JPS62168127A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent operator's eyes from being dazzled by mounting a polarizing filter which provides polarizing operation for a light source emitting polarized light in one direction inside an original cover, and confirming an original mounting state from above a transparent cover. CONSTITUTION:The light source 20 consists of a laser diode which has a polarizing direction as shown by an arrow (a) and the polarizing filter 1a having an angle of polarization as shown by an arrow (b) is provided inside the original cover 1 to transmit only polarized light perpendicular to the light source 20. A reflecting plate 5c is provided above an original detection sensor 5b at the rear part of a copying machine and light from an LED lamp group 5a is made incident on the sensor 5b. When an original is mounted and the cover 1 is closed, the light from the lamp 5b is cut off by the original to detect the original size and original setting state, and a blank lamp on a photosensitive body is turned on to prevent toner from sticking. Further, the light of the light source is not transmitted through the transparent cover 1 through the operation of the polarized light of the light source and the filter, so the operator's eyes are never dazzled.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image forming apparatus that forms an image by reflecting light emitted from a light source on a document and exposing a photoreceptor drum to the reflected light.

<Prior art and its disadvantages> Normally, in an image forming apparatus that forms an image by reflecting light emitted from a light source on a document and exposing the photoreceptor drum with the reflected light, the document is placed on a transparent document table. The light source is placed below the document table. With this configuration, the document or the light source moves, and the document on the document table reflects the light emitted from the light source.

When this reflected light exposes the photoreceptor drum surface,
An image is formed. Further, a document cover that can be opened and closed is provided on the document table, and the document placed on the document table is held down by this document cover.

However, in the image forming apparatus having the above configuration, the document cover is made opaque so that the operator is not distracted by the glare, so there is a problem in that it is not possible to confirm the placement status of the document on the document table.

<Configuration and Effects of the Invention> The present invention comprises a light source that emits polarized light in one direction, and a document cover that is made of a transparent material having a polarizing filter whose polarization angle is substantially perpendicular to the polarized light from the light source. It is characterized by being composed of a document cover body.

With the above configuration, according to the present invention, the document cover transmits polarized light in one direction, so that the placement status of the document can be easily confirmed, and the polarized light emitted from the light source is directed in a direction substantially perpendicular to this polarized light. The light is blocked by a polarizing filter with a polarization angle of , which prevents the operator from being dazzled.

<Embodiment> FIG. 1(A) is a perspective view of a copying machine which is an embodiment of the present invention. In the figure, on the upper surface of the copying machine main body 10,
A transparent document table 4 is arranged. A light source 20 is provided on the lower side of the document table 4 in close proximity to the document table 4 so as to be movable in the lateral direction of the copying machine main body. The light source 20 is an assembly of laser diodes 21 whose polarization directions are aligned in the direction of arrow a.

Above the copying machine main body 10, a document cover is provided, which has a polarizing filter having a polarization angle in the direction indicated by the arrow mark, attached to a transparent document cover main body, and can be opened and closed using the rear of the copying machine main body 10 as a fulcrum. FIG. 1(B) is a partial sectional view of the document cover 1. FIG. In the figure, a transparent document cover main body 1b is closely attached to the upper surface of a polarizing filter 1a that transmits only light polarized in a direction substantially perpendicular to the light source 20. In this embodiment, the polarizing filter 1a is attached to the original cover body lb as shown in the figure.
Although it is attached to the lower side of the

An LED lamp group 5a is provided below the copying machine operation panel 1) provided at the upper front of the copying machine main body 10, and a document detection device for detecting the document size is provided below the document table at the rear of the copying machine main body 10. A sensor 5b is provided. Above the document detection sensor 5b and above the document table 4, the L
The irradiated light from the ED lamp group 5a is transmitted to the document detection sensor 5.
A reflecting plate 5C is arranged to reflect light toward b. The document detection sensor 5b detects the size of the document by detecting which range of the light emitted from the LED lamp group 5C is blocked by the document placed on the document table 4.

FIG. 2 is a block diagram of the main parts of this copying machine.

At the top of the copying machine main body 10, there is provided a light source moving unit that is movable in the lateral direction of the copying machine main body 10 in close proximity to the original platen 4, and includes a light source 20 and a first mirror 22 integrated. The second mirror 23 and the third mirror 24 are integrally movable in parallel with the light source moving unit at 1/2 the speed. A lens 25 and a fourth mirror 26 are arranged on the optical axis of the reflected light from the third mirror 24. A photosensitive drum 12 is arranged in the center of the copying machine main body 10, and around the photosensitive drum 12 are a charging charger 13, a blanking lamp 6, a developing device 14, and a transfer/separation charger 1.
5. The cleaning devices 16 are arranged in the above order. The blank lamp 6 is attached parallel to the rotation axis of the photosensitive drum 12. In the above embodiment, most of the polarized light from light #20 having a polarization angle substantially perpendicular to the polarizing filter la of the transparent document cover main body 1b is absorbed in areas other than the document placement area. . Therefore, the portion of the photoreceptor drum 12 other than the document placement section, that is,
A non-image forming area where no image is formed by the original is not exposed, and toner adheres to this area. Then, the non-image forming area is exposed to light using a blank lamp 6 in order to prevent toner from adhering to the non-image forming area.

