JPS62119857A - Light source of optical printer - Google Patents

Abstract

PURPOSE:To reduce ineffective current flowing into a control electrode so as to prevent heat generation by forming the control electrode in a vacuum fluorescent lamp, which is used as the light source of an optical printer, with the surface of the control electrode except the control section coated with an insulation layer. CONSTITUTION:Electrons emitted from a cathode 15 are attracted to a 1st control electrode 13 to which positive voltage is always impressed. The whole surface of the electrode 13 except a slit 14 and a control section 13a is coated with an insulation layer 18 and electron trajectories are concentrated to the slit 14 and its vicinity. Electrons pass the slit 14 almost perpendicularly moving toward a second control electrode 6. On the second control electrode 6 which opposes light emitting dots, a positive voltage is applied and the electrons passing through its slit 11 bombard a fluophor layer 3 to cause light emission. If light emission is not desired, a negative voltage is impressed on the second control electrode to deflect the electrons, causing most of the electrons to reach the aforementioned first control electrode 13. Thus, out of the first control electrode 13, only the part which contributes to the control of light emission is made to work as a control electrode with the rest covered with the insulation layer 18, thereby current flowing through the first control electrode can be reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical printer, and in particular to a light source for an optical printer that uses a vacuum fluorescent tube, which applies the principle of a fluorescent display tube, as a light source. .

[Prior art]

Generally, as shown in FIG. 6, an optical printer includes a recording medium lot such as a photosensitive drum or a belt, a charging device 102 that uniformly charges the surface of the recording medium 101, and a recording medium 101 charged in the charging process. ON/O by write signal
FF L, and a light source 103 that emits light.

A developing device 104 that is irradiated with light through this exposure step, causes the charge to escape, and attaches toner to the area where the potential has decreased;
A transfer bag @105 to be transferred to paper after this development process,
A fixing device 106 that fixes the transferred paper using heat or the like; a static eliminator 107 that erases electric charge from the surface of the recording medium 101 after the transfer process; and a static eliminator 107 that removes toner remaining on the surface of the recording medium 101 after the static neutralization process and cleans the surface. The cleaning device 108 is comprised of a cleaning device 108 that performs cleaning operations.

Optical printers are classified as follows depending on the type of light source used in the exposure process.

Use a laser emitting device as a light source and turn on the laser beam.
A laser printer is a method that scans the recording medium while it is OFF, but the device is complicated and large, and
Since there is a drive mechanism for a high-speed rotating mirror that scans the laser beam, there are disadvantages in that it takes time to stabilize at high speed and a lack of reliability due to wear of the rotating parts.

In addition, LED printers that use LEDs as light sources are
The problem is that the technology to connect multiple D units is difficult, and since each LED element is an independent unit, there is variation in luminance, and it is difficult to sort them to make the luminance uniform. was there.

In order to solve these problems, a vacuum fluorescent tube based on the principle of a fluorescent display tube has been proposed as a light source for an optical printer.

For example, Japanese Patent Laid-Open No. 59-46740 discloses vacuum fluorescent tubes for optical printers with a static drive method with a duty of 1 and a dynamic drive method with a duty of 1/2. The tube has a large number of light-emitting dots, approximately 3,000 of which are required for an A4 size sheet, so there is a problem in that the number of anode leads and driving ICs increases and the manufacturing cost increases.

Therefore, in order to solve the above-mentioned problem, the present applicant proposed the fourth method.
＠, has proposed a dynamically driven vacuum fluorescent tube with a tetrode structure as shown in FIG. 5 as a light source for printers. In this light source for a printer, as shown in FIGS. 4 and 5, a substrate 1 is formed of an insulating material such as glass. Board 1
The size of the width varies depending on the size of the paper you are printing on.
For A4 size paper, approximately 300 cm is required, but regardless of the size of the paper, the length is approximately 20 mm, resulting in a long and narrow shape.

On the surface of the substrate 1, a plurality of linear anode conductors 2 made of aluminum thin films are arranged in parallel with each other at regular intervals in the longitudinal direction. The line width of the anode conductor 2 is 0.1 m or less, and the distance between the anode conductors 2 is also 0.1 m or less. Therefore, even if eight anode conductors 2 are arranged in parallel, the width of the anode conductors 2 in the arrangement direction is 1 to 2 mm. That is, it has a shape in which two groups of anode conductors each having a width of 1 to 2 mm are located in the center of a glass substrate 1 having a width of 20 m.

A phosphor layer 3 is formed by depositing a phosphor on the surface of the anode conductor 2 by electrodeposition.The anode 4 is constituted by the anode conductor 2 and the phosphor layer 3.

