JPS626236A - Exposing device - Google Patents

Abstract

PURPOSE:To turn off a fluorescent lamp when the tube wall temperature of the fluorescent lamp becomes too high by providing a light quantity detection sensor which detects the quantity of light of the fluorescent lamp and a fluorescent lamp turn-on control circuit which controls the lighting of the fluorescent lamp on the basis of the output of the light quantity control circuit. CONSTITUTION:The fluorescent lamp turn-on control circuit 32 which powers up and down the fluorescent lamp 20 by receiving the output of the light quantity detection sensor 31 detecting the quantity of light emission of the fluorescent lamp 20 is so constituted as to turn off the fluorescent lamp when the quantity of light of the fluorescent lamp 20 is less than the quantity Lo of light suitable for proper exposure and tends to decrease. The quantity of light of the fluorescent lamp is controlled by, for example, modulation on PWM basis and the tube wall temperature at which the light emission efficiency of the fluorescent lamp is denoted as t2. In this case, when the quantity of light emission decreases below a reference value Lo and a duty value increases, it is indicated that the tube wall temperature is exceeding t2, namely, that a dangerous state is entered. The fluorescent lamp 20 is therefore turned off in this case.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exposure apparatus such as an electronic copying machine that uses a fluorescent lamp as an exposure light source.

(Prior Art) An electronic copying machine exposes a charged drum to light in accordance with document information, and then forms a toner visible image on an electrostatic latent image formed on the drum surface. This is a device that transfers images onto copy paper.

FIG. 2 is a diagram showing an example of the conventional configuration of such an electronic copying machine. When the operator presses a copy start button (not shown), the illustrated device begins a copy operation. The photosensitive drum 1, which is rotating in the direction of the arrow, is cleaned by a blade in the cleaning section 2, after which the remaining toner on the photosensitive drum is scraped off by a blade, and then corona discharge is applied to the photosensitive drum 1 by the charged electrode 3, so that ten poles of electric charge are applied to the entire surface of the photosensitive drum 1. Becomes electrically charged. An unnecessary portion of the charge charged by the charging electrode 3 is erased by a charge eraser 4.

On the other hand, an exposure unit 6 whose on/off control is controlled by a fluorescent lamp lighting circuit 5 irradiates light onto a document 8 placed on a document table 7, and the reflected light is transmitted through a SELFOC lens (an example of a light transmitting body). (manufactured by Nippon Sheet Glass Co., Ltd.) 9 and irradiates the photosensitive drum 1.

Here, when the document table 7 is horizontally moved in the direction of the arrow in the figure,
Image information on the original 8 is focused by a SELFOC lens 9 and sequentially irradiated onto the photosensitive drum 1.

As a result, the unnecessary portion (area corresponding to a non-image area) is charged and erased by the charge erasing section 4, and an electrostatic latent image of the document image information is sequentially formed on the charged area of the photosensitive drum surface where an image is to be formed. Ru. The electrostatic latent image formed on the surface of the photosensitive drum 1 is converted into a visible image by adsorption of toner in the subsequent developing section 10. The toner image on the surface of the photosensitive drum is transferred to the transfer section 11.
The photosensitive drum 1 is transferred to the copy paper, and the copy paper that is in close contact with the photosensitive drum 1 is separated. The separated copy paper is sent to the fixing roller 13 via the conveyance mechanism 12, and the copy paper is heated and pressurized by the fixing roller 13 to fuse the toner on the copy paper to the copy paper, and the copying operation is completed. finish.

By the way, as the light source 20 used in the exposure section 6, a fluorescent lamp as shown in FIG. 3 is normally used.

In FIG. 3, (a) is a perspective view, and (b) is a sectional view taken along the line AA'. In the figure, 21 is a bottle, 22 is a cap, 23 is a heater formed surrounding a fluorescent tube 24, and 2
5 is a heat generating part of the heater 23. The heat generating portion 25 may be attached around the fluorescent tube 24 as shown in (b), for example, and may be further fixed thereon with a heat shrink tube (not shown) or the like. Alternatively, there are cases where the tube is simply attached to the surface of the fluorescent tube without using a heat shrink tube. 26
．． 27 is an electrode for applying current to the heater 23; 28
29 is a reflective film/fluorescent film, and 29 is an aperture portion. The heater 23 is provided to quickly raise the temperature of the tube wall of the fluorescent tube 24.

The relationship between the tube wall temperature and the amount of emitted light of a fluorescent lamp constructed in this manner is shown in FIG. 4. In the figure, the horizontal axis shows the fluorescent tube wall temperature, and the vertical axis shows the amount of emitted light. Here, the tube wall temperature of the fluorescent lamp reaches a predetermined reference value t within the warm-up time of the fixing heater provided in the fixing roller 13.
o and the amount of emitted light is Lo, proper exposure is performed and an accurate image is copied.

