JPH04282629A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent unlighting when the lighting of a fluorescent lamp used as a light source provided on the optical system of an image forming device is started. CONSTITUTION:When a transfer paper detecting signal is inputted from a transfer paper detecting switch 23, a control part 22 sends the lighting signal to a lighting control circuit 24 at prescribed timing. The lighting control circuit 24 receives the signal and supplies a driving voltage for turning on/off in a period set to the fluorescent lamp 13 in advance only for a prescribed time (for instance, one second). The fluorescent lamp 13 is turned on through the use of a change in a driving voltage as a trigger, within this time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine equipped with a fluorescent lamp as a light source, and more particularly to a light source lighting control device for an image forming apparatus that controls the lighting of the fluorescent lamp.

0002

[Prior Art] Conventionally, in an image forming apparatus such as a copying machine, light from a light source provided in an optical system is irradiated onto the surface of a document, and the reflected light is guided to a photoreceptor drum to form an electrostatic layer on the drum surface. An image is being formed. Generally, halogen lamps and fluorescent lamps are known as the light source. However, fluorescent lamps have the drawback that the lighting start time changes depending on the temperature of the filament, and that the lighting does not quickly rise to a predetermined level if the temperature at the time of lighting is low. Conventionally, in order to solve this problem, the amount of light emitted by the fluorescent lamp is detected when the fluorescent lamp is turned on, and the amount of light emitted from the fluorescent lamp is detected at 100% until the detection level reaches a predetermined level.
A lighting control device that supplies a drive voltage at a duty ratio of 100% has been proposed (Japanese Unexamined Patent Publication No. 1-303426).

0003

[Problems to be Solved by the Invention] By the way, while image forming apparatuses are becoming more multi-functional and high-performance as office equipment,
There is also a demand for simple and small-sized devices. Such a simple and compact image forming apparatus is made compact by reducing or eliminating various functions as much as possible. For example, efforts are being made to make extensive use of resin in various structural members, including the main body of the device.

[0004] In the above-mentioned simple and compact image forming apparatus, it is difficult to provide sufficient heat dissipation space and heat dissipation members within the apparatus, and there is also a problem with the heat resistance of the constituent members. It is necessary to suppress temperature rise. For this reason, fluorescent lamps are used as light sources because they have relatively good luminous efficiency and can provide high brightness with low power consumption. However, as mentioned above, fluorescent lamps have the disadvantage that their luminous characteristics are unstable depending on the temperature of the filament when emitting light. be. In particular, in image forming apparatuses, it is necessary to ensure that the fluorescent lamp is turned on within a certain period of time (several seconds) after the start of the copying operation, and to raise the light emission level to a predetermined level when starting exposure.

[0005] The conventional lighting control device described above has 10
By applying a 0% duty driving voltage, the amount of light emitted after lighting is quickly increased to a predetermined amount of light, but if the fluorescent lamp does not turn on when the driving voltage is applied,
There is a drawback that the fluorescent lamp does not turn on even if the driving voltage is continued to be supplied after that.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus that can reliably turn on a fluorescent lamp when it is turned on.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an image forming apparatus having a fluorescent lamp that irradiates light onto the surface of a document. The device is equipped with a drive voltage supply means that supplies a drive voltage that is turned on and off several times.

[0008]

According to the present invention, when a fluorescent lamp starts lighting, a driving voltage is supplied to the fluorescent lamp that turns on and off a plurality of times within a preset time. Then, the fluorescent lamp is turned on using a change in the supplied driving voltage as a trigger.

[0009]

Embodiment FIG. 3 is a schematic diagram showing an embodiment of an image forming apparatus according to the present invention. The image forming apparatus shown in the figure is a simple and compact image forming apparatus, and is composed of a movable table 2 consisting of a contact glass 11 and a document holder 12, and an apparatus main body 1, and the apparatus main body 1 can be separated. It consists of an upper body and a lower body.

