JPH03224756A - Optical scanner - Google Patents

Abstract

PURPOSE:To enable a latent image to be formed easily on a photosensitive medium such as a photosensitive drum by providing a light source system which projects light to a surface between the upper layer substrate and base substrate of a light signal generation device and an image condensation optical system which condensates an image at a specified position using a light signal emitted from the light signal genera tion device. CONSTITUTION:A light source system 20 emits a parallel beam to a light signal genera tion device 10 and therefore, a light emitted from a collimator lens 24 travels parallel to the entire longitudinal direction of a convex glass 12. In addition, a photosensitive medium 30 forms a latent image using a reflective light controlled by the light signal generation device 10 after being emitted from the light source system 20. An ordinary photosensitive drum is used as the photosensitive medium 30. In addition, a lens system consisting of refractive index distribution-type lens arranged in a dumbbell form is used as an image condensing optical system 40. The refractive index distribution-type lens is formed so that the refractive index is radially distributed to the periphery from the center of the lens. In addition, the lens can be installed a few mm to scores mm close to an object point and an erect magnification image can be focused.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an optical scanning device used in printers and the like.

(Prior art) In electronic devices such as printers, facsimile machines, and copying machines,
A latent image is formed on a photosensitive drum by controlling an optical signal, and this latent image is transferred to paper or the like to output characters or the like. Conventional methods for forming a latent image on the photosensitive drum include methods using a laser scanner, an LED array, a liquid crystal shutter, and the like.

The method using a laser scanner emits laser light from one direction and reflects the laser light with a mirror to form a latent image on the photosensitive drum. Mirrors are fixed on each surface of a hexagonal columnar base. The substrate is rotated by a motor and scanned on the photosensitive drum.

In addition, a method using an LED array involves arranging LEDs in a row in front facing the photosensitive drum, and arranging a gradient index lens between the LED array and the photosensitive drum.
A latent image is formed on the photosensitive drum by controlling the lighting of D.

Further, the method using a liquid crystal shutter is a method in which a liquid crystal shutter and an optical system are arranged between a light source and a photosensitive drum, and a latent image is formed on the photosensitive drum by controlling the liquid crystal shutter.

(Problem to be Solved by the Invention) As described above, as a method for forming a latent image on a photosensitive drum by controlling an optical signal, there are methods using a laser scanner, an LED array,
Liquid crystal shutters and the like are used, and each has advantages such as ease of manufacture, manufacturing cost, and accuracy, but among these, the most commonly used is a laser scanner. However, since this laser scanner has a mechanical control section for rotating the mirror, it has problems in terms of control. Furthermore, the method using a liquid crystal shutter has problems such as the inability to increase the extinction ratio.

Therefore, in view of the above-mentioned conventional method, the present invention has been made using a control method different from the conventional method of controlling optical signals, and its purpose is to easily form a latent image on a photoreceptor such as a photoreceptor drum. An object of the present invention is to provide an optical scanning device that can be used in printers and the like.

(Means for solving problems) The present invention has the following configuration to achieve the above object.

That is, an upper layer medium made of a light-transmitting medium having a temperature coefficient of refractive index that is relatively different from that of the base medium is placed on a base medium formed into a flat plate shape from a light-transmitting medium such as glass; An optical signal generating device in which heating elements are attached at predetermined intervals to a base medium and/or an upper layer medium, and a control section for turning on and off electricity to the heating elements; It is characterized by comprising a light source system that emits light toward the interface of the base medium, and an imaging optical system that images the optical signal emitted from the optical signal generating device at a predetermined position. Further, the imaging optical system is characterized in that gradient index lenses are arranged in an array.

(Function) A light beam emitted from the light source system toward the interface between the base medium and the upper layer medium of the optical signal generator is reflected at the interface between the base medium and the upper layer medium, exits from the upper layer medium, and passes through the imaging optical system. An image is formed at a predetermined position.

In the optical signal generating device, the base medium and/or the upper layer medium are heated by energizing the heating element, thereby changing the refractive index of the base medium and/or the upper layer medium and changing the amount of reflected light at the interface. By controlling the energization to the heating element, the amount of reflected light is controlled and a predetermined optical signal is generated.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing an embodiment of an optical scanning device according to the present invention.

The optical scanning device of the embodiment includes an optical signal generating device 10, a light source system 20, a photoreceptor 30, and an imaging optical system 40.

