JPH0234788B2 - EKITAIFUNSHAKIROKUHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording method, and particularly to a liquid jet recording method in which recording is performed by flying a recording liquid in the form of droplets.

Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among these, the so-called inkjet recording method (liquid jet recording method), which is capable of high-speed recording and can record on so-called plain paper as a recording material without the need for special fixing treatment, is an extremely powerful recording method. Various methods have been devised so far, some have been improved and commercialized, and efforts are still being made to put them into practical use.

In this inkjet recording method, recording is performed by flying droplets of a recording liquid called ink and attaching them to a recording member. There are several methods for controlling the flying direction of droplets, but they can be broadly classified into two methods.

For example, one of these methods is
USP3060429, USP3596275, USP3298030,
The other method is described in publications such as USP3416153.
It is described in detail in publications such as USP3683212, USP3747120, and USP3946398.

To summarize here, the former method uses a continuous vibration generation method to generate a droplet flow with a controlled amount of charge, and this generated droplet flow with a controlled amount of charge is controlled by a uniform electric field. Recording is performed on the recording material by flying between the deflection electrodes attached, or
Alternatively, an electric field is applied between a nozzle and a ring-shaped charging electrode, and droplets are generated by a continuous vibration generation method, atomized, and recorded.

The latter is called drop-on-demand.
on demand) type liquid jet recording method,
Since recording is performed by making all of the generated droplets adhere to the surface of the recording member, it has recently been attracting attention because it does not require collection of liquid unlike other methods.

In this method, an electrical recording signal is applied to a piezo vibrating element attached to a recording head that has an ejection orifice that ejects liquid as droplets for recording, and this electrical recording signal is transmitted to the mechanical vibration of the piezo vibrating element. Memorization is performed by replacing the vibration with mechanical vibrations by causing droplets to be ejected from the orifice and adhered to the recording member.

However, while each of the conventional systems has its own advantages, there are also points that are essential or that could be solved.

That is, in the former method, the direct energy for generating a droplet or droplet stream is electrical energy, and the deflection control of the droplet is also controlled by an electric field. It is unsuitable for high-speed recording because it requires voltage, and it is difficult to create a multi-orifice recording head, especially at high density. There are problems such as high and difficult target control and satellite dots are likely to occur on the recording member.

The method of atomizing the ejected droplets is difficult to precisely and precisely control the atomization state, fogging occurs in the recorded image, and it is difficult to use a multi-orifice recording head, making it unsuitable for high-speed recording. There are various problems such as:

In the latter method, there are problems in processing the recording head, and it is extremely difficult to miniaturize the piezo vibrating element with the desired resonance number, so it is necessary to downsize the recording head and make it multi-orifice. Furthermore, since droplets are ejected and ejected using the mechanical energy of the mechanical vibration of the piezo vibrating element, it is not suitable for high-speed recording, and the generation of satellite dots and fogging of recorded images is relatively common.
It has the following disadvantages.

As described above, the conventional method has several problems in terms of structure, high-speed recording, recording head manufacturing, multi-orifice design, especially high-density multi-orifice design, generation of satellite dots, and fogging of recorded images. However, there are essential shortcomings and points that can be improved.
There was a restriction that it could only be applied to applications that took advantage of its advantages.

In response to this, the present applicant proposed a liquid jet recording method based on a completely new concept that can solve the above problems in Japanese Patent Application No. 118798/1982.

The present invention relates to improvements in the recording method disclosed in Japanese Patent Application No. 52-118798, particularly when recording is performed using a laser beam.

In the recording method using a laser beam disclosed in Japanese Patent Application No. 52-118798, in order to maximize its characteristics, a discharge orifice is installed at the end of the recording method to jet the liquid in a predetermined direction. a flow path having a heat acting portion at a position where the acting force generated therein is effectively transmitted in the direction of the discharge orifice;
A multi-orifice recording head is used which has a structure in which a plurality of channels are arranged in an array and these plurality of channels communicate with a common liquid chamber for supplying liquid to each channel. Since the structure of such a recording head is much simpler than that of conventional recording heads, the flow channels can be arranged at a density comparable to the resolution of the recorded image.

Therefore, it is essential to irradiate the laser beam accurately to the heat-active portions of the flow channels arranged in such a high density. For example, if the laser beam is not accurately irradiated on the heat-effecting part that could be irradiated, and the irradiation spot hits the heat-effecting part of the adjacent flow path,
Even if droplets are ejected from the ejection orifice of the flow path, or even if they are not ejected, it is inevitable that the irradiation efficiency will be significantly reduced. In addition, if we want to improve the precision of the laser beam scanning system in order to accurately irradiate each heat-acting part with the laser beam, extremely high precision is required, and it is difficult to manufacture the optical system, etc. that makes up the scanning system. Advanced technology is required and therefore causes a significant increase in the cost of the equipment.