A slit 1a for exposure is formed in the upper body of the apparatus main body 1 at approximately the center of the upper surface, and a fluorescent lamp 13 is provided as a light source at the bottom of the slit 1a, and the amount of light emitted by the fluorescent lamp 13 is detected. An image reading unit 3 is provided, which includes a light amount detection sensor 4, a condensing lens 14, and the like. Further, the photosensitive drum 15 is disposed below the image reading section 3, and a charging device 1 is placed around the photosensitive drum 15 from the upstream side.
6, a developing device 6, and a cleaning device 18 are provided. Further, a storage section 18a for storing collected toner is formed on the left side of the cleaning device 18.

On the other hand, the lower body of the apparatus main body 1 is provided with a transfer paper supply tray 20 on one side and a paper discharge tray 21 for discharging the transfer paper on which an image has been formed on the other side. Further, a paper feed roller 5, a transfer/separation device 17, and a fixing device 19 are provided in this order from the transfer paper feed tray 20 side to the paper discharge tray 21 side.

The image forming apparatus main body 1 is completed by combining the upper main body and the lower main body.

[0013] In order to simplify the control mechanism for the image forming operation, this image forming apparatus is configured to form images on transfer paper that is manually fed one by one, and the transfer paper is placed on a supply tray. A copy operation is performed every time the flag is set to 20. In addition, in conjunction with this image forming operation, the fixing device 19 is also driven for each copying operation, and the lighting time of the fixing heater is made as short as possible to prevent a rise in temperature within the main body 1 of the apparatus.

To explain the copying operation, after placing an original at a predetermined position on the contact glass 11, when a transfer paper is inserted into the paper feed tray 20, the transfer paper is detected by a transfer paper detection sensor (not shown), and the transfer paper is detected by a transfer paper detection sensor (not shown). A copy operation is started by the detection signal.

[0015] First, the transfer paper is conveyed to point P by the paper feed roller 5 and is placed in a standby state. Further, the table 2, which is located at the center in the initial state, once moves to the left, and when its right end reaches above the document reading section 3, the direction of movement is reversed to the right and document scanning is performed. . The fluorescent lamp 13
is turned on so that exposure can be started at this document scanning timing, and its light emission amount is adjusted to a predetermined reference light amount. The lighting control of the fluorescent lamp 13 will be described later.

The light irradiated through the slit 1a is reflected on the document surface, and the reflected light is reflected by the condenser lens 14.
is projected onto the photoreceptor drum 15. The photosensitive drum 15 is rotated to an exposure position while the surface of the drum is charged to a predetermined potential by a charging device 16, and an electrostatic latent image of a document image is formed on the drum surface by projection of the reflected light.

The electrostatic latent image is visualized with toner by the developing device 6, while the transfer paper waiting at point P is conveyed at a predetermined timing, and the toner image on the photoreceptor drum 15 is made visible by the transfer/separation device 17. The image is transferred to this transfer paper. and,
The transfer paper on which the toner image has been transferred is separated from the photoreceptor drum 15, fixed by a fixing device 19, and then discharged to a paper discharge tray 21.

After the transfer, the photosensitive drum 15 is cleaned in the same manner as described above until the toner remaining on the drum surface is removed by the cleaning section 18, and charged again by the charging device 16 to complete the image formation of one document. The image forming operation is repeated. This is because the circumferential length of the photosensitive drum 15 is shorter than the original size, so the original image is divided and images are formed on the transfer paper.

During the image forming operation, the table 2 which has finished scanning the original reverses its moving direction and returns to its initial position.

FIG. 1 is a block diagram of a control system for a fluorescent lamp lighting control device according to the present invention. In the same figure,
Reference numeral 22 denotes a control unit that centrally controls the image forming operation, and also controls the timing of turning on and turning off the fluorescent lamp. Reference numeral 23 denotes a transfer paper detection switch that detects that transfer paper is inserted into the paper feed tray 20. The control unit 22 starts a copy operation based on this detection signal. 24 is a fluorescent lamp 1 based on a control signal from the control unit 22.
This is a lighting control circuit that controls lighting, turning off, and dimming of No. 3. This lighting control circuit 24 is a PW that drives the fluorescent lamp 13.
It incorporates an M control circuit, and adjusts the amount of light emitted by changing the duty ratio of the drive voltage supplied to the fluorescent lamp 13.