FIG. 2 (Δ) is an enlarged perspective view of the blank lamp, in which a large number of LED lamps 61 are housed in a housing 63 separated from each other by a partition wall 62 so as not to receive light interference from adjacent LED lamps. .

In the above configuration, when a document is placed on the document table 4 and the document cover 1 is closed, the polarizing filter 1a of the document cover 1 transmits light in one direction, so that the position of the document can be confirmed. Furthermore, since the polarizing filter 1a has a polarization angle in the direction of the arrow a which is substantially perpendicular to the polarization in the direction of the arrow a emitted from the light source, almost no light from the light source is transmitted therethrough.

Therefore, even during the copying process, the operator is not distracted by the glare. The document size of the document on the document table 4 is detected by the document detection sensor 5b. Depending on the document size, a blank lamp is turned on in a portion of the F3 optical drum 12 corresponding to a non-image forming area to prevent toner from adhering.

FIG. 3(B) is a diagram showing the corresponding position and time between the formed image on the photosensitive drum and the blank lamp.

The reference time t0 represents the timing at which the position of the blank lamp 6 and the position of the leading edge of the image on the photosensitive drum 12 coincide. Time t to t7 represents the timing at which the position of the blank lamp 6 and the position of the trailing edge of the image on the photosensitive drum 12 coincide.

For example, when the document size is 85, time t1 corresponds to the rear edge position of the image of the B5 document size. Further, the image reference position 10 coincides with one end of the blank lamp 6 parallel to the rotation axis of the photosensitive drum 12, and the maximum image forming position 17 coincides with the other end of the blank lamp 6. The reference position 10 coincides with one end where an image is formed, and is the image forming position! ,~lf
i coincides with the other end where an image of each document size is formed. For example, when the document size is B5, only the LED lamp 61 corresponding to the non-image area 1) and ln remains lit from the reference time t0 to tl,
During this period, the LED lamp 61 corresponding to the image area between 10 and 1 remains off. Time 1. After the time, all the LED lamps 61 corresponding to the period from 10 to 27 are lit.

In order to perform the above control, as will be described later, the length 1) from the image forming positions 1) to 27 of the copy original size to the maximum image forming position 17 is determined before copying. set in the buffer. When the copying process is executed, the blank lamp 6 is controlled to be on/off based on the cent data in these buffers.

FIG. 4 is a flowchart showing the general operation of the copying machine.

After completing preliminary work such as heating the fixing device, the first step n
1 (hereinafter step ni will be simply referred to as ni), the number of copies, etc. is input. At this time, the control unit simultaneously detects the document detection sensor 5.
The size of the original placed on the original platen 4 is detected by b. n20 to n20+n are document size determination steps. n20~n20+n and n30~n30+
n is the length corresponding to the original size, the length from the image forming position of the copied original size to the maximum image forming position) li, and time (the elapsed time from the reference time t0) t are input into each buffer. It is a step. n40 is a step for determining whether the copy start switch is on or off. n41
The copying process is executed while controlling the blank lamp based on the data input to the buffer.

At step n42, it is determined that the copying process for the number of copies has been completed, and the process ends.

As described above, it is possible to prevent toner from adhering to the blank lamp for purposes other than image formation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a perspective view of a copying machine that is an embodiment of the present invention. FIG. 1(B) is a partial sectional view of the document cover. FIG. 2 is a block diagram of the main parts of the copying machine. Figure 3 (
FIG. 3A is an enlarged perspective view of the blank lamp inside the copying machine, and FIG. 3B is a diagram showing the corresponding position and corresponding time between the image formed on the photosensitive drum and the blank lamp. FIG. 4 is a flowchart showing the general operation of the copying machine. 1-document cover, 1a-polarizing filter, lb-document cover body, 20-light source, 21-laser diode.

Claims (1)

[Claims] (1) In an image forming apparatus including a light source disposed below the document table for illuminating a document placed on the document table, and a document cover provided on the document table so as to be openable and closable, the light source is directed in one direction. What is claimed is: 1. An image forming apparatus comprising: a light source that emits polarized light; and wherein the document cover includes a polarizing filter having a polarization angle substantially perpendicular to the polarized light from the light source, and a transparent document cover body.