JP2503293Y2 - Electrophotographic copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an electrophotographic copying machine, and more particularly to an electrophotographic apparatus for controlling image forming conditions based on original density data obtained by exposing and scanning an original. Regarding copiers.

[Conventional technology]

2. Description of the Related Art Conventionally, in an electrophotographic copying machine, the exposure level of an exposure unit such as an exposure lamp or the level of a developing bias value of a developing unit is automatically controlled according to the background color of an original (hereinafter,
This is called automatic density adjustment) to improve the quality of the copy. An outline of such automatic density adjustment will be described with reference to FIG. 8 by taking as an example an electrophotographic copying machine which is a fixed original type and which controls the exposure level. FIG. 8 (b) shows a cross section of the upper part of the electrophotographic copying machine. This copying machine is provided with a document table 1 on which a document is placed, an exposure device 2, a developing unit 3, and a registration roller 5 for temporarily stopping the transfer paper 4 in order to keep timing with the exposure device 2. The document table 1 has a contact glass 12 on which a document 11 is placed, and a document holder 13 which opens and closes on the contact glass 12. The exposure device 2 has an exposure lamp 21 that exposes the original 11 by scanning under the contact glass 12 in the direction of arrow A. The emission intensity of the exposure lamp 21 is controlled by the output voltage of the AVR (not shown). Light reflected from the original 11 is reflected by the mirror.
It is sent to the photoconductor through 23 to 26 and the lens 27. lens
A document density detection sensor 28, on which a part of the reflected light 22 is incident, is arranged on the side of 27. Original on contact glass 12
When the print key of the copying machine is pressed after placing the original presser 13 at the upper predetermined position and pressing the print key of the copying machine, the exposure lamp 21 is turned on in FIG.
Then, move from the home position indicated by the solid line in the direction of arrow A by the minimum document size (usually A5 size or postcard size) and measure the document density (hereinafter referred to as prescan),
At the same time, the transfer paper 4 starts to be conveyed from the paper feed cassette (not shown) toward the registration roller 5. After the prescan, the exposure lamp 21 returns to the home position. FIG. 8A schematically shows how to scan the exposure lamp 21. In addition, HP in FIG. 8A indicates a home position, and a shaded portion indicates lighting of the exposure lamp 21.

The reflected light from this prescan is incident on the sensor 28, and a signal corresponding to the intensity of the reflected light is sent to the exposure control device such as a microcomputer (not shown) as document density data. The exposure control device controls the output voltage of the AVR by a conventionally known method based on the obtained document density data. After that, the exposure lamp 21 scans in the direction of arrow A for the required document size (up to the position indicated by the alternate long and short dash line in FIG. 8B), and returns to the home position again. The light emission amount of the exposure lamp 21 at this time, that is, the exposure level is a value corresponding to the output voltage of the AVR. In this way, automatic density adjustment is performed based on the document density data obtained by the prescan of the exposure device 2.

[Problems to be solved by the invention]

As described above, in the conventional electrophotographic copying machine, the prescan for automatic density adjustment is performed after the print key of the copying machine is operated. Therefore, when the transfer paper transport speed of the transport device is high, or when the distance between the paper feed cassette and the registration roller is short, the prescan is completed despite the transfer paper reaching the developing unit. Copying may not be performed because it is not done. Therefore,
In this type of conventional electrophotographic copying machine, the first copy (first copy) is made when the print key of the copying machine is operated.
There was a problem that it took a long time to be performed. The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an electrophotographic copying machine capable of shortening the time required for a first copy even if a prescan is performed by an exposure means. Especially.

[Means for solving problems]

The electrophotographic copying machine of the present invention detects a document placing means for placing a document, a document retainer attached so as to hold the document placed on the document placing means, and an open / closed state of the document retainer. A first detecting means for detecting the presence or absence of a document on the placing means after the closed state of the document pressing is detected by the first detecting means, and a document on the placing means. Mode setting means for selectively setting an automatic density adjustment mode for controlling image forming conditions based on the original density obtained by exposure scanning and a manual density adjustment mode for manually adjusting the image density; Then, the determination means for determining the setting of the automatic density adjustment mode after the presence of the original is detected by the detection means, and the exposure scanning for measuring the original density when the setting of the automatic density adjustment mode is determined by the determination means are opened. And a control means for controlling so that the above object is achieved.

