JPS6174298A - Fluorescent lamp lighting apparatus - 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 This invention relates to a lighting device for a fluorescent lamp used as a light source for illuminating documents in facsimiles and the like.

A lighting device for a fluorescent lamp, which is generally used as a light source for illuminating documents in facsimile machines, has a frequency of 30 to 50 KHz.
a high-frequency lighting device that lights a fluorescent lamp at a high frequency of
There is a low-frequency lighting device π that lights at a commercial frequency, and the former high-frequency lighting device is common.

An example of the above-mentioned fluorescent lamp high-frequency lighting device will be explained with reference to FIG. rectifier circuit,
(3) is a high frequency lighting circuit which, when a full-wave rectified DC voltage is inputted through a choke (4), exchanges it with an appropriate high frequency and applies it to a fluorescent lamp (5) to light it.

The high-frequency lighting circuit (3) includes, for example, an oscillation transformer T and two transistors T r1 connected to the next side of the oscillation transformer T in a push-pull manner via resistors R1-, R2 and a capacitor CI.
, T r 2.

When the full-wave rectified DC voltage is applied to the bases of the transistors Try and Tr2 via the choke (4), one of the transistors is turned on. As a result, the primary winding N1 of the oscillation transformer T is excited, and a voltage is induced in the feedback winding N2 of the oscillation transformer T. As a result of this voltage being applied to the bases of transistors T r 1 s T r 2 , both transistors T r 1
, Tr2 are alternately turned ON and OFF, and a high frequency voltage is generated in the secondary winding N3 of the oscillation transformer T in accordance with the winding ratio with respect to the primary winding N1, and a high frequency voltage is generated through the current limiting means, for example, the capacitor C2. The voltage is applied to the light lamp (5), whereby a lamp current determined by the capacitance of the capacitor C2 flows through the fluorescent lamp (5), and the fluorescent lamp (5) is lit at high frequency.

Due to the miniaturization of facsimile machines, etc., such fluorescent lamps (5) have a tube diameter of 15.5±21)1)1 and a tube length of 370 mm.
A lamp with an ffl1m and a lamp current of about 400mA is used.

By the way, fluorescent lamps for illuminating documents, such as those used in facsimile machines, are particularly required to have a good luminous flux rise, with a short time from the point of lighting until the light output reaches the level necessary for reading the document. However, like other general fluorescent lamps, this type of fluorescent lamp has a good luminous flux rise when lit at room temperature, at an ambient temperature of about 25°C, and has no problem, but when the ambient temperature is low, around 5°C. There was a problem with poor luminous flux rise characteristics.

For example, a fluorescent lamp with a tube diameter of 15.5m, a tube length of 3701, and 100% argon is used at an ambient temperature of 5°C and a lamp current of 4.
When the luminous flux rise characteristic when the light is turned on at a high frequency of 00 mA is determined, the curve (b) in FIG. 6 is obtained.

That is, approximately 18% of the stable light output 20 seconds after lighting, 4
The luminous flux rises slowly, at about 27% after 0 seconds and about 40% after 60 seconds, and in fact, at such a luminous flux rising speed, it takes several tens of seconds of waiting time for the light output to rise to a level that allows the document to be read. This was one of the factors that damaged the commercial value of facsimiles and the like.

The present invention was devised in view of the above-mentioned problems, and aims to improve the luminous flux rise characteristics during low-temperature lighting of a fluorescent lamp. The above object is achieved by adding lamp current control means for increasing the lamp current above the rated value for a certain period of time.

As in the present invention, when a fluorescent lamp is lit with a lamp current flowing higher than the rated value at the beginning of the rise of the luminous flux, the rise of the luminous flux becomes faster according to the increase in the lamp current, and therefore the originals such as facsimile etc. If applied to a lighting device for a fluorescent lamp for illumination, it is possible to shorten the waiting time required to read a document when using the invention at low temperatures.

An embodiment of the present invention applied to the fluorescent lamp high frequency lighting device shown in FIG. 7 will be described below with reference to FIGS. 1 to 4.

In the block diagram of FIG. 1, the same parts as those in the claw 7 figure are given the same reference numerals, and the explanation will be omitted. The only difference is that the following lamp current control means (6) is added. This lamp current control means (6) switches the lamp current flowing through the fluorescent lamp (5) into two stages, the rated value and the higher value, and is connected, for example, between the high frequency lighting circuit (3) and the fluorescent lamp (5). (1) A two-stage lamp current switching circuit (7) for switching the current flowing through the fluorescent lamp (5) to either a rated lamp current 1 or a predetermined non-rated lamp current I2 larger than 1;
), the lamp current two-stage switching circuit (7) operates for a certain period of time after the AC power supply (1) is turned on, and only during that time the fluorescent lamp (
5) and a timer circuit (8) that outputs a control signal to cause non-rated lamp current (2) to flow.

The three specific lamp current two-stage switching circuits (7) are shown in Figure 2~
This is shown in FIG. 4 and will be explained.