Furthermore, in order to achieve irradiation accuracy on the scanning system side as described above, it is necessary to replace the recording head, or if the position of the recording head is worn out for some reason, or if the arranged flow path When the arrangement state of the apparatus changes, there arises the inconvenience that the scanning system must be adjusted again, which poses a problem in terms of maintainability of the apparatus.

In view of the above points, the above-mentioned patent application filed in 1972-
In order to maximize the characteristics of the recording method disclosed in No. 118798, it is necessary to be able to accurately irradiate each of the heat-acting parts with a laser beam, and to have a high degree of precision in the scanning system itself. First, a recording method that can be provided at low cost is desired.

The present invention has been made in view of the above points, and is characterized by having a discharge orifice at the end thereof for jetting liquid in a predetermined direction, and the acting force generated there By arranging in an array a plurality of channels having heat acting parts at positions where the heat is effectively transmitted in the direction of the orifice, and by irradiating the heat acting parts with a laser beam, the liquid in the heat acting parts is steeply heated. In the liquid jet recording method, the liquid ejected from the ejection orifice is caused to change in state, and the liquid ejected from the ejection orifice is caused to fly as a droplet by the acting force based on the state change, and the liquid is attached to the recording surface to perform recording. The liquid jet recording method detects the road position and irradiates a laser beam at the timing of the detection signal.

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

An overview of the recording principle according to the present invention will be explained with reference to FIG.

FIG. 1 is an explanatory diagram for explaining the recording principle according to the present invention.

A desired pressure is applied inside the nozzle 101 by a suitable pressurizing means such as a pump, and the pressure P is such that it is discharged by the discharge orifice 102 or is not discharged from the orifice 102 by itself. A liquid 103 for recording is being supplied. Now, orifice 1
Liquid 1 in the nozzle 101 at a distance l from 02
When 03a receives the action of thermal energy in the portion of width △l (thermal action part), the state of liquid 103a changes sharply, and the liquid 103b existing within width l of nozzle 101 changes depending on the amount of applied thermal energy.
A part or all of the liquid is ejected by the orifice 102 and flies in the form of droplets in the direction of the recording member 104, and adheres to a predetermined position on the recording member 104.

To explain this point more specifically, the heat acting part △
When thermal energy is applied to the liquid 103a in the heat acting part Δl, a sudden change in state including the generation of bubbles occurs instantaneously in the liquid 103a in the heat acting part Δl. Depending on the applied force, part or all of the liquid 103b existing within the width l is discharged from the orifice 102. As a result, the action of thermal energy is stopped or the liquid 10 is discharged from the liquid supply side toward the discharge orifice 102.
If the movement of 3 occurs, or if the amount of liquid discharged is instantly replenished according to the thermal effect △l, the liquid 10
The bubbles generated in 3a are instantly reduced in volume and either disappear or are reduced to an almost negligible volume.

The discharged amount of liquid is caused by the contraction of the volume of bubbles, by capillary action in the nozzle 101, by forced pressure, or by a combination of two or more of these. The action replenishes the inside of the nozzle 101.

The size of the formed droplet 105 depends on the amount of thermal energy, the width Δl of the portion 103a that is affected by the thermal energy of the liquid present in the nozzle 101, and the volume of the liquid 103a within Δl. If the nozzle 101 is cylindrical, the average inner diameter d at the width l, or if the nozzle 101 is not cylindrical, the average cross-sectional area at the width l, or the position of the orifice 102. It depends on the distance l to the receiving position, the pressure P applied to the liquid, the specific heat, thermal conductivity, coefficient of thermal expansion, heat of vaporization, etc. of the liquid. Therefore, by changing any one or more of these elements that can be controlled, the size of the droplet 105 can be easily controlled, and the droplet size can be adjusted to any desired diameter. It is possible to record on the recording member 104 with a spot diameter of . In particular, being able to arbitrarily change the distance l means that the position of application of thermal energy during recording can be changed as desired, and therefore the amount of generated thermal energy per unit time can be changed. At least the size of the droplets 105 formed can be arbitrarily controlled during recording, and a recorded image with gradation can be easily obtained.

