JPS6250822A - Image forming device - Google Patents

Abstract

PURPOSE:To shorten the light quantity rise time of a light source at low cost by providing a detecting means which detects the quantity of light of the light source reaching a set value and a sequence control means which starts an exposure scan on an original after the set value is detected. CONSTITUTION:A photodetecting element 13 detects the quantity of light of a fluorescent lamp 3 and a light quantity control circuit 14 receives the output of the photodetecting element 13 to control the quantity of light of the fluorescent lamp to the specific set value. A high frequency stabilizer 15 receives a signal from the light quantity control circuit 14 and supplies a controlled tube current to the fluorescent lamp 3. A light quantity startup detection circuit 17 receives the signal from the light quantity control circuit 14 and detects the quantity of light at the startup of the fluorescent lamp 3 reaching the specific value or the specific rate of the specific set value, thereby transmitting its startup detection output to the sequence control circuit 16. Consequently, the sequence control circuit controls the forward movement of a platen 2. thus, the light quantity rise time of the light source is shortened at low cost.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a type of exposure scanning of an original using a light source for exposing an original having a predetermined amount of light, and an entire image is formed by the original light that is modulated on the original. The present invention relates to an image forming apparatus, and in particular to an image forming apparatus of the type that uses a fluorescent lamp as an exposure light source, which has a characteristic that the rise time of the light amount varies widely depending on the ambient temperature. Although the present invention is particularly suitable for application to electrophotographic copying devices, it is also applicable to other types of image forming devices, for example, welfare scanning devices of image reading devices that utilize photoelectric conversion elements such as COD.

[Background of the invention]

FIG. 3 schematically shows a conventional electrophotographic copying apparatus as an example of an image forming apparatus to which the present invention can be applied.

In the figure, 1 is an original, 2 is a platen, 3 is a fluorescent lamp which is a light source for exposing the original, 4 is a reflecting mirror, and 5 is a light-converging lens array 1.
6 is a primary charger, 7 is a developer, 8 is a resist roller 9
is a transfer charger, 1o is a cleaner, 11 is a photosensitive drum,
12 indicates a fixing device.

As is well known, during operation, the next document 1 placed on the platen 2 moves in the direction of the arrow, and the reflected light from the document 1 illuminated by the fluorescent lamp 3 is focused by the lens array 5 onto the photoreceptor drum 11. This latent image is developed by a developing device 7, transferred to a transfer material by the action of a transfer charger 9, and fixed by a fixing device 12. Further, the surface of the photosensitive drum after the transfer is cleaned by a cleaner 10 in preparation for the next image formation.

In the copying apparatus described above, when a copy command is issued, the motor starts rotating, and the photosensitive drum 1 shown in FIG.
1. Sleeve in developing device 7, roller in cleaner 10,
The rollers and the like in the fixing device 12 start rotating. The fluorescent lamp 3 also starts lighting at the same time as the motor starts, but fluorescent lamps have a characteristic that the rise time of the glow varies widely depending on the ambient temperature, and the start-up time when the ambient temperature is low is unnecessary. It will be necessary to Figure 4 shows the relationship between the relative light output of a fluorescent lamp and time. As shown in the figure, as the ambient temperature decreases from 25°C to 10°C to 0°C, the start-up time increases considerably. .

Therefore, conventionally, as shown in FIG. 5, a heat-retaining heater 18t is installed near the fluorescent lamp 3, and the temperature detecting element 19 adjusts the ambient temperature to the set temperature by controlling the control circuit 20 to send the temperature to the heat-retaining heater. Fluorescent lamp 3
It was devised to have good light intensity start-up characteristics.

However, in conventional devices of this type, the heat retention heater 18
The drawback is that the temperature control circuit 20 is expensive.

[Purpose of the invention]

As described above, in order to shorten the time required to start up the light intensity of a fluorescent lamp for document illumination, the present invention eliminates the need for an expensive heat-retaining heater and temperature control circuit, which have been conventionally used, and increases the size of a single image forming apparatus. An object of the present invention is to provide an image forming apparatus capable of achieving a wide cost reduction and shortening a light amount start-up time.

