JP2002248801A - Printer and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer and an imaging apparatus in which a high quality image free of color shift, uneven density and scattering of particles can be formed by eliminating positional variation of print pixels without requiring any intricate mechanism while satisfying both high speed and low power consumption. SOLUTION: Piezoelectric oscillators 4 are mounted on the side faces of a liquid pool 3 for containing liquid 2 and oscillated by means of a driver 6 to form a standing wave on the surface of the liquid 2. When particles 1 are supplied from a particle supply unit 5 to the liquid surface, the particles are captured at the nodes of a wave and a highly accurate particle array is formed. An optical scanner 13 is provided below a particle array forming unit 12 and a high quality image is formed by irradiating the particles 1 on the liquid surface selectively with laser light based on an image signal and ejecting the particles 1 by thermal expansion force to adhere to a sheet P. The particles 1 may be ejected by imparting charges thereto and forming an electric field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus used for a copying machine, a printer, a facsimile, etc., for forming a visible image by attaching colored particles, and an image forming apparatus using the printing apparatus. The present invention relates to a printing apparatus and an image forming apparatus that form an image by selectively flying an image on a recording medium such as a sheet.

[0002]

2. Description of the Related Art As a printing method in a conventional image forming apparatus, an electrophotographic method and an ink jet method have become mainstream because of their superiority in image quality, speed, price and the like. In the electrophotographic method, a toner image is formed by transferring toner to an electrostatic latent image formed on an image carrier, and after transferring this onto a recording medium, pressurizing and heating to form an image. It is. In addition, the ink jet system forms an image by directly transferring ink to a recording medium by heat or vibration from a head including nozzles and an ink discharge unit.

However, in the above-described method, there is a possibility that the position of image formation fluctuates due to the speed fluctuation of each driving unit, thereby causing density unevenness and color unevenness to deteriorate image quality.
For this reason, the mechanical accuracy of the drive unit has been improved, and various control mechanisms have been introduced to improve the performance. However, not only is the device complicated and expensive, but also its effect has an upper limit. It is not easy to solve this problem.

Further, in the electrophotographic system, there is provided a device (hereinafter, collectively referred to as a developing device) for containing toner, further holding the toner in a thin layer, and developing or flying it on an image forming medium such as a photoconductor. It is mandatory. In such a developing device, a method of forming a toner layer by rubbing a roller with a metal blade or the like when forming a thin layer is generally used.
At this time, the power consumption of the drive motor and the like becomes extremely large due to the frictional load, and this is one obstacle in reducing the power consumption of the apparatus. In addition, the electrophotographic method requires a number of processes such as charging, exposure, development, transfer, and cleaning processes to form a visible image on paper, making the device larger, more expensive, less reliable, and more power consuming. And so on.

[0005] In a direct recording system using liquid ink such as an ink jet system, integration of print nozzles,
Since it is difficult to form multiple arrays and it is expensive, it is necessary to print while scanning the print head in the direction perpendicular to the paper feed direction. For this reason, the speed of image formation becomes extremely slow, and power consumption increases due to a frictional load when scanning the head. Further, even when a high-resolution, large-size print head is used, it takes a certain time to dry the ink after printing, so that it is not always possible to increase the speed. Furthermore, the energy required when the liquid is discretized into minute liquid droplets in pixel units is much greater than that in the case of powder, which contributes to an increase in power consumption.

[0006] On the other hand, a method similar to the ink jet method for forming a large-sized head relatively easily and requiring no maintenance such as nozzle clogging is disclosed in
An apparatus described in Japanese Patent No. 178056 is proposed. This device generates a standing wave of a predetermined wavelength on the liquid surface by excitation, and then uses another vibration source installed at a position corresponding to the standing wave wavelength to generate a standing wave The part is selectively discharged in accordance with the image signal. According to such an apparatus, it is easy to increase the size of the head, but it is necessary to arrange a large number of pixel-based microdevices for applying a physical stimulus for ejection, which is unavoidably expensive. Further, since a liquid is used, the problem of drying as described above and the problem of energy at the time of discretization have not been solved at all. In addition, Japanese Patent Application Laid-Open No. 62-251153
JP, JP-A-62-251154, JP-A-5-251154
No. 2,699,992 and Japanese Patent Application Laid-Open No. 10-109422 also disclose similar liquid standing methods using surface standing waves, but have exactly the same disadvantages as described above.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the positional fluctuation of print pixels without using a complicated mechanism and high-precision parts. A printing apparatus and an image forming apparatus capable of achieving high-quality images without color shift, density unevenness, and particle scattering, and achieving both high-speed performance and low power consumption that cannot be achieved by conventional apparatuses. To provide.

