JPS61176041A - Optical recording head - Google Patents

Abstract

PURPOSE:To make an optical recording head compact and uniformalize the uneven brightness of each dot by comprising the optical recording head with dot array type phosphor, providing a split grid electrode, and adjusting the applied voltage. CONSTITUTION:An anode electrode 2 is formed on the glass substrate 1 of a dot array fluorescent tube and the luminous space S that is held in a vacuum state by a tube frame 3 is partition-formed on the electrode 2. Dot array phosphor 4 that is divided into two or more phosphor dots 4a in the longer direction of this electrode 2 through an insulating layer 5 and is arranged in an array shape is arranged. A first grid electrode 6 in which an opening 6a with a slightly larger area than the opening 6a on the upper surface (a) of this phosphor 4 is arranged on the layer 5 and the opening 6a is aligned to the upper surface (a) of the phosphor 4. In addition, a second grid electrode 7 is opposedly arranged separately from the electrode 6 and at the upper part of the phosphor 4. Besides, a pair of cathode filaments 8 are arranged at the upper part of the electrode 7 along the array direction. As a result, the fluorescent tube of an optical recording head is made compact and the uneven brightness of each dot is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording head for a non-impact printer that uses light, and more particularly, to an optical recording head that can be applied to recording devices such as intelligent copiers, facsimiles, word processors, and personal computers. This relates to recording heads.

Conventional optical recording devices include a method in which a laser is scanned by a rotating polygon mirror, and a method in which a light emitting diode (LED) array or a liquid crystal shutter array is used as an optical recording head, but none of these methods has been used. However, the problem is that the cost is high and the size is large. Furthermore, when using liquid crystal, it is difficult to connect the chips.

Therefore, a dot array fluorescent tube has been adopted as a recording head of an optical recording apparatus that does not have the above-mentioned drawbacks. However,
Dot array fluorescent tubes tend to vary in the amount of light emitted from each dot, which causes density unevenness in recorded images and deteriorates print quality.

1-Ki The present invention has been made in view of the above points, and provides a small and inexpensive optical recording head that can uniformize the amount of light emitted from each element and stably obtain high print quality. The purpose is to provide

In order to achieve the above object, the present invention provides an optical recording head in which a phosphor formed in a dot array is bombarded with thermoelectrons in a vacuum state to selectively cause each dot to emit light in accordance with an information signal. a cathode part emitting thermoelectrons extending in a predetermined direction; an anode part disposed opposite to the cathode part and provided with a plurality of terminals; A dot-array phosphor comprising a plurality of phosphor dots arranged in parallel, a first grid electrode disposed between the phosphor and the cathode part, and a dot array-like phosphor formed from the first grid electrode toward the cathode part. It is characterized by having a second grid electrode divided into an appropriate number of parts arranged along the direction in which the phosphor dots are arranged in spaced positions.

The causes of variations in the amount of light emitted from each dot of a dot array fluorescent tube are as follows.

First, the principle of light emission of a dot array fluorescent tube will be explained. In the dot array fluorescent tube constructed as shown in FIG. 5, when the cathode filament 8' is heated by applying an AC voltage of about 10 V, thermoelectrons are emitted, and these thermoelectrons are absorbed by the electric field applied to the grid electrode 6'. It is accelerated by the voltage applied to the anode electrode 2' and collides with the phosphor 4' arranged in a dot array. As a result, the thermoelectrons lose their energy, but instead, fluorescence having a unique emission spectrum is emitted from the colliding phosphor dots 4'. The wavelength distribution of this emission spectrum has a peak of 50
It has a wide distribution characteristic ranging from 410 to 650 nm at 5 nm. Therefore, the grid electrode 6'' and the anode electrode 2
' in response to an information signal.

By selectively applying a voltage, the desired dots 4' emit light and information can be optically recorded.

By the way, the amount of light emitted from each dot 4' is proportional to the brightness, assuming that the area of the dot is constant. Therefore, variations in the amount of light from a dot array fluorescent tube are caused by variations in the brightness of each dot.

Now, the grid voltage is Vg, the anode voltage is VP, the distance between the anode electrode and the grid is a, the distance between the filament and the grid is b, and the half width of the grid electrode 2' is C1.
The pitch between ', 2' is p, H= (2tc a/p −
in cosh (2πc/p))/in coth
(2πc/p) and the constant is K, then the anode current IP is.

I p=K・1/b2・(Vg+Vp/H)/(1+1
/H(1+4/3・a/b)). The relationship between the anode current Ip and the filament-grid electrode distance in the above equation is shown in a graph as shown in FIG.

