JPH0259777A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain images of equal density at any mode by setting a reflecting member, which constitutes an optical means, to a second position and having the image formed directly on a photosensitive body by a laser beam, in a printer mode. CONSTITUTION:Each image forming mode is selected by switching on a selection switch provided on the control panel, and the reflecting member 4, which constitutes a part of the optical means, is set in the first position, where the laser beam is reflected to the direction of the document surface, when a copying mode or a synthesizing mode is selected. On the other hand, when the printer mode is selected, the reflecting member 4 is set in a second position, where an image is formed directly on the photosensitive body by the laser beam. Further, the light quantity of a laser emitting means 2 is controlled to be large when activating the copying mode and the synthesizing mode, and small when the printer mode is activated. Thus, the equal image density can be obtained at any image forming mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to image forming apparatuses such as copying machines and laser beam printers.

Conventional technology and its problems In general, image forming devices that form a latent image on a photoreceptor by exposure to light containing image information and visualize that image on paper are electronic devices that utilize reflection from the surface of a document. photocopy machine,
2. Description of the Related Art Laser beam printers that use on/off of laser light as image information are known. These differ only in the exposure method, and other image forming parts including the image exposure section can be used in common.

Therefore, in Utility Application No. 62-28437, the present applicant proposed a method using a laser emitting means as a light source, and using a mirror and lens system to guide the laser beam onto a photoreceptor while avoiding reflection from the surface of the document or the side surface of the document. proposed an image forming apparatus that can form a latent image of a document image and an image formed by modulating laser light alone or by combining both.

By the way, in the case of a printer mode that forms an image by modulating laser light, when the laser light is guided to the platen glass, there is a loss in the amount of light due to reflection on the platen glass, and the resolution decreases and the reproducibility of dots deteriorates. This causes a problem. To this end, in the case of printer mode, it is conceivable to switch the reflective member and guide the laser beam directly to the photosensitive drum without passing through the document surface. However, simply controlling the switching of the reflective members has a problem in that image density differs between the printer mode, the copy mode, and the composite mode.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that uses a laser emitting means as a light source and that reflects the laser light on the document surface to form an image on a photoreceptor. By forming an image on the photoreceptor without going through the laser beam, preventing the diffusion of laser light, and improving dot reproducibility, and automatically adjusting the light intensity of the laser emitting means, it can be used in any image forming mode. The purpose is to obtain equal image density.

Means for Solving the Problems In order to solve the above problems, an image forming apparatus according to the present invention includes (a) a laser light emitting means as a light source, and (b) a laser beam emitted from the light emitting means on a document surface. (c) a first position forming a part of the optical means and reflecting the laser beam in the direction of the document surface; a reflective member movable to a second position for forming an image on the photoreceptor; (d) a printer mode for forming an image by modulating laser light; a copy mode for forming an original image; mode selection means for selecting one of the compositing modes for compositing the image and the original image; (e) when the printer mode is selected, setting the reflective member to a second position; (f) a control means for setting the light intensity of the laser emitting means to be larger when executing the copying mode and the combining mode than when executing the printer mode. It is characterized by having the following.

In other words, in the present invention, the laser beam from the laser emitting means is always on and reflected on the surface of the document, so that the document image is exposed on the photoreceptor, and a latent image of the document image is formed. is called copy mode. Further, by turning the laser beam on and off according to image information, a latent image is formed on the photoreceptor based on the turning on and off of the laser beam, and this is called a printer mode. Furthermore, by setting an arbitrary document and turning the laser beam on and off based on the image information, a composite image of the document image and the laser beam image is formed as a latent image on the photoreceptor, and this is set in composite mode. to be called.

Each of the image forming modes described above can be selected by turning on a selection switch Wt8 provided on a selection means, for example, an operation panel. The reflecting member, which constitutes a part of the optical means, is set at a first position where the laser beam is reflected in the direction of the document surface when copying mode or combining mode is selected. On the other hand, when the printer mode is selected, the reflecting member is set at a second position where the laser beam is directly focused on the photoreceptor. Further, the amount of light from the laser emitting means is controlled to be large when executing the copy mode and combining mode, and small when executing the printer mode. Now, when executing printer mode,
Diffusion of the laser light on the document table is prevented, improving the reproducibility of dots, and even a small amount of laser light is sufficient.On the other hand, increasing the amount of light when executing the copy mode or composition mode can improve dot reproducibility. The image density in each mode becomes equal.

Embodiment Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the accompanying drawings.

