.
given to 2. Here, it is assumed that the amount of delay on the outward path is 100 μsec as shown in FIG. 11 (the ink droplet arrival position R in this case is taken as the reference position). At the same time, data to be recorded is given to the head driver 12 via the data bus 13, and the head driver 12 drives the inkjet recording head in accordance with the recording data to print on the recording medium 19.
Recording will be done. Thereafter, similar recording is performed over one line according to the recording data. On the other hand, on the return trip, it is necessary to advance the timing by a steady correction amount at room temperature (the deviation correction amount accompanying the moving direction of the carriage 15 and the deviation correction amount due to backlash of the transmission means). For example, if this constant correction amount is 350 μSeC, the timing of the recording signal can be obtained by advancing the recording position by one position (500-350) and applying a delay of czsec, as shown in Figure 11. There is. At room temperature, the positional accuracy in bidirectional recording can be maintained only by changing the timing as described above (this is equivalent to the process explained in FIG. 5 of the conventional example).

On the other hand, if the operating temperature changes, see Figures 8 and 9 above.
It is necessary to increase or decrease the amount of delay by an amount corresponding to the amount of deviation shown in the figure. The amount of delay corresponding to the amount of deviation due to the change in ink temperature in FIG. 8 is shown in FIG.
This is shown in Figure 3(b). All values are increases and decreases relative to the reference value at room temperature. These values are obtained by converting the amount of deviation (distance m) into time according to the moving speed of the carriage 15. Note that corrections due to the flight speed of the ink droplets must be performed on the outward and return passes, but corrections due to backlash of the transmission means are carried out only on the return pass.

Assume that the temperature detected by the first temperature detection means is 0°C, and the temperature detected by the second temperature detection means is 10°C.

As shown in FIG. 12, on the outward journey, the delay amount is −89 μsec from Table 1, so the delay amount is the steady delay amount 100 μsec.
The value (10
0-89) μsec. On the other hand, on the return trip, the delay amount is -89 μsec from Table 1, and the delay amount is +25 μsec from Table 2.
sec, the corrected delay amount is the steady delay amount (500-3
50) Value added to μsec (500-350-89+
25) μsec. By adding this correction delay amount, it is possible to prevent temperature-dependent deviations.

In this way, since the two temperature detection means can each independently detect the temperature, accurate position correction can be made no matter what the temperature distribution inside the apparatus is.

〔Effect of the invention〕

According to the present invention, it is possible to provide an inkjet recording apparatus in which recording position correction is reliably performed with a simple configuration and the recording position is highly accurate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a structural diagram of an inkjet recording apparatus showing an embodiment of the present invention. FIG. 3 is a structural diagram showing a conventional example of an inkjet recording device. FIGS. 4(a) and 4(b) are diagrams for explaining the arrival positions of ink droplets. FIG. 5 is a diagram illustrating correction of conventional bidirectional recording. FIG. 6 is a characteristic diagram of a thermistor used as a temperature detection means in an embodiment of the present invention. Figure 7 is its circuit diagram. FIG. 8 is a diagram showing the amount of deviation of the printing position depending on the temperature of the inkjet printing head according to an embodiment of the present invention. FIG. 9 is a diagram showing the amount of change in backlash depending on the temperature of the transmission means according to an embodiment of the present invention. FIG. 10 is a delay circuit diagram of an embodiment of the present invention. FIG. 11 is a diagram illustrating correction at room temperature according to an embodiment of the present invention. FIG. 12 is a diagram illustrating correction when the operating temperature changes according to an embodiment of the present invention. Fig. 13(a) shows the relationship between the ink temperature and the amount of delay corresponding to the amount of deviation due to the change in the ink temperature, and Fig. 13(b) shows the relationship between the temperature of the transmission means and the amount of delay corresponding to the amount of deviation due to the change. Diagram showing relationships. 1...CPU 2...ROM 3...First temperature detection means 4...A-D converter 5...Second temperature detection means 6...A-D converter 7... Carriage drive motor 8...Rotary encoder 9...Position counter 10...Recording signal generator 11...Delay circuit 2...Head driver 3...Data bus 4...Infusiera 5...・Cal notch 6...Timing belt 7...Drive pulley 8...Platen 9...Recording medium O...Motor mounting is on board Suzuki Kizobu (other names) MU571fii spear 21 1 15 N spear 2.゛(G) (b) r'lz4 Illustrated language included 1 (Itate 1 [ ◆ O ζ Soshi t et n+1 Figure 6 Figure 7 Figure 1' 8 Figure 9 Figure 10 Ho' So 1 line n-+7 n+2 Figure 11 Position 1 line n+7 n+2 Figure 12

Claims (1)

[Claims] an inkjet recording head that ejects ink whose viscosity changes depending on temperature; a carriage that carries the inkjet recording head and reciprocates with respect to the recording medium; a motor that drives the carriage; and a motor that drives the carriage. In an inkjet recording apparatus, the inkjet recording apparatus includes a transmission means for transmitting a signal to the inkjet recording head, and a recording signal output means for supplying a recording signal to the inkjet recording head, the first temperature detection means for detecting a temperature near the inkjet recording head, and the transmission means. a second temperature detection means for detecting a temperature in the vicinity of the temperature detection means; and a timing correction for changing the timing of a recording signal given to the inkjet recording head according to the detection results of the first temperature detection means and the second temperature detection means. An inkjet recording device characterized by being provided with means.