On the other hand, when the change in luminance fL with respect to the anode current Ip is actually measured, the characteristics shown in FIG. 8 are shown. That is, when the anode current IP exceeds the value, the brightness fL increases in proportion to the anode current Ip. Therefore, assuming that the variables a*Q+p representing each dimensional factor are constant, the luminance fL of each dot largely depends on the distance #Ib between the filament and the grating electrode. actually.

When manufacturing a dot array fluorescent tube, variations are most likely to occur in the distance between the filament and the grid electrode, which causes variations in luminance and deteriorates print quality. The reason why the distance bb between the filament and the grid electrode tends to vary is that, as shown in FIG. 6, deformation such as warping occurs in the substrate 1'' supporting the anode electrode.

A detailed description will be given below based on one embodiment of the present invention. FIG. 1 is a plan sectional view showing a dot array fluorescent tube as an embodiment of the present invention, and FIG. 2 is a side sectional view thereof. Second
In the figure, an anode electrode 2 is formed on the surface of a substrate glass 1, which in this example has a rectangular shape. A tube frame 3 made of glass is fixed onto the anode electrode 2.
In this example, a rectangular parallelepiped-shaped light emitting space S maintained in a vacuum state is divided. At both ends of the anode electrode 2 in the longitudinal direction where the tube frame 3 is not covered, as shown in FIG. - field terminal 2a is taken out.

In the widthwise center of the anode electrode 2 in the light emitting space S, a dot array phosphor 4 is disposed extending in the longitudinal direction. That is, a plurality of phosphor dots 4a are arranged in an array along the longitudinal direction of the anode electrode 2 to form the dot array phosphor 4. The dot array phosphor 4 of this example is made of ZnO:Zn. has been done.

An insulating layer 5 is provided around the dot array phosphor 4 except for its upper surface α. In this case, the thickness of the insulating layer 5 is set so that the upper surface 5a of the insulating layer and the upper surface α of the dot array phosphor form a substantially continuous plane. Note that this insulating layer 5 can be easily formed by screen printing. On the insulating layer 5, there is a slit-shaped opening 6a (having an area slightly larger than the upper surface α of the dot array phosphor 4).
A first grid electrode 6 having a perforation (see FIG. 1) is disposed with its opening 6a aligned with the upper surface α of the dot array phosphor 4, and only the upper surface α of the dot array phosphor 4 has an absorption space S. is open to

A second grid electrode 7 is disposed above the first grid electrode 6 at a suitable distance apart from the dot array phosphor 4 along both sides of the dot array phosphor 4 so that the upper part thereof can be opened. The second grid electrode 7 is divided into an appropriate number of parts, and each pair of divided electrodes 7a, 7a facing each other functions as a grid electrode for an appropriate number of dots 4a of the dot array phosphor 4. The second grid electrode 7 of the example with 0 lines is
It has an L-shaped cross section, and is erected on the insulating layer 5 on which the first grid electrode 6 is attached, spaced apart from the first grid electrode 6.

Above the second grid electrode 7 is a pair of cathode filaments 8.
, 8 are stretched so as to extend along the direction in which the divided second grid electrodes 7a are arranged in parallel (the direction in which the dot array phosphors 4 are arrayed). In this example, as shown in FIG. 1, one end of each cathode filament 8 is fixed by a fixing member 9, and the other end is fixed by a spring plate 11 via a support member 10.
A cathode filament 8 is stretched with appropriate strength. Above the cathode filament 8, on the inner surface of the upper tube frame 3a,
A transparent NESA electrode 12 for antistatic purposes is deposited thereon.

Although not shown, the anode drive circuit for lighting each phosphor dot 4a is provided on a separate board on which an IC is mounted, and the board is made of a multilayered ceramic board, flexible tape, or the like. . Either connect the bonding pads of the board on which this driving IC is mounted and the lead terminals 2a taken out on both sides from the anode of the dot array fluorescent tube shown in FIG. 1 with bonding wires, or
Alternatively, the flexible tape may be connected by thermocompression bonding.

In the dot array fluorescent tube constructed as described above,
In the following manner, variations in the amount of light emitted from each phosphor dot are suppressed.

The applied voltage V L g of the first grid electrode 6 is set constant,
Applied voltage V to each second grid electrode 7a divided into a plurality of parts
zg is selectively adjusted according to the light intensity of the corresponding phosphor dot 4a. That is, by increasing the voltage applied to the divided second grid electrode 7a corresponding to the phosphor dot 4a with low brightness, the corresponding anode current is increased and the brightness of that dot 4a is increased.