The optical signal generator 10 controls the reflected light from the light beam emitted from the optical system 20 and passes it through the imaging optical system 40 to the photoreceptor 3.
0 to form a latent image.

FIG. 3 shows the configuration of this optical signal generator 10.

As shown in the figure, the optical signal generating device 1o is constructed by bonding a transparent convex glass 12, which is an upper layer medium with a semicircular cross-sectional shape, to a transparent base glass 11, which is a base medium formed into a flat plate, with its convex surface facing upward. There is. Figure 2 shows this optical signal generation bag [
The state in which light is incident on and reflected by the base glass 10 is shown, and as shown in the figure, the base glass 11 and the convex glass 12 are formed to be elongated in the direction perpendicular to the direction of emission of the incident light.

In FIG. 3, a heating resistor 1, which is a thin band-shaped body, is provided as a heating element between the joint surfaces of the base glass 11 and the convex glass 12.
3 is installed across the width direction of the convex glass 12, and electrodes 14 are connected to both ends of the heating resistor 13. The other end of the electrode 14 is drawn out from the edge of the convex glass 12 onto the base glass 10 and connected to a power source, and the control section controls energization of the heating resistor 13.

As shown in FIG. 2, the heating resistors 13 are provided at predetermined intervals in the longitudinal direction of the convex glass 12. The heat generating resistor 13 is installed for the purpose of controlling the optical signal by controlling the energization to the heat generating resistor 13 as will be described later, and the arrangement interval thereof is set in accordance with the dots, etc. when printing out.

The optical signal generating device 10 according to the above configuration includes a base glass 1
1 and the temperature change in the refractive index of the convex glass 12 to control the amount of reflected light incident on the convex glass 12. Therefore, in order to utilize the temperature change in the refractive index, a medium that satisfies the following conditions is selected for the base glass 11 and the convex glass 12. That is, ■ The refractive index of the convex glass 12 is set to No, and the base glass 1 is
When the refractive index of 1 is Na, the refractive index of the convex glass is made to be slightly larger than the refractive index of the base glass. In other words, there is a relationship of N,>N8.

■ α is the temperature coefficient of the refractive index NA of the convex glass. , α4(
Must have a relationship of α8. This relationship means that when heated, the refractive index of the convex glass decreases more sharply than the refractive index of the base glass. therefore,
If the refractive index of the convex glass during heating is NA + the refractive index of the base glass is N [1', then N, -r'tr8>N,
'-N8'.

Examples of combinations that meet the above conditions include the following.

(a) NA diphosphate glass NB: heavy flint, lanthanum flint glass (b) N, : fluoride phosphate glass N8 diphosphate glass (c) NA: fluoride phosphate glass NB : Heavy flint, lanthanum flint type glass (d) N, diborate glass, phosphate glass, T of lO weight X or more
Silicate glass NB containing iO2: Most silicate glasses Although the examples (a) to (d) above all use glass as the material, it is of course possible to use materials other than glass. , for example, it may be made of plastic or the like. Furthermore, a combination of plastics or other solids or liquids may be used.

In FIG. 1, a light source system 20 emits parallel light beams toward the optical signal generator 1°. The light source system 20 of the embodiment includes a light source 21, a concave mirror 22 installed on the rear side which is the light output side of the light source 21, a condenser lens 23 installed in front of the concave mirror 22 across the light source 21, and a condenser lens 23. It consists of a collimator lens 24 installed on the front side.

The light emitted from this collimator lens 24 is
As shown in the figure, the light is emitted in parallel over the entire length of the convex glass 12.

Further, the photoreceptor 30 forms a latent image by reflected light emitted from the light source system 2o and controlled by the optical signal generating device 10, and a normal photoreceptor drum or the like is used. In the embodiment, as the imaging optical system 40, a lens system in which gradient index lenses are arranged in an array is used. A gradient index lens is formed to have a parabolic index distribution from the center to the periphery, and has a distance of several meters at the object point.
They are characterized in that they can be installed close to each other from a distance of approximately several tens of millimeters and can form an erect, life-sized image.

Next, a method of forming a latent image on the photoreceptor 30 using the apparatus of the above embodiment will be explained.

A parallel light beam is made incident from the light source system 20 toward the interface between the base glass 11 and the convex glass 12 of the optical signal generating device 10 at an angle equal to or slightly larger than the critical refraction angle for almost total reflection at the interface. .