Next, a second control electrode 6 is placed at a certain height above the anode 4.
to be placed. In order to maintain a constant height, an insulating layer 5 mainly composed of crystalline glass frit is printed on both edges of the anode 4 of the substrate 1 to a constant height, and then baked and fixed. A second control electrode 6 is provided on this insulating layer 5 with a constant gap therebetween. Since one second control electrode 6 controls the number of anode conductors 2, approximately 380 sheets are required for A4 size.

This second control electrode 6 includes a control portion 7 located on the anode 1 body 2 and diagonally crossing the anode conductor 2, and a control portion 7 extending integrally from both ends of the control portion 7 in a direction perpendicular to the anode conductor 2. It is composed of holding parts 8, 8.

Further, a terminal portion 10 is formed by extending from one holding portion 8 to the outside of the envelope 9.

The control portion 7 of the second control electrode 6 has a slit 11 formed in a direction obliquely intersecting the anode conductor 2 .

The width of this slit 11 is the width of the light emitting dot, so all the slits 11 are formed to have the same width. Further, the length of the slit 11 is set so that all of the plurality of anode conductors 2 can face each other.

The holding portion 8 of the second control electrode 6 is made of the same metal plate as the control portion 7 and is formed to hold the control portion 7 at a constant distance from the anode.

The second control electrodes 6 are electrically insulated from adjacent second control electrodes 6 with a space for individual control.

A spacer 12 made of an insulating material is provided above the second control electrode 6.
The first control electrode 13 is adhesively fixed thereto. 1st
The control electrode 13 is made of a single metal plate.

At the center thereof, at a position facing the slit 11 of the second control electrode 6, one
A slit 14 with a large circumference is formed to form a control section 13a. Further, holding portions 13b made of metal plates are provided on both edges of the control portion 13a. A positive potential voltage is always applied to the entire first control electrode 13 from a terminal (not shown).

Above the first control electrode 13, two filament-shaped cathodes 15 are stretched in the longitudinal direction. The cathode 15 is disposed above both ends of the anode conductor 2 in the arrangement direction.

A front container portion consisting of a side plate 16 and a front plate 17 is sealed so as to cover the electrodes such as the anode, control electrode, and cathode,
1 which constitutes an envelope 9 together with the glass substrate 1 and maintains the inside of the envelope 9 at a high vacuum, and each terminal 10 of the second control electrode 6 led out from the envelope 9 are as shown in the figure. The anode 4 is scanned with a time-division pulse signal, and a positive write pulse signal is applied to a desired second control electrode 6 in synchronization with this scan, thereby causing the cathode 15 to be connected to a driver IC. The structure is such that electrons can pass through the slits 11.14 and strike the phosphor layer 3 to emit light. At this time, since a positive voltage is always applied to the first control electrode 13 as shown in FIG.
3. Electrons from the cathode will be attracted to the entire surface. However, the only effective electrons that contribute to light emission are the slit 14 and the control section 13a in its vicinity, and the electrons flowing to the holding section 13b become an ineffective grid current that does not directly contribute to light emission.

When the grid current increases, the control electrode generates heat, which causes thermal deformation of the control electrode, and the distance between the anodes 4 and 4 changes, resulting in a change in brightness, making it impossible to obtain a constant brightness. There have also been problems such as a decrease in luminous efficiency due to an increase in the temperature inside the envelope 9, and a problem that the substrate warps due to the difference in coefficient of thermal expansion.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and is intended to reduce the reactive current flowing to the control electrode in a light source for an optical printer that applies a dynamic drive, anode scan type vacuum fluorescent tube. It is an object of the present invention to provide a light source for an optical printer that can eliminate variations in brightness, decreases in brightness, and warpage of a substrate due to heat generation.

[Structure of the invention]

To achieve the above object, the light source for an optical printer of the present invention comprises: a plurality of anode conductors arranged parallel to each other in the longitudinal direction on a substrate; and a phosphor layer coated on the surface of the anode conductors. a control electrode spaced apart above the anode; a filament cathode spaced apart above the control electrode; The light source for an optical printer that emits light in a shape is characterized in that an insulating layer is provided on the surface of the control electrode excluding the control portion.

[For production]

A structure in which an insulating layer such as a glass plate is disposed on the cathode side surface excluding the slit and the control part in the vicinity of the first control electrode, which is constructed by diagonally drilling slits in a single metal plate. It has become.

