JPH06167884A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the ejection of a poor quality copy resulting from a sudden decrease in concentration when successively making prints of a developed image with high image density during a period of time from the detection of the exhaustion of toner to the automatic stop of a device. CONSTITUTION:When the exhaustion of toner is detected by a toner exhaustion detecting sensor 12, the value of the low-concentration detection level of a toner concentration control means 20 is changed to a high value compared to the ordinary case by a low-concentration detection level changing means 22. When the exhustion of toner is detected by the toner exhaustion detecting sensor 12 and low concentration is detected by the toner concentration control means 20, the device is stopped by a second device stopping means 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus equipped with a device stopping means for detecting the presence or absence of toner in a toner replenishing device and stopping the device in the absence of toner (empty).

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, when a toner-free condition is detected, a toner replenishment display is displayed on a console panel to prompt an operator to replenish toner. It is automatically stopped and the device is not started until toner is replenished. On the other hand, on the image carrier such as the photoconductor drum, the density of the developed image (density control pattern) visualized by the developing device is detected, and the toner supplied from the toner replenishing device to the developing device based on the detection result. Is controlled, and the apparatus is stopped when the detected concentration becomes lower than a predetermined value.

[0003]

However, in the conventional image forming apparatus, when a high-density developed image is continuously printed during the period from the detection of the toner-free state to the reaching of a certain number of sheets, However, there is a problem that the density is drastically reduced by the time the set number of sheets is reached, and poor quality copies are discharged.

Further, in the conventional image forming apparatus, when the apparatus is stopped by detecting the low density state of the developed image, it is treated as an abnormal state, and the operator himself restarts the apparatus even if toner is replenished. I couldn't do it.
Therefore, it is necessary to call a service person, and there is a problem that a user's loss is large.

Further, as another drawback, even if the toner-free condition is detected, the toner-free condition may be canceled by the operation of the agitating mechanism in the toner replenishing device, and the toner-free condition may be eliminated by chattering of the sensor itself. It may be repeated to detect and then resolve. In such a case, the toner is not replenished, which may cause the problems described above.

The present invention has been made in view of the above problems, and an object of the present invention is to continuously develop a developed image having a high image density between the detection of the toner-free state and the automatic stop of the apparatus. Another object of the present invention is to provide an image forming apparatus which does not discharge a poor quality copy when printed and the density is drastically reduced.

The present invention also prompts the operator to replenish toner once the toner-out condition is detected, and can replenish toner even if the toner-out detection condition is erroneously canceled due to chattering of the sensor. An object is to provide an image forming apparatus.

Furthermore, the present invention provides an image forming apparatus capable of automatically restarting the apparatus without delay when the apparatus is stopped by detecting a low density state and toner is replenished. The purpose is to do.

[0009]

According to a first aspect of the present invention, there is provided an image forming apparatus including: a developing unit that visualizes an electrostatic latent image formed on an image carrier; and a developing unit that visualizes the electrostatic latent image. First detecting means for detecting the density of the image, toner replenishing means for replenishing the developing means with toner, and the toner replenishing means to the developing means according to the density detected by the first detecting means. Toner density control means for controlling the amount of toner to be replenished to the toner control means, and detecting the density when the density detected by the first detection means becomes lower than a preset value, and the toner density control Means for stopping the apparatus when a low density state is detected by the means, a second detecting means for detecting the presence or absence of toner in the toner replenishing means, and a toner-free state by the second detecting means. Detected When it is obtained by including a low concentration detection level changing means for changing the value of the low density detection level to a value higher than the normal in the toner density control means.

In this image forming apparatus, when the absence of toner is detected by the second detection means, the low density detection level changing means raises the low density detection level of the toner density control means to a higher value than in the normal case. Is changed to the value of. For this reason, the toner density control means can detect the low density state quickly, and the apparatus stop means can quickly and automatically stop the apparatus. Therefore, between the time when the toner-free condition is detected and the apparatus is stopped, a developed image with a high image density is continuously printed, and the density does not drop sharply and a poor quality copy is not discharged. .