[Action]

When an original is placed on the contact glass as the placing means and the original holder is closed, the limit switch as the first detecting means is turned on, and the presence or absence of the original on the contact glass is detected by the second detecting means. After that, when it is determined by the determination means that the automatic density adjustment mode is set before the print key for generating the image formation command signal is operated, the exposure device is operated to control the document density measurement. Control by means.

〔Example〕

 An embodiment of the present invention will be described below.

In this embodiment, an original detection sensor is provided in an electrophotographic copying machine which is of a fixed original type and which controls the exposure level. The same reference numerals are used for those parts of the present embodiment that have substantially the same configuration as the parts of the conventional example described above, and the description thereof will be omitted.

FIG. 1 is a perspective view showing the vicinity of the document table 1 of this embodiment. A switch operation unit 6 is provided in front of the upper portion of the main body of the copying machine.

The document table 1 on the upper part of the main body is provided with a placing means composed of a contact glass 12 for placing a document and a document holder 13. The document 11 is placed on the side (left side in FIG. 1) on which the index line 12a showing each size is formed. Document holder 13
Is rotatable about the mounting portion 13a to the main body in the directions of arrows B and C. A rod-shaped member 14 projects in front of the mounting portion 13a. An enlarged plan view of the switch operating portion 6 is shown in FIG.

A print key 61 is provided at the right end of the switch operation portion 6, and when the key 61 is pressed, an image forming command signal is issued and the image forming process is executed. A numeric keypad 62 used for setting the number of copies and the like is provided on the left side thereof.

In the central portion of the switch operating unit 6, an automatic control is provided for controlling image forming conditions such as the exposure level of the exposing unit or the level of the developing bias value of the developing unit based on the document density obtained by exposing and scanning (prescanning) the document. An automatic density adjustment key 63 for setting the density adjustment mode and a manual density adjustment key 64 for setting a manual density adjustment mode for manually adjusting the image density are provided, and these keys 63, 64 constitute a mode setting means. .

A cross-sectional view of the document table 1 is shown in FIG. The first detection means for detecting the open / closed state of the document retainer 13 is composed of a rod member 14, a spring 15 and a limit switch 16 shown in this figure. The rod-shaped member 14 is biased by a spring 15.
When the document pressing member 13 is rotated in the direction of arrow B to close the contact glass 12 surface to an angle of about 30 degrees or less as shown in the figure, the end of the bar-shaped member 14 of the document pressing member 13 is pressed, The base end of 14 pushes the limit switch 16,
The switch 16 is turned on. On the contrary, when the document pressing member 13 is opened by rotating it in the direction of arrow C, the rod member 14 is released and the limit switch 16 is turned off.

FIG. 4 shows a perspective view of the detection means for detecting the presence / absence of a document. The configuration of the detection means used in this embodiment is known (for example, Japanese Patent Laid-Open No. 62-9205), and the exposure lamp 21 and the mirror 23 are integrally incorporated and move along the guide rails 28 and 29. The movable frame 30 has a first rod 71 whose one end is rotatably connected, and a second rod 72 whose one end is rotatably connected to the main body of the copying machine. The other ends of both rods 71 and 72 are rotatably connected to each other. First to third optical sensors 73 to 75 are mounted on the first rod 71, and fourth to sixth optical sensors 76 to 78 are mounted on the second rod 72. (These optical sensors function as a second detecting means for detecting the presence or absence of the original.) As the moving frame 30 moves, both rods 71 and 72 open and close.

When the moving frame 30 is at the home position,
As shown in FIG. 5, each of the optical sensors 73 to 78 is located below the contact glass 12 corresponding to each document size, and emits light under the control of a microcomputer described later (see FIG. 3). ). Therefore, the size of the document and the presence / absence of the document can be detected based on the information indicating which optical sensor receives the reflected light.

