JPH0642360B2 - Light source for printer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light source for an optical printer to which the principle of a fluorescent display tube is applied, and in particular, the fluorescent material is provided through a transparent substrate provided with a phosphor layer. The present invention relates to a light source for a printer, which utilizes the principle of a front emission type fluorescent display tube for observing light emission of a body layer.

[Prior Art] In recent years, optical printers using various light sources have been proposed. FIG. 4 schematically shows the structure of a general optical printer as an example. In FIG. 4, 1 is a photosensitive drum as a recording medium. The photosensitive drum 1 rotates clockwise in the figure, and the surface of the photosensitive drum 1 is charged by the charger 2. On the surface of the charged photosensitive drum 1, the light source 3
Is irradiated with dot-shaped light to form a latent image such as characters and figures, and the latent image is developed by the developing device 4. The transfer paper 6 stored in the cassette 5 is designed to be sent between the surface of the photosensitive drum 1 and the transfer heater 7, and the characters and figures on the surface of the developed photosensitive drum 1 are transferred to the transfer paper 6. The transfer sheet 6 is configured so as to be continuously heat-sensitively transferred. In the figure, numeral 8 is an erasing lamp for erasing transferred characters and the like, and numeral 9 is a cleaning blade for cleaning the surface of the photosensitive drum 1.

The light source of the optical printer includes a laser device, an LED,
Although a CRT or the like can be used, from the viewpoint of reliability as a light source, manufacturing cost, etc., recently, in addition to these various light emitting devices, a light source applying the principle of a fluorescent display tube has come to be used. .

A fluorescent display tube is a type of multi-pole electron tube in which various kinds of electrodes and a phosphor serving as a light emitting portion are provided inside an envelope kept in a high vacuum atmosphere. In the conventional fluorescent display tube, an anode conductor having a phosphor is provided on the inner surface of an anode substrate that constitutes an envelope, and electrons emitted from a filament cathode are emitted to the anode substrate to make it emit light. This light emitting display is observed through the facing front plate. There is also known a front emission type fluorescent display tube in which the anode substrate and the anode conductor are made of a translucent material so that the emission of the phosphor can be observed through the anode substrate.

FIG. 5 is a partially cutaway plan view showing a printer light source 10 having a quadrupole structure proposed by the present applicant in Japanese Patent Application No. 60-174997. The printer light source 10 has a configuration to which the conventional fluorescent display tube is applied.

As shown in the figure, a plurality of linear (or band-shaped) anode conductors 12 are arranged in parallel with each other on the surface of the substrate 11, and a phosphor layer 13 is provided on the upper surface of each anode conductor 12. A plurality of anodes 14 are formed by successively depositing each.

A plurality of second control electrodes 15 are provided above the anode 14 via an insulating layer (not shown) provided in the peripheral portion of the substrate 11.
Is provided. The second control electrodes 15 are made of flat plate members that obliquely intersect the arrangement direction of the anode conductors 12 and are arranged in parallel with each other. Further, the second control electrodes 15 are electrically separated from each other, and are configured to receive print signals respectively. In addition, the anode conductor 12 is provided at the center of each second control electrode 15.
Slit-shaped openings 16 (hereinafter referred to as slits 16) are formed obliquely across each other, and only the portion of the phosphor layer 13 defined by the slits 16 is exposed to electrons. Light-emitting dot 1 that receives and emits light
It is said to be 7. That is, the second control electrode 15 is the phosphor layer 1
This means that it has both a function of forming the light emitting dots 17 by partitioning the three, a function of controlling blinking of the light emitting dots 17, and two functions.

Next, insulating spacers (not shown) are provided on both edges of the second control electrode 15, and the first control electrode 18 is provided above the second control electrode 15 with the spacers interposed therebetween. It is provided. The first control electrode 18 is formed of a single plate material, and a slit 19 that is slightly larger than the slit 16 is formed at a position corresponding to each slit 16 of the second control electrode 15. Therefore, the portion of the phosphor layer 13 of the anode 14 that appears in the gap between the second control electrodes 15 is hidden by the first control electrode 18, and the effective emission portion is the emission dot 17 as described above. Will only be. It is not necessary to continuously deposit the phosphor layer 13 on the anode conductor 12 as described above, depending on the manufacturing convenience, etc., and the phosphor layer 13 is deposited on at least the portion seen through the slit 16. You should keep it as it is.