Variations in the brightness of the entire dot array phosphor 4 can be reduced. In this case, the voltage applied to the second grid electrode V z g is adjusted within a range lower than the voltage applied to the first grid electrode V t g.

FIG. 4 shows an embodiment in which a dot array fluorescent tube in which variations in the amount of emitted light are suppressed as described above is incorporated into an optical recording device. In FIG. 4, a uniform charger 22 is disposed at a suitable position on the moving path of a photoreceptor belt 2J- stretched in a freely rotatable manner, and a dot array fluorescent tube P of the present invention is placed downstream of the uniform charger 22 in an optical recording head. Optical writing unit 23 used as
is formed. The dot array fluorescent tube P is arranged with its tube frame upper surface 3a facing the photoreceptor belt 21, and the fluorescent light corresponding to the information signal emitted from it is transmitted through the same-magnification imaging element 23a disposed between them. The light is projected onto the photoreceptor belt 21 without variation in the amount of light, and a high-quality electrostatic latent image is formed on the surface thereof.

On the back side of the imaging area on the photoreceptor belt 21 where the fluorescent light is projected, there is a roller 23 for preventing the belt 21 from wobbling. b are arranged so as to be in rolling contact. On the downstream side of the optical writing section 23, there is a developing device 24. A transfer device 25, a static elimination lamp 26, and a cleaner 27 are arranged in this order to form an electrostatic image forming process.

Therefore, after the formed electrostatic latent image is visualized, the transfer paper T
It is possible to stably obtain a high-quality printed image without density unevenness by transferring it onto the surface.

Next, another embodiment of the present invention will be described based on FIG. 3. Incidentally, the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In the dot array fluorescent tube of this example, an insulating layer 13 is interposed between the first grid electrode 6 and the second grid electrode 7. As a result, the second grid electrode 7 can be accurately aligned with the first grid electrode 6.
In addition, electrical leakage with the first grid electrode 6 can be reliably prevented. in this case,
The insulating layer 13 is.

It can be easily formed by screen printing a glass material. Other configurations and each phosphor dot 4
The operation for suppressing variations in the brightness of a is the same as in the above embodiment.

According to the present invention, as described in detail above, an inexpensive and compact optical recording head can be obtained by constructing the optical recording head using a dot array-shaped phosphor, and a divided optical recording head can be obtained. By providing two grid electrodes and adjusting the applied voltage, the brightness of each dot can be made uniform and variations in the amount of emitted light can be suppressed. Therefore, it is possible to stably obtain high printing quality without density unevenness. still,
It goes without saying that the present invention is not limited to the specific embodiments described above, and that various modifications can be made within the technical scope of the present invention.

[Brief explanation of the drawing]

1 and 2 are a plan sectional view and a side sectional view showing a dot array fluorescent tube according to one embodiment of the present invention, FIG. 3 is a side sectional view showing another embodiment of the present invention, and FIG. The figure is a schematic diagram showing an optical recording device using the optical recording head of the present invention, FIG. 5 is an explanatory diagram showing the principle of a dot array fluorescent tube, FIG. 7 and 8 are graphs showing the relationships between the anode current IP, the filament-lattice electrode distance, and the luminance fL, respectively. (Explanation of symbols) 2'', 2: Anode electrode 4', 4: Dot array phosphor 6: First grid electrode 7: Second grid electrode 8', 8: Cathode filament Patent applicant Rico Co., Ltd. - Figure 1 Figure 4 Figure 4 T Figure 5 Figure 6 Figure 7 Figure 8 Anode current (Ip)

Claims (1)

[Scope of Claims] 1. In an optical recording head that causes thermoelectrons to collide with a phosphor formed in a dot array in a vacuum state to selectively emit light from each dot in accordance with an information signal, the phosphor extends in a predetermined direction. a cathode part that emits thermoelectrons; an anode part disposed opposite to the cathode part and provided with a plurality of terminals; and a plurality of terminals arranged in parallel on the anode part along the direction in which the anode part extends. a dot array-shaped phosphor consisting of phosphor dots; a first grid electrode disposed between the phosphor and the cathode; What is claimed is: 1. An optical recording head comprising: a second grid electrode divided into an appropriate number of electrodes arranged along the direction in which phosphor dots are arranged. 2. The optical recording head according to item 1 above, characterized in that an insulator is interposed between the first and second grid electrodes.