In other words, only the portion necessary for electrical action as a control electrode is made conductive, and the surface of the other mechanically necessary portions is insulated. Therefore, the electrons emitted from the cathode are attracted only to the control part of the control electrode, and the area of the conductive control electrode is reduced to 1/2 compared to the conventional one.
It will be about 3.

The grid current decreases accordingly. However, since the reactive current was reduced, the heat generation of the control electrode was also reduced, and the temperature rise of the light source was almost eliminated.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings shown in FIGS. 1, 2, and 3.

FIG. 1 is a plan view with a part of the light source of the present invention cut away, and FIG. 2 is a plan view with the same embodiment cut away and the main parts enlarged. FIG. 3 is an enlarged longitudinal sectional view of the same embodiment.

The same parts as in the conventional example will be described with the same numbers as in the conventional example.

Reference numeral 1 indicates an insulating substrate, and a glass substrate is generally used. The dimensions of the board depend on the printing capacity of the optical printer to which the device is installed, but for example, if the light source is for a printer used to print on A4 size paper, the width in the longitudinal direction is about 300 na, and the vertical width is the same as the print size. Regardless, they all have an elongated shape of about 20 mm.

On the surface of the substrate 1, a plurality of (eight in this embodiment) linear anode conductors 2 are formed in parallel to each other in the longitudinal direction. This anode conductor 2 can be formed by leaving an aluminum thin film deposited on the entire surface of the substrate 1 as a linear anode conductor by photolithography. Also,
The end of the linear anode conductor 2 is formed of the same aluminum thin film as the wiring pattern (not shown), and is connected to the anode terminal 20 .

Next, an insulating layer 5 is formed on the entire surface of the substrate 1 except for the anode conductor 2 portion by a thick film printing method. This insulating layer 5 is formed to a certain thickness by depositing a paste containing crystalline glass frit as a main component and then firing it.

Then, the substrate 1 with the insulating layer 5 formed thereon is deposited by electrodeposition.
A phosphor layer 3 is formed by depositing a phosphor on the linear anode conductor 2.
to form. The phosphor layer 3 is evenly deposited on the linear anode conductor 2. The anode conductor 2 and the phosphor layer 3 form an anode 4.

Above the anode 4, a large number of second control electrodes 6 are arranged in parallel with gaps between them so as to be insulated from each other with the insulating layer 5 interposed therebetween. Each of the second control electrodes is made of a metal flat plate member that diagonally intersects with the arrangement direction of the anode conductor 2, and a slit 11 is provided in the center of this obliquely intersecting portion.
is drilled.

Therefore, when viewed through the slit 11, the linear anodes look like dots and are arranged diagonally. A cathode 15, which will be described later, is formed by the diagonal portion having the slit 11.
Since it controls the electrons from the

Holding parts 8 made of a flat metal member are continuously formed at both ends of the control part 7, and hold the control part 7 at a constant height from the anode. Further, one of the holding parts is connected to the substrate 2 and the side plate 16.
A terminal 10 is formed extending outside the envelope 9 from between the terminals 10 and 10.

Each group of pixel light emitters is constituted by each dot-shaped light emitting portion of the anode 4 diagonally arranged along the slit 11 of each second control electrode.

Next, on the surface of the holding part 8 of the second control electrode 6.

An insulating layer 12 is formed. As an example of the insulating layer 12, a flat glass plate 12 coated with an adhesive is provided. This glass flat plate 12 is used to adhesively fix the second control electrode, to insulate the first control electrode 13 (to be described later), and to space the first control electrode from the second control electrode by a certain height. It is configured.

A first control electrode 13 is provided above the second control electrode 6 via a pair of flat glass plates 12 having a uniform thickness.

The first control electrode 13 is formed from a single metal flat plate member, and is provided with slits 14 that are one size thicker than the slits 11 at positions facing each of the slits 11 of the second control electrode 6. It is set up. This slit 11 and its periphery form a control section 13a. However,
Of the phosphor layer 3, only the portion visible through both slits 11 and 14 is an effective light emitting portion.

Both edges of the slit 14 of the first control electrode 13 are
A holding part 13b made of a metal plate and holding the control part 13a is formed, and an insulating layer 18 made of a flat glass plate is adhesively fixed onto this holding part 13b with an adhesive made of sealing cement or the like. This insulating layer 18 fixes the first control electrode 13 to the insulating layer 12 and also serves as a holding portion 1 which is an electrically unnecessary conductive portion on the surface of the first control electrode 13.
3b to prevent electrons from flowing in from the cathode 15, thereby reducing reactive current. Therefore, the insulating layer 18 may be formed of a material having insulating properties, such as frit glass, instead of a flat glass plate.

Next, above the first control electrode 13, a plurality of filament-shaped cathodes 15 are strung in the longitudinal direction.

Two cathodes 15 are hung above both ends of the slit 14 so as not to block the light emitted from the anode 4.

Then, a box-shaped container portion consisting of a side plate 16 and a flat plate 17 is sealed on the periphery of the substrate 1 with a sealing material so as to cover the electrodes such as the anode 4, control electrodes 6, 13, and cathode 15. It is worn. An envelope 9 is formed by the substrate 1, the side plate 16, and the flat plate 17, and the inside of the envelope 9 is maintained at a high vacuum.

Next, the terminal 10 of the second control electrode 6 led out from the sealed envelope 9 is connected to a driver circuit (not shown), etc., and the anode 4 is scanned by time-division pulses, and a display synchronized with the scanning is performed. It is configured such that a pulse signal is applied to a desired second control electrode to selectively cause the target light-emitting dots of the phosphor layer 3 to emit light.

Next, the operation of the above configuration will be explained.

Electrons emitted from the cathode 15 are attracted to the first control electrode 13 because a positive voltage is always applied thereto. However, since the first control electrode 13 is entirely covered with the insulating layer 18 except for the slit 14 and the control portion 13a at the periphery thereof, the trajectory of the electrons is as shown in FIG. It will be concentrated at the periphery. The electrons accelerated by the electric field pass through the slit 14 in a substantially vertical trajectory and head toward the second control electrode 6. A positive voltage is applied to the second control electrode 6 facing the dot to be emitted. Therefore, the electrons passing through the slit 11 of the second control electrode 6 impinge on the phosphor layer 3 and emit light.

When not emitting light, a negative voltage is applied to the second control electrode, so the path of electrons is bent and most of them reach the first control electrode 13. Therefore, the second control electrode 6
The light does not pass through the slit 11 and strike the phosphor layer 3.

In this way, only the part of the first control electrode 13 that contributes to control of the internal origin functions as a control electrode, and the remaining part, that is, the part that functions to hold the first control electrode and provide mechanical strength. By covering the first control electrode with an insulating layer 18 to eliminate electrical action, the current flowing through the first control electrode can be reduced.

〔effect〕

As explained above, the light source for an optical printer of the present invention has a structure in which the slit portion of the first control electrode near the filamentary cathode and its surroundings are covered with an insulating layer, and the other portions are covered with an insulating layer. The grid current flowing through the 1 control electrode was approximately 150+IIA, but the light source of the present invention was 5
The current was reduced to 0 mA or less, and the same brightness as the conventional one was obtained.

This makes it possible to reduce reactive current that does not contribute to light emission, and has the effect of saving energy.

In addition, since the reactive current can be reduced, the grid current can be reduced and heat generation of the control electrode can be prevented, which has the effect of preventing warpage of the substrate due to heat generation and reduction in brightness due to temperature rise and fall of the phosphor.

Furthermore, since it is possible to reduce the power capacity of the filament-shaped cathode, it leads to cost reduction and has a great practical effect.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view of an embodiment of the present invention;
Figure 2 is an enlarged plan view showing the main parts of Figure 1 with cutouts;
FIG. 3 is an enlarged sectional view of the main part of FIG. 1, FIG. 4 is a plan view of the main part of a conventional vacuum fluorescent tube, FIG. 5 is an enlarged sectional view of the same embodiment, and FIG. , is an explanatory diagram showing the configuration of an optical printer. 1... Substrate 2... Anode conductor 3... Phosphor layer 4
...Anode 6...Second control electrode 7...Control unit 1
3... First control electrode 13a... Control section 15...
・Filamentary cathode 18... Insulating layer Patent applicant Futaba Electronics Co., Ltd. Figure 4 Figure 6

Claims (3)

[Claims] (1) An anode consisting of a plurality of anode conductors arranged parallel to each other in the longitudinal direction on a substrate, a phosphor layer deposited on the surface of the anode conductor, and a phosphor layer spaced apart above the anode. In a light source for an optical printer, the light source has a control electrode arranged and a filament-like cathode stretched apart above the control electrode, and causes a phosphor layer of the anode to emit light in a dot shape. A light source for an optical printer, characterized in that an insulating layer is provided on the surface excluding the control section. (2) The optical printer according to claim 1, wherein the control electrode includes a first control electrode close to the cathode and a second control electrode close to the anode, and an insulating layer is provided on the surface of the first control electrode. light source. (3) A light source for an optical printer according to claim 1 or 2, wherein the insulating layer is a flat glass plate.