Next, a filament cathode 20 is stretched over the first control electrode 18. And the substrate 1
A container portion composed of a side plate 21 and a front plate 22 is sealed to 1 by a sealing material, and the inside thereof is kept in a high vacuum atmosphere.

Next, each electrode such as the grid terminal 23 led out of the sealed container is connected to a driver circuit (not shown),
Each anode 14 is scanned with a time-division pulse signal, and a positive display pulse signal synchronized with the scanning is applied to a desired second control electrode 15
Is applied to selectively emit light from the light emitting dots 17 of the phosphor layer 13.

Further, a negative voltage (cut-off bias) can be applied to the second control electrode 15 corresponding to the phosphor layer 13 (or the emission dot 17) which is not desired to emit light, in order to prevent leakage light emission. . Also, due to the negative potential created by this cut-off bias, the electrons are repulsed and their course is bent, so that they cannot hit the luminescent dot 17 desired to be luminescent-displayed, and part of the luminescent dot 17 does not emit light. It may happen. A positive voltage is applied to the first control electrode 18 provided in order to prevent such a phenomenon (called vignetting), and the first control electrode 18 and the filamentous cathode 20 are connected to each other. It is configured so that the electric field can be kept substantially uniform.

Next, when the printer light source 10 having the above configuration is mounted as a light source of an optical printer, the printer is arranged so that the moving direction of the photosensitive drum 1 as a recording medium and the longitudinal direction of the anode conductor 12 intersect at a right angle. Light source 10 for photosensitive drum 1
Install near the. The oblique arrangement direction of the light emitting dots 17 divided by one slit 16 is inclined with respect to the axial direction of the photosensitive drum 1. However, the width of each light emitting dot 17 determined by the width of the slit 16 in the longitudinal direction of the anode conductor 12 (that is, the axial direction of the photosensitive drum 1) is set appropriately, and the light emitting timing of each light emitting dot 17 is set by an appropriate electrical signal processing. If is adjusted appropriately according to the rotation speed of the photosensitive drum 1, dot-like light emitted by each light-emitting dot 17 is continuously connected to a position on a straight line parallel to the axis of the surface of the photosensitive drum 1. Can be reached.

[Problems to be Solved by the Invention] The printer light source has the following problems.

In order to improve the printing quality of the optical printer, the photosensitive drum 1
Each luminescent dot 1 is placed on a straight line parallel to the surface axis.
In order to allow the light emitted by 7 to reach and form a continuous linear latent image, a large number of second control electrodes 15
The anode 1 is placed at a precise position on the substrate 11 at a predetermined interval.
4 must be installed side by side with an accurate inclination. If the number of the second control electrodes 15 is small and their size, arrangement pitch, etc. are large to some extent, it is not so difficult to dispose them on the substrate 11 accurately. However, actually, the number of the second control electrodes 15 is very large, and the size and the like are also very small. For example, the second control electrode 1
Reference numeral 5 is a metal strip having a width of 1 mm or less and a slit 16 of about 0.1 mm formed therein, and several hundreds of such fine electrodes are arranged at intervals of 0.1 mm or less. There must be. Therefore, the conventional printer light source 10 has a problem that it is difficult to dispose a large number of second control electrodes 15 at accurate positions and at correct angles.

Next, even if a large number of the second control electrodes 15 and the insulating layer of the substrate 11 can be accurately arranged, the second control electrodes 15 are attached to the substrate 11 by a glass adhesive material having a low melting point frit glass as a main component. When fixing on the insulating layer or fixing the envelope by sealing, the substrate 11 or the entire envelope is 400 ° C.
It must be heat treated at a temperature of ~ 500 ° C. At this time, since a difference in thermal expansion occurs between the glass envelope and the metal second control electrode 15, the position and angle of the second control electrode 15 are displaced. Also,
Since the second control electrode 15 is fixed while being heated and expanded, stress is generated after cooling. Then, there is a problem that the second control electrode 15 may be deformed by this stress, and the position and the tilt may be displaced.

Next, when the printer light source 10 is driven, there is a problem that the second control electrode 15 may be heated by a control current and may be deformed by heat.