In Figure 1, (1) is the document table glass, and arrow (a)
It is possible to scan in the direction shown in FIG. 1, and FIG. 1 shows the scanning in progress. (2) is a laser diode, (3) is a polycon mirror for beam scanning, (4) is a mirror, and (5) is a lens array in which single converging light transmission bodies (trade name: SELFOC) are arranged in parallel. The laser beam emitted from the laser diode (2) is scanned by each reflective surface of a rotationally driven polycon mirror (3), and then passes through the mirror (4) to the document platen glass <1.
) is reflected by the original (D) placed on the photoreceptor drum (10) through the lens array (5).

As shown in Fig. 8, the laser diode (2) generates mechanical control sound ■5 based on data from the memory (50) that stores image signals from the host computer (CPU).
1) is controlled on and off via Polygon mirror (
3) is also rotationally driven at a constant frequency. Such image signal control is well known, and its details will be omitted.

The photosensitive drum (10) can be rotated in the direction of the arrow (b), and around it is an eraser lamp (11) for residual charge.
), an electrostatic charger (12), a developing device (13) using a magnetic brush method, a transfer chiller (14), and a residual toner cleaning device (15) using a blade method. Copy paper is fed one by one from the right side in the diagram.
The toner image is transferred by passing between the transfer charger (14) and the photoreceptor drum (10), and then conveyed to the left, where the toner is thermally fixed by the runner device (16).

On the other hand, the mirror (4) has front and back surfaces (4a) and (4b) as reflective surfaces, as shown in FIGS. 2 and 3.
Installation is done using the claws (41) and (4) provided on the upper and lower surfaces of the tool (40).
0, and the mounting can be rotated integrally with the tool (40) using the support shaft <42), (42) as a fulcrum. This mirror (4) has its front reflective surface (4a) at a first position where the laser beam is reflected in the direction of the document surface (shown by the solid line in Figures 1 and 2), and its rear reflective surface (4b). It can be rotated to a second position M (indicated by a dotted line in FIGS. 1 and 2) at which the laser beam is reflected onto the photoreceptor drum (10) and an image is formed on the photoreceptor.

Specifically, the mounting tool (40) has an arm (43), and this arm (43) is attached to the solenoid (4) in the guide groove (43a).
7) (7) A pin (49) provided on the plunger (48) is loosely fitted, thereby connecting it to the solenoid (47). Further, it is biased in the direction of arrow (C) in FIG. 3 by a torsion coil spring (45) wound around one of the support shafts (42).

In this installation, when the solenoid (47) is turned off, the coil spring (45) rotates the arm (40) in the direction of the arrow (C), and the arm portion <43) is rotated by the stopper (39) (see Fig. 2). (see), the mirror (4) is positioned to maintain the second position. On the other hand, the solenoid (
47) is turned on, the mirror (4) is attached to the mounting tool (40).
) and moves in the direction of arrow (C') to the first position, and when the arm (43) comes into contact with another stopper (38), it is switched to the first position.

Furthermore, in this embodiment, a locking means (30) is installed to prevent the document cover (2o) from being opened during the copying mode and composition mode, which will be described in detail below.

That is, the document cover (20) is movable together with the document table glass (1) in the direction of arrow (a), and as shown in FIG. It can rotate vertically to open and close the document table glass (1). Therefore, as shown in FIG.
) is provided so that it can move forward and backward in the groove (26) of A saw that is configured to lock.

Specifically, the lock lever (31) is rotatably attached to the device main body (25) using a pin (32) as a fulcrum,
It is always biased in the direction of arrow (d) by a tension coil spring (33), and the end (31a) can come into contact with the arm (43) of the mounting member (40) from below. The claw part (31b) formed at the upper end of the lock lever (31) is in the closed state.
can be engaged with the claw portion (35a) of.

In the above configuration, in the printer mode or when the main body of the apparatus is not operating, the solenoid (47) is turned off and the mirror (4) is held at the second position. At this time, the laser light emitted from the laser diode (2) is reflected by the dust emitting surface (4b) of the mirror (4),
An image is formed on the photoreceptor drum (10). At the same time, the mounting tool (40>) is also rotating in the direction of the arrow (c), the tip of the arm (43) is rotating upward, and the lock lever (31) is also rotating in the direction of the arrow (d). ) direction, and as shown in Fig. 5b, the claw part (31b>
35a). In this state, the document cover (20) can be opened and closed freely, and the laser beam is reflected by the mirror (
Since the dust particles 4) are reflected by the surface (4b), there is no risk of the operator being exposed to radiation.

