JPH0622104B2 - Optical writing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical writing device used in an optical printer or the like, and more particularly to an optical writing device composed of a dot array fluorescent tube.

2. Description of the Related Art In recent years, as an electrophotographic optical printer for recording the output from a computer or the like, an optical writing device for converting the output into an optical signal has been developed which is composed of a dot array fluorescent tube.

Such a conventional dot array fluorescent tube will be described with reference to FIGS. 6 and 7. In this dot array fluorescent tube 1, a face glass 4 is placed on a substrate 2 via a spacer glass 3 to form a vacuum container. 5 is formed.

In this vacuum container 5, a large number of anode electrodes 6 are arranged on the surface of the substrate 2 to form dot-like phosphors 7 on the surface of each anode electrode 6, and the filaments corresponding to the anode electrodes 6 are connected. A (cathode electrode) 8 is provided, and one grid electrode (lattice electrode) 10 is interposed between the anode electrode 6 and filament 8 via an insulating layer 9 on the substrate 2.

The method of forming the dot array fluorescent tube 1 will be described in detail. First, the anode electrode 6 is formed on the substrate 2, the insulating layer 9 is formed on the anode electrode 6 by screen printing except for the width of 200 μm, and then, for example, The dot-shaped phosphor 7 of 60 × 60 μm is formed in the central portion of the portion (200 μm portion) where the insulating layer 9 is absent by an electrodeposition method or a photo-etching method,
Next, the grid electrode 10 is fixed on the insulating layer 9.

In the dot array fluorescent tube 1 thus constructed, thermoelectrons are emitted by supplying an alternating voltage of, for example, 20 V to the filament 8, and at this time, a positive voltage of, for example, 40 V is applied to the anode electrode 6 and a grid. For example, 20V for electrode 10
The positive electrons are applied to the fluorescent electrodes 7 while being accelerated by the grid electrode 10 while being accelerated, so that the fluorescent substances 7 emit light.

Therefore, by selecting the anode electrode 6 to which the voltage is applied according to the print information, the light corresponding to the image or the like is emitted to the outside through the face glass 4, so that the emitted light is used for charging. An electrostatic latent image can be formed by scanning the formed photoconductor, and a desired image can be recorded on a recording sheet by executing a normal electrostatic recording process thereafter.

However, in such a dot array fluorescent tube 1, since a part of the anode electrode 6 is exposed, the potential distribution near the anode electrode 6 becomes as shown by the broken line in FIG. 8, and the thermoelectrons emitted from the filament 8 are generated. Since a part of the current flows to the exposed portion of the anode electrode 6 where the phosphor 7 is absent, it does not contribute to light emission.
Luminous efficiency deteriorates.

Therefore, when an optical writing device is configured by the dot array fluorescent tube 1, the anode voltage applied to the anode electrode must be increased in order to make each light emitting dot emit light with high brightness, and a high withstand voltage drive IC is required. In addition to the necessity, there arises a problem that the deterioration of the phosphor becomes severe.

Aim The present invention has been made in view of the above points, and an object thereof is to improve the luminous efficiency of a dot array fluorescent tube.

In order to achieve the above-mentioned object, the present invention is an optical writing device comprising a dot array fluorescent tube provided with a large number of anode electrodes having dot-shaped phosphors formed on the surface thereof and cathode electrodes corresponding to the anode electrodes. In the device, an insulating layer that covers a portion of the anode electrode other than the phosphor is formed, and a first grid electrode having a window having substantially the same shape as the phosphor is provided on the insulating layer, and the first grid electrode A second grid electrode having slit-shaped openings corresponding to the rows of phosphors is provided between the cathode electrode and the first grid electrode, and a voltage lower than the voltage applied to the second grid electrode is applied. It is a feature.

Operation According to the optical writing device configured as described above, the potential distribution near the anode electrode becomes as shown by the broken line in FIG.
The thermoelectrons accelerated by the grid electrode and the anode electrode are concentrated on the phosphor portion by the action of the focusing lens by the first grid electrode.

As a result, luminous efficiency is increased, and high-luminance light emission by low voltage driving is possible.

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

Hereinafter, a specific description will be given based on an embodiment of the present invention.

FIG. 1 and FIG. 2 are a side sectional view and a plan view of an essential part showing an example of a dot array fluorescent tube constituting an optical writing device embodying the present invention.

This dot array fluorescent tube 11 comprises a face glass 1 on a substrate 12 made of glass or the like via a spacer glass 13.
4 is mounted and the vacuum container 15 is formed. In addition, the bonding of each of these glasses is usually performed with a low melting point glass.

Further, on the inner surface of the face glass 14, in order to prevent the influence of an external electric field and to prevent the electric field distribution from being disturbed due to the charging of the surface by a thermoelectron beam, a transparent electrode film is formed to form a cathode potential or It is better to apply a grid potential.

Then, inside the vacuum container 15, a large number of anode electrodes 16 made of a metal thin film such as Al are arranged in a row in the longitudinal direction of the vacuum container 15 on the substrate 12, and ZnO powder, for example, is formed on the surface of the anode electrode 16. Reduced Zn-rich ZnO:
The dot-like phosphor 17 using Zn is formed to form a light emitting dot.

On the other hand, above the inside of the vacuum container 15, a filament 18 corresponding to the anode electrode 16 is formed by applying an oxide to a thin wire of tungsten along the arrangement direction of the anode electrode 16 by means of supports 19 and 19. The spring members 20 and 20 are tensioned and tensioned by the spring members 20.

Then, between these anode electrodes 16 and filaments 18, a first insulating layer 22 is formed on the substrate 12 to cover a portion other than the phosphor 17 made of SiO ₂ and the first insulating layer 22 is formed. And a second insulating layer 24 made of glass is formed on the substrate 12.
The second grid electrode 25 is provided on the second insulating layer 24.

The method of forming this dot array fluorescent tube 11 will be described in detail. First, an anode electrode 16 is formed on a substrate 12 made of glass or the like by a photo-etching method or the like, and a first insulating layer 22 is formed on the substrate 12 by a sputtering method of SiO 2. It is formed of a film, and the first grid electrode 23 is further formed on it as a thin film.

Then, in order to form the phosphor 17 also with reference to FIG. 3, a window is opened in the first lattice electrode 23 and the first insulating layer 22 by the photo-etching method, and the fluorescent light is emitted in the portion W where the window is opened. By attaching the body by an electrodeposition method (electrophoresis method) to form the phosphor 17 on the anode electrode 16, the phosphor 1
The structure other than 7 is covered with the first insulating layer 22, and the first lattice electrode 23 is provided on the first insulating layer 22.

Next, by forming the second insulating layer 24 on the substrate 12 and forming the second lattice electrode 25 thereon, the second lattice electrode 25 is formed between the first lattice electrode 23 and the filament 18. It has an intervening structure.

It should be noted that slits 25a are formed in the second grid electrode 25 in correspondence with the rows of the phosphors 17 so that the light emitted from each minute light emitting dot is not blocked and the effective rate of the light emitted is improved. At the same time, the variation in the brightness of the emitted light is suppressed.

Further, the respective anode electrodes 16 of the dot array fluorescent tube 11 are extended alternately (in a zigzag pattern) on both sides outside the vacuum container 15, and driving ICs (not shown) are connected by wire bonding or the like. Configure an optical writing device.

In the dot array fluorescent tube 11 configured as described above, thermoelectrons are emitted by supplying an alternating voltage of 10 to 20 V to the filament 18 for heating.

At this time, by applying a voltage of, for example, +40 V to the anode electrode 16 while applying a voltage of, for example, +20 V to the second grid electrode 25, the thermoelectrons hit the phosphor 17 while being accelerated by the second grid electrode 25. , The phosphor 17 emits light. The voltage applied to the first grid electrode 23 will be described later.

At this time, the emission spectrum when the phosphor 17 is ZnO: Zn has a peak at 505 nm and is shorter than 410
nm, a wide characteristic of 650 nm on the long wavelength side.

Therefore, by selectively applying a drive voltage to each anode electrode 16 in accordance with the print information, it is possible to cause the required light emitting dots to emit light for printing.

By the way, in this dot array fluorescent tube 11, as described above, since the portion other than the phosphor 17 on the anode electrode 16 is covered with the first insulating layer 22, the anode electrode 16 is not exposed and 2 Lattice electrode 25 and first insulating layer 2
A first grid electrode 23 having a window having substantially the same shape as that of the phosphor 17 is provided between the first grid electrode 23 and the second grid electrode 23.