By the way, if we focus on the relationship between the fluorescent lamp, the tube wall temperature, and the amount of emitted light in Fig. 4, the amount of emitted light reaches the maximum LIIlax when the tube wall temperature is tl, and tends to decrease when the tube wall temperature becomes higher than tl. Therefore, when the tube wall temperature exceeds t+nax, the light decreases to less than the light required for proper exposure. That is, if the tube wall temperature exceeds t max, five quantum feet of light will occur, making it impossible to accurately copy an image.

(Problems to be Solved by the Invention) In order to solve the above-described insufficient light amount when the tube wall temperature exceeds tmax, conventionally, the tube wall temperature of the fluorescent lamp is increased as shown by the broken line in FIG. Fluorescent lamps were used because they produced a sufficient amount of light even though they were expensive. For this reason, a fluorescent lamp and a lighting circuit that emit a large amount of light are required, which is a factor in increasing costs. Furthermore, even if the temperature of the tube wall of the fluorescent lamp became extremely high, it could not be detected because no temperature detection means was provided.

The present invention has been made in view of these points, and its purpose is to realize an exposure apparatus that at least turns off the lighting of the fluorescent lamp as an abnormality when the tube wall temperature of the fluorescent lamp becomes too high. It's about doing.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, is an exposure device that obtains image information by irradiating a document surface with a fluorescent lamp.
and a fluorescent lamp lighting control circuit that controls lighting of the fluorescent lamp based on the output of the light amount detection sensor, and includes a fluorescent lamp lighting control circuit that controls lighting of the fluorescent lamp when the amount of light from the fluorescent lamp is below a predetermined value and the amount of light is below a predetermined value. The present invention is characterized in that it is configured to turn off at least the lighting of the fluorescent lamp if there is a decreasing tendency.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

Components that are the same as those in FIG. 2 are designated by the same numbers.

In the figure, 31 is a light amount detection sensor that detects the amount of light emitted from the fluorescent lamp 20, and 32 is a fluorescent lamp lighting control circuit that receives the output of the light amount detection sensor 31 and controls the on/off of energization to the fluorescent lamp 20. be. The fluorescent lamp lighting control circuit 32 is configured to turn off the lighting of the fluorescent lamp 20 if the amount of light from the fluorescent lamp 20 is below the above-mentioned Lo and the amount of light is decreasing. □The operation of the device configured as described above is as follows.When the power of the electronic copying machine is turned on, the fixing roller 13 is first activated.
The fixing heater (not shown), the fluorescent lamp 20, and the fluorescent lamp heater 23 (see FIG. 3) are started to be energized. As a result, the tube wall of the fluorescent lamp generates self-heating due to energization and the heater 2
Due to the heat generated from the heat generating part 25 by energizing 3,
gradually rises. As the temperature of the tube wall increases, the amount of light emitted from the fluorescent tube through the aperture section 29 also increases accordingly, as shown in FIG. The light quantity detection sensor 31 detects the light from the fluorescent lamp 20 and applies its output to the fluorescent lamp lighting control circuit 32. Then, the fluorescent lamp lighting control circuit 32
is the amount of light from the fluorescent lamp 20.

It is detected whether the amount of light is decreasing or increasing. That is, when the light amount is less than Lo and the light amount is increasing, it can be determined that the tube wall temperature of the fluorescent lamp is less than to,
If the light intensity is 10 or more and the light intensity is increasing, the tube wall temperature can be judged to be between to and 11. If the light intensity is 10 or more and the light intensity is decreasing, the tube wall temperature can be determined to be between tl and tmax. If the light amount is less than Lo and the light amount is decreasing, it can be determined that the tube wall temperature is abnormal if it is more than t max. When an abnormality in the tube wall temperature is detected in this way, the fluorescent lamp 20
Turn off the power to the fluorescent light *F20.

Regarding fluorescent lamp replacement when abnormal lighting occurs, if the abnormality occurs continuously, or if it occurs more than a certain number of times within one replacement, replacement or repair is required as an abnormality in the fluorescent lamp, heater, or control circuit. and stop the copy operation.

Next, a method for detecting that the amount of light from a fluorescent lamp tends to decrease will be described in detail. For example, when the light amount of a fluorescent lamp is controlled by PWM (pulse width modulation) modulation, the relationship between the duty and the amount of emitted light is as shown in FIG. In the figure, the vertical axis is the amount of light emitted, and the horizontal axis is the duty (%). The figure shows the tube wall temperature (t
, , t2.

Three types of light emission characteristics are shown with j3> as a parameter. The magnitude relationship of the tube wall temperature is 1, <12〈t3
where tl is the tube wall humidity at which the luminous efficiency of the fluorescent lamp is maximum. As shown in the figure, the luminous efficiency decreases whether the tube wall temperature is higher or lower than tl.

FIG. 6 is a diagram showing the relationship between the fluorescent lamp tube wall temperature and the amount of emitted light. In the figure, the vertical axis is the amount of emitted light, and the horizontal axis is the fluorescent tube wall temperature. jl+j2+mu3 on the horizontal axis is the same as that in FIG. Lo on the vertical axis is the aforementioned light amount reference value.