If each second control electrode 15 is thus deformed or is not arranged with an accurate interval and inclination, the light emitted from each set of light emitting dots 17 divided by each slit 16 will be on the surface of the photosensitive drum 1. So there are no gaps between them,
They overlap unnecessarily. In addition, the light emitted from the two sets of light emitting dot groups partitioned by the two adjacent second control electrodes 15 and 15 is the photosensitive drum 1 respectively.
It breaks without continuation above. That is, a continuous linear latent image parallel to the axis cannot be formed on the surface of the photosensitive drum 1, and the latent image has a broken line shape. Therefore, the printing quality of the optical printer cannot be improved to a desired level.

Next, the first control electrode 18 has a plurality of slits 1 on one plate.
Because of the structure in which 9 is formed, the interval between the slits 19 can be accurately set by using the photolithography method or the etching method. However, as described above, it is difficult to dispose the second control electrode 15 at an accurate position, and it is difficult to arrange the second control electrodes 15 adjacent to each other.
The distance between the control electrodes 15 and 15, that is, the distance between the adjacent slits 16 and 16 is not necessarily constant. Therefore, when disposing the first control electrode 18 above the second control electrode 15, it is not easy to make the upper and lower positional relationships of both slits 16 and 19 overlap each other. There was a problem. Therefore, the arrangement position of the first control electrode 18 is adjusted so that each slit 16 of the second control electrode 15 can be seen from each slit 19 of the first control electrode 18 at least. I had to do some alignment.

[Object of the Invention] A printer in which the arrangement pitch, inclination, and size of light-emitting dots arranged obliquely with respect to the moving direction of a recording medium can be set with high accuracy, and the printing quality of an optical printer can be improved. It is intended to provide a light source for use.

[Structure of the Invention] The light source for a printer of the present invention includes an envelope whose inside is kept in a high vacuum state, a translucent substrate that forms a front plate of the envelope, and is parallel to the inner surface of the translucent substrate. A plurality of band-shaped anode conductors having a light-transmitting property, to which a scanning signal is applied, a phosphor layer deposited on the surface of the anode conductors, and the anode conductors obliquely intersecting the anode conductors. Dot-shaped light emitting portions of the phosphor layer that are provided in a direction in which the slits are formed and are separated from the phosphor layer and that display signals synchronized with the scanning signal are applied and are obliquely arranged along the slits. To the surface of the recording medium that moves in a direction orthogonal to the longitudinal direction of the anode conductor, comprising a control electrode for controlling the emission of light, and a filament cathode extended further from the control electrode. A substrate that transmits the light emitted from the phosphor layer is used. In a front emission type vacuum fluorescent tube that irradiates through the phosphor layer, the dot-shaped light emitting portions of the phosphor layer are arranged so that a plurality of light emitting dots are arranged without gaps when viewed from a direction orthogonal to the longitudinal direction of the anode conductor. A plurality of positioning slits for partitioning into a plurality of light emitting dots are characterized in that a positioning slit portion provided at a position corresponding to the slit of the control electrode is arranged on the translucent substrate.

[Operation] Since the positioning slit portion is provided on the translucent substrate forming the envelope, the positioning slit can be aligned with the light emitting portion of the phosphor layer with high accuracy. Further, since the positioning slit portion can be configured so as not to be adversely affected by the heat treatment in the manufacturing process of the vacuum fluorescent tube, the positional accuracy and the slit interval at the time of disposition do not change.

[Embodiment] FIG. 1 is a sectional view showing a first embodiment of the present invention, in which a positioning slit portion is formed on a front surface emission type vacuum fluorescent tube 24 (hereinafter simply referred to as fluorescent tube 24) having a triode structure. 25 is provided. The main structure of the fluorescent tube 24 is the light source 1 for a printer having the quadrupole structure described in the section [Prior Art].
It can be considered that the first control electrode 18 is excluded from 0. Translucent substrate 26 (hereinafter referred to as substrate 26)
Is made of a glass plate having an insulating property and a high light transmittance. On the inner surface of the substrate 26, a plurality of strip-shaped anode conductors 27 made of a transparent conductive film (ITO film, NES film, etc.) are arranged in parallel to each other by a photolithography technique. Then, a phosphor layer 28 is deposited on the anode conductor 27 to form an anode 29. Further, as shown in FIG. 2, a black insulating layer 30 (crossover 30) is formed on the substrate 26 around the anode 29 by a thick film printing method.