On the other hand, when the copy mode and the composition mode are executed, the solenoid (47) is turned on. With this, the installation is done with the tool (40
> rotates in the direction of the arrow (C''), and the mirror (4) is switched to the first position.At this time, the laser beam is transmitted to the mirror (
4) is reflected on the surface of the document platen (1).
) is imaged onto one photoreceptor drum (10). At the same time, the arm part (43) of the tool (40) is attached to the lock lever (
31) and press the end (31a) of the lock lever (31).
) rotates in the direction of arrow (d'), as shown in Figure 5a.
The claw portion (31b) engages with the claw portion (35a) of the claw holder (35) to lock the document cover (20) in the closed position.

By the way, when executing copy mode or composition mode,
The document cover (20) is attached to the document table glass (1) along with the arrow (
a) move in the direction. In order to maintain the locked state even during this movement, the claw holder (35) is attached to the document cover (20).
) is provided over almost the entire length.

Furthermore, in this embodiment, when the document cover (20) is opened, the solenoid (47) is turned on and the lock lever (31) is activated.
is set in the state shown in Figure 5a, the original bar (2)
0) is adopted. That is, as shown in FIG.
) with the bottles (22) and (22) as fulcrums, and is biased in the direction of arrow (e) by a torsion coil spring (23), and this biasing force is applied to the claw receiver formed at both ends of the tool (35). The protrusion (35b), (35b) is the protrusion (21>,
It is regulated by coming into contact with the projecting pieces (21a) and (21a) of (21).

Therefore, the solenoid (47) is turned on and the lock lever is turned on.
(31) is set in the lock position, the claw holder will not move when closing the open document cover (20).
35), as shown in Figures 6a and 6b, the claw part (35)
a) comes into contact with the claw part (31b) of the lock lever (31) and rotates in the direction of the arrow (e), and when it is completely closed, the claw part (31b>) is pushed by the biasing force of the coil spring (23). Climb over and return in the direction of arrow (e), engage with the claw portion (31b>,
It is considered to be in a locked state.

Next, the process of forming an image on copy paper in the above configuration will be explained.

First, in a printer mode in which an image is printed out using laser light, image information is output from the laser diode (2) based on LD data from the mechanical control section (51). For example, the laser diode (2) is turned off during scanning corresponding to the circular image area (X) shown in (a-2) in FIG. It is turned on during scanning. The laser beam is reflected by the dust emitting surface (4b) of the mirror (4) set to the second position and forms an image on the photoreceptor drum (10).
10) On the top, as shown in (a-3) in Figure 9, there is an image area (
An electrostatic latent image is formed in which the charge of X) remains and the charge of the background part (Y) is erased.

In addition, in the copy mode to print out the original image, place any original (D) shown in (b-1) in Figure 9 on the original platen glass (1), keep the laser light on, and All you have to do is scan the base glass (1) at a constant speed.The laser beam is reflected from the document surface via the scale projection surface (4a) of the mirror (4) set at the first position, and is exposed to light. imaged onto the body drum (10). For example, (b-1) in Figure 9
If the laser diode (2) is output with the laser diode (2) always on [Fig. 9 (b-2)] for the document (D) shown in Fig. 9, the image shown in Fig. 9 (b-3 ), as shown in
An electrostatic latent image is formed in which the charges in the image area (X) remain and the charges in the background area (Y) are erased.

Furthermore, in the composite mode that combines the original image and the laser beam image and prints out, any original (D)
Place it on the original glass (1) and
At the same time, the radar diode (2) is turned on and off to output image information. Also at this time, the mirror (4) is set at the first position. For example, for the manuscript (D>) shown in (c-1) in FIG.
The portion of the laser diode (2) corresponding to the circular image area (X) shown in Figure 9 (c-2>) is off, and the background area shown with diagonal lines <
Y) A corresponding portion is turned on. With this, in Figure 9 (c-3
), an electrostatic latent image is formed by combining the two images. In this case, the (xl) part is the part where the laser output is on, but since it is the original image part, a charge remains, and (X2)
The area (X,) is the background part of the document, but the laser output is off, so a charge remains; the part (X,) is the image area of the original, and the laser output is off, so a charge remains, and the other parts (Y) The charge is erased as a background part.

By the way, it is preferable to form an image directly on the photosensitive drum 10) via the dust projection surface (4b) of the mirror (4) in the printer mode for the following reasons.

