JPS63204865A - Exposure device - Google Patents

Abstract

PURPOSE:To obtain necessary quantity of light at all time irrespectively of the environmental temperature by providing a light reduction means which reduces the quantity of light from a light source freely movably between the light source and an object to be read. CONSTITUTION:If the quantity of light from an exposure lamp 22 is adjusted by means of a dimming knob and the illuminance comes above a prescribed value, a moving mechanism 66 is turned off. That is, the driving of a solenoid 55 is stopped, and the attracting action of an armature 56 is released. Accordingly, a light reduction filter 51 is returned to a position above an opening part 22a by the force of a spring 59. A dimming circuit 63 controls an inverter 62 based on the set value of an exposure volume 65 corresponding to the amount of turning the dimming knob and the detection result by a sensor 64, so that the quantity of light from the lamp 22 is adjusted. Therefore, the extend of the adjustment of light can be expanded without using a heater, and at the same time, a necessary quantity of light can be easily obtained irrespectively of the environmental temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an exposure apparatus applied to, for example, an electronic copying machine.

(Prior Art) As is well known, an electronic copying machine is equipped with an exposure device Ii having an exposure lamp (light source). The original image is read using reflected light obtained from the original surface.

In such an exposure apparatus, a fluorescent lamp is used as an exposure lamp.

By the way, in exposure equipment that uses fluorescent lights, when performing dimming, the ratio between the time the fluorescent lights are on and the time they are off (duty ratio) is changed using a pulse width modulation method. , the amount of light from the fluorescent lights can be changed. However, in general, fluorescent lights used in exposure equipment have a narrower dimming range than halogen lamps, so if the difference between the required maximum and minimum light amounts becomes large, the ratio of lighting time at the minimum light amount will decrease. The light became too small, making it impossible to turn on the light, and sufficient dimming could not be achieved. In addition, since fluorescent lights are affected by changes in ambient temperature, heaters are used to increase the moisture content of the tube walls of fluorescent lights, reducing the range of dimming required, that is, the range of fluctuations due to temperature of fluorescent lights. was becoming smaller.

However, as shown in Figure 6, the surrounding concentration is 0°C.
When the lighting time ratio is at the minimum limit for stable lighting of fluorescent lights (A) at low temperatures of 60℃ and at high temperatures of 60℃, the required minimum light amount is the minimum required light amount, and when the lighting time ratio is at the maximum limit (B), the required minimum light amount is If the lighting time ratio is set to obtain each of . On the contrary, 20
If the above settings are made when the temperature is ℃, the amount of light will be insufficient at high and low temperatures. Therefore, the above method has the disadvantage that the dimmable range becomes narrow and the required amount of light cannot be obtained.

(Problems to be Solved by the Invention) This invention solves the problem that if the required width of dimming is reduced using a heater or the like, the amount of light may become excessive over a wide range, or conversely, the amount of light may become excessive at high or low temperatures. This eliminates the drawback of not being able to obtain the required amount of light because the dimming range becomes insufficient, and the dimming range can be greatly expanded without using a heater. An object of the present invention is to provide an exposure apparatus that can always obtain the required amount of light regardless of the temperature.

[Structure of the Invention] (Means for Solving the Problems) In the exposure apparatus of the present invention, the exposure apparatus adjusts exposure according to the amount of light of a light source that irradiates light onto an object to be read. A light attenuating means for attenuating the light from the light source is movably provided between the light source and the object to be read.

(Function) The present invention provides an optical device that adjusts exposure according to the amount of light from a light source that irradiates light onto an object to be read, in which light from the light source is reduced between the light source and the object to be read. A movable dimming means for emitting light is provided, and when the light quantity of the light source exceeds a predetermined brightness, the light quantity is reduced by the dimming means.

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

2 and 3 schematically show an image forming apparatus to which the present invention is applied, such as an electronic copying machine.
2 is a copying machine main body with a built-in copying mechanism; 2 is a paper feed tray mounted on the right side of the copying machine main body 1; and 3 is a paper discharge tray mounted on the left side of the copying machine main body 1. Further, a table 4 is provided on the upper surface of the copying filter main body 1 and is capable of reciprocating in the left-right direction (in the directions of arrows a and b in the figure).