As shown in FIG. 1, this parallel light beam is made incident as a thin beam when viewed from the side, but instead of the parallel light beam, the incident light may be made incident so as to be focused at the interface.

Note that the reason why the convex glass 12 has a semicircular cross-sectional shape is to allow incident light to enter the surface of the convex glass 12 almost perpendicularly, and to allow reflected light to exit almost perpendicularly from the surface of the convex glass 12. This is to suppress light reflection on the surface of the convex glass 12.

Since the refractive indices of the base glass 11 and the convex glass 12 satisfy the relationship N,>N8 as described above, the incident light is totally reflected at the interface due to the above incident angle condition, and the other side of the convex glass 12 emitted as reflected light from the side of the Here, when the heat generating resistor 13 is heated by supplying current to the heat generating resistor 13, the base glass 11 and the convex glass 12 around the heat generating resistor 13 are heated, and the refractive index of each becomes N7'.
and NR'. According to the above conditions, NA-N, 〉
Since N , I N , l, this heating causes refracted light at the interface, and as a result, the amount of reflected light decreases. Note that, of course, it does not matter if the value of NB' becomes larger than the value of NAl due to heating. In this case, no total reflection occurs at the interface.

Then, when the power to the heating resistor 13 is removed, the refractive indexes of the convex glass and the base glass return to the original values of N4 and N8, and the incident light is totally reflected at the interface again.

In this way, the electricity to the heating resistor 13 is turned on and off.
By controlling F, the reflected light can be turned off. FIG. 4 shows the calculation results of how much the reflected light changes when the refractive index of the base glass 11 and the convex glass 12 changes slightly. The horizontal axis of the graph is the incident angle of incident light, and the vertical axis is the reflectance. In the graph, the refractive index N4 of the convex glass at room temperature is 1.500, the refractive index N A' when heated is 1.495, and the refractive index N of the base glass at room temperature is 1.400.1.450. 1.49
The results calculated assuming 0 are shown. It is assumed that the refractive index of the base glass does not change even when heated.

Graph a is at room temperature N11=1.500 + N8=1.400 when heated Na'=1.495 + N,'=1.400 Graph b is at room temperature Nh=1.500, Nl1=1.450 when heated N,'=1.495, N,'=1.450 Graph C is at room temperature N,=1.500. This is the case where N, = 1.490 during heating, N, 1' = 1.495, and N,' = 1.490.

It can be seen from the graph that the reflectance decreases as the refractive index changes, and the decrease in reflectance is particularly significant when the values of N7 and N8 are close to each other. For example, in graph C, there was almost total reflection at N, = 1500 and N, = 1.490, but due to the change in the refractive index, the reflectance decreased to about 5%. The extinction ratio in this case is about 1:20.

In this way, controlling the reflected light using the temperature change in the refractive index of the base glass and the convex glass is very effective, and if this effect is used, it is possible to turn on and off the electricity to the heating resistor 13. The reflected light can be controlled to turn on and off.

In the optical signal generator 10, as shown in FIG. 2, a large number of heating resistors 13 are arranged close to each other, and each heating resistor is individually electrically controlled to control the reflected light at each heating resistor. are doing. 12 to 1 heating resistor per 1 mm
Since it is easy to install about 6 lines, characters, etc. can be easily expressed. In commonly used dot printers, the arrangement density is about 6 to 8 lines per mm, so there is no problem in terms of resolution.

The light beam reflected from the optical signal generating device 10 is projected onto the photoreceptor 30 via the imaging optical system 40 shown in FIG. 1 to form a latent image. Here, the convex glass 12 in the optical signal generator 10 is elongated in the longitudinal direction as shown in FIG.
is provided, the above-mentioned imaging optical system 40 accurately transmits the optical signal controlled by each heating resistor 13 to the photoreceptor 3.
need to be transmitted to 0. That is, each heating resistor 13
If the part that reflects the incident light is the emission position of the reflected light, then
It is necessary to form an image on the photoreceptor 30 in the same arrangement as these heating resistors.

The gradient index lens used in the examples can form an erect, equal-magnification image of the object point, and the object points extend in the longitudinal direction and are arranged in an array in the longitudinal direction like the object points. By doing so, it is possible to form an image at the same location as the object point, so it is extremely suitable for use in the imaging optical system 40 of this scanning device. As a result, a latent image is formed in the longitudinal direction on the photoreceptor 30 by the reflected light controlled by the optical signal generating device 20. Furthermore, when a gradient index lens is used, the distance between the object point and the image point can be made extremely close, so there is an advantage that the configuration of the device can be made compact and the device can be simplified.