Next, the control operation of the lighting control device will be explained. When a transfer paper detection signal is input to the control unit 22 from the transfer paper detection switch 23, the control unit 22 starts the copying operation and performs a predetermined copy operation. A lighting signal is sent to the lighting control circuit 24 at the appropriate timing. The lighting control circuit 24 receives this light emission signal and supplies the fluorescent lamp 13 with a drive voltage that turns on and off at a preset cycle for a predetermined period of time (for example, one second). Within this time, the fluorescent lamp 13 is turned on using a change in the driving voltage as a trigger, and the amount of light emitted is detected by the light amount detection sensor 6.

After the fluorescent lamp 13 is turned on, the lighting control circuit 24 adjusts the duty ratio of the driving voltage based on the detected light amount, so that the amount of light emitted from the fluorescent lamp 13 is adjusted to a predetermined reference level.

In the above embodiment, the lighting control circuit 24 is configured to supply the driving voltage to the fluorescent lamp 13 for a predetermined time, but the control circuit 22 is configured to supply the driving voltage to the fluorescent lamp 13 for a predetermined time. It may be configured as follows.

Further, in the above embodiment, the driving voltage is turned on and off.
Although the lighting control is performed by estimating that the fluorescent lamp will be turned on due to the off operation, the lighting state of the fluorescent lamp 13 may be controlled by checking the lighting state based on the detection data of the light amount detection sensor 4. For example, each time a drive voltage is supplied to the fluorescent lamp 13, it is determined whether the fluorescent lamp 13 is lit based on the light quantity data from the light quantity detection sensor 4, and if it is not lit, the drive voltage is supplied again.

The lighting control operation of the second embodiment will be explained using the flowchart of FIG. 2. When the lighting control circuit 24 receives a lighting signal from the control section 22,
3 to start lighting (#1). Next, after a waiting time of about 0.5 seconds, for example, the light amount data input from the light amount detection sensor 4 is compared with a preset threshold level to determine whether the fluorescent lamp 13 is turned on (# 2, #3). When it is determined that the fluorescent lamp 13 is lit, the duty ratio of the drive voltage is adjusted and the fluorescent lamp 1 is turned on.
The light emission amount of No. 3 is adjusted to a predetermined reference level (#5). Then, when the exposure scan is completed and a turn-off signal is input from the control unit 22, the supply of drive voltage to the fluorescent lamp 13 is stopped and the process ends (#6).

On the other hand, if it is determined in #3 that the fluorescent lamp 13 is not lit, the supply of driving voltage to the fluorescent lamp 13 is temporarily stopped (#4), and the process returns to #1 and the driving voltage is applied again to the fluorescent lamp 13.
supply to. Below, execute the loop from #1 to #4 above,
When the fluorescent lamp 13 is turned on, the process moves to #5 and the above-mentioned dimming control is performed. This ensures that the fluorescent lamp 13 is lit,
There is no possibility that the image forming operation will be hindered due to the non-lighting state.

[0027]

Effects of the Invention As explained above, the present invention supplies a drive voltage that turns on and off multiple times within a preset time to the fluorescent lamp at the start of lighting, so that the fluorescent lamp does not change due to changes in the drive voltage. can be used as a trigger to start lighting and prevent the occurrence of a non-lighting state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control system for an image forming apparatus according to the present invention.

FIG. 2 is a flowchart showing a control operation of a second embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention.

[Explanation of symbols]

1 Image forming device main body 2 Table 3 Image reading section 4 Light amount detection sensor 6 Developing device 13. Light source (fluorescent lamp) 14 Condensing lens 15 Photoreceptor drum 22 Control section 23 Transfer paper detection switch 24 Lighting control circuit

Claims (1)

[Claims] 1. An image forming apparatus having a fluorescent lamp that irradiates light onto a document surface, comprising a driving voltage supply means for supplying a driving voltage that is turned on and off a plurality of times within a preset time when the fluorescent lamp is turned on. An image forming apparatus comprising: