JPH078218Y2 - Dot array device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dot array device.

(Prior Art) There is an optical scanning device that irradiates a photoconductive medium of a dot array device with a laser beam emitted from a deflector to drive the dot array device.

Here, the dot array device is a dot-shaped light-emitting body, optical shutter, electrode, or heating element,
It has a dot array arranged in an array and a drive circuit for driving these light emitters, optical shutters, electrodes, or heating elements.

For example, it is known as an LED array, a liquid crystal shutter array, a multi-stylus, a thermal head and the like.

In the dot array device as described above, the drive circuit is usually formed as an IC, and the terminal of the drive circuit and the terminal of the dot-shaped segment in the dot array device are electrically connected.

As a connection method, a wire bonding method, an anisotropic conductive film method, a tape carrier method, or the like is known, and an appropriate method depending on the material, shape, pitch, etc. of the connection terminal in consideration of manufacturability, cost, and the like. Is selected.

However, as the dot array device becomes longer and higher in density, the number of drive circuits increases, and the number of connection terminals also increases, which raises problems such as an increase in material cost and a decrease in yield.

Therefore, a dot array device has been proposed in which a photoconductive medium is used as an electrical connection means and a new driving method of irradiating light such as a laser beam on the photoconductive medium is adopted.

That is, an electrode array electrically connected to the dot array, a common electrode having a predetermined distance from the electrode array, and a photoconductive medium provided in the electrode array direction to connect both electrodes are provided. Then, by exposing the photoconductive medium by the optical system in a state where the potential is applied to the common electrode, a potential corresponding to the potential given to the common electrode in advance is obtained at the exposure position of the photoconductive medium. It is a dot array device that drives a dot array.

FIGS. 5 and 6 explain the principle of a printer to which an optical scanning device including a dot array device according to this new driving method is applied.

In these figures, the laser beam emitted from the semiconductor laser 20 enters a deflector 22 via a collimator lens 21.

The deflector 22 is composed of, for example, a polygon mirror, and according to its rotation, a reflected beam is continuously emitted with a point on the mirror surface as a deflection point and passes through an fθ lens 23 and a plane mirror 24 to form a dot array using a fluorescent tube. It is incident on the photoconductive medium of device 25 as a scanning beam. In this example, the type in which scanning is performed from the back surface of the fluorescent tube is shown.

Then, fluorescence is emitted corresponding to the dot-shaped portion of the photoconductive medium which has been irradiated with light. This fluorescent light emission is imaged on the photosensitive drum 27 via the imaging device 26.

Since the drive current of the semiconductor laser 20 is previously modulated with the information signal, the laser beam is turned on / off in accordance with the information signal, and thus a latent image drawn by dots is carried on the photosensitive drum 27. It is a translation.

As described above, the method of scanning the laser beam on the dot array device instead of directly forming the image on the photosensitive drum 27 has an advantage that the precision of the optical system is not required to be so high.

The dot array device 25 will be further described with reference to FIGS. 7 to 9. The main structure of the dot array device 25 is an electrode array 25A drawn out of the vacuum vessel of the fluorescent tube and a common structure formed at a predetermined interval. It has an electrode 25B and a photoconductive medium 25C provided so as to extend over both electrodes.

Also, semiconductor laser 20, collimator lens 21, deflector
An optical system for exposing the photoconductive medium is constituted by 22, the fθ lens 23, the plane mirror 24, and the like.

The photoconductive medium 25C is composed of a medium having a photoelectric conversion function (for example, a photoconductor).

A potential is applied to the common electrode 25B in advance, and when scanning the photoconductive medium 25C with a laser beam, the impedance of the photoconductive medium decreases in the exposed portion, and the impedance is not exposed in other portions. Since it is maintained as it is, if the exposure is performed according to the information signal, the switching similar to the well-known IC driving becomes possible.
The arrow K1 shown in FIG. 7 indicates the position to be optically scanned.

In FIG. 9 showing an enlarged view of the photoconductive medium 25C portion, the reference symbol Lb indicates a laser beam irradiation portion, which indicates that every other dot is exposed to generate an ON / OFF state and emit light. ing. Arrows indicate the direction of current flow.

The dot array device 250 shown in FIG. 10 is an improved version of the dot array device shown in FIGS. 7 to 9, and the common electrode 25B has an uneven shape at the same pitch as the electrode array 25A, aiming to reduce so-called crosstalk. It is a thing.