In the present invention, the heat acting portion Δl of the nozzle 101
Thermal energy acting on the liquid 103a may be provided or generated continuously over time, or may be provided or generated discontinuously by turning on and off in pulses, but continuous recording is not possible. When this is done, in order to improve the droplet generation frequency, it is preferable to repeatedly supply or generate droplets discontinuously in a pulsed manner.

In the recording principle applied to the present invention, by applying thermal energy to the liquid in the heat acting portion Δl in a temporally discontinuous manner, it is possible to cause the applied thermal energy to carry recorded information. That is, by applying thermal energy to the liquid 103a in the heat action section Δl in accordance with the recording information signal, a state change is caused in the liquid 103a in the heat action region Δl in accordance with the signal. Therefore, any of the formed droplets 105 can carry recording information, and therefore all of them can be transferred to the recording member 104.
It is possible to record by attaching it to Clogged,
A so-called drop-on demand recording method can be implemented.

When applying thermal energy to the liquid 103a in a pulsed manner, the amplitude and width of the pulse at this time can be easily selected and changed as desired, so the size and unit of the droplet can be adjusted. The number N ₀ of droplets generated per time can be extremely reduced.

The liquid 103 in the heat acting part △l is discontinuously stored without causing recorded information to be carried by the applied thermal energy.
When making it act on a, it is made to act repeatedly at a certain constant frequency.

The frequency in this case is determined by taking into account the type of liquid used and its physical properties, the shape of the nozzle, the volume of liquid in the heat acting part Δl, the liquid supply rate into the nozzle, the orifice diameter, the recording speed, etc. It is determined as appropriate depending on the request, but usually 01.~1000KHz,
The frequency is preferably 1 to 1000 KHz, most preferably 2 to 500 KHz.

In this case, the pressure applied to the liquid 103 is caused by thermal energy being provided to the liquid 103a or by the pressure applied to the liquid 103a.
The orifice 102 is not generated in the
The liquid 103 may be set to such a level that the liquid 103 is ejected, or may be set to such a level that the liquid 103 is not ejected by itself. At any pressure, the liquid 103a undergoes a thermal action in the heat acting part Δl to cause a state change, and by repeating the state change and/or vibrations based on the repetition of the state change, the liquid 103a has a desired diameter and a droplet. It is possible to form a droplet stream at the generation frequency.

The droplets formed in such a state are controlled according to recording information by other means such as charge control, electric field control, or air flow control, and recording is executed.

Generating thermal energy based on laser beam irradiation and causing the liquid to undergo a sharp state change, for example, a state change including the generation of bubbles due to vaporization, is in the heat acting part △l. Either the liquid itself absorbs the laser beam and generates heat, or a heat converter that absorbs the laser beam and generates heat is provided in the heat action part △l, and the thermal energy generated by the heat exchanger is transferred to the heat action part △l. This is achieved by acting on a certain liquid. The heat converter may be provided in direct contact with the inner wall surface or outer wall surface of the heat acting portion Δl of the nozzle 1, or may be provided with a substance with good heat conduction efficiency interposed therebetween, but in either case, In this case as well, the structure and arrangement are such that the thermal energy generated from the heat converter can be effectively applied to the liquid 103a.

Alternatively, at least the wall of the heat acting portion Δl of the nozzle 101 may be made of a heat converter. The heat converter is selected depending on the wavelength of the laser beam to be irradiated, and is made of a material that has an absorption region in the wavelength region of the laser beam. If such a laser beam absorbing material has film properties and adhesive properties, it is sufficient to directly form a coating film on a predetermined portion of the outer wall of the heat acting portion Δl of the nozzle 101.
If the laser beam absorbing material alone does not have coating properties or adhesive properties or is weak, it can be mixed and dispersed in a suitable binder that has coating properties and adhesive properties and is heat resistant to form a coating film. good.

Many commonly known dyes and pigments can be used as the laser beam absorbing material. For example, when infrared rays are used as the electromagnetic wave, dyes and pigments can be used as infrared absorbing exothermic agents.

Next, one preferred embodiment of the liquid jet recording method of the present invention will be described in detail with reference to the drawings.

FIG. 2 is an explanatory diagram schematically shown to explain a preferred embodiment of the liquid jet recording method of the present invention.

