JPH1170691A - Electrostatic recording head and electrostatic printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic recording head for driving recording needles (anode electrodes) by electric field discharge elements. SOLUTION: A drive substrate 1 is loaded with IC circuits 5A, 5B, 5C, 5D for driving an electrostatic recording head. An electron discharge part 2 is held to a vacuum state by a vacuum envelope 6 and has a large number of electric field discharge cathodes, gates and anodes charged by discharged electrons formed thereto in a line form. A plurality of outgoing lines connected to the strip like anodes provided in the vacuum envelope 6 are provided to a recording head part 3 formed by vapor deposition of transparent electrodes or metal act as an electrode part for charging a latent image on the surface of a dielectric or electricity-sensitive recording paper and the leading end parts thereof become anodes P1, P2, P3,.... A latent image can be formed on a recording medium by discharging the charge of the anodes to the recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording head, and more particularly, to an electrostatic recording head suitable for performing electrostatic recording by electrons emitted from a cold cathode disposed in a vacuum, and to an electrostatic recording head. The present invention relates to an electrostatic printer using an electrostatic recording head.

[0002]

2. Description of the Related Art A recording medium, such as a dielectric sheet or photographic paper, is placed on a conductor surface, an electrode is brought into contact with the surface of the recording medium, and a predetermined voltage is applied between the conductor and the electrode. A method of forming an electrostatic latent image on a printer is used in many printers and copiers. An electrostatic printer is classified into a solid-state scanning method, an electronic scanning method, and an ion scanning method according to a method of recording an electrostatic latent image to be printed as a latent image on a recording medium surface.

[0003]

As the conventional electrostatic recording, a solid-state scanning recording method, an electronic scanning recording method, a gas discharge recording method and the like are mainly known, but the solid-state scanning recording method corresponds to a recording pitch. A head that applies a voltage corresponding to a recording signal to the stylus by various types of matrix circuits by using a desired number of recording needles (multi-stylus) and control electrodes. However, this method has the problems that the price of the multi-stylus becomes expensive and that the recorded image becomes uneven depending on the arrangement of the control electrodes and the method of supplying the control voltage.

In the electronic scanning method, a cathode ray tube is used, and a predetermined potential is supplied while scanning an electron beam directly on a multi-stylus (recording needle) implanted on the surface of the cathode ray tube. However, there is a problem that the head becomes large due to the use of the cathode ray tube. Also, it is necessary to embed a thin metal pin in a glass cathode ray tube,
The price becomes expensive, and tailing, a previous effect, and the like occur due to the capacitance between the pin electrodes, making it difficult to improve image quality. In addition, those utilizing gas discharge require a high-potential power supply, and spread distortion occurs due to capacitive coupling between recording styluses, which is regarded as a multi-stylus,
There is a problem that the image quality is not improved by the previous effect due to charge accumulation.

Further, ion gas is generated by a corona charger, and this ion gas is transmitted from an aperture electrode.
The scanning method of forming a latent image by emitting directly to the surface of a dielectric,
Since there is no recording needle, there is an advantage that low voltage driving can be performed and the aperture electrode can be manufactured at low cost. However, there is a problem that it is difficult to perform matrix driving on the aperture electrode that emits ion gas, and the driving circuit becomes expensive.

[0006]

According to the present invention, a field effect element which can be formed by a thin film technique or the like is used as an electrostatic recording head with respect to the recording heads of the above types. A field emission cathode formed on one surface of a vacuum envelope, and a plurality of strip-shaped anode electrodes formed of a metal film on the other surface of the vacuum envelope facing the field emission cathode. Have. The plurality of anode electrodes are directly led out of the vacuum envelope to form a pin array. Further, the field emission cathode is composed of a large number of cone-shaped emitters and a blocked gate for extracting electrons, and is selectively driven with respect to the anode electrode by performing dynamic driving with the emitter electrode and the gate electrode. To supply electrons.

[0007]

FIG. 1 is a perspective view showing an outline of an electrostatic recording head according to the present invention. A part 1 is a wiring circuit for driving the electrostatic recording head and various IC circuits 5 for driving.
A, 5B, 5C, 5D, etc. are drive substrates on which are mounted.
The drive board 1 is provided with a connection terminal section 4 for connecting to a connector, so that the drive board 1 can be mounted on an electrostatic printer or the like, as described later, or the head can be easily replaced. 2
Numeral denotes an electron-emitting portion in which a field-emission element is stored. In an internal space that is evacuated by the vacuum envelope 6, a large number of field-emission devices formed by thin-film technology as described later are used. The cathode, the gate, and the anode charged by the emitted electrons are arranged in a line.