[0008]

Means for Solving the Problems In order to solve the above problems, the invention according to the present application comprises a liquid holding means for containing a liquid, and a supply of printing particles to be adhered onto a recording medium on the liquid. A liquid supply means, a vibrating means for vibrating the liquid or the liquid holding means, and a physical medium which selectively gives a physical stimulus to each of the particles arranged on the vibrating liquid to face the recording medium. And a vibrating means, wherein the vibrating means is fixed to a side surface of the liquid holding means.

In the above printing apparatus, a surface standing wave having a constant period can be formed on the liquid surface by vibrating the liquid or the liquid holding means by the vibrating means. By supplying the particles on the surface standing wave, the particles can be trapped at the node of the wave to form a periodic arrangement. This makes it possible to form a highly accurate particle arrangement with a simple configuration. Then, high-quality images are formed by selectively discharging these particles based on an image signal and attaching the particles to a recording medium. Further, since the vibrating means is fixed to the side surface of the liquid holding means, a space can be secured below the liquid holding means, so that the arrangement of each component means of the printing apparatus becomes easy, and the size of the printing apparatus is reduced. Is possible. Further, since the particles are used as the coloring material, the energy required for the particles to fly is smaller than in the case where the liquid ink is used, and the power consumption can be reduced.

According to a second aspect of the present invention, there is provided a liquid holding means for containing a liquid, a particle supply means for supplying the particles on the liquid, a vibration means for vibrating the liquid or the liquid holding means, A particle discharge unit for selectively applying a physical stimulus to each of the particles arranged on the liquid to fly the particles onto a recording medium facing the liquid discharge unit, wherein the vibrating unit includes the liquid holding unit , And supported below the particle array.

In the above-described printing apparatus, a high-precision particle array can be formed with a simple configuration, and a high-quality image free from uneven density and color shift can be obtained. Required energy is reduced. In addition, by directly vibrating the liquid, the mass of the vibrated portion is reduced, so that the energy for forming the surface standing wave is reduced.

According to a third aspect of the present invention, there is provided: a liquid holding means for containing a liquid; a particle supply means for supplying the particles on the liquid; a vibrating means for vibrating the liquid or the liquid holding means; A particle ejection means for selectively applying a physical stimulus to each of the particles thus obtained and causing the particles to fly onto a recording medium facing the medium, wherein the layer thickness of the liquid contained in the liquid holding means is It is an object of the present invention to provide a printing apparatus, wherein the particle diameter is equal to or less than an average diameter of the particles, and the particles supplied onto the liquid are set so as to contact the bottom surface of the liquid holding means.

When the particles are supplied on the surface standing wave formed on the surface of the liquid, the particles are trapped in the node of the wave and form a periodic arrangement in contact with the bottom surface of the liquid holding means. Form. The particle array is supported on the bottom surface of the liquid holding means,
Since the liquid crystal is in a stable state, the arrangement of particles is less likely to be disturbed even when the liquid fluctuates, for example, when the standing wave is temporarily disturbed, and a highly accurate pixel position can be maintained. Further, since the mass of the liquid is reduced, the energy for forming the surface standing wave is reduced.

According to a fourth aspect of the present invention, there is provided: a liquid holding means for containing a liquid; a particle supply means for supplying the particles on the liquid; a vibrating means for vibrating the liquid or the liquid holding means; And a particle ejection means for selectively applying a physical stimulus to each of the particles, and causing the particles to fly onto a recording medium facing the medium, and a volume density ρ of the particles.
It is intended to provide a printing apparatus characterized in that _p [kg / m ³ ] satisfies ρ _p ≤1600.

When the particles are supplied on a surface standing wave,
They are trapped at the nodes of the wave without disturbing the standing wave, forming a particle array. For this reason, the accuracy of the pixel position is improved, and a high-quality image free from uneven density and color shift can be obtained. If the volume density of the particles exceeds the above value, the standing wave is likely to be disturbed by the mass of the particles, and the particles are less likely to be trapped at the nodes of the standing wave.

According to a fifth aspect of the present invention, in the printing apparatus according to any one of the first to fourth aspects, the particle discharge means selectively emits a laser beam to the arranged particles. It is characterized by having.

