JPH01250938A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the characteristic in a low temperature, to miniaturize an image forming device, and to reduce cost by detecting the ambient temperature of a fluorescent lamp, and controlling both the discharging light of the lamp and energizing heat of each electrode filament. CONSTITUTION:In switching on the fluorescent lamp 2, the electrode filaments 2(a) and 2(b) of the fluorescent lamp 2 is lit on simultaneously when its ambient temperature is lower than a set value, thereby raising the ambient temperature quickly: the device is constituted in such a way that the illuminance of the fluorescent lamp 2 is immediately raised to the target value. Therefore, the fluorescent lamp 2 does not need any flat external heating element; the life of the lamp 2 is not shortened since the electrodes filaments 2(a) and 2(b) are not lit when the lamp 2 is not lit; and it is not necessary to provide the device with a means emitting a sufficient amount of light even at a low temperature. Consequently, the device is miniaturized and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus equipped with a fluorescent lamp for illumination, and particularly to an image forming apparatus with improved characteristics at low temperatures.

[Conventional technology]

2. Description of the Related Art Some image forming apparatuses, such as copying machines, use a fluorescent lamp as a light source, which is used to illuminate an original to read its image, or as a light source for erasing a photoreceptor. At that time, the fluorescent lamp is turned on as follows.

(A) A current is passed through the electrode filament for a certain period of time to raise the temperature and make it easier for electrons to discharge from the electrode.

(A) Next, the electrical heating of the electrode filaments is stopped, and a voltage is applied between each electrode filament to cause discharge, and the fluorescent lamp is turned on.

Here, if the temperature of the fluorescent lamp decreases when it is turned on, the luminous efficiency will be poor, and the amount of light emitted will decrease, making it impossible to obtain a predetermined amount of light, resulting in insufficient illuminance. Therefore, it has been proposed to raise the temperature of the fluorescent lamp in advance by attaching a planar heating element to the fluorescent lamp, or to raise the temperature of the fluorescent lamp by constantly energizing the electrode filament. It has also been proposed to provide a lighting circuit for fluorescent lamps with a large capacity so that the illuminance is not insufficient even at low temperatures. However, without these measures, it will take a long time to obtain the necessary illuminance at low temperatures.

[Problem to be solved by the invention]

Since conventional image forming apparatuses are configured as described above,
It takes a lot of time to obtain the necessary illuminance at low temperatures,
Another problem is that the equipment becomes large and expensive, and the lifespan of the fluorescent lamp is shortened, resulting in poor serviceability.

That is, when a heating element is attached to a fluorescent lamp, a driving circuit for the heating element is also required, increasing costs and wasting space. Furthermore, if the electrode filament is constantly heated by electricity, the life of the filament will be shortened, the fluorescent lamp will have to be replaced many times, and serviceability will be reduced. Furthermore, when providing a lighting circuit for a large-capacity fluorescent lamp, the device becomes large, expensive, and serviceability deteriorates.

The present invention was made by focusing on these problems.
It is an object of the present invention to provide an image forming apparatus that is small and inexpensive, has a long fluorescent lamp life, is easy to service, and has improved characteristics at low temperatures.

[Means to solve the problem]

The image forming apparatus of the present invention is provided with a lighting circuit that discharges a fluorescent lamp for lighting and lights it, a heating means that heats each electrode filament of the lighting circuit, and a temperature detection means that detects the ambient temperature of the fluorescent lamp, When the detected temperature is lower than a preset temperature, each electrode filament is heated at the same time as the fluorescent lamp is turned on.

[Effect]

In the image forming apparatus of the present invention, when the ambient temperature detected by the temperature detection means falls below a preset temperature, each electrode filament is heated at the same time as the fluorescent lamp is turned on. The necessary illuminance can be obtained.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, showing the circuit configuration of a fluorescent lamp control system. In the figure,
1 is a CPU that controls the fluorescent lamp 2 for lighting, and 3 is a lighting circuit that discharges the fluorescent lamp 2 and lights it.
A voltage is applied to the electrode filaments 2a and 2b. 4a,
A filament drive circuit 4b is provided as a heating means for heating each electrode filament 2a, 2b, and applies a drive current to each electrode filament 2a, 2b during heating. 5
is a temperature sensor (temperature detection means) that detects the ambient temperature of the fluorescent lamp 2, and its detection signal is manually input to the CPUI via the interface 6.