Figure 2 shows a capacitor C2 connected to a circuit line between the secondary side of an oscillation transformer T and a fluorescent lamp (5), a lamp current two-stage switching capacitor C3, and a series circuit of a switching element s1 connected in parallel. It is. Switching element S1
is a relay contact, for example, and its opening and closing are controlled by the relay Ry built in the timer circuit (8) as follows. AC 1fl
(i) is turned on, the timer circuit (8) is started, and when the relay Ry is activated, the relay contact S1 is closed. Then, a non-rated lamp current I2, which is determined by the parallel capacitance of the two capacitors c2 and c3, flows through the fluorescent lamp (5), causing high-frequency lighting. When a certain period of time t has passed since this lighting, the timer circuit (8) stops, and the relay Ry stops, which opens the relay contact S1 (Then, the current flowing through the fluorescent lamp (5) is determined by the capacity of one capacitor C2. The rated lamp current is switched to ■1, and thereafter the fluorescent lamp (5) is lit at this rated lamp current.

Specifically, lamp lighting by such two-step lamp current switching is performed as follows.

Now, a fluorescent lamp lit according to the curve (b) in FIG.
500mA, set at t = 60 seconds, ambient temperature 5℃
When the light is turned on under the following conditions, the luminous flux rises as shown in curve (a) in Figure 6, and the light output level of the present invention product is compared to the rated light output of the conventional product when turned on in 10 second increments after lighting. If you calculate the level as 100, it will look like the following table.

In the case of the present invention, the fluorescent lamp is lit at a lamp current of 500 mA, which is higher than the rated lamp current of 400 mA, for 60 seconds after lighting, so the luminous flux rises quickly, and the light output is reduced by 20% after 10 seconds compared to the conventional lamp. It was found that this rate of increase increased over time, increasing by 47% after 60 seconds. Also, after 60 seconds, the lamp current returns to the rated value and the light output level decreases a little, but at this time the fluorescent lamp has already passed 60 seconds after lighting and the tube wall temperature has risen, so after 60 seconds Even if the optical output level decreases, it will not decrease to the conventional level, and 6
Even after 0 seconds, the light continues to be lit with a level-amplified optical output compared to conventional ones.

This improvement in the rise of the luminous flux during low-temperature lighting can shorten the waiting time required for the light output to level up to the point where the original can be read after the lamp is turned on, and in the above-mentioned product of the present invention, the waiting time is shortened by several tens of seconds. That's what I found out.

The effect of shortening the waiting time becomes more pronounced as the unrated lamp current ■2 increases, but as I2 increases, the damage to the electrodes of the fluorescent lamp increases and the lamp life shortens. Practically speaking, it is preferable to set the current (2) to a value approximately 30% higher than the rated lamp current (1).

Next, the lamp current two-stage switching circuit (7) shown in FIGS. 3 and 4 will be explained.

Figure 3 shows that two taps (9a) and (9b) are provided at one end connected to the fluorescent lamp (5) on the secondary side of the oscillation transformer T, and these are alternately switched by the switching element S2. , the secondary voltage applied to the fluorescent lamp (5) is switched in two stages, and the lamp current is switched in two stages.

Figure 4 shows a choke ballast (1) having two taps (10a) and (10b) inserted into one circuit line between the oscillation transformer T and the fluorescent lamp (5).
, (10b) by a switching element Sa, the lamp current is switched in two stages.

In each of the above embodiments, the switching elements 31 to S3 are controlled by the timer circuit (8) after a certain period of time from lamp lighting. It is also possible to use means for detecting the output level one by one and returning the lamp current to the rated value when the detected level reaches a constant value. For example, as shown in Figure 5, a temperature sensor (1) is placed near a fluorescent lamp (5), and the fluorescent lamp (5) is lit with a lamp current exceeding the rated value so that its light output remains constant. When the tube wall temperature rises to a certain level, a temperature sensor (1)) may detect this and return the lamp current to the rated value.

In the embodiment shown in FIG. 1, the lamp current of the fluorescent lamp (5) can also be switched by means such as tap switching on the primary side of the oscillation transformer T of the high frequency lighting circuit (3).

Furthermore, the present invention is applicable not only to high-frequency lighting devices but also to low-frequency lighting devices.

According to the present invention, the luminous flux rises even faster when the fluorescent lamp is turned on at low temperatures, so if it is applied to a fluorescent lamp lighting device for document illumination such as a facsimile, it will be possible to read documents from lamp lighting at low temperatures. It becomes possible to shorten the waiting time until the machine is ready, and it is possible to improve the commercial value of facsimiles and the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 32 to 4 are partial circuit diagrams showing three specific parts of FIG. 1, and FIG. 5 is another embodiment of the present invention. FIG. 6 is a block diagram illustrating an example, FIG. 6 is a characteristic diagram of the luminous flux rise of fluorescent lamps when the product of the present invention and a conventional product are lit at low temperatures, and FIG. 7 is a circuit diagram showing an example of a conventional fluorescent lamp lighting device. (5) - fluorescent lamp, (6) - lamp current control means, I - rated lamp current, I2 - non-rated lamp current (I2 > 1)).

Claims (1)

[Claims] (1) A fluorescent lamp lighting device characterized in that a lamp current control means is added for increasing the lamp current above the rated value for a certain period of time within the luminous flux rising period from lighting of the fluorescent lamp.