JPS61214080A - Preheating control circuit for fluorescent lamp - Google Patents

Abstract

PURPOSE:To reduce the cost of production of the titled control circuit by turning on a fluorescent lamp to increase the temperature when the temperature is lower than a prescribed level within a device and therefore informing an applicable state of the device to a host device. CONSTITUTION:When the application of a power supply is detected by a power supply application detecting circuit 3, a control circuit 4 checks the temperature detected by a detector 2 and sends a device applicable signal to a host device when said temperature exceeds 20 deg.C. While the circuit 4 sends a lighting signal to a power supply circuit 5 to turn on a fluorescent lamp 1 when the detected temperature is lower than 20 deg.C. Thus the rise of temperature due to the self- generation of heat is awaited. Then a turning -off signal is sent to the circuit 5 to turn off the lamp 1 when the detected temperature exceeds 20 deg.C. Then only an electrode is heated and at the same time the device applicable signal is sent to the host device. As a result, the temperature is kept at >=20 deg.C within the device together with the generation of heat of other circuits within the device.

Description

[Detailed Description of the Invention] [Summary] A luminescent lamp preheating control circuit included in an optical reading device using a fluorescent lamp as an illumination source, which performs a luminescent lamp preheating control circuit when the ambient temperature of the fluorescent lamp does not exceed a predetermined value. , once it is turned on, its self-heating causes the temperature to rise, and when the temperature exceeds a predetermined value, a device availability signal is generated.

[Industrial application field]

The present invention relates to a light emitting lamp preheating control circuit provided in an optical reading device that uses a fluorescent lamp as an illumination source.

Optical reading devices such as optical character reading devices and optical code reading devices include CCDs used as reading elements.
(charge coupled device) A fluorescent lamp is generally used as the illumination source due to the optical characteristics of the device.

A fluorescent lamp generates visible light by stimulating a fluorescent substance with ultraviolet rays generated during a discharge in low-pressure mercury vapor of about 1 g of O, O] amml, and in addition to a small amount of mercury inside the tube, Argon gas at a pressure of about 1/200 atmosphere is filled in the filament in order to facilitate the start of the discharge and prevent evaporation of the oxide coated on the filament to extend its life.

Fluorescent lamps have a characteristic that when they are turned on at low temperatures, argon gas discharges and emits infrared rays until the ambient temperature reaches a predetermined temperature. For this reason, for example, when the light is turned on at 0°C, at first about 50% of the total light intensity
% is infrared rays, and over the course of 3 hours, the vapor pressure of mercury rises due to temperature rise due to self-heating, and the infrared rays are gradually emitted by a phosphor due to discharge in the mercury vapor, and the infrared rays are extinguished.

Further, generally, a fluorescent lamp for an optical reader uses a fluorescent substance that generates green color, and therefore the optical system is designed based on the wavelength of green light.

For this reason, if infrared rays with different wavelengths are emitted, the resolution of the optical system decreases, which is not desirable, and appropriate measures are required.

[Prior Art] Conventional optical reading devices use electric heaters designed specifically for preheating fluorescent lamps.

This electric heater has a shape that is in close contact with the tube wall of the fluorescent lamp over the entire length G in the tube axis direction and approximately half in the circumferential direction, and is designed to maintain the tube wall at a predetermined temperature using a thermostat.

[Problem that the invention seeks to solve]

The above configuration has a problem in that the cost of the product increases.

[Means for solving problems]

FIG. 1 is a principle block diagram of the fluorescent lamp preheating control circuit of the present invention. In FIG. A power-on detection circuit 4 detects that the power is turned on, and after the power-on detection circuit 3 detects that the device power is turned on, if the temperature detected by the temperature detector 2 does not exceed a predetermined value, the fluorescent lamp is turned on. Thereafter, when the temperature exceeds a predetermined value, 9 is a control circuit that generates a device availability signal to a host device (not shown), and 5 is a power supply circuit for lighting the fluorescent lamp 1.