From FIG. 6, the following can be seen. That is, when the amount of emitted light is below the reference value Lo, the duty decreases with time when the tube wall temperature is below t2, and increases when the tube wall temperature is 12 or above.

Therefore, by sampling the duty value at regular intervals,
That I11! increases or decreases, the temperature of the tube wall becomes 1
It can be seen whether it is 2 or more or t2 or less. That is, when the duty value increases, the temperature of the tube wall is 12 or more, and when the duty value decreases, the temperature of the tube wall is t2 or less. Therefore, the light amount detection sensor 31 detects the fluorescent lamp 20.
Constantly monitor the amount of light emitted by the
When the duty value increases when the value falls below o, it can be said that the amount of emitted light tends to decrease. If it is found that the amount of emitted light is decreasing, it indicates that the tube wall temperature is becoming 12 or higher, that is, the tube is in a dangerous state. Therefore, in this case, the lighting of the fluorescent lamp 20 is turned off as described above.

With this configuration, an abnormal rise in tube wall temperature can be prevented, and the fluorescent lamp and lighting circuit can be made smaller, resulting in cost reduction.

Meanwhile, during this time, the fixing heater also generates heat and becomes ready for fixing. When fusing is possible, the READY lamp of the electronic copying machine lights up to notify the operator that copying is possible, but as mentioned above, an abnormally high tube wall temperature is detected. A message indicating that copying is not possible is displayed until a certain period of time has elapsed, and a message that copying is possible is displayed after the specified period of time has elapsed. When the operator presses the copy button in a state where copying is possible in this manner, the fluorescent lamp lighting control circuit 32 starts energizing the fluorescent lamp 20 again, and performs the copying operation in the manner described in connection with FIG. I do. Note that during the copying operation, the amount of light emitted from the fluorescent lamp 20 is controlled to be constant. - After the power supply to the fluorescent lamp 20 was stopped, the temperature of the wall of the fluorescent lamp tube hardly decreased and reached approximately t, partly because the external heater 23 was always energized. is maintained. Therefore, when the operator presses the copy button,
When the fluorescent lamp 20 starts to be energized, the amount of emitted light quickly reaches the reference value LO, providing a sufficient amount of light.

In addition, in the explanation of (e) above, we explained the case where the abnormally high temperature of the tube wall is detected and the energization to the fluorescent lamp is stopped, but if necessary, the energization to the tube wall heater and fixing heater can also be stopped. The power consumption can be kept low.

Additionally, if a certain document is being scanned when it is determined that the fluorescent lamp is abnormal, the fluorescent lamp is kept on during the scanning until the copying operation is completed, and the fluorescent lamp is turned off when the scanning is completed. Preferably, the light lamp is turned off and the next scan is not performed.

In addition, in the above explanation, the case where the tube wall temperature of the fluorescent lamp is indirectly detected based on the output of the light amount detection sensor has been explained, but it is also possible to directly detect the tube wall temperature of the fluorescent lamp using the temperature detection sensor. A similar effect can also be obtained by detecting it.

Further, in the above description, the case of an exposure device used in an electronic copying machine has been described, but the present invention is also effective for other image reading devices and image forming devices.

<Effects of the Invention> As described above in detail, according to the present invention, when the tube wall temperature of the fluorescent lamp becomes too high, the exposure device at least turns off the lighting of the fluorescent lamp as an abnormality. realizable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the conventional structure of an electronic copying machine, FIG. 3 is a diagram showing an example of the structure of a fluorescent lamp, and FIG. 4 is a diagram showing a structure of a fluorescent lamp. FIG. 5 is a diagram showing the relationship between the duty of the fluorescent lamp and the amount of emitted light, and FIG. 6 is a diagram showing the relationship between the fluorescent lamp tube wall temperature and the amount of emitted light. . 1... Photosensitive drum 2... Cleaning section 3.
... Charged electrode 4 ... Charge erasing section 5 ... Fluorescent lamp lighting circuit 6 ... Exposure section 7 ... Document table
8... Original 9... SELFOC lens 10... Developing section 11... Transfer section 12...
Conveyance mechanism 13... Fixing roller 20... Fluorescent lamp 31... Light amount detection sensor 32... Fluorescent lamp lighting control circuit Patent applicant Roku Konishi Photo Industry Co., Ltd. Representative Patent attorney Osamu Ijima Fuji Outside 1 person Figure 3 (A) A (B) 28 pieces A size M 涛Qiao gravel press white g 291 aperture part (1g! Low!! 1) Fluorescent lamp good wall temperature Figure 5 Figure 6 Figure fluorescent tube wall waterfall

Claims (1)

[Claims] An exposure device that obtains image information by illuminating the surface of a document with a fluorescent lamp, which includes a light amount detection sensor that detects the amount of light from the fluorescent lamp, and a fluorescent lamp that controls lighting of the fluorescent lamp based on the output of the light amount detection sensor. An exposure apparatus comprising a light lamp lighting control circuit, and configured to at least turn off the lighting of the fluorescent lamp if the light amount of the fluorescent lamp is below a predetermined value and the light amount tends to decrease. .