In the figure, a first laser beam oscillated by a first laser oscillator 201 is guided to an entrance aperture of an acousto-optic modulator 202. In the modulator 202, the first laser beam is modulated in intensity according to the input of the recording information signal to the modulator 202. The modulated first laser beam is reflected by a reflecting mirror 203.
The beam expander 204
The beam is bent in the direction and enters the beam expander 204. The beam diameter of the modulated first laser beam is expanded by the beam expander 204 while it remains a parallel beam. Next, the first laser beam with the enlarged bead diameter is incident on the polygon 205. The polygon 205 is attached to the rotating shaft of a hysteresis synchronous motor 206 and rotates at a constant speed. polygon 205
The first laser beam swept horizontally by the f-theta lens 207 passes through the reflecting mirror 208 to the channel array 210 arranged in an array at the tip of the full-line high-density multi-orifice recording head 209. An image is formed at a predetermined position (thermal action part) of each flow path. Due to the imaging of the first laser beam on the channel array 210, the recording liquid in each channel is affected by thermal energy, and droplets of the recording liquid are ejected from the orifice of each channel and fly to the recording surface. Recording is performed on member 211. Recording liquid is supplied to each flow path of the recording head 209 from a liquid storage tank 214 via a supply pipe 212 and a common liquid chamber provided inside a common liquid chamber member 213. The recording member 211 is in the form of a sheet in the figure, and recording is performed from a cassette 215 containing a large number of recording members 211 in synchronization with a recording signal, although not shown in the figure. It is fed by sheet feeding means commonly used in the field and transported over the drum 216 by sheet transport means.

On the other hand, the second laser beam oscillated by the second laser oscillator 217 has its optical path directed toward the beam expander 219 by the reflecting mirror 218, and thereafter, similarly to the first laser beam, the polygon 205f-θ laser 207 The light passes through a reflecting mirror 208 and is irradiated onto each flow path of the recording head 209.
The second laser beam scans and irradiates the channel array with energy that is less than enough to eject the recording liquid.

FIG. 2b shows a schematic partial perspective view of the recording head 209 used in the apparatus of FIG. 2a, viewed from the ejection orifice side, and FIG. 2c shows a cross-sectional view.

At the tip of the recording head 209, 4800 nozzles 220 are provided in a line array over a total length of 300 mm with an orifice density of 16/mm. Nozzle row member 221 provided with 220 rows of nozzles
An irradiating section 222 is provided on the upper surface of the nozzle 220 so that a laser beam is focused and irradiated onto a predetermined position of each heat acting section of the nozzle 220 .

The 220 rows of nozzles form a liquid flow path 223 parallel to and isolated from each other in the nozzle row member 221, and a laser beam is irradiated from each orifice of each of the 220 rows of nozzles to a portion of the irradiation unit 222 corresponding to each nozzle 220. Each time a droplet is ejected and flies toward the surface of the recording member 211.

Each of the liquid flow paths 223 communicates with a common liquid chamber provided inside the common liquid chamber member 213,
The structure and dimensions are such that liquid can be smoothly supplied from the common liquid chamber into the nozzle 220 as needed. The nozzle row member 221 has a liquid flow path 223 in order to provide a predetermined number of nozzles 220 at a desired pitch.
a groove plate 224 in which grooves forming grooves corresponding to the number of nozzles to be formed are provided by an etching process;
A groove 225 provided with an irradiation surface 222 for irradiating a laser beam onto each heat acting part of the nozzle 220.
The groove plate 224 and the groove cover 225 are precisely joined using a suitable adhesive. The structure of nozzle 220 is shown as a cross-sectional structure in FIG. 2c.

The irradiation part 222 is placed above the heat action part 227 provided at a predetermined position from the orifice 226, with dimensions, structure, and material determined so that the heat action part 227 is efficiently and effectively irradiated with the laser beam. It is provided.

In the nozzle structure shown in FIG. 2c, a groove is provided in a part of the groove cover 225 by a method such as etching or mechanical cutting to reduce the wall thickness and provide good transparency to the laser beam. Select the material,
In addition, it is coated for anti-reflection, and
A heat converter 228 having a function of absorbing a laser beam and generating heat is provided on the bottom surface of the heat acting section 227 of the groove plate 224.

Now, the first laser beam 229 is applied to the irradiation section 222.
When the laser beam is irradiated to the heat converter 228 so as to be focused through the laser beam, the heat converter 228 absorbs the laser beam and generates heat, and the heat acts on the liquid in the heat acting section 227 . The liquid subjected to the thermal action undergoes a sudden state change, and droplets are ejected from the ejection orifice 226 due to the acting force based on the state change.

If the liquid filling the liquid flow path 223 absorbs the first laser beam and generates heat, causing a sufficiently rapid change in state, there is no need to provide the heat converter 228, and the irradiation unit 222 is not directed toward the laser beam 229. It is sufficient if it is made of a material with good transparency.