In the above-described printing apparatus, the laser beam can be selectively irradiated on the particles having the array based on the image signal by the laser irradiation apparatus. The particles absorb the laser beam and rapidly rise in temperature. The particles themselves or the liquid in contact therewith are vaporized, and the particles are ejected toward the recording medium by the vaporizing and expanding force at that time. The ejected particles collide with and adhere to the recording medium to form an image.

According to a sixth aspect of the present invention, in the printing apparatus according to any one of the first to fourth aspects, the particles have photoconductivity, and the particle discharging means charges the particles. It is characterized by having charge applying means for applying, light scanning means for selectively irradiating the arranged particles with light, and electric field forming means for forming an electric field in a region including the arranged particles.

In the above-described printing apparatus, the arrangement of the photoconductive particles to which the electric charge is applied can be selectively irradiated with light by the optical scanning means based on the image signal. The charges held by the photoconductive particles are attenuated by light irradiation, and by applying an electric field in this state, particles in a portion where the charges do not attenuate can be selectively caused to fly toward the recording medium.

According to a seventh aspect of the present invention, there is provided a printing apparatus which discharges printing particles adhered to a recording medium based on an image signal, and transports the recording medium so as to pass through a position close to and facing the printing apparatus. And a fixing unit for fixing particles ejected from the printing device and adhered onto the recording medium, wherein the printing device is configured to perform the following operations. The present invention provides an image forming apparatus characterized in that it is a printing apparatus.

The image forming apparatus has a printing device capable of forming a high-precision particle arrangement with a simple mechanism, and the structure of the image forming apparatus is simplified, so that the number of operating parts is reduced. For this reason, the pixel position hardly fluctuates,
Particles can be attached to desired positions of the recording medium,
High quality images can be obtained. Further, since particles are used as the coloring material, energy required for flying the particles is small, and power consumption can be reduced.

An eighth aspect of the present invention provides a printing apparatus which discharges printing particles to be adhered to a recording medium based on an image signal, and an endless peripheral surface which moves orbitally, wherein the peripheral surface is the printing device. An intermediate recording medium disposed so as to be close to and opposed to, a recording medium transporting unit that transports the recording medium so as to pass through a position facing or abutting on the intermediate recording medium, and ejected from the printing apparatus. The printing apparatus according to claim 1, further comprising: a transfer unit configured to transfer the particles attached on the peripheral surface of the intermediate recording medium to the recording medium; and a fixing unit configured to fix the particles on the recording medium. An image forming apparatus according to any one of items 6 to 6, which is an image forming apparatus.

The image forming apparatus has a printing device capable of forming a high-precision particle arrangement with a simple mechanism. When a full-color image is formed, a plurality of the printing devices apply to the intermediate transfer member. Each color toner image is formed. These toner images are satisfactorily superimposed on the intermediate transfer member, and thereafter, are collectively transferred to a recording medium. For this reason, a high quality image with little color shift can be obtained.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a printing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus to which the printing apparatus is applied and showing an embodiment of the invention according to claim 7. The image forming apparatus shown in FIG. 2 includes yellow, magenta, cyan,
The printer is provided with four printing devices 22a, 22b, 22c, and 22d for printing using particles of four colors of black. Below the printing devices 22a, 22b, 22c and 22d, a paper tray 23 for storing paper P and a paper tray 2 are provided.
And a paper feed roller 24 that feeds the paper P one by one. Further, a transport roller 25 disposed along a paper transport path (curve in the figure) from the paper feed roller 24 toward the upper part of the printing apparatus, a transport apparatus 28 for sucking and transporting the paper at a position facing the printing apparatus, and a printing apparatus And a fixing device 26 for fixing an image formed on the sheet by pressing and heating the sheet.

The fixing device 26 fixes the particles on the paper, and heats and fuses the particles depending on the properties of the particles.
Types such as pressurization and overcoat (lamination) can be selected. In this embodiment, two rolls having a heat source are pressed against each other, and the particles are fixed on the paper by heating and pressing. The transport device 28 is composed of an endless belt stretched over two support rolls 27a and 27b. The rotation of the support roll causes the endless belt to circulate, thereby adhering the paper P sent out onto the endless belt. It is designed to be transported.

Such an image forming apparatus includes a paper tray 2
The paper P in the sheet 3 is fed out one by one by the paper feed roller 24, and the paper P is transported by the transport roller 25 to the vicinity of the printing unit. Then, the paper P is transported by the transport device 28 so as to pass above the printing devices 22a, 22b, 22c, and 22d at predetermined intervals. Each printing device is
As described later, colored particles are ejected based on a signal from an image signal processing device (not shown) or the like, and each color image is formed on a sheet. After the respective color images are superimposed on the paper, they are pressed and heated by the fixing device 26. The colored particles on the paper are melted by heating, then solidify with cooling, and adhere to the paper to form a full-color image.