7 is a temperature setting means using a variable resistor, and the filament drive circuit 4a according to the set temperature.

4b is activated.

Next, the operation of the fluorescent lamp control system will be explained with reference to the flowchart shown in FIG.

First, in step S1, it is determined whether the fluorescent lamp 2 is to be turned on or not, and if it is in the lighting mode, the process proceeds to step S2. At this time, if it is not the lighting mode, control other than fluorescent lamp control is performed.

In step S2, the electrode filaments 2a and 2b are turned on (energized) for a certain period of time (necessary and sufficient time to turn on the fluorescent lamp 2), and then in step S3, the temperature detected by the temperature sensor 5 falls below the set temperature. In other words, it is determined whether the ambient temperature of the fluorescent lamp 2 is higher than the set temperature preset by the temperature setting means 7, and if it is higher than the set temperature, the process moves to step S4 and the electrode filament 2a is turned off.

Turn off 2b. At this time, an OFF signal is output from the CPU to the filament drive circuits 4a and 4b. Then, the process proceeds to step S5 and the fluorescent lamp 2 is turned on. At this time, the CPU 1 outputs an ON (lighting) signal to the lighting circuit 3.

Further, if the ambient temperature is not higher than the set temperature in step S3, the process directly proceeds to step S5, and the fluorescent lamp 2 is turned on while the electrode filaments 2a and 2b are kept turned on.

Next, in step S6, it is determined whether it is the timing to turn off the fluorescent lamp 2, and if so, the process proceeds to step S7, in which the fluorescent lamp 2 and its respective electrode filaments 2a, 2b are
Turn off the light. At this time, a signal is output from the CPU 1 to the lighting circuit 3 and the filament drive circuits 4a and 4b to turn them off. Further, if it is determined in step S6 that the timing for turning off the light has not come, the process returns to step S3 and the above-described operation is repeated.

In this way, when the fluorescent lamp 2 is turned on, if the ambient temperature of the fluorescent lamp 2 is lower than the set value, the electrode filaments 2a and 2b of the fluorescent lamp 2 are also turned on at the same time to quickly raise the ambient temperature of the fluorescent lamp 2. ing. In other words, it is configured to quickly increase the illumination intensity (light amount) of the fluorescent lamp 2 to the target value.
Therefore, there is no need to provide a planar external heating element to the fluorescent lamp 2, and it is possible to shorten the life of the fluorescent lamp 2 by lighting the electrode filaments 2a and 2b when the fluorescent lamp 2 is not lit, or to reduce the lifespan of the fluorescent lamp 2 at low temperatures. It is no longer necessary to provide a device with enough room to emit a sufficient amount of light, making it possible to reduce the size and cost of the device, and improve serviceability.

In the above embodiment, the lighting of the electrode filaments 2a and 2b of the fluorescent lamp 2 is terminated by measuring the ambient temperature near the fluorescent lamp 2. However, when measuring the ambient temperature of the fluorescent lamp 2, It is also possible to measure the room temperature where the control device is installed, and from that room temperature it is possible to judge whether it is better to turn on the electrode filaments 2a and 2b while the fluorescent lamp 2 is turned on, and also, How long the electrode filaments 2a and 2b should be lit is determined in advance from the correlation between the room temperature and the lighting (filament) time.
It is also possible to program this into the CPUI.

〔Effect of the invention〕

As described above, according to the present invention, since the ambient temperature of the fluorescent lamp is detected to control the discharge lighting of the fluorescent lamp and the energization heating of each electrode filament, the required temperature can be achieved in a short time even at low temperatures. This has the effect that the characteristics at low temperatures are improved, the device can be made smaller and cheaper, the life of the fluorescent lamp is longer, and serviceability is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a flow chart showing the operation of the fluorescent lamp control system of FIG. 1... CPU 2... Fluorescent lamps 2a, 2b... Electrode filament 3...
- Lighting circuits 4a, 4b...Filament drive circuit (heating means) 5...Temperature sensor (temperature detection means) 7...
・Temperature setting means

Claims (1)

[Claims] In an image forming apparatus equipped with a fluorescent lamp for illumination, a lighting circuit for discharging and lighting the fluorescent lamp, a heating means for heating each electrode filament thereof, and a temperature detection means for detecting the ambient temperature of the fluorescent lamp are provided. 1. An image forming apparatus characterized in that, when the detected temperature is lower than a preset temperature, each electrode filament is also heated at the same time as the fluorescent lamp is turned on.