JPH01403A - lighting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field 1) The present invention relates to a lighting device using a fluorescent lamp as a light source.
The present invention relates to a lighting device suitable for image measurement using a camera or the like.

[Prior art] The light source of the lighting device used for image measurement includes fluorescent lamps,
There are many types of lamps, including halogen lamps and tungsten lamps, but the most commonly used lamp is the fluorescent lamp. The reason for this is that the fluorescent lamp has a long lifespan and is cheap, but it is also believed that it is convenient for image measurement to be able to make the illuminance distribution in the measurement field of view relatively uniform.

- In the case of dimensional measurement, by using a straight tube lamp that is sufficiently good for the length of the field of view, and in the case of two-dimensional measurement, by using a ring tube lamp with a diameter that matches the field of view, uniform illuminance that does not cause any practical problems can be achieved. distribution is obtained.

However, the weak point of fluorescent lamps is that the illuminance cannot be maintained constant because the illuminance changes over time, the illuminance changes due to ambient temperature, and the illuminance changes due to applied voltage fluctuations. When detecting delicate scratches and defects or measuring shapes with high precision using image measurement, changes in illuminance directly result in changes in the image input signal, which adversely affects the measurement results.

[Purpose of the Invention] Therefore, the inventor of the present invention has developed a luminous flux 1, IItIll, in which an optical sensor is attached (near the light source) to detect the luminous flux, and the voltage applied to the fluorescent tube is adjusted so that the illuminance is constant. Tried. As a result, we discovered that there are cases in which the luminous flux can be controlled to a constant value and cases in which it is not possible depending on the ambient temperature conditions. When the cause was investigated, it became clear that this phenomenon was caused by the temperature characteristics of the fluorescent lamp, that is, the characteristics of ambient temperature versus light. As shown in FIG. 2, the temperature characteristics of a fluorescent lamp are such that when the ambient temperature is low, the luminous flux is low, and as the ambient temperature rises, the luminous flux increases (positive correlation), and the luminous flux peaks at a certain temperature.

When the ambient temperature further increases, the luminous flux decreases (negative correlation). Such temperature characteristics are related to the basic principle of a fluorescent lamp, in which ultraviolet rays scattered by collision with mercury vapor discharge electrons sealed in the fluorescent tube collide with a fluorescent surface and emit light. In other words, as the temperature rises, the activity of mercury vapor increases and there are more opportunities for collisions with electrons, resulting in an increase in luminous flux, but if the temperature becomes too high, there will be more collisions with electrons that have just jumped out of the cathode and are not sufficiently accelerated. This is because, on the contrary, the luminous flux decreases.

Therefore, when performing the above-mentioned luminous flux control under conditions where the ambient temperature is high and the temperature characteristics exhibit a negative correlation, even if the voltage applied to the tube is increased to increase the previous value, it will be converted into thermal energy and further Since the temperature of the tube increases, the amount of light does not increase due to the negative correlation.

General fluorescent lamps produce the highest luminous flux when the ambient temperature is around 20°C, and the temperature of the tube wall at that time is about 40°C, so luminous flux control is performed under conditions higher than this temperature. That is difficult.

The present invention is based on the above knowledge, and aims to provide a lighting device that can stably control the illuminance obtained in a lighting device using a fluorescent lamp as a light source, thereby contributing to precise image measurement and the like.

[Structure and operation of the invention] The above objectives will be achieved by the following Honbunan.

That is, the present invention provides a lighting device using a fluorescent lamp as a light source, which includes a cooling means for cooling the fluorescent lamp to a temperature within a range where the temperature characteristics thereof have a positive correlation, so that the fluorescent lamp can be controlled in luminous flux. The present invention is characterized in that the illuminance is stabilized by stably controlling the luminous flux to a constant value using a luminous flux control means that controls the luminous flux to a constant value.

The details of the present invention will be explained below based on examples.

FIG. 1 is an explanatory diagram of the configuration of the embodiment.

In the figure, 1 is a fluorescent lamp, 10 is a cooling means for cooling the fluorescent lamp 1 to a temperature within a range where its temperature characteristics have a positive correlation, and 20 is a luminous flux control means for controlling the luminous flux of the fluorescent lamp 1 to a constant value. It is.

The cooling means 10 includes a sealed case 11 with a fluorescent lamp 1 attached to one side thereof and a transparent glass window 11a on the front side, and a vibrator 12 for circulating cooling air through the case 11. It consists of a compressor (not shown) that blows this air. and cooling means 104. The fluorescent light 1
Specifically, the temperature of the tube wall of fluorescent lamp 1 is 4.
Range of 0° C. or Less In this example, for simplicity, air was blown so that the ambient temperature, that is, the temperature inside the case 11, was 20° C. or less. Note that the cooling means differ depending on the cooling conditions, and in case 11
A jacket structure should be designed to suit the surrounding conditions, such as water cooling.

The light flux control means 20 includes a light sensor 2 such as a photodiode that detects the light flux of the fluorescent lamp 1 attached to the side wall of the case 11.
1, a control circuit 22 consisting of a differential arithmetic amplifier that receives a detection signal from the optical sensor 21 and outputs a control signal to a set value to be described later, and a control circuit 22 that controls the voltage applied to the fluorescent lamp 1 in accordance with the control signal. It consists of a power supply circuit 23 for adjustment. For the power supply circuit 23, a commercially available high frequency power supply device (LS-1 manufactured by Kyoto@Ki@J) was used. The setting values are stored in a commercially available analog memory (Seebeck ■
By combining a memory circuit 24 made up of the following products (manufactured by Mimaki, Ltd.) and a command circuit 25, the value of the detection signal at the time when the command is issued to the command circuit 25 is stored in the memory circuit 24, and the value is used as a set value.

Therefore, the design value of the fluorescent lamp 1 to be used can be set by simply issuing a command when the luminous flux becomes stable during measurement.

With the above configuration, it was confirmed that even when the room temperature was changed from 15° C. to 29.5° C., a very stable luminous flux could be obtained, with the luminous flux change of fluorescent pair 1 being less than ±0.3%.

In this example, the fluorescent pair 1 was placed in the tightly packed case 10 to stabilize it by blocking external influences, especially since the amount of light changes rapidly when the wind hitting the tube changes. The purpose is to prevent storage, and the cooling means 10 may be simply blowing cold air, etc., depending on the case.

As described above, the present invention allows the luminous flux of the fluorescent pair to be controlled by the cooling means yA11.
This is an illumination device using a fluorescent pair with a stable luminous flux by controlling the luminous flux at a constant value using a luminous flux control means while maintaining the luminous flux at 1 t, which greatly contributes to improving the accuracy of dimension measurement, shape measurement, etc. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of the embodiment, and FIG. 2 is a graph of the temperature characteristics of the fluorescent pair. 1: Fluorescent pair 10: Cooling means 20: Luminous flux control means\,.

Claims (1)

[Claims] 1. In an illumination device using a fluorescent lamp as a light source, a cooling means for cooling the fluorescent lamp to a temperature within a range where its temperature characteristics have a positive correlation, and controlling the luminous flux thereof to a constant value. A lighting device characterized by being provided with a luminous flux control means. 2. The cooling means comprises a sealed box that houses a fluorescent lamp and has a transparent plate on the front side of the fluorescent lamp, and a ventilation device that allows cooling gas to pass through the box. lighting equipment. 3. The light flux control means according to claim 1 or 2, further comprising a setting circuit that stores the value of the detection signal of the luminous flux of the fluorescent lamp at the time of the command and outputs the value as a set value. lighting equipment.