Each part of this embodiment is controlled by a microcomputer (hereinafter referred to as a microcomputer) 8 as shown in FIG. (This microcomputer 8 determines the setting of the automatic adjustment mode depending on whether or not the automatic density adjustment mode signal from the automatic density adjustment key 63 is output, and measures the original density when the automatic density adjustment mode is set. It has a function as a control means for controlling to start the exposure scanning.) The control of this embodiment will be described with reference to the flowchart shown in FIG.

(A) When the automatic density adjustment mode is set Check whether the document retainer 13 is closed or not with the limit switch.
Judgment is made by turning ON / OFF of 16 (step S1). The limit switch 16 generates a timing signal for detecting the presence / absence of a document by the detecting means. If the document retainer 13 is closed, the process proceeds to step S2, and it is determined whether it is the moment when the document retainer 13 is closed. If it is the moment of closing, the process proceeds to step S3, and the microcomputer 8 operates the detecting means to determine the presence or absence of the document. In this state, the document retainer is closed, so that it is not affected by extraneous light when determining the presence or absence of a document.
When it is determined that there is a document, it is next determined whether or not the mode is the automatic density adjustment mode (step S4). Now that the automatic density adjustment mode is set, the process proceeds to step S5, and it is determined whether the prescan flag is 0 or not. Since the prescan has not been performed yet, the prescan flag is 0. Therefore, the process proceeds to step S6 and the prescan flag is set to 1.
And after a delay of a predetermined time (a few tens of msec is appropriate) (step S7), the exposure apparatus 2 is operated to perform a prescan (step S8), and the obtained document density data is stored in the microcomputer 8 in a predetermined manner. Store in storage area. still,
The delay is performed to wait for the document retainer 13 to be completely closed.

Then, the process proceeds to step S9, it is determined whether or not the print key 61 is pressed, and when the print key 61 is pressed, an image formation command signal is issued and the process proceeds to step S10. In step S10, it is determined whether or not the automatic density adjustment mode is set,
Now that the automatic density adjustment mode is set, step
Move to S11. Since the prescan flag is already 1 in step S11, the process proceeds to step S12, the exposure level is controlled by the AVR 10 based on the document density data obtained in step S8, and the necessary number of image forming processes are executed (step S13). .

If the setting of each mode related to image formation is not completed in step S9, the print key 61 is not pressed,
After step S1, the process proceeds to step S2. In step S2, the time has already passed since the document pressing member 13 was closed, so the process proceeds to step S14. In step S14, the document is placed on the contact glass 12, so the process proceeds to step S15. Since the automatic density adjustment mode is set in step S15, the process proceeds to step S9. In this way, the setting of each mode related to image formation is completed, and the print key 61
Steps S9 → S1 → S2 → S4 → S15 → S9 until is pressed.
Running the routine.

(B) When the setting is changed from the manual density adjustment mode to the automatic density adjustment mode In this case, when the document presser 13 is closed in step S4 after the step S1 → S2 → S3 → S4, the manual density adjustment is performed. Mode is set so step
Move to S9. In step S9, the print key 61 is not pressed because each mode is being set.
1, shift to S2. Contact glass 12 in step S2
Since the document is placed on the document and the document retainer 13 is closed, the time has already passed, and therefore the process proceeds to steps S14 and S15.
In step S15, since the manual density adjustment mode was set at the moment when the document presser 13 was closed, the process proceeds to step S16. If the automatic density adjustment mode is not operated in step S16, the process proceeds to step S9
The routine of S1 → S2 → S14 → S15 → S16 → S9 → S1 is executed. When the automatic density adjustment key 63 is operated during execution of this routine, the process proceeds from step S16 to step S17, and the automatic density adjustment mode is set, and steps S5 → S6 → S7 → S8 → S9 are performed in the same manner as described above. If the print key 61 is operated here, the process proceeds to steps S10 → S11 → S12 → S13.

