JPS5845066A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To easily obtain a signal of which drive characteristic is excellent by such an arrangement wherein an image signal is normalized by a signal from an encoder for detecting the amount of relative movement of a recording medium and a head drive signal is taken off from a point where the phase of a sine wave carrier is 180 deg.. CONSTITUTION:From a rotary encoder 21 directly connected to a drum 20 which rotates with a recording medium being equipped, a basic clock 22 which is the same as the frequency of a head drive signal is obtained, and an image signal 23 is latched by a latch circuit 24 at the first edge of the basic clock 22 and it is changed-over by the next edge and a normalized image signal 25 is obtained. On the other hand, a pulse 30 is made by deviating the phase of the basic clock 22 by 2 monostable multivibrators 27, 29 and a sine wave carrier 32 is obtained by inputting the pulse 30 into a low pass filter 31. Then an output 33 which is obtained as the product of the normalized image signal 25 and the sine wave carrier 32 becomes an optimum signal for driving a head 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus, and an object of the present invention is to generate a drive signal for driving an inkjet head in an optimal state with a simple circuit configuration.

Figure 1 is described in Japanese Patent Publication No. 53-45698 27.7
・This is a dispute about conventional inkjet heads. In this inkjet head, a signal generator 9
When the head drive signal 10 is applied to a vibrating body such as the piezo element 2 and the diaphragm 3, the vibrating body 3 undergoes bending vibration,
The volume of the pressure chamber 4 changes, and accordingly, ink is sucked through the ink channel 6 and the first nozzle 6, and then the first nozzle 6 and the first nozzle 6.

The ink droplets 8 are ejected through all of the two nozzles 7.

This head can be driven by pulse voltages of various waveforms, but when driven by sinusoidal pulses starting from a phase of 18o0 as shown in Figure 2, the best results are obtained, such as fewer unnecessary satellite drops and a good ejection start-up. Demonstrate characteristics.

Conventionally, a sine wave gate oscillator has been used to generate drive signals with such waveforms. FIG. 3 is a block diagram showing the configuration of the gate oscillator, and FIG. 4 is a waveform diagram. The image signal 11 is input to the gate sine wave oscillator 12, and the output sine wave pulse 13 is amplified by the amplifier 14 and sent to the head 15. was being applied.

In this method, a honeycomb oscillator or the like is used as the gate sine wave oscillator 12, but it is composed of capacitors, coils, etc., has a large number of parts, is troublesome to adjust, deteriorates over time, and It is difficult to create a waveform with low harmonic distortion from Furthermore, when a plurality of heads are used for color recording, etc., there is a drawback that as many oscillators as the number of heads are required.

The present invention aims to provide an inkjet recording apparatus that uses an encoder, has a simple circuit configuration, and is free from the above-mentioned drawbacks. An embodiment of the present invention will be described below.

The configuration of one embodiment of the present invention is shown in FIG. 6, and the signal waveforms of each part are shown in FIG. In the figure, a clock pulse 22 having a frequency equal to the frequency of the head drive signal is output from a rotary encoder 21 directly connected to a rotating drum 20 loaded with a recording medium.

This clock pulse 22 will hereinafter be referred to as a basic clock. The image signal 23 is latched by the latch circuit 24 at the edge of the basic clock 22, and a normalized image signal 26 that switches at the edge of the basic clock 22 is created and input to the modulation circuit 26.

On the other hand, in order to generate three carriers optimal for driving the head 16 from the basic clock 22, the clock 22 is
It is input to a phase shifter consisting of two monostable multivibrators 27°29. That is, the edge of the basic clock 22 triggers the monostable circuit 27 to create a pulse 28, and the edge of this pulse 28 triggers the monostable circuit 29 'k) IJ
to create pulse 3o. The pulse 30 is input to a low pass filter 31 to obtain a sine wave carrier 32. Since the signal passing through the low-pass filter 31 has a phase shift, the width of the pulse 28 is adjusted to compensate for the shift. pulse 3o
The width of is adjusted so that the duty ratio is 50% to obtain a sine wave. The modulator 26 is composed of an analog switch, and uses the normalized image signal 26 to transmit the carrier 3.
The switch is changed at the point of phase 2 of 180°, and the head drive signal 33 is output. The signal 33 is amplified by the amplifier 14 to drive the head 16.

1. The normalized image signal 26 refers to an image signal whose carrier phase is changed at a point of 5 pages 18o0.

Even if the frequency of the output pulse of the rotary encoder 21 is not equal to the frequency of the head driving carrier, the image frequency is generally a ratio of a simple number, so by multiplying this output pulse, etc., the carrier frequency can be adjusted. It is possible to create pulses of equal frequency. If this pulse is used as pulse 22 in FIG. 6, subsequent processing can be performed in exactly the same way.