Next, the printing device 22 will be described with reference to FIG. This printing apparatus is composed of a particle array forming device 12 that forms a wave on the liquid 2 to form an array of particles 1 on the surface thereof, and an optical scanning device 13 that irradiates a laser beam from the back side of the device. The above particle array forming apparatus 1
2 is a liquid pool 3 containing the liquid 2 and a liquid pool 3
A piezoelectric vibrator 4 fixed to a side surface of the liquid pool 3, a particle supply device 5 for supplying particles 1 to the liquid pool 3, and a driving device 6 for vibrating the piezoelectric vibrator 4.

The optical scanning device 13 includes a laser device 8 for emitting a laser beam, a laser driving device 7 for driving and controlling the laser device, a lens 9 for converging the emitted laser beam, and a laser beam for scanning. Rotating mirror 10 for turning the laser beam and a mirror 11 for turning the laser beam back and irradiating the lower part of the particle array forming device 13
And

Next, the configuration of the printing apparatus will be described in detail. The particles 1 are colored particles ejected from above the liquid by irradiation with laser light, and have optimal characteristics selected from wettability to the liquid 2 to be used, specific gravity, size for the wavelength to be formed, and the like. Optically,
Since a laser beam is used as a means for discharging the particles, it is necessary that the particles have a sufficient absorptivity according to the characteristics of the laser beam used. In addition, by using hydrophobic particles having a small number of adhesion interfaces, it is possible to reduce energy for discretizing the particles in pixel units.

In order to stably form a surface standing wave, it is desirable to select an optimal liquid 2 in consideration of viscosity, surface tension and the like. Optically, it is necessary that the laser beam can be sufficiently transmitted. In this embodiment, water or silicone oil can be used.

The piezoelectric vibrator 4 is fixed to the side surface of the liquid pool 3 and vibrates at a constant frequency when a voltage having a constant frequency and amplitude is supplied from the driving device 6. Thereby, the liquid pool 3 and the liquid 2 are vibrated. The material of the piezoelectric vibrator 4 has almost no optical restrictions because a laser beam, which is a means for discharging particles, is irradiated from below the liquid pool 3.

The particle supply device 5 is disposed at an end of the particle arrangement forming device 12 and supplies a predetermined number of particles 1 to the surface of the liquid 2 by mechanical pressure or pressure of a fluid (air or the like). It is. At this time, control is performed such that the number of particles consumed in the image section is counted in advance from the image signal, and the consumed amount is supplied. Further, by detecting the particles optically supplied by the supply unit and controlling the supply pressure and the like, the number of supplied particles can be accurately counted, and the necessary particles can be supplied. It is necessary to temporarily stop the discharge operation during supply, and the printing speed decreases. However, a plurality of discharge heads are provided so that a plurality of heads sequentially discharge one line, and a certain head performs the discharge operation. If the other heads operate so as to supply particles and prepare for ejection during the operation, a reduction in printing speed can be substantially avoided.

The configuration and operation of the optical scanning device 13 are almost the same as those of a laser exposure device in a conventional electrophotographic image forming apparatus. However, since the laser device 8 needs to irradiate a laser with energy sufficient to discharge the particles 1, it is desirable that the laser device 8 has a high output.

Next, the operation of the printing apparatus will be described. When the liquid pool 3 is vibrated by the piezoelectric vibrator 4, a surface standing wave is formed on the surface of the liquid 2. As shown in FIG. 3, this wave has a portion that vibrates with time and a portion that does not vibrate and stays still. The section that is marked as a clause. When the particles 1 are supplied from the particle supply device 5 onto the surface standing wave of the liquid 2, the particles 1 are captured by the node B of the wave, and a particle arrangement is formed.

When the laser driving device 7 is turned on / off in response to the image signal, the laser light is scanned by the rotating polygon mirror 10 and is incident on the lower portion of the particle array forming device 12. The laser light passes through the liquid pool 3 and the liquid 2 and is irradiated only to a desired pixel position corresponding to an image in the particle arrangement on the liquid 2. At this time, the particles 1 generate heat by absorbing the laser light. If the amount of supplied laser light is sufficient, a part of the particles 1 is heated to 300 ° C. to 3000 ° C. in a short time and vaporized. The particles 1 are discharged in the direction of the paper P by the expansion force at this time. The ejected particles 1 collide with the paper P and are held by an adhesive force such as van der Waals force, thereby forming a visible image.

