JPH05232324A - Element for linear illumination - Google Patents

Abstract

PURPOSE:To provide the element for linear illumination with which linear illumination light having a uniform illuminance distribution is obtd. by making light incident from an external light source and which can be inexpensively produced. CONSTITUTION:A silver plating film 22 is applied on the lateral peripheral surface of a transparent bar-shaped body 21 consisting of glass in which phase splitting is generated. The specified width part is then polished and lapped along the ridge line of the lateral peripheral surface to form a light releasing part 23. The light within progresses toward the other end while repeating the irregular reflection by the phase splitting of the glass and the total reflection by the silver film on the outer periphery when the light source light is made incident on this element 20 from its one end. The light arriving at the light releasing part 23 is released as scattered light to the outside in the process of this reflection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear illumination element which emits light from the end face through a side peripheral surface thereof, and in particular, improves the light emission efficiency and the light emission uniformity. The present invention relates to a linear illumination element.

[0002]

2. Description of the Related Art Recently, linear illumination using a light emitting diode has been used as illumination for illuminating an original or partially exposing a photosensitive surface in a reading unit such as a facsimile, a scanner or a copying machine. The linear illumination is basically arranged by arranging a group of light emitting diode elements 12 in one or two rows on a long substrate 11 as shown in FIG. It has a structure in which a rod-shaped lens 14 for condensing light from the light source is arranged above.

In recent years, cost reduction, weight reduction, and size reduction have progressed, and the number of light emitting diode elements has been reduced, or linear illumination without a reflection frame or rod lens has been used.

[0004]

In such a linear illumination, since light is emitted for each individual light emitting diode element arranged in a plane at a distance, the unevenness of illuminance in the effective irradiation length range is large. When used as illumination for facsimiles or the like, it is necessary to correct the output signal, and when used as a copying machine, uneven exposure occurs on the photosensitive surface.

In order to reduce the unevenness of the illuminance, it is effective to increase the number of light emitting diode elements arranged, but there are problems that the manufacturing cost increases and the power consumption increases. In particular, the linear illumination having the rod-shaped lens cannot be made compact because it becomes large as a whole. On the contrary, when the rod-shaped lens is removed, there is a problem that the light collection efficiency of the light source light is lowered and the directivity is lowered. In addition, since the light emitting diode element emits light of a single wavelength, it is not suitable for colorization.

[0006]

In order to solve the above-mentioned conventional problems, in the present invention, a heat treatment is carried out in advance at a uniform temperature or a temperature having a gradient so that a uniform or gradient distribution is formed therein. Using a rod-shaped glass body with phase separation as the element body, a reflective coating is provided on the side peripheral surface by silver plating, etc., and the light emitting section is roughened by scoring along one ridgeline on the side peripheral surface. Formed.

Light is incident on the device of the present invention from both end faces or one end face.
Simultaneous light incidence from both end faces is desirable. A halogen lamp or a light emitting diode element can be used as the light source. At that time, the method of light incidence from the light source to the lighting element is
It may be directly incident or may be indirectly incident.

However, in order to increase the light collection efficiency, indirect light incidence is desirable. For example, there is a method using an optical fiber bundle or a method using a condenser lens.

[0009]

According to the present invention, the light entering from the end face of the device is
It reaches the light emitting portion on the roughened ridge while repeating total reflection on the boundary surface of the surrounding reflective film inside thereof. At that time, light is diffusely reflected by the effect of the rough surface and is radiated from the side surface to obtain high uniformity.

In the present invention, since two-phase glass having different refractive indexes by heat treatment, that is, a glass body in which so-called phase separation is caused is used as the element main body, light entering from the end face is divided into the inside of the glass. Diffuse reflection occurs depending on the phase, and some light reaches the roughened light emitting part and radiates to the outside, so compared to the case where a glass body without phase separation is used as the element body. Emit more light.