(C) When the setting is changed from the automatic density adjustment mode to the manual density adjustment mode In this case, steps S1 → S2 → S3 → S4 → S5 → S6 → S7 → S8
→ S9 → S1 → S2 → S14 → S15 → S16, and in step S16, the automatic density adjustment mode is switched to the manual density adjustment mode by the operation of the manual density adjustment key 64, and therefore, the operation proceeds to step S9. At this time, when the print key 61 is operated, the process proceeds to step S10, and since the mode is switched to the manual density adjustment mode, the process proceeds to step S21. Step S21
Then, although the original density data is determined in step S8, the exposure level is controlled by the AVR10 based on the image density set by the manual density adjustment key 64 because the manual density adjustment mode has already been switched, and the image formation is performed. Is executed (step S13).

(D) Other cases When image formation is performed with the document retainer 13 open (for example, when the document is a book), steps S1 to S1
After shifting to 8 and setting the prescan flag to 0,
The process proceeds to step S9.

When each mode setting is completed and the print key 61 is operated, the process proceeds to step S10, and it is determined whether or not the automatic density adjustment mode is set. When the automatic density adjustment mode is set,
The process proceeds from step S10 to step S11, and the prescan flag is determined. Since the flag is 0 at this point, the flag is set to 1 in step S19, prescan is executed (step S20), and steps S12 and S13 are executed. Transition.

If the manual density adjustment mode is set in step S10, the process proceeds to step S21, the exposure level is controlled by the AVR10 based on the image density set by the manual density adjustment key 64, and image formation is executed in step S13.

As described above, in the configuration of the present invention, it is determined whether or not the automatic density adjustment mode is set after detecting the presence or absence of the original and before performing the prescan for measuring the original density. Therefore, for example, when the user intentionally sets the manual density adjustment mode, the unnecessary prescan operation is not executed.

(Effect of the Invention) As described above, the electrophotographic copying machine of the present invention detects the presence or absence of a document after detecting the closed state of the document holder before the image formation command signal is generated, and then the automatic density adjustment mode is set. If it is determined that the automatic density adjustment mode is set, the measurement of the original density is started, so that the first image formation is not affected by the external light. Is set to the manual density adjustment mode, the time until the first image formation is executed can be shortened without performing unnecessary document density measurement.

[Brief description of drawings]

FIG. 1 is a perspective view showing an essential part of an embodiment of the present invention, FIG. 2 is an enlarged plan view of a switch operating portion of the embodiment, FIG. 3 is a sectional view in the vicinity of a document table, FIGS. 5 is a perspective view and a plan view showing the original detection sensor, FIG. 6 is a block diagram of a control portion of the embodiment, FIG. 7 is a flow chart showing a control method of the embodiment, and FIG. 8 is a conventional example. FIG. 6 is an explanatory diagram of a method of scanning. 2 ... Exposure device, 8 ... Microcomputer, 13 ... Document holder, 16
...... Limit switch, 28 ...... Document density detection sensor, 61
…… Print key, 63 …… Automatic density adjustment key, 64 …… Manual density adjustment key

Claims (1)

(57) [Scope of utility model registration request] 1. A placing means for placing a document, a document holder attached so as to open and close so as to hold the document placed on the placing means, and a first detection for detecting an open / closed state of the document holder. Means, second detecting means for detecting the presence or absence of an original document on the placing means after the closed state of the original document pressing means is detected by the first detecting means, and exposing and scanning the original document on the placing means. Mode setting means for selectively setting an automatic density adjustment mode for controlling the image forming condition based on the original density obtained by the above and a manual density adjustment mode for manually adjusting the image density, and the detecting means before the image forming command signal is generated. A determination unit for determining the setting of the automatic density adjustment mode after detecting the presence of the original by the control unit; and a control for starting the exposure scanning for measuring the original density when the determination unit determines the setting of the automatic density adjustment mode. Electrophotographic copying machine, characterized by comprising a control means that.