The table 4 has a document table (glass plate) 12 on which the document Q is placed, and a document cover 13 that covers the top surface of the document table 12. A fixed scale 121 is provided.

Furthermore, on the front edge of the top surface of the copying machine main body 1, there is a display section 5 for notifying, for example, the operating status of each part or the occurrence of an abnormality, and number setting keys 6r, 62 for setting the number of copies per copy.
, an operation panel 10 on which input keys including a light control knob 7 for setting copy density, a print (copy) key 8, and a clear/stop key 9 are arranged.

On the other hand, the paper feed tray 2 has a manual feed tray 18 for feeding paper as a transfer material, and one or more sheets of paper can be set on this manual feed tray 15. It is said that

Next, referring to FIG. 3, the internal machine fil (
Copying mechanism) will be explained. In the figure, reference numeral 20 denotes a photoreceptor drum as an image carrier disposed approximately in the center of the main body 1 of the copying machine, and the photoreceptor drum 20 is moved at a scanning speed of the document Q in the direction of arrow C by a drive mechanism (not shown). rotates at the same speed. First, the surface of the document is charged by a charging device 21, and the document image uniformly irradiated by an exposure lamp 22 constituting an exposure device is transferred to an exposure section PH by a focusing light transmitter (trade name: SELFOC lens array) 23. to form an image with
An electrostatic latent image is formed on the surface of the photosensitive drum 20. This electrostatic latent image is made into a visible image by applying toner to it by the border marker 24.

On the other hand, the M (transfer material) set on the manual feed tray 15
are taken out one by one by a delivery roller 26I3 and a separation roller 27, guided through a paper guide path 28 to a pair of registration rollers 29, and sent to a transfer section by this pair of registration rollers 29.

The paper sent to the transfer section comes into close contact with the surface of the photoreceptor drum 20 at the transfer charger 30, so that the toner image on the photoreceptor drum 20 is transferred by the action of the charger 30. This transferred paper is electrostatically peeled off from the photoreceptor drum 20 by the action of the static elimination brush 31 for peeling.
The sheet is conveyed by the feed roller 32 along the conveyance guide 33 and sent to a pair of fixing rollers 34 as a fixing device provided at the end thereof. The transferred image is fixed by passing through the pair of fixing rollers 34, and the fixed paper is discharged onto a paper discharge tray 3 outside the main body 1.

Further, the photosensitive drum 20 after the transfer is returned to its initial state by removing residual toner on the surface by a cleaner 35 and erasing the afterimage. In addition, 3
7 is a cooling fan for preventing the temperature inside the main body 1 from rising by 1 degree;
38 is an ozone filter that neutralizes ozone odor generated from the charging device 21, etc.; 39 is a paper detection switch that detects paper feeding errors and paper jams; and 40 is a paper discharge switch that detects paper jams.

Next, the exposure apparatus will be briefly explained.

4 and 5 schematically show the dimming means according to the present invention. In FIG. 4, the exposure lamp 22
A neutral density filter 51 is slidably provided on the outer circumference of the exposure lamp 22, and this neutral density filter 51 is moved using the outside of the exposure lamp 22 as a working surface, and is formed along the longitudinal direction of the exposure lamp 22. A part of the light emitted from the unpainted opening 22a of the phosphor 52 is blocked, and the exposure lamp 22
The light intensity is reduced (attenuated). The neutral density filter 51 is made of a transparent material such as colored acrylic or glass.

Further, as shown in FIG. 5, the neutral density filter 51 is
Both ends 51a and 51b of the filter 51 are supported in contact with the surface of the exposure lamp 22, and a wire attachment part 53 is provided on the one end 51a side. This wire installation is done in section 53.
One end of the wire 54 wound around one end 51a of the filter 51 is fixedly attached. The other end of this wire 54 is connected to a solenoid 5 as shown in FIG.
The attachment is fixed to an armature 56 which moves by suction of the armature 5. Furthermore, both ends 51 of the neutral density filter 51
Spring attachment portions 57a and 57b are provided on the filter 51c between a and 51b. This spring is attached at part 57a.

A spring 59 supported by the frame 58 of the main body 1 is fixedly attached to the filter 57b, and the filter 51 is urged in the direction of the arrow d in the figure.

