JPS60263933A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the formation of a defective image due to dew condensation through simple constitution by providing a means which detects part of liminous flux passed through an optical system by a photodetecting element and decides whether dew condensation occurs in the optical system or not on the basis of the detection output. CONSTITUTION:A standard white plate 10 is irradiated by a lamp 2 and a photosensor 12 photodetects part of the luminous flux passed through the optical system consisting of reflecting mirrors 4-6, a lens 7, and a reflecting mirror 8. The output of this sensor 12 is compared with a reference signal by a comparing circuit 15, which generates an H output when the sensor output exceeds a specific level, so that an LED16 does not illuminate. If even one of optical systems is in a dew condensation state, on the other hand, the quantity of light detected by the sensor 12 drops below the specific value and the circuit 15 outputs an L-level signal, so that the LED16 illuminates. Consequently, the dew condensation of the mirrors 4-6, and 8 or lens 7 of the optical system is displayed and a signal is sent to a CPU, thereby inhibiting copying operation so that the copying operation does not start even when a copy key is turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an image forming apparatus that projects an original image onto a photosensitive surface through an optical system having a lens or, if necessary, a mirror.

(Prior Art and Problems) When an image forming device that has been kept under low temperatures for a long time is suddenly exposed to a warm place, water droplets condense on the lenses and mirrors (glass) that make up the optical system. Image defects often occurred. The degree of condensation will vary depending on temperature or humidity differences, but if condensation occurs on image exposure optical systems such as mirrors and lenses, it will inevitably cause diffuse reflection of light, resulting in problems such as pitch-black images and blurred images. there were.

In order to prevent this, in the conventional case, a heater dedicated to preventing dew condensation was installed near the lens and mirror, and the heater was constantly energized or turned off by a switch. Heater is on even at the bottom
There was a lot of wasted electricity.

(Objective of the Invention and Summary of Structure) An object of the invention is to detect whether or not there is condensation on an optical member constituting an optical system, and to eliminate waste of power and operation.

Therefore, in the present invention, a means is provided for detecting a part of the light beam passing through the optical system with a light receiving element and determining whether or not there is dew condensation on the optical element.

(Example) FIG. 1 is a simple explanatory diagram of a non-inventive embodiment.

In the figure, 1 is a platen glass that constitutes the document placement surface, 2 is a document illumination lamp, and a 3-piece reflective shade. The image is projected onto the photosensitive drum 9.

The non-embodiment is a copying machine with a fixed manuscript table, in which a lamp 21, a reflecting shade 39, and a reflecting mirror 4 are arranged on one unit, and the reflecting mirrors 5 and 6 move back and forth according to the copying process. reeds on another unit,
The unit performs reciprocating motion at one-half the speed.

Reference numeral 10 denotes a standard white plate as a reflective member having a predetermined # degree, and is arranged near the platen glass 1 so as to face it at a position before the mirror 4 starts scanning the original on the glass glass 1. There is.

11 A plate that partitions the optical system and the developing/fixing unit, etc., 12
A light sensor (light receiving element) that forms an output corresponding to the amount of light received by Fi, 15 is a reflection mirror 4 to 6 of the optical system when removing dew
, 8 and the lens 7 to remove dew condensation by blowing air. 14 is a heater that heats the air to increase the efficiency of dew condensation removal.

Next, a method for detecting dew condensation on the reflecting mirrors 4 to 6 and 8 of the optical system and the lens 7 will be explained with reference to FIG.

First, the standard white plate 1o is irradiated with the lamp 2, and at that time, light is reflected by the white plate 1o and projected onto the photosensitive drum 9 by an optical system consisting of reflection mirrors 4, 5° 6, a lens 7, and a reflection mirror 8. A part of the light is received by the optical sensor 12.

When at least one of the reflecting mirrors 4 to 6, 8 and the lens 7 is dewy, a considerable amount of light is diffusely reflected by the dewy reflecting mirror or lens, and the optical sensor 12
The amount of light detected will be significantly lower than when there is no dew. If the sight detected by the light sensor 12 is lower than when there is no dew condensation, it means that at least one of the reflection mirrors 4 to 6, 8, and 8 lenses 7 of the optical system has dew condensation. That's why. However, in the dew condensation detection operation mode, which is carried out before the copying operation (image forming operation) in which a document is scanned and the image is projected onto a drum to form a copy image on paper, the lamp 2 has a constant illuminance. to operate with
It is preferable to turn on the light at a specified voltage. Further, the optical sensor 12 is installed at a location where it does not interfere with the original image light flux projected onto the drum 9 during exposure of the original image.

Next, a non-inventive embodiment will be described in more detail.

FIG. 2 shows block i of an optical dew condensation detection device that is not an example.