In molding the above-mentioned phase-separated glass body, heat treatment is performed at a temperature having a gradient so that the density or state of the phase separation has a distribution, and the probability of irregular reflection occurs in the longitudinal direction of the device (light When gradually changing to
The uniformity of the emitted light can be further increased. The configuration that gives the phase separation distribution that changes in the element length direction as described above is
This is particularly effective when light is incident from one end surface of the element.

[0012]

The present invention will be described in more detail based on the following examples. Example 1 Glass composition was SiO ₂ : 65 mol%, Na ₂ O: 10 m
ol%, B ₂ O ₃ : 25 mol% of a round rod-shaped glass body having a diameter of 3 mm and a length of 230 mm was subjected to heat treatment at 700 ° C. for 20 minutes to give a glassy material rich in SiO ₂ and B ₂ O ₃
A so-called phase separation was caused to separate into two vitreous phases rich in components.

As shown in FIG. 2, the phase-separated glass rod 21
After coating the reflective film 22 by silver-plating all the side peripheral surfaces, grinding one ridgeline on the side surface with a width of 2 mm, the surface is ground with abrasive grains of JIS standard grain size No. 1000. The linear illumination element 20 was manufactured as the rough surface light emitting portion 23. This is Example 1.

Next, for the purpose of performance comparison, a commercially available quartz glass round bar having a diameter of 3 mm and a length of 230 mm was also processed in the same manner as the above-mentioned example element to manufacture an illuminating element. This is Comparative Example 1.

The radiant light intensities of the linear illumination devices of Examples and Comparative Examples thus produced were measured as follows. A device as shown in FIG. 3 was used to measure the intensity of radiated light on the side surface, and light was incident from both ends of the element 20 from the halogen light source 31 using the bifurcated fiber bundles 32A and 32B having an outer diameter of 2 mm.

The intensity of light emitted from the light emitting section 23 of the device was measured by scanning the optical power meter 33 along the length direction of the light emitting section 23.

The measurement results are shown as "Example 1, Comparative Example 1" in the graph of FIG. Further, the result of measuring the emitted light intensity of a conventional linear lighting device having a length of 230 mm in which 30 light emitting diode elements are arranged in the longitudinal direction is shown as "Comparative Example 2" in the figure.

From the results shown in FIG. 4, the illuminating device of Example 1 has a higher radiant light intensity as a whole than the device of Comparative Example 1, and the incident light is efficiently radiated from the light emitting portion, and the illuminating device has a component in the glass. It can be seen that the diffuse reflection effect due to the phases greatly contributes. Further, in Comparative Example 2, large light intensity unevenness corresponding to the light emitting diode elements arranged in the longitudinal direction clearly appears, whereas it can be seen that the element having the structure of the present invention has extremely high light emission uniformity.

Example 2 The glass composition was SiO ₂ : 70 mol%, Na ₂ O: 5 m.
A glass round bar sample having a diameter of 3 mm and a length of 230 mm, which is ol%, B ₂ O ₃ : 25 mol%, was heat-treated in a temperature gradient type heat treatment furnace as shown in FIG.

A glass sample 50 is placed in a temperature gradient type electric heating furnace 5
1 was inserted horizontally and heat-treated for about 15 minutes. The temperature of the Kanthal heater 52 was divided into 5 zones and controlled so that the temperature gradient from the one end to the other end of the furnace was in the range of 600 ° C to 750 ° C at almost equal intervals. And, in order to prevent deformation due to softening of the glass during the heat treatment, the clay container 53
The glass sample was held at.

After the heat treatment for about 15 minutes, the glass sample 50 was rapidly cooled so as not to be broken by thermal shock, and taken out of the furnace. At that time, the glass sample was wrapped with a heat resistant ceramic fiber and cooled to room temperature. The reason why the glass sample is not gradually cooled after the heat treatment is that the glass is devitrified during the slow cooling.