That is, the neutral density filter 51 normally has the following characteristics as shown in the figure:
The opening 22a of the exposure lamp 22 is kept covered. In this state, when the armature 56 is attracted by the solenoid 55 in the direction of arrow e in the figure, the neutral density filter 51 is pulled in the direction of arrow f in the figure by the wire 54, comes off from above the opening 22a, and slides to the position shown by the broken line. It is designed to be moved. And solenoid 55
When the suction is turned off, the neutral density filter 51 is returned to the position shown in the figure by the biasing force of the spring 59, and covers the opening 22a of the exposure lamp 22.

FIG. 1 schematically shows the main parts of an exposure apparatus. In FIG. 1, an inverter 62 is connected to a power supply circuit 61, and an exposure lamp 22 and a dimming circuit 63 are connected to the inverter 62. This dimmer circuit 63 includes
A sensor 64 that detects the light intensity of the one-light lamp 22 and an exposure volume controller 65 are connected, and a moving volume 414116 that controls the position of the neutral density filter 51 is connected to the exposure volume volume 65.
6 is connected.

The light control circuit 63 controls the inverter 62 according to the set value of the exposure volume 65 according to the copy density set by the light control knob 7 and the detection result of the sensor 64, and controls the exposure lamp 22 to turn on. The light from the exposure lamp 22 is controlled to the required light m by changing the time and the time when the light is turned off, that is, the duty ratio for supplying power from the power supply circuit 61.

Depending on the amount of light from the exposure lamp 22, the neutral density filter 51 can be placed over the opening 22a or removed from over the opening 22a.

The moving mechanism 66 is turned on and off by a cam provided on the shaft of the light control knob 7 that changes the exposure volume 65, for example.
By controlling the solenoid 55 with a microswitch (none of which is shown) that is turned off, the neutral density filter 5
1 can be placed on the opening 22a of the exposure lamp 22 or removed from the opening 22a.

That is, a cam is provided on the shaft of the dimming knob 7, and when the light amount of the exposure lamp 22 is set to a predetermined brightness or less in accordance with the operation of the dimming knob 7, the microswitch is turned on by the cam. It has become. When this microswitch is turned on, the armature 56 is attracted by the drive of the solenoid 55. As a result, the neutral density filter 51 is slid in the direction of the arrow shown in the figure, and is moved to a position away from above the opening 22a. Therefore, exposure lamp 2
The light from 2 is directly irradiated onto the surface of the document Q. Furthermore, when the light amount of the exposure lamp 22 is set to a predetermined brightness or higher in accordance with the operation of the dimming knob 7, the microswitch is turned off. When this microswitch is turned off, solenoid 5
The suction operation of the armature 56 by the armature 5 is stopped. Thereby, the neutral density filter 51 is returned to the position covering the opening 22a. Therefore, the light from the exposure lamp 22 that is irradiated onto the document Q is attenuated by the attenuation filter 51. In this case, the document filter 51 is placed at a position away from above the opening 22a,
The original filter 51 may be moved to a position covering the opening 22a when the brightness of the light from the exposure lamp 22 is set to a predetermined brightness or higher.

In the above configuration, it is assumed that, for example, the light amount of the exposure lamp 22 is set to a predetermined brightness or less by the dimming knob 7 of the operation panel 10. Then, the moving mechanism 66 is set to the on state. That is, the solenoid 55 is driven, and the armature 56 is attracted by this drive. As a result, the wire 54 is pulled as the armature 56 moves, and the neutral density filter 51 is moved to a position away from above the opening 22a. Then, the light intensity of the exposure lamp 22 is controlled by the light control circuit 63 controlling the inverter 62 based on the setting value of the exposure volume 65 according to the operation of the light control knob 7 and the detection result of the sensor 64. . The light from this exposure lamp 22 is designed to directly irradiate the document Q. Therefore, the document Q is exposed and scanned by light of a predetermined brightness from the exposure lamp 22 according to the setting operation of the light control knob 7.

On the other hand, assume that in the above state, the light layer of the exposure lamp 22 is set to a predetermined brightness or higher using the dimming knob 7.