When the main switch is turned on and power is applied to the copying machine, the standard white plate 10 is first irradiated by the lamp 2, and the optical system consisting of the reflecting mirrors 4 to 6, the lens 7, and the reflecting mirror 8 is detected by the optical sensor 12. It receives the light beam that passes through it. The output of this optical sensor 12 is compared with a reference signal of a predetermined level in a comparator circuit 15, and if the output is higher than this predetermined level, that is, if the reflective mirrors 4 to 6, 8 and lens 7 of the optical system are all free from condensation, The output of the comparator circuit 15 becomes 'H' level, and the LFiD 16 serves as a display element to indicate whether or not there is dew condensation.
does not light up. Also, the transistor 17 is turned off.
The contact 1 of the relay 18 is open, and the drive motor 13' of the fan 13 and the heater 14 are not operated. Also 1. This signal is transmitted to the control circuit CP that controls the image forming operation, that is, the copying operation.
The information is also sent to U, and the circuit CPU puts the device into a copy-enabled state.

On the other hand, if any seven of the reflecting mirrors 4 to 6, 8 and the lens 7 are closed, the amount of light detected by the optical sensor 12 will be below the predetermined level, and the comparison circuit 15Fi"L"
It outputs a level signal, lights up the LED 1ts, and displays that there is dew condensation on the reflecting mirrors 4 to 6, 8 of the optical system or the lens 7, and also sends a signal to the control circuit CPU and turns on the Cisco key. Also, copy operations cannot be performed.
Prohibit copy operations. Also, the transistor 17 is turned on, the contact 1 of the relay 18 is closed, the fan motor 13' and the heater 14 are activated, and the reflection mirrors 4 to 6, 8 of the optical system are activated.
And warm air is sent to the lens 7 to remove dew condensation. Once the dew condensation is removed, the light received by the sensor 12 will exceed a predetermined amount, so that IJi;D 16, the contact 1#1 is turned OFF, and the copying becomes possible. In this case, as shown in FIG. 3, after a predetermined period of time, for example, one minute, the standard white plate 1Q is
Alternatively, the amount of light may be detected by the optical sensor 12. This operation is continued until the dew condensation on the reflecting mirrors 4 to 6 and 8 of the optical system and the lens 7 is completely removed, and copying is prohibited during this time.

Conventionally, dew condensation often occurs when exposed to low temperatures for a long time and then suddenly exposed to a warm place, such as first thing in the morning, so in the uninvented embodiment, the dew condensation detection device is activated when the copier is turned on. I mentioned that it should be activated, but this can be done at any time except during copying. Particularly, when the amount of sillumbetic light is controlled automatically before the start of the image forming operation, the dew detection device can be operated at the same time.

Further, in this case, the optical sensor 12 can also be used as a sensor for detecting lamp sight. Alternatively, it can also be used as a so-called AE detection sensor in which the original is irradiated with the lamp 2, the density of the original is detected with the optical sensor 12, and the amount of light or development bias is controlled.

Furthermore, the invention can be applied to a device in which a solid-state image sensor such as a COD is used instead of the electrophotographic photosensitive drum 9 to read a document image and convert it into an electrical signal. It can also be used as a detection element.

(Effects) As explained above, the occurrence of defective images due to dew condensation can be prevented from occurring with a simple configuration in which a light receiving element for detecting the amount of light is placed in the optical path of the optical system.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a block diagram of main parts of an embodiment of the present invention, and FIG. 3 is a flowchart. 10... Standard white plate 12... Optical sensor 13... - Fan 14... Heater 15... Comparison circuit i (5,,, LED

Claims (1)

[Scope of Claims] (1) A light-receiving element that receives a part of the light flux passing through an optical system that projects an original image onto a photosensitive surface, and an output of this light-receiving element that is used to expose an optical element constituting the optical system. An image forming apparatus comprising: a determining means for determining whether dew condensation has occurred; and a display means for displaying whether dew condensation has occurred in response to an output of the determining means. (2) A reflective member is provided near the document support surface, and this reflective member is illuminated by a document illumination light source, and at this time, a part of the light beam that is reflected by the reflective member and passes through the optical system is given to the light receiving element. %rf The image forming apparatus according to claim 1. (6) A light-receiving element that receives a part of the light flux passing through the optical system that projects the original image onto the photosensitive surface, and the output of this light-receiving element.
An image forming apparatus comprising: a determining means for determining whether or not the optical element KN is used to constitute the optical system; and a dew condensation removing means for removing the dew condensation in response to the output of the determining means. . (4) A reflective member is provided near the document support surface, and this reflective member is illuminated by a document illumination light source, and at this time, a part of the light beam that is reflected by this reflective member and passes through the optical system is given to the light receiving element. An image forming apparatus according to claim 3. (5) Whether or not there is dew condensation on the light-receiving element that receives a portion of the light flux passing through the optical system that projects the original image onto the photosensitive surface, and on the optical elements that make up the optical system using the output of this light-receiving element. An image forming apparatus comprising a determining means for determining, and means for prohibiting an image forming operation when the dew condensation occurs in response to an output of the determining means. (6) A reflective member is provided near the document support surface, and this reflective member is illuminated by a document illumination light source, and at this time, a part of the light beam that is reflected by the reflective member and passes through the optical system is given to the light receiving element. An image forming apparatus according to claim 5.