A plurality of control electrodes 31 are provided on the upper surface of the crossover 30.
Is provided. The control electrode 31 is indicated by an arrow A in FIG.
When viewed from the direction, the control electrodes 31 are arranged in a direction that obliquely intersects the longitudinal direction of the anode conductor 27, and the control electrodes 31 are parallel to each other. Further, the respective control electrodes 31 are electrically provided separately from each other, and are configured to receive print signals respectively. A slit 32 is formed in the center of each control electrode 31 in a direction diagonally crossing the anode conductor 27 as viewed in the direction of arrow A. In the conventional printer light source 10, the second control electrode 15 not only controls the blinking of the light emitting dots 17, but also partitions the phosphor layer 13 to form the light emitting dots 1 having a predetermined size.
It also had the role of forming 7. Therefore, the slit 16
The width and position of the light emitting element had to be set accurately, but the control electrode 31 of the present embodiment has a main function of controlling light emission, and the division of the light emitting dot 33 is formed by the positioning slit portion 25 described later. . Therefore, the width of the slit 32 formed in these control electrodes 31 can be set wider than in the past. That is, for example, when the width of the light emitting dot 33 in the longitudinal direction of the anode conductor 27 is set to 0.1 mm, the opening width of the slit 32 of the control electrode 31 is set to be larger than this, 0.2 mm to 0.3 mm, and light is emitted. The part is 0.
It will be 2 mm to 0.3 mm. Even if the position where the control electrode 31 is arranged is slightly shifted, the predetermined portion of the phosphor layer 28, which becomes a light emitting dot having a width of 0.1 mm, is 0.2 mm from the light emitting portion.
It should be 0.3 mm.

Next, a filament cathode 34 is stretched below the control electrode 31. A container portion including a side plate and a back plate 35 (not shown) is sealed to the substrate 26 via a sealing material, and the inside thereof is maintained in a high vacuum atmosphere.

Next, a positioning slit portion 25 is formed on the outer surface of the substrate 26.
Is provided. Positioning slits 25 are formed with positioning slits 36 oblique to the longitudinal direction of the anode conductor 27 in parallel with each other at positions corresponding to the slits 32 of the control electrode 31. These positioning slits 36 partition the light emitting portions of the phosphor layer 28, which are partitioned and set by the slits 32 and are arranged obliquely to the longitudinal direction of the anode conductor 27,
The light emitting dot 33 having an accurate size is formed. That is,
These light-emitting dots 33 are made to emit light at slightly different timings, and the dot-shaped light is applied to a straight line on the surface of the recording medium that is perpendicular to the moving direction. It is possible to form a linear latent image without connecting.

The positioning slit portion 25 of the present embodiment has a positioning slit 3 formed on a stainless plate by using a photolithography method.
6 is formed. However, when driving the fluorescent tube 24
The material is not particularly limited to a metal material such as stainless steel as long as the material has a coefficient of thermal expansion that is as small as possible so that it is less likely to be affected by heat generated, has a light shielding property, and can accurately perform slit processing. For example, a resin plate or the like can be used. Further, the positioning slit portion 25 does not have to be made of a plate-shaped material. For example, the positioning slit portion 25 may be formed by depositing a light-shielding film on the entire outer surface or inner surface of the substrate 26 and removing only the light-shielding film in the portion that becomes the positioning slit 36 by a photolithography method.

Next, when this printer light source is mounted on an optical printer, the printer light source is arranged so that the moving direction (rotating direction) of the photosensitive drum 1 as a recording medium and the longitudinal direction of the anode conductor 27 are at right angles. Is disposed near the photosensitive drum 1.
Then, by scanning the anode 29 and applying a print signal synchronized with this scanning to the control electrode 31, it is possible to illuminate an arbitrary light emitting portion of the phosphor layer 28. The light from the phosphor layer 28 passes through each positioning slit 36 and is applied to the surface of the photosensitive drum 1 at a predetermined size and at a predetermined interval. If the above-described light emission drive in the printer light source and the rotation of the photosensitive drum 1 are synchronized, a continuous linear latent image parallel to the rotation axis can be formed on the surface of the photosensitive drum 1.
Therefore, if the printer light source of this embodiment is used, it is possible to improve the printing quality of the optical printer. Further, since the positioning slit portion 25 can be attached after the assembling work of the fluorescent tube 24 including the heating step, the accuracy of the positioning slit 36 is not affected by the adverse effect of heat. Further, since the positioning slit portion 25 divides the light emitting dots 33, the control electrode 31 does not need to be strictly aligned as in the conventional case.