(2) There is no diffusion of laser light on the document platen glass (1) and document surface, resulting in good dot reproducibility and improved resolution. In the printer mode, since the image is composed of dots, the reproducibility of the dots greatly contributes to the quality of the image. on the other hand,
In the copy mode, the laser light only has to function as illumination light.

■There is no loss of light intensity due to reflection on the document surface, and low current and low power laser diodes can be used.

Therefore, in this embodiment, the laser diode (2) is driven with a low current of 2 mW in the printer mode, and is controlled to have an output 10 to 15 times that amount in the copy mode or composition mode.

(2) Even if the document cover (20) is opened during execution of the printer mode, the laser light will not leak to the outside and there is no risk of exposure, so it is possible to set the document in advance. Further, in this embodiment, the mirror (4) is set to the second position even when the main body (25) of the apparatus is not in operation. As a result, even if the laser diode (2) accidentally emits light, the laser light will not irradiate the document table glass (1), making it possible to protect the operator from unexpected exposure to radiation.

Further, the laser light that irradiates the document surface needs to be sufficiently focused in order to obtain good reproducibility of the document image. If the beam is not focused, there will be a large proportion of the beam spanning the white and black image areas of the document, and the degree of scattering of reflections on the document surface will be large, resulting in poor image reproducibility. Furthermore, the beam needs to be sufficiently focused when the beam reflected by the dust emitting surface (4b) of the mirror (4>) is imaged on the photoreceptor drum (10).

On the other hand, during the scanning exposure of the document by laser light, that is, when the laser light illuminates the document table glass (1) and there is a risk that the operator may be exposed to radiation, the locking means (30 ) operates, and the document cover (20) is locked in the closed state by the lock lever (31). This reliably eliminates the risk of operator exposure to radiation.

Next, the apparatus as a whole is constructed as shown in FIG. The image forming apparatus main body (25) is connected to a host computer (CPU) operated by a keyboard (K),
The post computer (CPU) is a display device (C
RT) is also connected.

Post computer (CPU) 4i device main body (25)
Memory (50) of the image information output device (see Figure 8)
It is connected to the. The memory (50) outputs image data in response to a data request signal from the mechanical control section (51), and based on this data, the LD data is sent to the LD drive section (51).
2), and the laser diode (2) is turned on and off according to this LD data. Further, the mechanical control section (51) outputs an LD output control signal to the LD drive section (52) based on the signal sent from the mode selection switch, and the LD drive section (52) operates the laser diode <2> according to this signal. ) control the output level. The mechanical control unit (51) simultaneously turns on the solenoid (47) that moves the mirror (4).

Drive off.

A copy mode selection switch (28a), a printer mode selection switch (28b), and a composition mode selection switch (28c) are installed on the operation panel (27) of the device body (25), and each mode is set by turning on these mode selection switches. Selected by In addition, the device body (25)
A switch (not shown) is installed to detect whether the document cover (20) is opened or closed. Signals from these switches are input to the mechanical control section (51), and necessary control is performed.

Here, an outline of the image forming control procedure based on the control circuit shown in FIG. 8 will be explained with reference to the flowcharts in FIGS. 10 and 11.

FIG. 10 shows an example of a control procedure.

First, in step (Sl), the mode selection switch (28a
).

Check whether either (28b) or (28c) is turned on. In this example, the ON signals of these switches are also used as print start signals for the main body (25) of the apparatus. Subsequently, in step (S3) it is checked which mode has been selected. If the printer mode is selected, the laser output is set to low in step (528), data is requested from the memory (50) in step (525), and the print operation is started in step (526). let In this case, the document table glass (1) is in a stopped state. At step (527), when data output ends, the printing operation also ends. In this printer mode, the solenoid 47) remains off, the mirror (4) remains set at the second position, and the laser beam does not irradiate the document table glass (1). Further, the laser diode (2) has a low output.

On the other hand, when the copy mode and the composition mode are selected, in either case, the solenoid (47) is first turned on in steps (54') and (515). Mirror with this (4)
switches to the first position, and the laser beam illuminates the document glass (
1) becomes possible. At the same time, the lock lever (31)
However, the claw receivers are engaged with both (35) and set in a position to lock the document cover (20). Next, step (55
) and (516), after confirming that the document cover (20) is closed, copy mode and composition mode are executed, respectively.

In the copy mode, the laser output is set to high in step (511), the laser diode (2) is forced to emit light in step (S6), and the copying operation is started in step (S7). In this case, use the document platen glass (1
) moves. In step (S8), place the original platen glass (1)
At the same time as the movement of
to stop it. In the case of continuous copying, the following two processes are repeated, and when the copying process is completed, the solenoid (47) is turned off in step (510), allowing the original to be replaced.