When the surface standing wave fluctuates for some reason during the operation of the apparatus and the position of the particle 1 fluctuates, the laser beam spot size is optimally selected and the desired particle is irradiated with the laser without fail. It can be carried out. Also, it is easy to increase the printing speed by forming a large number of particle arrays or increasing the laser scanning speed.

FIG. 4 shows the relationship between the excitation frequency and the surface standing wave wavelength when water or silicone oil is used as the liquid 2. The theory of wave generation, the frequency of vibration, the relationship between the amplitude and the wavelength of the wave, the amplitude, and the vibration amplitude necessary for wave formation are described in Rayleigh, JWS, The theory of
sound, 2 <SUP> nd </ SUP> .Ed., Vol.II, Chap.XX (194
5), Dover Publications, and Eisenmenger, W., Dynamic
properties of the surface tension of water and aq
ueous solutions of surface active agents with stan
ding capillary waves in the frequency range from 1
0 kc / s to 1.5 Mc / s, Acoustica, 9 (1959), 327-340. The inventors of the present application have actually verified that water and silicone oil (Shin-Etsu Chemical Co., Ltd.)
Manufactured by KF96-10CS), etc., almost satisfied the theoretical values described in these documents.

In the above printing apparatus, the cycle of the particle arrangement can be continuously and arbitrarily changed by changing the frequency of the vibration. In this embodiment, assuming that one particle is one pixel, when water is used as the liquid 2, the frequency is about 17%.
When excited at 0 kHz, a wave with a half wavelength of about 20 μm is formed,
Printing equivalent to spi (Spot Per Inch) can be performed. When silicone oil is used, the frequency is about 90 kHz.
When shaken at z, a wave having a half wavelength of about 20 μm is formed, and the same printing resolution can be obtained.

Further, by providing a plurality of rows of particle arrays captured at the nodes of the standing wave and displacing them at equal intervals, a high resolution can be obtained at a relatively low frequency, and the energy required for the amplitude can be reduced. As shown in FIG.
By providing five rows of the captured particle array at the node of the 0 μm wave, printing equivalent to 1200 spi can be performed.

By using the above-described printing apparatus, it is possible to form a highly accurate particle arrangement with a simple configuration, and it is possible to easily and widely change the printing resolution. In addition, since the operating part is only the piezoelectric vibrator 14, the pixel position does not easily change. For this reason, the particles land on a desired position of the recording medium by laser irradiation, and a high-quality image free from uneven density and color shift can be obtained. Also,
Since the piezoelectric vibrator 14 is supported on the side surface of the liquid pool 3, a space can be secured below the liquid pool 3. For this reason, the arrangement of each component of the printing apparatus is facilitated, and the size of the printing apparatus can be reduced.

FIG. 6 is a schematic structural view showing a printing apparatus according to an embodiment of the present invention, which can be used in the image forming apparatus shown in FIG. This printing device includes a particle array forming device 46 and an optical scanning device 47.
The optical scanning device 47 is the same as the printing device shown in FIG.

The particle array forming apparatus includes a liquid pool 33 containing a liquid 32, a piezoelectric film 34 supported in the liquid 32, a particle supply device 35 for supplying particles 31 to the liquid pool 33, and a piezoelectric film 34. And a driving device 36 for vibrating the. Further, a corona charging device 37 for applying a charge to the particles 31 is provided downstream of the particle supply device 35, and charges the particles 31 to be sent. On the other hand, a high-voltage power supply 38
, A bias electrode 39 to which a bias voltage is applied is disposed, and a ground electrode 40 that is electrically grounded is provided on the back surface of the paper P, and an electric field is formed therebetween. The ground electrode 40 is connected to the sheet conveying device 28 shown in FIG.
May be made conductive and grounded. In addition, liquid 3
2. Liquid pool 33, particle supply device 35, drive device 36
Is the same as the printing device shown in FIG.

The particles 31 have photoconductivity and can transmit laser light to be irradiated to some extent. Then, when the laser light having an appropriate intensity is applied, the charges of the particles move to the surrounding liquid.
In addition, in this embodiment, since the laser light is irradiated from the lower part of the liquid pool 33, the bias electrode 39 also needs to have light transmittance. Therefore, if laser light irradiation is performed from the side surface of the liquid pool 33 and irradiation is performed from the surface side of the particle layer, the above-described restrictions are almost eliminated.