Next, a second embodiment of the present invention will be described.

The printer light source of the present embodiment is a front emission vacuum fluorescent tube 37 (hereinafter simply referred to as fluorescent tube 37) having a quadrupole structure, in which a positioning slit portion 38 and the like are provided. The structure of the display tube 37 is substantially the same as that of the printer light source 10 described in the section [Prior Art], if it is considered to be a front-side light emitting type. Therefore, as shown in FIG. 3, the same or similar components are given the same reference numerals as in FIG. However, the substrate 11a and the anode conductor 12a of this embodiment need to be transparent. For example, I. T.
The anode conductor 12 is made of a transparent conductive film such as an O film or an aluminum thin film formed in a mesh or stripe pattern.
a is formed. The substrate 11a is made of a glass material having a good translucency. Further, the slit width of the second control electrode 15 of the present embodiment is made larger than the width of the light emitting dot 39 to be set, like the slit 32 of the first embodiment. Therefore, it is not necessary to strictly arrange the second control electrode 15 as in the conventional case.
The slit width of the first control electrode 18 is set to be the same as or larger than the slit width of the second control electrode 15. The control electrodes 15 and 18 are fixed by crystalline glass.

As shown in FIG. 3, an antireflection film 40 is formed on the entire inner surface of the substrate 11a of the fluorescent tube 37, and the light-transmissive anode conductor 12a is formed on the antireflection film 4a.
It is arranged through 0. Although the structure is not shown in detail, the antireflection film 40 is composed of a dielectric layer deposited on the inner surface of the substrate 11a and an absorbing metal layer deposited on the dielectric layer.

The type of the dielectric material forming the dielectric layer and the type of the absorbing metal forming the absorbing metal layer are the reflectance R at the interface between the two layers.
Is set to a value close to 0.

The reflectance R is generally expressed by the following equation, where n ₂ is the refractive index of the dielectric and n ₁ is the refractive index of the absorbing metal.

Therefore, there are many possible combinations of the refractive indices n ₁ and n ₂ so that the reflectance R at the interface is 0 or close to 0. However, in view of the types of materials that can be actually used, the refractive index n of the dielectric substance is ₂ is preferably in the range of 1.0 to 3.5. The type of the absorbing metal may be selected according to the formula (I) according to the type of the dielectric, but if the refractive index n ₁ is 0.8 or more, the reflectance R is close to 0 and can be used.

Next, the thickness of the dielectric layer is set so that the light reflected at the interface between the dielectric layer and the absorbing metal layer and the light reflected at the interface between the substrate and the dielectric layer interfere with each other and weaken each other. It is set to satisfy.

For example, since the refractive index of the substrate is generally smaller than that of the dielectric, the phase of the light reflected at the interface between the substrate and the dielectric layer is half a wavelength. It just shifts.

In this case, when the refractive index of the dielectric is smaller than that of the absorbing metal, the phase of light reflected at the interface between the dielectric layer and the absorbing metal is also half a wavelength. It just shifts. Therefore, the value of the film thickness d of the dielectric layer is calculated by (However, if n is the refractive index of the dielectric substance), the lights reflected at both interfaces weaken each other due to the interference effect.

In the above case, when the refractive index n ₂ of the dielectric is larger than the refractive index n _{1 of the} absorbing metal, the phase of the light reflected at the interface between both layers does not deviate. However, if n is set so that the refractive index of the dielectric is satisfied, the lights reflected at the both interfaces weaken each other due to the interference effect.