In the above embodiment, the phase of the carrier signal is adjusted, but the phase can also be adjusted on the image signal side, and examples thereof are shown in FIGS. 7 and 8. In the figure, the same parts as in FIG. 6 and FIG. The monostable circuit 27 is triggered by the output pulse 22 of the rotary encoder 21 to create a pulse 28, and the latch circuit 24 latches the image signal 23 at the edge of the pulse 28 to obtain a normalized image signal 26. On the other hand, the monostable circuit 29 is triggered by the pulse 22 to create a 6-pane pulse 30 with a duty ratio of 60%, which is passed through a low-pass filter 31 to create a sine wave carrier 32. The carrier 26 is modulated by the normalized image signal 26 to obtain a head drive signal 33, which is amplified to drive the head 16. The width of the pulse 28 passes through a low pass filter 31 and the carrier 32 is out of phase.
The adjustment is made so that the image signal can be latched at a point with a phase of 180°.

Next, an embodiment including a plurality of heads is shown in FIG. 9, and its waveform is shown in FIG. 10. Figure 5 in the figure.

Components that are the same as those in FIG. 6 are designated by the same reference numerals and their explanation will be omitted. In FIG. 9, two heads 151 and 162 are arranged on the same circumference of the drum 2o, and perform two-color recording by ejecting black and red ink, for example.

When the rotational direction of the drum is in the direction of the arrow, the signal 43 applied to the head 162 needs to be delayed with respect to the signal 34 from the head 161. The latch circuit 24 latches the image signal 231 at the edge of the output pulse 22 of the rotary encoder 21 to create a normalized image signal 25, and drives the delay circuit 40 at the same edge to delay the image signal 232 and generate the signal 41. It is normalized so that the change point is at the point where the phase is 180°.

Two normalized image signals 25.41i are each modulated by an analog switch 261. -262 and modulates the carrier 32 to obtain a head drive signal 33.42. These pass through amplifiers 141 and 142 to the head 151,
Added to 152.

Even when three or more heads are provided, the same implementation is possible, so the explanation will be omitted.

Next, an embodiment implemented in a plane scanning printer as shown in FIG. 11 will be briefly described. Figures 9 and 10
Components that are the same as those in the drawings are given the same reference numerals and their explanations will be omitted. In FIG. 11, the recording paper 60 is fed upward and the head 1
Carriage 61 carrying 61,152 is left and right (arrow direction)
is scanned. The carriage 61 has a linear encoder 52
The encoder 52 is manufactured so that the detection unit 63 is attached and the number of pulses as the carriage 61 moves is the density of the dots to be recorded or an integer ratio thereof, and the output pulse 22 is
It is possible to carry out all the processing similar to the output pulse 22 of the rotary encoder 21 in FIG. 6 by utilizing the sine wave pulse starting from the phase 18o0.

As explained above, according to the present invention, the recording head can always be driven with the optimum waveform using a simple circuit configuration, and even if the number of heads increases, all the heads can be driven without providing a separate oscillator. It can be driven optimally.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a recording head used in the present invention, FIG. 2 is a diagram showing signal waveforms for optimally driving this head, and FIG. 3 is a conventional circuit configuration of a head drive circuit. , FIG. 4 is a signal waveform diagram thereof, FIG. 6 is a block diagram showing the configuration of a drive circuit of an inkjet recording apparatus in an embodiment of the present invention, FIG. 6 is a signal waveform diagram of each part, and FIG. 9 is a block diagram showing the structure of a drive circuit according to another embodiment of the present invention, FIG. 8 is a signal waveform diagram of each part, and FIG. 9 is a block diagram showing the structure of a drive circuit according to another embodiment of the present invention. 10 is a signal waveform diagram of each part, and FIG. 11 is a block diagram showing the configuration of a drive circuit according to an embodiment of the present invention in the case of a plane scanning type. 1...Head body, 2.Old...piezo element, 3
...Vibration plate, 4...Pressure chamber, 5...
...first nozzle, 6...°° ink flow path, 7...
...Second nozzle, 8...Ink droplet, 9...
... Drive signal source, 10... mark, drive signal, 11...
...image signal, 12...mark gate sine wave oscillator,
1300301. Head drive signal, '14,141.1
42°°°°°°Amplifier, 15,151,152...
...head, 2o river...drum, 21...
Rotary encoder, 22...Encoder output pulse, 23.231. 232... Image signal, 24... Latch circuit, 2641... Normalized image signal, 2
6,261゜262...Modulator, 27.29.
River: monostable multivibrator, 3o: phase shift output, 31: low-pass filter, 32: head drive carrier, 3342: head drive signal, 4o・Mountain: Delay circuit, 60: Recording paper,
61... Carriage, 62... Linear encoder 4-163 Mountain... Detection section. Figure 2 Figure 3 Figure 4 Figure 5 Figure 20 Figure 6 WA7 Figure 8 Figure 9 Figure 0 Figure 10 Figure 2

Claims (1)

[Claims] It is equipped with an encoder that detects the amount of relative movement between the recording medium and the recording head, a phase shift circuit, a low-pass filter, and a modulation circuit. At the same time, the encoder output of both signals or a signal created based on it is passed through a low-pass filter to create a carrier signal for driving the head, and the image signal is used to convert the carrier signal into a carrier signal. An inkjet recording device characterized by modulation.