The piezoelectric film 34 is supported at the bottom of the liquid pool 3 and vibrates at a constant frequency when a voltage having a constant frequency and amplitude is supplied from the driving device 6.
Thereby, the liquid 32 is vibrated. Optically, it is necessary that the laser light can be sufficiently transmitted, and a material made of a piezoelectric plastic such as polyvinylidene fluoride can be used. In the present embodiment, an electromagnetic vibrator such as that used for a piezoelectric vibrator or a speaker can be used as a vibration source.

Next, the operation of the printing apparatus will be described. When the piezoelectric film 34 vibrates in the liquid 32,
A surface standing wave is formed on the surface of the liquid 32. The particles 31 are supplied by the particle supply device 35 onto the surface standing wave, and a particle arrangement is formed. Regarding the formation of the particle array, the relationship between the frequency and the wavelength of the vibration, the amplitude of the vibration necessary for the formation of the wave, and the like are the same as those of the printing apparatus shown in FIG.

The particles 31 are charged by a corona charging device 37, and a laser beam is applied from a laser driving device 7 to a desired pixel position corresponding to an image in response to an image signal. The particles 3 irradiated with laser light
1 has conductivity and the charge is attenuated. By irradiating laser light according to the image signal for one line, switching the voltage applied to the bias electrode 39 at the same time as the completion of the irradiation, and applying an electric field, the particles 31 other than the light irradiating part fly and fly the image. Can be formed. The flying electric field strength is determined by the adhesion of the particles 31 and the like, and it is necessary to determine the bias value according to the characteristics of the particles.

In this printing apparatus, since the piezoelectric film is supported in a liquid, the liquid 2 is directly vibrated to form a particle array. For this reason, the weight of the portion to be vibrated is reduced, and the energy required for vibration can be reduced. Also,
Since the photoconductive particles and the electric field are used as means for discharging the particles 31, the energy of the laser light to be applied is not so large. For this reason, a low-light semiconductor laser or LED array can be used, and the size and cost of the device can be reduced. Note that, in the present embodiment, similarly to the printing apparatus shown in FIG. 1, a particle discharging unit using a laser may be employed.

FIG. 7 shows a third, fourth or fifth aspect of the present invention.
FIG. 3 is a schematic configuration diagram illustrating a printing apparatus according to an embodiment of the invention described in (1), and can be used in the image forming apparatus illustrated in FIG. 2. This printing device includes a particle array forming device 62 and an optical scanning device 63, and the optical scanning device 63
A printer similar to the printer shown in FIG. 1 is used. The liquid pool 53, the piezoelectric vibrator 54, the particle supply device 55, and the driving device 56 of the particle array forming device
The piezoelectric vibrator 54 is fixed to the bottom of the liquid pool 53. Here, the piezoelectric vibrator 54 does not prevent the arranged particles from being irradiated with laser light. For example, a material that can sufficiently transmit laser light is selected as the piezoelectric vibrator 54. Further, the piezoelectric vibrator 54 may be disposed at a position that does not intersect with the optical path to the arranged particles.
In this embodiment, similarly to the printing apparatus shown in FIG. 6, a particle discharging unit using an electric field may be employed.

The particles 51 have a volume density ρ _p [kg / m ³ ] ≦
1600. By selecting the particles having such a volume density, when the particles 51 are supplied on the surface standing wave, the particles can be surely captured by the node of the wave and form a particle arrangement. Optically, it is necessary to have a sufficient absorptivity according to the characteristics of the laser light used in consideration of the ejection properties of the particles. As the liquid 52, for example, water or silicone oil is used, the layer thickness is set to be equal to or more than the amplitude of the surface standing wave, and the layer thickness of the node portion when the surface standing wave is formed is set to be equal to or less than the average particle diameter of the particles 51. I do. Thereby, the particles supplied on the liquid are set so as to contact the bottom surface of the liquid pool 53.

In the present printing apparatus, when the particles 51 are supplied on the surface standing wave, the particles captured in the node of the wave come into contact with the bottom surface of the liquid pool 53 as shown in FIG. A particle arrangement can be formed in a stable state. Particle 51
Is supported by the bottom surface of the liquid pool 53,
Even if the liquid 52 fluctuates, the disturbance generated in the particle arrangement is reduced. For this reason, it is possible to maintain a highly accurate particle arrangement, and the accuracy of the pixel position is improved. Also,
Since the volume of the liquid is small, the weight of the portion to be vibrated by the piezoelectric vibrator 54 is reduced, and the energy required for the vibration can be reduced.