Note that the imaging optical system 40 is not limited to a gradient index lens, and it is also possible to use a normal optical lens, a mirror, or the like in combination. However, when using a normal optical lens or multiple optical lenses, the distance between the object point and the image point cannot be made very close, and there is a problem that the optical system inevitably becomes complicated. .

After a latent image such as a character is formed by optically scanning the photoreceptor 3o using the method described above, this latent image is transferred to paper or the like to be printed. Note that various materials can be used for the photoreceptor 30.

For example, a color photosensitive sheet that provides color output may be used, or a light-fixing type heat-sensitive sheet that is fixed by light may be used. In the case of a photo-fixable thermosensitive sheet, the entire surface may be heated with a heat roller or the like after optical scanning.

FIG. 5 is an explanatory diagram showing another embodiment of the optical signal generating device. FIG. 5(a) is an example in which a heating resistor 13 is provided on the lower surface of the base glass 11, and FIG. 5(g) is an example in which the convex glass 1
This is an example in which a heat generating resistor 13 is provided on the upper surface of 2. Figure 5 (
C) is an example in which the cross-sectional shape of the convex glass 12 is triangular. The light is incident almost perpendicularly on the surface of the convex glass 12,
This is also for emitting the reflected light almost vertically.

In addition, in the above explanation, the reflected light is
Although N-OFF control has been described, if we look at the refracted light that is refracted in the base glass 11, refracted light is obtained when it is heated.

Heating ON-light signal 0■ control. This makes it possible to utilize this refracted light when forming a latent image on the photoreceptor. It should be noted that if the heating ON/light signal OFF control is to be performed in the same way using the reflected light in the above example, the conditions may be set as follows. That is, (1) at room temperature +N, <N, that is, the refractive index of the convex glass is smaller than the refractive index of the base glass.

■ Temperature coefficient of refractive index α. >α8, that is, the temperature coefficient of the refractive index of the convex glass should be larger than the temperature coefficient of the refractive index of the base glass, so that N^'≧NB' during heating.

Under these conditions (1) and (2), the incident light from the convex glass 12 is refracted at room temperature, and almost no reflected light is generated. When the heating resistor 14 is energized, N
Under the condition of a'≧N8'', the light is totally reflected at the interface and reflected light is generated.

The present invention has been variously explained above using preferred embodiments, but the present invention is not limited to these embodiments.
Of course, many modifications can be made without departing from the spirit of the invention.

(Effects of the Invention) The optical scanning device according to the present invention can increase the extinction ratio by heating the base medium and the upper layer medium of the optical signal generating device, and electrically control the energization to the heating element. This eliminates the need for a mechanical part such as a laser scanner for scanning on the photosensitive drum, making it less likely to break down, and as a result, the apparatus can have higher precision and resolution. Further, by using an optical system having a parabolic refractive index distribution as the imaging optical system, it is possible to produce a compact apparatus with high precision.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the optical scanning device according to the present invention, FIG. 2 is a perspective view of the optical signal generating device and an explanatory diagram showing human emitted light, and FIG. 3 is a cross section of the optical signal generating device. Figure 4 is a graph showing the difference in reflectance between room temperature and heating.
The figure is an explanatory diagram showing another embodiment of the optical signal generator. DESCRIPTION OF SYMBOLS 10... Optical signal generator, 11... Base glass, 12... Convex glass, 13... Heating resistor, 14... Electrode, 20... Light source system, 24
... Collimator lens, 30 ... Photoreceptor, 4
0...Imaging optical system. Figure 2 1 3 4 Figure 2 5 (a 3 (C) 3 1 (b) 3 1 2 .4flQ-

Claims (1)

[Claims] 1. A base medium formed into a flat plate of a light-transmitting medium such as glass, and an upper layer medium made of a light-transmitting medium having a temperature coefficient of refractive index different from that of the base medium. an optical signal generator, the base medium and/or the upper layer medium having heat generating elements attached to the base medium and/or the upper layer medium at predetermined intervals, and a control unit that turns on and off electricity to the heat generating elements; A light source system that emits light toward an interface between an upper layer medium and a base medium of a generator, and an imaging optical system that images an optical signal emitted from the optical signal generator at a predetermined position. optical scanning device. 2. The optical scanning device according to claim 1, wherein the imaging optical system includes gradient index lenses arranged in an array.