JPS61144000A - Fluorescent lamp lighting control circuit - 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 [Field of Industrial Application] The present invention relates to a fluorescent lamp lighting control circuit used for lighting a fluorescent lamp for illuminating a document in, for example, an optical character reader (OCR).

Optical reading devices used for reading single characters or codes, including OCR, have a CCD (charge coupled device) used as a reading element.
ce) Due to the optical characteristics of the device, fluorescent lamps are widely used for illuminating the original to be read.

In order to turn on a fluorescent lamp, first, the electrodes are preheated to make it easier for discharge to occur around each electrode, and then a relatively high voltage is temporarily applied between the two electrodes. A relatively low voltage is then applied between the electrodes to sustain the discharge.

By the way, the ambient temperature affects the lighting conditions of a fluorescent lamp.9 If the ambient temperature is high, the electrode preheating time will be short, but if the ambient temperature is low, the preheating will take a long time. (See Figure 3).

At this time, it is desirable that the fluorescent lamp be turned on as quickly as possible so that reading of the original can be started immediately.

[Conventional technology]

FIG. 2 is a circuit diagram showing the configuration of a conventional fluorescent lamp lighting control circuit. In the figure, +la and 1b are two fluorescent lamps connected in series, and 2a and 2b are power supplies that supply the voltage for preheating the electrodes of the fluorescent lamps 1a and 1b and the voltage for discharging applied between the electrodes. The components of the circuit source 2 are an automatic high frequency oscillator 2a and a transformer 2b.

In addition, 3 is a relay, SL, 32, 33, and 34 are switches that are opened and closed by relay 3, and 4 outputs a binary signal of "1" when the lighting signal S is input, and after a certain period of time has passed. This shows a timer that outputs a binary signal of “0” when

8 to g indicate the terminals on the secondary side of the transformer 2b, between a and b.
A voltage of 20 volts as a power source for preheating the electrodes of the fluorescent lamps 1a and 1b is supplied from between de and fg, and a voltage of 20 volts to be applied between the electrodes is supplied from between bc.

With the above configuration, the fluorescent lamps 1a and 1b are lit in the following order.

When the i0 lighting signal S is input, the timer 4 outputs a binary signal of "1".

11 When "1" is input from the timer 4, the relay 3 is activated, switches S1, S2, S3 and S4 are closed simultaneously, and preheating of the electrodes of the fluorescent lamps 1a and 1b is started.

iii. When a predetermined period of time has elapsed since the fluorescent lamp lighting signal S was input, the timer 4 outputs a binary signal "O".

iv. When "0" is input from the timer 4, the relay 3 is activated and the switches S1, S2, S3 and S4 are simultaneously opened, and the preheating of the fluorescent lamps 1a and 1b is completed. At the same time, by opening switch S2.

As a result, a high voltage is temporarily induced between bd by the inductance of transformer 2h and capacitor C.

Fluorescent lamps 1a and 1b are turned on.

[Problem that the invention seeks to solve]

In the fluorescent lamp lighting control circuit with the above configuration, the preheating time of the fluorescent lamp is determined based on cold weather, and the fluorescent lamp is turned on after preheating for a certain period of time, for example, 10 seconds, regardless of the ambient temperature of the fluorescent lamp. are doing.

Therefore, even when the ambient temperature of the fluorescent lamp is high and heating for about 2 seconds is sufficient, for example, there is a problem that the fluorescent lamp cannot be turned on until 10 seconds have elapsed.

[Means for solving problems]

The fluorescent lamp lighting control circuit according to the present invention includes a power supply circuit that supplies a voltage for preheating the electrodes of the fluorescent lamp and a voltage for discharging applied between the electrodes, and a temperature detection circuit that detects the ambient temperature of the fluorescent lamp. The above-mentioned problem is solved by providing a preheating time control section that determines the preheating time of the electrode of the fluorescent lamp according to the temperature detected by the temperature detector.

[Effect]

That is, by changing the preheating time of the fluorescent lamp in accordance with the temperature detected by the temperature detector, unnecessary preheating over a long period of time can be avoided.

〔Example〕

The gist of the present invention will be specifically explained below using examples.

FIG. 1 is a configuration diagram of one embodiment of the present invention, and in FIG. 2,
Reference numerals common to those in the conventional example in FIG. 2 refer to the same objects.

In addition, 5 is a temperature detector installed near the fluorescent lamp 1a, and 6 and 7 are preheating times for determining the preheating time of the electrodes of the fluorescent lamps 1a and 1b according to the temperature detected by the temperature detector 5. It is a component of the control section.

6 is a read-only memory that stores necessary and sufficient preheating time according to the ambient temperature of the fluorescent lamp 1a as a table.
(ROM), 7 outputs a binary signal “1” when the lighting signal S is input, and then the read-only memory 6
This is a timer that outputs a binary signal of "0" when a given time has elapsed.

With the above-described configuration, the fluorescent lamps 1a and 1b can be turned on after necessary and sufficient preheating is performed depending on the temperature around the two.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent a fluorescent lamp from being preheated for an unnecessarily long period of time.

Since the fluorescent light can be turned on in a short time, it is possible to start reading the original in the shortest possible time in OCR, etc.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention. FIG. 2 is a configuration diagram of a conventional example. FIG. 3 is an explanatory diagram regarding the residual heat time of the fluorescent lamp. In the figure. 1a and 1b are fluorescent lights + 2a is a self-excited high frequency oscillator. 2b is a transformer, 3 is a relay. 5 is a temperature sensor, 6 is a read-only memory. 7 is a timer. ”If-t times

Claims (1)

[Claims] A power supply circuit that supplies a power source for preheating the electrodes of the fluorescent lamp and a discharge voltage applied between the electrodes, a temperature detector that detects the ambient temperature of the fluorescent lamp, and a preheating time for the electrodes of the fluorescent lamp. A fluorescent lamp lighting control circuit comprising: a preheating time control section that determines a preheating time according to a temperature detected by the temperature detector.