Furthermore, in the nozzle structure shown in FIG. 2c, the groove cover 225 and the irradiation section 222 are made of the same material; 222 and groove cover 224
It may be made of a different material.

However, as shown in the figure, it is preferable to use an integrated structure from the viewpoint of ease of construction and cost reduction.

The heat converter 228 may be provided on the irradiation section 222 side. In this case, it is advantageous if the irradiation section 222 itself is made of a heat converter, since the energy loss of the laser beam at the irradiation section 222 can be further reduced.

In addition, when the liquid in the heat effecting part 227 absorbs the laser beam and generates heat, the bottom surface of the heat effecting part 227 (the side opposite to the laser beam incident side) is used to efficiently use the energy of the laser beam. If a member that reflects the laser beam is provided, for example, a reflective member made of a metal surface or a mirror surface, the laser beam that has passed through the liquid in the heat acting section 227 will be reflected by the reflective member and travel through the liquid again. This allows energy efficiency to be improved.

In FIG. 2c, the second laser beam 230
irradiates the diffuser plate 231 while being scanned in the same manner as the first laser beam 229. however,
When the second laser beam passes through the liquid channel 223, it is blocked or partially absorbed by the liquid, so that the light pattern on the diffuser plate 231 becomes a pattern that is a projection of the liquid channel 223. This pattern is sequentially detected by photodetector 232. The timing of irradiation of the first laser beam is controlled by this detection signal. 233 and 234 are shielding plates for preventing external backlight.

Further, in FIGS. 2a and 2b, 235 is a start detector for detecting the scanning start position of the second laser beam 230.

It is confirmed that scanning starts when the second laser beam 230 is detected by the start detector 235, and thereafter, when the liquid flow path 223 is irradiated with the second laser beam, it is detected by the photodetector 232. Irradiation with the first laser beam 229 is performed at the timing of the signal.

In order to irradiate the first laser beam at the timing of the detection signal, for example, a binary data signal carrying desired recording information (characters, figures, etc.) is first transferred to a shift register having a desired number of bits. etc., and read out the input data while shifting the clock using the detection signal as a clock pulse. That is, the signal output from the shift register at this time is one of the data signals.
Each bit becomes a signal that is read out sequentially at time intervals that reflect the spacing of each flow path, and by inputting the signal that reflects this flow path pattern as it is to the modulator, the irradiation timing of the first laser beam can be easily controlled. It becomes possible to do so.

Although the present invention has been described above based on embodiments, various modifications may be made within the scope of the claims.

For example, the second laser beam may be split from a laser oscillator for the first laser beam using a beam splitter or the like.
Further, although the detection of the liquid flow path by irradiation with the second laser beam was performed using transmitted light, it is of course possible to perform detection using reflected light.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the outline of the recording principle related to the present invention, FIG. 2a is an explanatory diagram schematically shown for explaining a preferred embodiment of the present invention, FIG. 2b is a schematic partial perspective view of the recording head 209 used in the apparatus shown in FIG. 2a, and FIG. 2c is a schematic cross-sectional view thereof. 101... Nozzle, 102... Discharge orifice, 103... Liquid, 104... Recorded member, 1
05...liquid, 201...laser oscillator, 20
2... Acousto-optic modulator, 203... Reflector, 2
04...beam expander, 205...polygon, 206...motor, 207...f-theta lens, 208...reflector, 209...recording head, 210...channel array, 211...recorded member,
212... Supply pipe, 213... Common liquid chamber member, 2
14...Liquid storage tank, 215...Cassette, 21
6...Drum, 217...Laser oscillator, 21
8...Reflector, 219...Beam expander, 220...Nozzle 4, 221...Nozzle row member, 220...Irradiation section, 223...Liquid flow path, 2
24... Groove plate, 225... Groove cover, 226... Orifice, 227... Heat acting part, 228... Heat conversion body, 229... First laser beam, 230...
Second laser beam, 231...Diffusion plate, 232
...Photodetector, 233,234...Shielding plate, 23
5...Start detector.

Claims (1)

[Claims] 1. A plurality of flow channels having a discharge orifice at the end thereof for jetting the liquid in a predetermined direction, and a heat acting part at a position where the acting force generated therein is effectively transmitted in the direction of the discharge orifice. By irradiating the laser beam onto the heat effecting part, a sharp state change is caused in the liquid in the heat action part, and the action force based on the state change causes the liquid to be ejected from the discharge orifice. In the liquid jet recording method, in which recording is performed by making liquid droplets fly and adhere to the recording surface, the method is characterized in that the flow path position is detected and a laser beam is irradiated at the timing of the detection signal. liquid jet recording method.