Then, the moving mechanism 66 is set to the OFF state. That is, the drive of the solenoid 55 is stopped and the armature 56 is stopped.
The suction operation is canceled. As a result, the neutral density filter 5
1 is returned onto the opening 22a by the biasing force of the spring 59. Then, the light intensity of the exposure lamp 22 is controlled by the light control circuit 63 controlling the inverter 62 based on the setting value of the exposure volume 65 according to the operation of the light control knob 7 and the detection result of the sensor 64. . The light from the exposure lamp 22 is attenuated by a dark filter 51 and then irradiated onto the document Q. Therefore, the document Q is exposed and scanned by light from the exposure lamp 22 whose light is attenuated by the dark filter 51, that is, by light having a predetermined brightness.

As described above, when the amount of light from the exposure lamp exceeds a predetermined brightness, the amount of light is reduced by blocking a portion of the light. In other words, a neutral density filter is movably provided between the exposure lamp and the document table, and when the light from the exposure lamp is higher than a predetermined brightness, the filter reduces the light from the exposure lamp to a predetermined brightness. I try to do that. This prevents an excessive amount of light and enables scanning at a predetermined brightness. Therefore, it is possible to widen the dimmable range without using a heater or the like, and it is also possible to easily obtain the required amount of light at all times regardless of the surrounding environmental temperature.

In the above embodiment, a solenoid is used to move the neutral density filter, but the invention is not limited to this; for example, a motor may be used, or it may simply be moved in accordance with the operation of the dimming knob. You may also let them do so. Furthermore, the position of the filter may be controlled by comparison with the electrical value of the exposure volume, for example, comparison with a predetermined volume value, or by comparison between the output value of the sensor and the set value of the exposure volume. Position control may be performed depending on the result.

Furthermore, the present invention can also be applied to a device in which a sensor is placed at a position where light from an exposure lamp can be directly detected.

Furthermore, although the description has been given using an electronic copying machine with a movable document table as an example, the invention is not limited thereto, and can also be applied to, for example, an electronic copying machine with a moving optical system (fixed document table), or an image scanner.

Furthermore, the light attenuation filter, which serves as a light attenuation means, is moved on the outside of the exposure lamp as a sliding surface, but it can also be moved freely along the surface of the document table that is illuminated with light from the exposure lamp, which is the scanning position. It may also be provided.

Of course, various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the present invention, the dimmer sheath area can be greatly expanded without using a heater or the like.
It is possible to provide an exposure apparatus that can always obtain the required amount of light regardless of the ambient temperature.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the main parts of an exposure apparatus which is an embodiment of the present invention, and FIGS. 2 and 3 respectively show the structure of an electronic copying machine to which the present invention is applied. , second
The figure is an external perspective view, Figure 3 is a side sectional view, Figures 4 and 5.
The figure schematically shows the light reduction means according to the present invention.
FIG. 4 is a side sectional view, FIG. 5 is a perspective view, and FIG. 6 is a characteristic diagram showing the temperature characteristics of a fluorescent lamp as an exposure lamp. DESCRIPTION OF SYMBOLS 1... Copying machine main body, 4... Table, 7... Light control knob, 10... Operation panel, 12... Original platen, 2
0... Photosensitive drum, 21... Charger for charging, 22
...Exposure lamp, 23...Focusing light transmission body, 24.
...Developer, 30... Transfer charger, 51... Dark filter, 54... Wire, 55... Solenoid,
56...Amateur, 5...Spring, 61.
...Power supply circuit, 62...Inverter, 63...Dimmer circuit, 64...Sensor, 65...Exposure volume, 6
6...Moving mechanism, Q...Manuscript.

Claims (5)

[Claims] (1) In an exposure device that adjusts exposure according to the amount of light from a light source that irradiates light onto an object to be read, a dimming means for reducing the light from the light source is provided between the light source and the object to be read. An exposure apparatus characterized by being provided with a movable structure. (2) The exposure apparatus according to claim 1, wherein the light attenuation means is constituted by a filter that blocks part of the light from the light source. (3) The dimming means is inserted between the light source and the object to be read when the amount of light from the light source exceeds a predetermined value. exposure equipment. (4) Any one of claims 1 to 3, characterized in that the light attenuation means is inserted between the light source and the object to be read in conjunction with an exposure volume that sets the exposure amount. The exposure apparatus described. (5) The exposure apparatus according to claim 1, wherein the light source is constituted by a fluorescent lamp.