The dot array device shown in FIGS. 11 and 12 is a photoconductive medium 25C segmented at substantially the same pitch as the electrode array 25A. These types are the photoconductive medium 25C.
It is easy to understand that the structure is such that crosstalk is extremely unlikely to occur because the impedance change is applied only to the portion in which crosstalk exists.

Further, FIG. 13 shows a case where the photoconductive medium portion of the fluorescent tube is viewed from the back side.Since it is easy to control the size of the exposed portion sandwiched by both electrodes, the condition for providing the photoconductive medium 25C is relaxed. There are great advantages in terms of manufacturing. However, in order to enable back surface exposure, it is necessary to use a material having a high light transmittance such as glass for the switching unit substrate.

In the figure, symbol P is the pitch of the electrode array, symbol W is the electrode width,
Symbol g is the distance between the electrode array and the common electrode, and symbol d (the 14th
Indicates the thickness of the photoconductive medium 25C, and W / P
= 0.3 to 0.7, g / W = 0.2 to 2.0, d / g = 0.2 to 1.0.

When an optical scanning device for a laser printer is configured using such a dot array device, it is possible to always scan the same relative position with respect to the moving photoconductor drum, and it is difficult for the photoconductor jitter and scan position fluctuation to occur. There is an advantage that the accuracy required for the scanning optical system is not required to be so severe.

However, it is necessary to interpose the fθ lens 23 in order to satisfy the so-called fθ characteristics such as the scanning speed and the uniformity of the beam spot diameter over the entire scanning line on the photosensitive drum 27.

(Object) Therefore, an object of the present invention is to provide an improved dot array device capable of performing scanning equivalent to that using an fθ lens without using an fθ lens which is a special optical system for satisfying the fθ characteristic. To do.

(Structure) In order to achieve the above-mentioned object, the present invention is such that the electrode array forming the electrode array is arranged such that f · tan θ (where f is the laser beam for exposure scanning) from the center of the electrode array toward both ends. The distance is from the deflection point to the photoconductive medium, and θ is the deflection angle.).

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

In the following embodiments, a dot array device having a configuration conforming to the above-mentioned dot array device 25 is used.

The dot array applied to the present invention includes an array of light emitters, optical shutters, multi-needle electrodes or heating elements.

As described above, the dot array device to which the present invention is applied has an electrode array electrically connected to the dot array and a common electrode having a predetermined distance from the electrode array. A photoconductive medium having a coupling property, which corresponds to the position of the photoconductive medium exposed by an optical system including a light source configured to expose an arbitrary position of the photoconductive medium in the electrode array direction. The electrode array is driven by applying a potential corresponding to the potential applied to the common electrode in advance.

Example 1 (see FIG. 1).

The basic configuration of this example is such that the fθ lens 23 is eliminated in the configuration shown in FIG. 5 and a collimator lens 21 or an imaging lens (not shown) disposed between the deflector 22 and the collimator lens 21 is used. The focused laser beam is the photoconductive medium of the dot array device 2500 (see FIG. 1).
Optical scanning is performed so that an image is formed at 2500C. In FIG. 1, reference numeral 2500A indicates an electrode array, and reference numeral 2500B indicates a common electrode.

In the dot array device 2500 according to this example, the deflector
When the distance from the deflection point O of 22 to the scanning position of the photoconductive medium 2500C is f, the pitch P of the electrode array 2500A is f.
・ It is given as a function of tan θ.

That is, only the right half electrode array 2500A shown in FIG. 1 will be described. The center line of the electrode (1) forming the electrode array and the laser beam scanning position indicated by the one-dot chain line on the photoconductive medium 2500C are described. Intersection P _{1 of} the electrode (2) with corresponding intersection P _{2 of} the electrode (n) (where n ≧ 1)
Expressed as Pn, the angle θ ₁ formed by the line O-Q where the deflection point O of the laser beam is orthogonal to the light beam scanning position and OP ₁ is given by θ ₁ = tan ⁻¹ (W + S / 2f) , Where W is the width of the electrode (1) or electrode (-1), and S is the electrode (1) (-1).
It is a space between.

Here, the pitch between the minimum electrodes (1) (-1) is 2θ ₁ =
If θ is given and the electrode pitch is given for each θ, θ ₂ = θ ₁ + θ = 3 θ ₁ , θn = θ ₁ + (n−1) × θ = (2n−1) × θ ₁ Will be given.