When the particles 51 ′ having a volume density ρ _p [kg / m ³ ] ≦ 1600 and lighter than the specific gravity of the liquid 52 are used, as shown in FIG. Particle 5
1 'forms a high-precision particle arrangement while floating from the liquid pool 53. Also in this case, the effect that the energy required for excitation can be reduced can be obtained.

On the other hand, when particles 51 ″ having a volume density ρ _p [kg / m ³ ]> 1700 are used, the gravity of the particles is larger than the force for forming the surface standing wave. As shown, the particles are not trapped at the nodes of the waves but settle down at the bottom of the liquid pool, so that no particle arrangement is formed.

FIG. 11 shows another example of the image forming apparatus provided with the printing device according to any one of claims 1 to 6, and is an embodiment of the image forming apparatus according to claim 8. It is a schematic structure figure of an apparatus. This image forming apparatus includes four printing devices 72 a, 72 b, 72 c, and 72 d for printing using particles of four colors of yellow, magenta, cyan, and black inside a housing 71, and faces the printing device 72. And an intermediate transfer member 74 of an endless belt stretched around the support rollers 73a and 73b. Further, a support roll 73 is provided with the intermediate transfer member 74 interposed therebetween.
A transfer roll 75 is provided at a position opposite to a, and a fixing device 76 for fixing the toner image transferred to the paper P by heating and pressing is provided on the downstream side. Further, a paper tray 77 and a paper tray 7 are provided below the printing device 72.
A paper feed roller 78 for feeding out the paper P one by one
And a transport roller 79 for transporting the paper P along a paper transport path (curve in the figure).

Such an image forming apparatus includes the intermediate transfer member 7
Along with the rotation drive of No. 4, a plurality of color toner images are superimposed on the intermediate transfer member 74 by the printing device 72, and a full color toner image is formed. The toner image is conveyed to a position opposed to the transfer roll 75, contacts the sheet P sent from the sheet tray 77 at the same timing, and the toner image is transferred to the sheet P. The sheet P carrying the unfixed toner image is sent to the fixing device 76, and the toner image is heated and melted and pressed against the sheet P. The sheet P is conveyed toward the exit, and the toner image is cooled and solidified and adheres to the sheet P to form a full-color image. Note that the printing device 72 can be the same as the printing device shown in FIG. 1, FIG. 6, or FIG. 7, and the operation of forming the particle array and discharging the particles is also the same.

The image forming apparatus is provided with a printing device capable of forming a highly accurate particle arrangement with a simple configuration, and selectively discharges these particles based on an image signal and causes the particles to adhere to an intermediate transfer member. . For this reason, a high-precision toner image is formed on the intermediate transfer member, and the toner images of the respective colors are superimposed satisfactorily, so that a high-quality full-color image can be obtained.

[0056]

As described above, in the printing apparatus according to the present invention, it is possible to form a highly accurate particle arrangement with a simple configuration, and it is difficult for the image forming position to fluctuate due to the small number of operating parts. . For this reason, a high-quality image free from uneven density and color shift can be obtained. Further, by appropriately selecting and using the layer thickness of the liquid and the volume density of the particles, a more accurate particle arrangement can be stably obtained. Then, the energy for forming the surface standing wave can be reduced by directly vibrating the liquid by vibrating means or reducing the volume of the liquid.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus using the printing apparatus shown in FIG. 1, which is one embodiment of the invention according to claim 7;

FIG. 3 is a view for explaining formation of a particle array in the printing apparatus shown in FIG. 1;

FIG. 4 is a diagram illustrating a relationship between a frequency of vibration of a liquid used in the printing apparatus illustrated in FIG. 1 and a wavelength of a surface standing wave.

FIG. 5 is a diagram illustrating another example of particle array formation in the printing apparatus illustrated in FIG. 1;

FIG. 6 is a schematic configuration diagram showing a printing apparatus according to an embodiment of the invention described in claim 2 or 6;

FIG. 7 is a schematic configuration diagram showing a printing apparatus according to an embodiment of the present invention described in claim 3, 4 or 5.

FIG. 8 is a diagram illustrating the formation of a particle array in the printing apparatus shown in FIG. 7;

9 is a diagram illustrating another example of the particle array formation in the printing apparatus illustrated in FIG.