The glass composition of this example is heat-treated in the above temperature range (600 ° C. to 750 ° C.) for about 15 minutes to obtain a glassy material rich in SiO ₂ component and a glassy material rich in B ₂ O ₃ component. Separation into two phases causes a so-called phase separation phenomenon. However, in the temperature range of the present example, since the phase separation at a higher temperature, that is, a temperature near 750 ° C. has a higher density than the phase separation at a lower temperature, that is, a temperature near 600 ° C., the glass rod length increases. A gradient distribution is given to the degree of phase separation over the entire direction. The glass round bar having the gradient distribution in the phase separation thus produced was subjected to the same processing as in Example 1 to manufacture a linear illumination element. This is Example 2.

The emitted light intensity of the above device was measured in the same manner as in Example 1. However, in this embodiment, the light is incident only from the end face 50A on the side where the heat treatment temperature is low, using the one fiber bundle 32A. Figure 6 shows the measurement results.
It was shown as "Example 2" in the graph. The graph of FIG. 6 also shows the same measurement results of Comparative Example 1 (light emitting diode array) described above.

As is clear from FIG. 6, the radiant light intensity of Comparative Example 1 is rapidly attenuated as the distance from the light-incident end face is increased, whereas the radiant light intensity of the product of this embodiment is not uniform throughout. It is high, and the intensity of emitted light is also slightly high.

Here, light is made incident on the element from the end surface 50A that has been heat-treated on the lower temperature side, that is, the side on which the phase separation density is smaller, and the closer to the other end surface 50B, the higher the density. This is to cause a large amount of diffused reflection of light in the phases to improve the uniformity of light emission in the length direction of the device.

As described above, the radiated light intensity of this embodiment is high over the entire device and radiates light with extremely good uniformity.

As the glass used in the present invention, in addition to the glass composition of the above embodiment, a glass composition that causes a phase separation, for example, SiO ₂ —Na ₂ O type glass or SiO ₂ -L.
i ₂ O type glass is also effective.

[0028]

According to the present invention, it is possible to obtain a linear illuminating element with improved uniformity of light emission. Therefore, it is extremely useful as a light source for illuminating an original or partially exposing the photosensitive surface in a reading unit such as a facsimile, a scanner, or a copying machine.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a conventional linear lighting device using a light emitting diode element.

FIG. 2 is a plan view and a cross-sectional view showing an embodiment of the element of the present invention.

FIG. 3 is a schematic diagram showing an apparatus for measuring radiant light intensity.

FIG. 4 is a diagram showing comparative measurement results of emitted light intensities of an element of the present invention, an element using quartz glass, and a conventional linear lighting device using a light emitting diode.

FIG. 5 is a cross-sectional view showing a temperature gradient type electric heating furnace used when manufacturing the element of the present invention in which a phase gradient is applied in glass.

FIG. 6 is a diagram showing a comparison of radiant light intensities of a device according to the present invention and a quartz glass device having a phase separation gradient when light is incident on one end surface.

[Explanation of symbols]

 Reference Signs List 11 substrate 12 light emitting diode element 13 reflective frame 14 rod lens 20 linear illumination element 21 phase-separating glass rod 22 reflective film (silver film) 23 roughened light emitting portion 31 halogen light source 32A, 32B bifurcated fiber bundle 33 optical power Meter 50 Phase gradient glass rod (element body for linear lighting) 51 Temperature gradient type electric heating furnace 52 Kanthal heater 53 Clay container

Claims (2)

[Claims] 1. An illuminating element which emits light to the outside through a side peripheral surface by allowing light to enter from an end surface, wherein a rod-shaped main body is made of phase-separated glass, and silver is provided on the peripheral side surface of the main body. An element for linear illumination, which is provided with a light emitting portion which is covered with a reflective coating such as a film and which is roughened along one longitudinal ridgeline on the side peripheral surface. 2. The linear lighting element according to claim 1, wherein the phase separation density in the glass body gradually changes in the length direction of the element.