Therefore, a predetermined voltage V ₁ (V ₂ > V ₁ , lower than the voltage V ₂ applied to the second grid electrode 25 is applied to the first grid electrode 23).
However, by applying (V ₁ may be positive or negative), the potential distribution in the vicinity of the anode electrode 16 becomes as shown by the broken line in FIG. 4, so that the second grid electrode 25 and the anode electrode 16 The accelerated thermoelectrons are concentrated on the phosphor 17 part.
That is, since the first grid electrode 23 acts as a focusing lens, the luminous efficiency is improved.

As a result, high-luminance light emission can be achieved by driving at a low voltage, so that the driving IC can have a lower voltage and the phosphor can have a longer life.

In addition, as described above, the first insulating layer 22 and the first grid electrode 2
By opening the window in 3 to form the phosphor 17,
In addition to facilitating the production of the grid electrode, the size of the phosphor 17 is restricted to the size opened through the first insulating layer 22, so that the size of the light emitting dot becomes substantially constant.

Therefore, in the conventional phosphor forming method, the electrodeposition method causes protrusion from the electrode portion, and the photo-etching method causes variations in size, resulting in variations in the size of each light emitting dot and uneven light amount. However, such uneven light amount is suppressed.

FIG. 5 is a schematic configuration diagram showing an example of an optical printing apparatus using the optical writing device embodying the present invention.

In this optical printing device (optical printer), the photosensitive drum 31 is rotated in the direction of arrow P at the start of printing, and the charging charger 32 uniformly charges the surface of the photosensitive drum 31. Let

Then, each light emitting dot of the dot array fluorescent tube of the optical writing device 33 constituted by connecting the driving IC to the dot array fluorescent tube embodying the present invention selectively emits light according to the print information, and the optical writing device 33 is formed. The light emitted from the dot array fluorescent tube is radiated onto the photosensitive drum 31 via an equal-magnification imaging element 34 composed of a converging optical fiber lens or the like, and an electrostatic latent image corresponding to the print information is radiated on the photosensitive drum 31. Form an image.

After that, the electrostatic latent image on the photoconductor drum 31 is visualized by a developer attached to the developer by the developing device 35, and transferred to the recording paper 37 fed by the transfer charger 36.

Then, the recording paper is passed through a fixing device (not shown) to be fixed and discharged to an external paper discharge tray or the like, while the residual charges on the photoconductor drum 31 are erased by the discharging lamp 38, and then the residual development is performed. The agent is removed by the cleaner 39 to prepare for the next recording step.

In addition, in the above-mentioned embodiment, the example in which one second grid electrode is provided is described, but a plurality of second grid electrodes may be provided.

Effect As described above, according to the present invention, the light emission efficiency of the dot array fluorescent tube that constitutes the optical writing device is improved, and high-luminance light emission by driving at a low voltage becomes possible. Therefore, it is also possible to reduce the voltage of the driving IC and extend the life of the phosphor.

[Brief description of drawings]

FIGS. 1, 2 and 3 are a side sectional view, a plan view of a main part and an enlarged plan view of a main part of a dot array fluorescent tube showing an embodiment of the present invention, and FIG. FIG. 5 is a schematic diagram showing an example of an optical printing apparatus using the optical writing device embodying the present invention, and FIGS. 6 and 7 are conventional dot array fluorescent tubes. FIG. 8 is a side sectional view, an enlarged plan view of an essential part, and FIG. 8 is an explanatory view showing a potential distribution near the anode electrode. 11-dot array fluorescent tube, 12-substrate 15-vacuum container, 16-anode electrode 17-phosphor, 18-filament (cathode electrode) 22-first insulating layer, 23-first grid Electrode 24: second insulating layer, 25: second lattice electrode

Claims (1)

[Claims] 1. An optical writing device comprising a dot array fluorescent tube having a large number of anode electrodes having dot-shaped phosphors formed on the surface thereof and cathode electrodes corresponding to the anode electrodes.
An insulating layer is formed to cover a portion of the anode electrode other than the phosphor, and a first grid electrode having a window having substantially the same shape as the phosphor is provided on the insulation layer, and the first grid electrode and the cathode electrode. A second grid electrode having slit-shaped openings corresponding to the rows of the phosphors is provided between the first and second grid electrodes, and a voltage lower than the voltage applied to the second grid electrode is applied to the first grid electrode. Optical writing device.