Specifically, the dielectric layer of this embodiment is made of ZrO ₂ , and the absorbing metal layer is made of Cr. In addition, since Al ₂ O ₃ , TiO ₂ or the like can be used for the dielectric layer and Cr, Ge, Mo, Fe, W or the like can be used for the absorbing metal layer, they can be combined in various ways. Anti-reflection film 4
0 can be configured.

Next, a positioning slit portion 38 having a large number of positioning slits 41 is provided on the outer surface of the substrate 11a. The positioning slit portion 38 has substantially the same structure and function as those in the first embodiment, and the description thereof will be omitted.

The method of driving the printer light source of this embodiment is the same as that of the first embodiment, in which the anode 14a is scanned and a print signal is input to the second control electrode 15a. Further, according to the present embodiment, since the antireflection film 40 is provided on the inner surface side of the substrate 11a, the reflectance of the substrate 11a seen through the positioning slit 41 can be kept low. Therefore, by using this printer light source, it is possible to further improve the printing quality of the optical printer.

In this embodiment, the antireflection film 40 is provided on the inner surface side of the substrate 11a, but the outer surface side of the substrate 11a, that is, the substrate 1a.
An antireflection film 40 is provided between 1a and the positioning slit portion 38.
May be provided.

[Effects of the Invention] In the light source for a printer of the present invention, the emission dots are divided by the positioning slit portions provided on the translucent substrate. Therefore, the slit width of the positioning slits, the arrangement pitch, and the like can be set with high accuracy, and the positioning slit portion can be configured so that adverse effects of heating on the positioning slits are reduced in the manufacturing process of the vacuum fluorescent tube. Further, the various control electrodes arranged in the envelope do not need to be precisely positioned as in the conventional case.

Therefore, according to the present invention, the arrangement accuracy of the light emitting dots is high,
There is an effect that it is possible to easily manufacture a light source for a printer that can improve the printing quality of an optical printer.

[Brief description of drawings]

1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a view showing an inner surface side of a substrate in the same embodiment, FIG. 3 is a sectional view showing a second embodiment of the present invention, and FIG. FIG. 5 is a schematic view showing the structure of a general optical printer, and FIG. 5 is a partially cutaway plan view in which the central portion of a quadrupole light source for a printer is omitted. 1 ... Photosensitive drum as recording medium, 11a, 26 ...
Translucent substrate (substrate), 12a, 27 ... Anode conductor, 13
a, 28 ... Phosphor layer, 15a ... Second control electrode as control electrode, 31 ... Control electrode, 16a, 32 ... Slit, 20a, 34 ... Filament cathode, 24, 3
7 ... Front emission type fluorescent arc tube (arc tube), 25, 38 ...
... Positioning slits, 33, 39 ... Emitting dots, 3
6,41 …… Positioning slit.

Claims (4)

[Claims] 1. An envelope whose inside is kept in a high vacuum state,
A translucent substrate forming a front plate of the envelope, a plurality of translucent strip-shaped anode conductors arranged in parallel with each other on the inner surface of the translucent substrate and applied with a scanning signal; A phosphor layer deposited on the surface of the anode conductor, and a display signal in synchronization with the scanning signal, which is provided with a slit formed in a direction diagonally intersecting the anode conductor and provided away from the phosphor layer. And a control electrode for controlling emission of dot-shaped light emitting portions of the phosphor layer obliquely arranged along the slit, and a filament cathode extended further apart from the control electrode. , In a front emission type vacuum fluorescent tube for irradiating the surface of a recording medium moving in a direction orthogonal to the longitudinal direction of the anode conductor with the light emitted from the phosphor layer through a transparent substrate, Orthogonal to the longitudinal direction The plurality of positioning slits partitioning the dot-shaped light emitting portion of the phosphor layer into a plurality of light emitting dots so that the plurality of light emitting dots are arranged without gaps when viewed from a direction corresponding to the slits of the control electrode. A light source for a printer, characterized in that a positioning slit portion provided on the transparent substrate is disposed on the transparent substrate. 2. The light source for a printer according to claim 1, wherein the slit width of the control electrode is larger than the width of the positioning slit. 3. The invention according to claim 1, wherein another control electrode having a structure in which a slit is formed in one metal plate is provided between the control electrode and the filament cathode. Light sources for printers. 4. A light source for a printer according to claim 1, 2 or 3, wherein an antireflection film is provided on the surface of said transparent substrate.