[Summary of the invention]

An image forming apparatus according to the present invention is an image forming apparatus that exposes and scans an original using an original exposure light source having a light intensity of a predetermined set value, and forms a multi-image on the original that is modulated by the original. The present invention further includes a detection means for detecting that the light intensity of the light source reaches the set value or a predetermined ratio of the set value, and a sequence control means for starting exposure scanning of the document after detecting the set value. Features.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows an example in which the present invention is applied to an electrophotographic copying apparatus. Since the copying apparatus itself is the same as that shown in FIG. is omitted.

In FIG. 1, 13 is a photodetecting element that detects the light f111 of the fluorescent lamp 3, and 14 is a photodetecting element that receives the output from the photodetecting element 13 and detects the fluorescent lamp's light j! tt a light amount control circuit for controlling to a predetermined set value; 15 is a high frequency ballast that receives a signal from the light amount control circuit 14 and supplies a controlled tube current to the fluorescent lamp; 16 is a sequence for controlling the process of the copying machine; control circuit, 17
is a circuit that receives a signal from the in control circuit 14 and detects that the light scattering at startup of the fluorescent lamp 3 has reached a predetermined set value or a predetermined ratio of the predetermined set value. By transmitting the detection output to the sequence control circuit 16, the sequence control circuit 16 controls the advancement of the platen.

FIG. 2 shows a time chart of the sequence according to the invention. When a copying command is generated, the motor starts rotating in the same manner as explained with reference to FIG. starts rotating. The fluorescent lamp 3 also starts lighting at the same time as the motor starts, but the fluorescent lamp has a light startup characteristic due to the influence of the ambient temperature, and the lower the ambient temperature, the faster the startup characteristic is as shown in Figure 4. This will require additional time. Therefore, conventionally, as shown in FIG.
A heat-retaining heater 18 is installed near the fluorescent lamp 3, and the control circuit 20 controls the power supply to the heat-retaining heater so that the temperature detection element 19 brings the ambient temperature to the set temperature. It was devised to have good start-up characteristics.

However, in this type of conventional device, the heat retaining heater 18 and the temperature control circuit 20 are expensive. Therefore, in the present invention, the second
As shown in the figure, when the light output of the fluorescent lamp 3 reaches the set value or a predetermined ratio of the set value, it is detected by the light amount rise width detection circuit 17 shown in FIG. Proceed to execute the copy sequence after high voltage output. In addition, if the present invention is not implemented and the light intensity of the fluorescent lamp is started up (Fig. 2)'t - and the copy sequence is ignored, the light intensity is insufficient.
This may cause problems such as not being able to obtain clear images.

Furthermore, the ninth aspect of the present invention is to shorten the start-up time Tt, especially at low temperatures, by designing the ballast 1st in the direction of increasing the maximum tube current that can flow through the fluorescent lamp. There is.

〔Effect of the invention〕

As mentioned above, the present invention eliminates the need for a heat-retaining heater and temperature control circuit, which have been commonly used in the past, and achieves a significant cost reduction.In addition, the present invention reduces the light intensity rise time by increasing the maximum tube current of the ballast. By simply increasing the amount of light, it is possible to provide an image forming apparatus t which is free from image defects due to insufficient light quantity and is free from any practical problems.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a timing chart diagram of the apparatus shown in FIG. 1, and FIG. 3 is a schematic diagram showing an example of a conventional image forming apparatus. FIG. 4 is a diagram showing the light intensity rise characteristic of a fluorescent lamp depending on the ambient temperature, and FIG. 5 is a diagram showing an example of a conventional light intensity control device for a fluorescent lamp. 1... Original, 2... Platen, 3...
... Fluorescent lamp, 4... Reflector, 5... Light-converging lens array, 6... -order charger, 7... Current equipment, 8...
-Registration roller, 9--Transfer charger, 10--Cleaner, 11--Photoconductor drum, 12--Fixer, 13--Photodetection element, 14--Light amount control circuit, 15--・High-frequency stabilizer, 16...
・Control circuit, 17...Detection circuit, 1B...
Heater for heat retention, 19...Temperature detection element. Shin 1 figure IZ red utensil figure 2

Claims (1)

[Claims] In an image forming apparatus that exposes and scans a document using a document exposure light source having a light intensity of a predetermined setting value, and forms an image using document light modulated by the document, the light intensity of the light source is set to the predetermined value or the setting value. An image forming apparatus comprising: a detection means for detecting that a predetermined ratio of values has been reached; and a sequence control means for starting exposure scanning of a document after detecting the set value.