Therefore, the inter-electrode pitch P is P = f · tan {(2i-1) × θ ₁ } (where i = 1 to n)
Therefore, in this example, the electrodes are arranged at this pitch.

With this arrangement, without using the fθ lens,
An effect equivalent to that obtained by scanning with the fθ characteristic is obtained.

Example 2 (see second).

In the example shown in FIG. 2, in addition to the configuration of the first embodiment, a laser beam is obliquely incident on the electrode array portion at the end portion of the dot array, and therefore, in order to correct the decrease in the exposure amount, The electrode width is increased toward the end.

As shown, the width W of the electrodes that make up the electrode array 2500A
₁ is the same as the electrode width W in Example 1, and the deflection point O
Is given by φtan ⁻¹ (W / f), and if the electrode width is given at an angle of φ at each electrode, then W ₁ = f {tan (θ ₁ + φ / 2) − tan (θ ₁ −φ / 2)} W ₂ = f {tan (θ ₂ + φ / 2) −tan (θ ₂ −φ / 2)} :: W _n = f {tan (θ _n + φ / 2) − tan (θ _n −φ / 2)}, where θ ₁ , θ ₂ ... θ _n are the same as those given in the first embodiment.

Example 3 (see FIGS. 3 and 4).

In each of the above-described embodiments, the waist position of the laser beam is scanned while being coincident with the intersection O ₁ of the laser beam scanning position and the line 0-Q. The relationship between the scanning position of the photoconductive medium indicated by the alternate long and short dash line is different from that shown in FIG. 3 except for points A and B, whereby the laser beam diameter at the scanning position is as shown in FIG. It varies depending on the deflection angle.

In FIG. 3, reference symbol Lb indicates a laser beam for scanning, and arrow K indicates the scanning direction.

Thus, the laser beam diameter at the scanning position is the fourth
As shown in the figure, it changes to a W shape.

Therefore, by changing the electrode width of the electrode array according to the beam diameter given in FIG. 4, the effect aimed at in the second embodiment can be obtained.

That is, if the electrode width is also given by the W-shaped distribution shown in FIG. 4, the exposure amount can be made constant for each electrode.

Since the specific shape and the like are obtained by setting the conditions of the optical system, further detailed description will be omitted.

In the embodiments described above, the dot array device is driven by using the photoconductive medium and the laser beam, and the fθ lens optical system can be omitted. Therefore, the structure is simplified and the device can be easily manufactured. There are advantages such as being able to.

Furthermore, the functioning dot array part is arranged with a predetermined width and interval as in the conventional case, but only the driving part is
Since the electrode array is formed with the intervals and widths as described above, it can be applied to various dot array devices.

(Effect) According to the present invention, since the fθ lens optical system is not required, it is possible to provide a low-cost optical scanning device with a simple structure, which is convenient.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are front views of a main part of a dot array device for explaining an embodiment of the present invention, and FIG. 3 is a view for explaining fluctuation of beam waist position, and FIG. FIG. 5 is a diagram for explaining the variation of the beam diameter at the scanning position, FIG. 5 is a perspective view showing the entire optical scanning device, FIG. 6 is a front view of the same figure, FIG. 7 is a perspective view of a dot array device, and FIG. Figure 9, Figure 10, Figure
11 and 12 are plan views of the dot array device, FIG. 8 is a sectional view corresponding to FIG. 9 of the above, FIG. 13 is a view of the photoconductive medium from the back side, and FIG. It is sectional drawing corresponding to a figure. 2500A ... Electrode array, (1), (2) ... (n),
……… The electrodes that make up the electrode array.

Claims (1)

[Scope of utility model registration request] 1. An electrode array electrically connected to a dot array, a common electrode having a predetermined distance from the electrode array, and a photoconductive member provided in the electrode array direction so as to connect both electrodes. By exposing and scanning the photoconductive medium having a medium and applying a potential to the common electrode, a potential corresponding to the potential is obtained at the exposure position of the photoconductive medium to drive the dot array. In the dot array device, the array of electrodes forming the above electrode array is f · tan θ (where f is from the deflection point of the exposure scanning laser beam to the photoconductive medium) from the center of the array toward both ends. , And θ is the deflection angle.).