Reference numeral 3 denotes a recording head section in which a plurality of lead lines connected to a strip-shaped anode provided inside the vacuum envelope 6 are formed by transparent electrodes or metal deposition. . The recording head section 3 functions as an electrode section for charging a latent image on, for example, a dielectric surface or electrostatic recording paper, and in fact, the tip of a lead line formed by vapor deposition or the like on the back surface of the recording head section. The portions are the anode electrodes P1, P2, P3,...,... P corresponding to the dot pitch obtained by horizontally decomposing the image or character to be copied as in the conventional multi-stylus.
n. Therefore, the number n of the anode electrodes is set according to the resolution of the recorded image, and the arrangement is such that a latent image can be formed on the recording medium by discharging the electric charge charged on the anode electrode to the recording medium.

In general, the vacuum envelope 6 is formed by fusing two glass substrates with frit glass or the like through a predetermined gap, and forming a laminated amorphous silicon layer and insulating layer on one of the glass substrates. The above-described field emission cathode, wiring circuit, and the like are formed by processing using a thin film technique such as an etching technique, a vapor deposition technique, or a sputtering technique. A plurality of strip-shaped anodes are formed on the back side of the other anode electrode substrate 7, and, for example, aluminum metal is vapor-deposited such that extension lines thereof become lead lines and anode electrodes.

FIG. 2 shows a part of a field emission cathode formed inside the vacuum envelope 6 and an anode for capturing emitted electrons which are enlarged in the width direction. , 11 is a first glass substrate on which the charge emission cathode is laminated, and 12 is a second glass substrate on which the anode is formed. These first and second glass substrates are welded by a glass frit or the like via the side wall 13, and the internal space is evacuated. Note that a getter is arranged inside as necessary.

A plurality of cathode electrodes 14 are patterned in a strip shape on the first glass substrate 11, and an emitter cone 15 for emitting electrons, an insulating layer 16, And a gate 17 driven to extract electrons is laminated by thin film technology. A plurality of strip-shaped anodes 18 are formed on the second glass substrate 12 so as to face each field emission cathode array, and the tip electrode portion is arranged, for example, close to a dielectric drum 19 serving as a recording medium. .

FIG. 3 is a top view showing the arrangement of the field emission cathode, and only a part of the anode is shown. As shown in this figure, a plurality of band-shaped field emission cathode arrays are divided into blocks B0, B1, B2, B3,... . Then, the first cathode electrode c ₁₁ of the block B0 is connected to the last cathode electrode c _2n of the next block B1 via the cathode line C0,
This cathode electrode c _2n is subsequently connected to the first cathode electrode c ₃₁ of the next block B2. In this manner, the cathode electrodes divided into the blocks B0, B1, B2, B3,..., Bn are respectively connected to the cathode lines corresponding to the next block by the cathode lines C0, C1, C2,.
Are connected in a zigzag pattern, and the cathode electrodes of n × several blocks are configured to output the number of electrodes to be driven as 1 / Bn−1.

Each block B0, B1, B2, B3,...
Each of the cathodes belonging to the group is controlled by one gate electrode. That is,
In the case of FIG. 3, the gate electrodes are G0, G1,
G3... Are output. By applying a driving voltage to the derived cathode electrode and gate electrode at a predetermined timing, a dynamic drive is performed to reduce the number of electrons emitted from the field emission cathode and accumulated and discharged to the anode electrode. It is controlled by. GA indicates a separate electrode for reducing the interelectrode capacitance of the anode electrode, but this electrode GA is not always required.

FIG. 4 shows a band-like emitter 1 as described above.
5, an anode electrode 18 is formed in a vacuum for the field emission cathode blocks B0, B1, B2, B3,... 2 shows a dynamic drive circuit in the case where a counter electrode 20 in which are laminated. Hereinafter, a drive signal supply circuit for causing the dielectric 19 to perform a dynamic drive for copying a latent image will be described. C
0, C1, C2, C3. . . . Denotes cathode electrodes derived when each block is divided into four cathode arrays, and G0, G1, G2, G
3. . . . . Is a gate electrode drawn for each block. The cathode electrodes C0, C1, C2, and C3 are input to the demulti-switch M1, and are controlled so that the contacts are sequentially switched at a predetermined timing, thereby sequentially supplying a driving voltage + Vd to each emitter. The gate electrodes G0, G1, G2, and G3 are also connected to the demultiswitch M2.
For example, a control voltage is supplied to each block (four emitters in this case). Note that -VS is a charging power supply for charging the anode in a floating state to a potential of -VS when electrons are emitted.