FIG. 10 is a diagram illustrating another example of particle array formation in the printing apparatus illustrated in FIG. 7;

FIG. 11 is a schematic configuration diagram of an image forming apparatus using the printing apparatus shown in FIG. 1, FIG. 6, or FIG. 7, which is an embodiment of the invention according to claim 8;

[Explanation of symbols]

 1, 31, 51 Particles 2, 32, 52 Liquid 3, 33, 53 Liquid pool 4, 54 Piezoelectric oscillator 5, 35, 55 Particle supply device 6, 36, 56 Driving device 7, 41, 57 Laser driving device 8, 42, 58 Laser device 9, 43, 59 Lens 10, 44, 60 Rotating polygon mirror 11, 45, 61 Mirror 12, 46, 62 Particle array forming device 13, 47, 63 Optical scanning device 21, 71 Housing 22, 72 Printing Apparatus 23, 77 Paper tray 24, 78 Feed roller 25, 79 Transport rollers 26, 76 Fixing device 28 Transport device 34 Piezoelectric film 37 Corona charging device 38 High voltage power supply 39 Bias electrode 40 Ground electrode 73 Support roll 74 Intermediate transfer body 75 Transfer roll

Claims (8)

[Claims] 1. A liquid holding means for containing a liquid, a particle supply means for supplying printing particles to be deposited on a recording medium onto the liquid, and a vibration means for vibrating the liquid or the liquid holding means. And a particle ejection unit for selectively applying a physical stimulus to each of the particles arranged on the oscillating liquid and causing the particles to fly onto a recording medium facing the liquid ejection unit. A printing device fixed to a side surface of a holding means. 2. A liquid holding means for containing a liquid, a particle supply means for supplying printing particles deposited on a recording medium onto the liquid, and a vibration means for vibrating the liquid or the liquid holding means. And a particle ejection unit for selectively applying a physical stimulus to each of the particles arranged on the oscillating liquid and causing the particles to fly onto a recording medium facing the liquid ejection unit. A printing apparatus, which is supported inside the holding means and below the particle array. 3. A liquid holding means for holding a liquid, a particle supply means for supplying printing particles to be attached to a recording medium onto the liquid, and a vibration means for vibrating the liquid or the liquid holding means. And a particle discharge unit for selectively applying a physical stimulus to each of the particles arranged on the oscillating liquid and causing the particles to fly onto a recording medium facing the liquid discharge unit. A layer thickness of the liquid is equal to or less than an average diameter of the particles, and the particles supplied on the liquid are set so as to contact a bottom surface of the liquid holding means. 4. A liquid holding means for containing a liquid, a particle supply means for supplying printing particles deposited on a recording medium onto the liquid, and a vibration means for vibrating the liquid or the liquid holding means. And a particle discharge means for selectively applying a physical stimulus to each of the particles arranged on the vibrating liquid and causing the particles to fly onto a recording medium facing the liquid, and a volume density ρ _p [ kg / m ³ ], wherein ρ _p ≦ 1600. 5. The apparatus according to claim 1, wherein the particle discharging means has a laser irradiation device for selectively irradiating the arranged particles with a laser beam, and vaporizes the particles or a liquid in contact with the particles. The printing device according to any one of claims 1 to 4. 6. The particle has photoconductivity, the particle discharging unit includes: a charge applying unit that applies a charge to the particle; an optical scanning unit that selectively irradiates light to the arranged particles; The printing apparatus according to claim 1, further comprising: an electric field forming unit that forms an electric field in a region including the arranged particles. 7. A printing apparatus for discharging printing particles to be attached to a recording medium based on an image signal, and a recording medium conveying means for conveying the recording medium so as to pass a position close to and facing the printing apparatus. Fixing means for fixing particles ejected from the printing device and adhering to the recording medium, wherein the printing device is the printing device according to any one of claims 1 to 6. An image forming apparatus comprising: 8. A printing apparatus for discharging printing particles to be attached to a recording medium based on an image signal, and an endless peripheral surface moving in a circling manner so that the peripheral surface is closely opposed to the printing device. An intermediate recording medium to be disposed, a recording medium conveying means for conveying the recording medium so as to pass through a position facing or abutting on the intermediate recording medium, and a periphery of the intermediate recording medium ejected from the printing device. 7. A printing device, comprising: transfer means for transferring particles adhered on a surface to the recording medium; and fixing means for fixing the particles on the recording medium. An image forming apparatus, which is the printing apparatus according to claim 1.