[Effect]

When the power-on detection circuit 3 detects that the device is powered on, the control circuit 4 checks the temperature detected by the temperature detector 2, and (1) sends a message to the host device if the detected temperature exceeds 20°C. Sends a device availability signal to (2
) When the detected temperature is below 20°C, a lighting signal is sent to the power supply circuit 5 to turn on the fluorescent lamp 1, wait for the temperature to rise due to self-heating, and then the temperature detected by the temperature detector 2 reaches 20°C. When the temperature exceeds .degree. C., a turn-off signal is sent to the power supply circuit 5 to turn off the fluorescent lamp 1 and only heat the electrodes, and a device availability signal is sent to the host device.

As a result, the temperature is maintained at 20'C or higher with the addition of heat generated by other circuits within the device.

(Embodiment) FIG. 2 is a configuration diagram of an embodiment of the present invention, in which a circuit consisting of a diode 31, a capacitor C1, a resistor R, and a negative element 32 is used as the power-on detection circuit 3, and when the device power is turned on, Then, the voltage stripes at point A and point B change as shown in Figure 3 (81 and (g)), and (bl
A signal shown in is sent to the control circuit 4 as a detection signal.

The power supply circuit 5 is composed of a self-excited high-frequency oscillator 51, a transformer 52, a relay 53, switches S1, S2, S3, S4, and a capacitor C2. ``1'' is input to close switches S1, S2, S3, and S4, and after a predetermined period of time, for example, 3 seconds, a binary signal ``0'' is input and switches S1, S2, S3, and S4 are closed.
The fluorescent lamp 1 is turned on by opening S2, S3, and S4, and then when the binary signal "1" is input to the relay 53 and the switches S1, S2, S3, and S4 are closed, the fluorescent lamp 1 is turned off. Only heating of the electrodes takes place.

Further, the control circuit 4 is activated by a detection signal inputted from the power-on circuit 3, and performs control in the following order.

1. The automatic high frequency oscillator 51 is activated.

2. Check the temperature detected by temperature detector 2.

(1) If the detected temperature exceeds 20° C., a device availability signal is sent to the third-position device.

(2) When the detected temperature is around 20°C.

B. Send a binary signal ``'1'' to the relay 53.

The fluorescent lamp 1 is turned on by sending out a binary signal "0" after a predetermined time, for example, 3 seconds.

After that, the temperature detected by the temperature detector 2 is checked, and when it exceeds 20"C, the fluorescent lamp 1 is turned off and each electrode is turned off by sending a binary signal "1" to the relay 53. It only performs heating and also sends a device availability signal to the three-way device.

Note that a standard product using a thermistor is used as the temperature detector 2, and as the control circuit 4, a part of the microprocessor built in the optical reading device is used for controlling each part.

It can be configured extremely inexpensively.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide an optical reading device that is cheaper than the conventional example.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention. FIG. 2 is a configuration diagram of an embodiment of the present invention. FIG. 3 is a partial explanatory diagram of the same embodiment. In the figure. 1 is a fluorescent light, 2 is a temperature detector. 3 is a power-on detection circuit, and 4 is a control circuit. 5 is a power supply circuit. υ External injection detection ￯ positive pressure $3 Threshold Curved theory []bar

Claims (1)

[Claims] An optical reading device for reading an image illuminated by a fluorescent lamp is equipped with: a temperature detector (2) for detecting the ambient temperature of the illuminating fluorescent lamp (1); and a device power source. A power-on detection circuit (3) detects that the power is turned on, and after the power-on detection circuit (3) detects that the device power is turned on, the temperature detected by the temperature detector (2) exceeds a predetermined value. 1. A fluorescent lamp heat control circuit comprising: a control circuit (4) which turns on the fluorescent lamp (1) and generates a device availability signal when the temperature exceeds a predetermined value if the temperature of the fluorescent lamp (1) exceeds a predetermined value.