The timing at which the voltage applied between the gate and the cathode by the demulti-switches M1 and M2 becomes Vd, that is, the switches S1, S2, S3,. . . .
The cathode array consisting of the emitter and gate when the black circle contact is selected is activated.Electrons are emitted from the emitter cone, and the electron flow reaches the floating anode. Charge. The anode potential is charged so as to be substantially the same as the cathode potential. However, when the dielectric drum is opposed to the anode electrode via a small gap, the discharge occurs when the anode potential further drops below the firing voltage V1. An electric current (corona discharge) flows through the dielectric 19 (drum side), and the surface of the dielectric drum is locally charged. Therefore, the opening and closing of each of the demulti-switches M1 and M2 is sequentially controlled in synchronization with the rotation of the drum, and the electron current (anode charging current) emitted from each emitter 15 corresponds to one line of image data. Drive voltage Vd
By changing the potential of each anode according to the recorded image by this control, an electrostatic latent image can be formed on the surface of the dielectric 19.

FIG. 5 shows an example of the voltage of each part when the above-described control is performed.
For example, when the anode potential has dropped to -Vs,
The discharge returns to the discharge start voltage V1 due to the discharge, indicating that the voltage is maintained at this point. However, when the gate voltage becomes an electron emission state (gate on, cathode off) higher than the emitter voltage by Vd in the period T2, electrons are emitted from the emitter, so that the anode potential falls again below the discharge start potential V1 and discharge starts. When a current equal to or greater than the discharge current is supplied, the potential drops to the −Vs side, but when the emission of electrons from the emitter stops, the anode potential recovers toward the discharge start potential V1 and returns to the potential immediately before the start of discharge. It will be maintained. Thereafter, discharge is started for each of the anode electrodes driven to turn on the gate and turn off the emitter, and a latent image is recorded by charging the surface of the dielectric. Then, except for the gate ON and the cathode OFF described above, the discharge is OFF, and a non-writing state in which writing is not performed.

The discharge starting voltage V1 is determined by the following formula based on the gap between the anode end face and the dielectric surface, the thickness of the dielectric, the dielectric constant, and the like.

(Equation 1) The relationship between the distance d between the dielectric and the anode electrode and the discharge start recording voltage (V) is approximately as shown in FIG. The optimum gap distance is empirically said to be 10 to 30 μm, and the thickness of the dielectric is preferably 10 to 80 μm. Further, the discharge start recording voltage at this time is about 600 to 700V. In the case of the electrostatic recording head of this embodiment, when the gate drive voltage is 100 V, the voltage Vs applied to the head is considered to be 800 to 1000 V.

The current drawn from the cathode constituting the field emission device can be estimated by the resolution of the printer and the printing speed. For example, in the case of a conventional multi-stylus type electrostatic head, a value of 0.4 mA is set as an appropriate current. When the field emission device of the present invention is used, it is considered that a current of 20 nA can be output by one emitter cone. A current of 4 mA can be drawn. At this time, if one emitter cone is formed with a pitch of 5 μm, the pitch becomes 20 μm with 20 emitter cones. 5 mm is sufficient, and a very small electrostatic recording head can be obtained.

The lateral dimension of the recording head is determined by how the resolution is set, and is, for example, A4 paper (width = 2).
In order to achieve a resolution of 300 DPI at 10 mm), the number of dots may be 2560 dots. Uses two 32-bit ICs for data and four for scanning
If one 0-bit IC is used, the transfer rate will be 3.6
MHz.

FIG. 7 is a schematic view showing a case where the electrostatic recording head of the present invention is applied to an electrostatic printer 30. Numeral 31 denotes a rotating drum, and a dielectric film 32 is formed on the outer periphery. A metal roller 33 is provided around the circumference. Numeral 34 denotes an electrostatic recording head (FEH) comprising an anode electrode in which a plurality of anodes which are provided with a field emission cathode therein and which can be charged by emitted electrons are arranged side by side in a line direction as shown in FIG. It is. The electrostatic recording head 34 is a drum 3
4 is driven so as to form a latent image of the input image by discharging charges charged through the air gap to the dielectric surface.

Reference numeral 35 denotes a developing device for causing the toner charged inside to adhere to the latent image on the drum surface. And
The latent image to which the toner has been attached is printed on the paper surface of the recording paper 39 supplied by the transfer device 36, the latent image is recorded on the paper surface, and the image printed on the paper surface is fixed by the fixing device 37. The electrostatic recording head 34 has a computer 4
A video signal of 0 or one frame to be recorded is supplied from the image pickup device or the like at a fixed timing in synchronization with the rotation of the drum 31. The drum 31 on which the latent image has been transferred to the recording paper 39 is cleaned by the charge removing cleaning device 38 of the surface, and enters a standby state for recording the next video signal. In the case of a color image, the video signal is 3
Achieved by overprinting of primary colors. Further, the electrostatic recording head of the present invention can be used for a printer that directly prints a latent image on recording paper.