In the synthesis mode, the radar output is set to high in step (522), and the memo J (5) is set in step (517).
Step (518) and subsequent steps control the laser output on and off based on the image data.
The same processing as in the copy mode is performed.

In this case as well, the laser diode (2) has a large output.

FIG. 11 shows another example of the control procedure.

Here, basically the same processing as the control procedure shown in FIG. 10 is performed. However, if the copy mode and the composite mode have been selected after checking the mode selection in step (S3), step (55) is performed.

After confirming that the document cover (20) is closed in step (516), the solenoid (47) is turned on in steps (54) and (515) to move the mirror (4) to the first position. In this way, by simply turning on the solenoid (47) and checking whether the document cover (20) is open or closed, the claw holder shown in FIGS.
5) can be retracted in the direction of the arrow (e), and a mechanism for engaging the claw portion (31a) of the I71 lever (31) is not required.

Note that the image forming apparatus according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist.

For example, instead of the solenoid (47), a pulse motor may be used as a means for moving and positioning the mirror (4) to the first position or the second position. Furthermore, in this embodiment, the laser beam is always guided onto the photoreceptor or the document surface via the mirror (4), but in the copy mode and composition mode, the laser beam is directly irradiated onto the document surface, and in the printer mode, the laser beam is directed directly onto the document surface. Various other methods can be employed to change the optical path, such as changing the optical path by intervening a mirror in the optical path.

Further, in the embodiment, mode selection switches (28a) to
Although (28c) shows a switch that also serves as a print operation start switch, a separate print switch may be provided on the operation panel (27) so that the timing for starting the print operation can be inputted arbitrarily.

Furthermore, scanning of the original image may be performed by an optical system moving type in addition to the original table moving type.

Examples of the InventionAs is clear from the above description, according to the present invention, in the printer mode, the reflective member constituting the optical means is set to the second position so that the laser beam is directly focused on the photoreceptor. Therefore, the laser light is not diffused by the document surface or the document table glass, the reproducibility of dots is good, the resolution is improved, and there is no loss of light quantity, so the output of the laser emitting means can be small.

In addition, in the copying mode and the composition mode, the reflecting member is set to the first position to guide the laser beam to the document surface, and the output of the laser emitting means is set to be large, so that an image with the same density can be obtained in either mode. be able to.

[Brief explanation of the drawing]

The drawings show an embodiment of the image forming apparatus according to the present invention, in which FIG. 1 is a schematic configuration diagram, FIG. 2 is an explanatory diagram of changing the optical path, FIG. 3 is a perspective view of a mirror support section and driving means, and FIG. The figure is an exploded perspective view of the main part of the document cover, Figures 5a, 5b, 6a, 6b, and 6c are explanatory diagrams showing the locking operation of the document cover, and Figure 7 is a perspective view of the entire device. Figure 8 is a block diagram of the control circuit, Figure 9 is an explanatory diagram of the document surface, laser diode output, and latent image, Figure 10 is a flowchart showing an example of the control procedure, and Figure 11 is the control procedure. It is a flowchart figure which shows another example. (1)...Document glass, (2)...Laser diode, (3)...Polygon mirror, (4)...
Mirror, (4a), (4b)... Reflective surface, (5).
... Lens array, (10) ... Photosensitive drum, (2
0)...Document cover, (28a), (28b), (2
8c) -Mode selection switch, (40)...Mounting tool, (47)...Solenoid, (51)...Mechanical control unit, (D)...Document.

Claims (1)

[Scope of Claims] 1. An image forming apparatus that forms a latent image on a photoconductor by exposure from a light source and visualizes the image on a sheet of paper, comprising: a laser emitting means as a light source; and from the light emitting means. an optical means for reflecting the emitted laser light on the document surface and forming an image on the photoreceptor; a first position forming a part of the optical means and reflecting the laser light in the direction of the document surface; and a photoreceptor. a reflective member movable to a second position to form an image on a photoreceptor by reflecting the light in a direction; a printer mode in which an image is formed by modulating laser light; a copy mode in which a document image is formed; mode selection means for selecting one of the combination modes in which the modulated image and the original image are combined; and when the printer mode is selected, the reflective member is moved to a second
driving means for setting the reflecting member to the first position and setting the reflecting member to the first position when copying mode and combining mode are selected; An image forming apparatus characterized by comprising: a control means for setting a value larger than a time.