FIG. 8 shows an example of a manufacturing method for forming a Spindt-type field emission device. First, the cathode electrode layer 10 is formed on a substrate 100 such as glass by sputtering.
1 and a resistance layer 10 is formed on the cathode electrode layer 101.
2 is formed, and an insulating layer 103 is formed on the resistance layer 102.
Is formed. Then, a gate electrode layer 104 is formed over the insulating layer 103 to form a stacked substrate. Note that the resistance layer 102 can be omitted.

Further, after a photoresist layer 111 is applied on the gate electrode layer 104, which is the outermost surface of the laminated substrate, the photoresist layer is patterned using a mask 112 to form an opening pattern in the photoresist layer. Then, the gate electrode layer 1 is anisotropically etched by reactive ion etching (RIE) from the direction in which the photoresist layer is applied, as shown in FIG.
An opening 11 similar to the pattern of the photoresist layer
3 is manufactured.

Then, the insulating layer portion is anisotropically etched to form a hole 114 in the insulating layer 103 as shown in FIG. 1C, and the laminated substrate is rotated in the same plane while Al (aluminum) is formed. When the oblique vapor deposition is performed, Al is selectively deposited only on the surface of the gate electrode layer 104 without being vapor-deposited in the hole 114 to form a peeling layer 105.

Next, when Mo (molybdenum) as an emitter material is deposited on the hole side of such a substrate by vapor deposition, the vapor deposited Mo is deposited on the bottom of the hole 114, that is, the resistance layer as shown in FIG. Simultaneously with the deposition and deposition on the emitter layer 102, the emitter material is also deposited on the release layer 105. The opening is closed by the emitter material 106 deposited on the peeling layer 105, and at the same time, a cone-shaped emitter (hereinafter, referred to as “emitter cone”) 115 is formed on the resistance layer 102. Become. Thereafter, the substrate is immersed in phosphoric acid, which is a solution of the release layer 105, and the release layer 105 and the emitter material 106 on the gate electrode layer 104 are removed to remove the FEC as shown in FIG. Obtainable.

The field emission device used in the present invention is not limited to the Spindt-type manufacturing method described above.
For example, a flat-type field emission device can be used as long as the device performs field emission. Further, the present invention can be applied to a surface conduction type field emission device.

[0027]

As described above, the electrostatic recording head of the present invention uses a field emission element, and the recording needle is formed by leading the anode to the outside by a metal thin film pattern. A small head can be used, and a high resolution electrostatic latent image can be projected with a sufficiently small recording needle (pin) interval. In addition, it is easy to design so as to reduce the capacitance between the anodes, so that image distortion and image unevenness can be prevented. Each field emission cathode can be made to draw sufficient current despite its small size,
Further, by adopting the dynamic driving method, there is an effect that the circuit can be simplified easily.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an outline of an electrostatic recording head of the present invention.

FIG. 2 is a configuration diagram viewed from a side surface of a cathode array and an anode electrode constituting the field emission device.

FIG. 3 is an explanatory diagram showing an example of an arrangement of field emission cathodes and wiring patterns of electrodes.

FIG. 4 is an explanatory diagram showing an embodiment of a drive circuit for performing dynamic driving.

FIG. 5 is a signal waveform diagram of a change in anode potential and a drive voltage between a gate and a cathode.

FIG. 6 is a graph showing a relationship between a discharge start recording voltage and a gap distance.

FIG. 7 is a schematic diagram when an electrostatic recording head using a field emission element is applied to an electrostatic printer.

FIG. 8 is a process chart showing an example of a method for manufacturing a field emission cathode.

[Explanation of symbols]

Reference Signs List 1 drive board, 2 electron emission section, 3 recording head section, 6
Vacuum envelope, 7 anode electrode substrate

Claims (4)

[Claims] 1. A field emission cathode formed on one surface of a vacuum envelope, and a plurality of strips formed of a metal film on the other surface of the vacuum envelope facing the field emission cathode. Wherein each of the plurality of anode electrodes is directly led out of the vacuum envelope to form a pin array. 2. The electrostatic recording head according to claim 1, wherein said field emission cathode comprises a cone-shaped emitter and a gate, and is blocked corresponding to the anode. 3. The electrostatic recording head according to claim 1, wherein said electrostatic recording head is connected so as to be dynamically driven by an emitter electrode and a blocked gate electrode. 4. A field emission cathode formed on at least one surface of a vacuum envelope in proximity to a dielectric layer formed on a surface of a drum, and a cathode of the vacuum envelope facing the field emission cathode. A plurality of strip-shaped anode electrodes formed of a metal film on the other surface, and each of the plurality of anode electrodes is directly led out of the vacuum envelope and provided with an array of pins. And a developing device for developing a latent image formed by the electrostatic recording head, and a transfer device for transferring an image developed by the developing device to recording paper.