According to a second aspect of the present invention, there is provided an image forming apparatus, which comprises developing means for visualizing the electrostatic latent image formed on the image carrier.
First detecting means for detecting the density of the developed image visualized by the developing means, toner replenishing means for replenishing toner to the developing means, and density detected by the first detecting means. Accordingly, the amount of toner replenished from the toner replenishing means to the developing means is controlled, and this is detected when the density detected by the first detecting means becomes lower than a preset value. A toner density control means, and a first device stopping means for stopping the device when a low density state is detected by the toner density control means,
Second detection means for detecting the presence / absence of toner in the toner replenishing means, and when the second detection means detects a toner-absent state, the value of the low density detection level in the toner density control means is set to a normal value. The low density detection level changing means for changing the value to a value higher than the case, and the second detection means for stopping the apparatus when the toner-free state is detected and the density control means detects the low density state. It is provided with a second device stopping means and a display means for operating the second device stopping means and displaying a message to the effect that the toner replenishment is prompted at the same time.

In this image forming apparatus, when the second detecting means detects the toner-free state and the density controlling means detects the low density state, the second apparatus stopping means stops the apparatus and A message prompting the replenishment of toner is displayed to prompt the operator to replenish the toner.

An image forming apparatus according to a third aspect of the present invention detects the density of the developed image visualized by the developing means and the developing means that visualizes the electrostatic latent image formed on the image carrier. Of the toner supplied to the developing means according to the density detected by the first detecting means. A toner density control unit that controls the amount and detects the density when the density detected by the first detection unit becomes lower than a preset value, and a low density state by the toner density control unit. When the toner is detected, the first device stopping means for stopping the apparatus, the second detecting means for detecting the presence / absence of toner in the toner replenishing means, and the second detecting means detect the toner-free state. Tato A low density detection level changing means for changing the value of the low density detection level in the toner density control means to a value higher than in a normal case; and a toner absence state detected by the second detection means, and the density A second device stopping device for stopping the device when the control device detects a low density state; and a display device for activating the second device stopping device and at the same time displaying a message prompting replenishment of toner. When the apparatus is stopped by the second apparatus stopping unit, the apparatus start-up control unit prohibits the start-up of the apparatus until the toner is replenished, and releases the start-up prohibition when the toner is replenished. is doing.

In this image forming apparatus, when the apparatus is stopped by the second apparatus stopping means, the start of the apparatus is prohibited until the toner is replenished, and when the toner is replenished, the start is automatically prohibited. Will be canceled. Therefore, the user can restart the printing operation without waiting for the maintenance by the service person.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a schematic configuration of a printer device according to an embodiment of the present invention. In the apparatus, a photosensitive drum 1 for forming an electrostatic latent image is arranged rotatably in the direction of the arrow in the figure. Around the photosensitive drum 1, a charging corotron 2 for uniformly charging the surface of the photosensitive drum 1 with electric charges, and electrostatically writing image information on the surface of the charged photosensitive drum 1 by a laser beam. A writing device 3, a developing device 4 that visualizes the image information written by the writing device 3 with toner to obtain a developed image, and a toner image obtained by the developing device 4 is transferred onto a copy sheet 10. A transfer corotron 5, a peeling corotron 6 for peeling off the copy paper 10 on which the toner image has been transferred, and a reflection type density detection sensor 7 for optically detecting the density of the toner image on the surface of the photosensitive drum 1. The cleaning device 8 for removing the toner remaining on the surface of the photoconductor drum 1 and the discharging lamp 9 for neutralizing the electric charge remaining on the surface of the photoconductor drum 1 are arranged in this order. It is.

The developing device 4 is integrated with a toner replenishing device 11 for replenishing the developing device 4 with toner according to the density of a developed image (density control pattern).
Inside the toner replenishing device 11, a toner-free detection sensor 12 for detecting the presence / absence of internal toner is provided. The output signal of the toner-free detection sensor 12 and the detection signal of the density detection sensor 7 are sent to the control unit 13.

The control unit 13 receives the output signal of the density detection sensor 7 and controls the amount of toner replenished from the toner replenishing device 11 to the developing device 4, and the detected concentration is higher than a predetermined low density level. When it is low, the device is stopped.

Further, the control unit 13 changes the value of the low density detection level of the density detection sensor 7 to a value higher than the normal value when the toner-free detection sensor 12 detects the absence of toner. When the density of the developed image detected by the density detection sensor 7 becomes lower than the changed level, the apparatus is stopped and a console panel (not shown) displays a message prompting toner replenishment. Further, the control unit 13 prohibits the activation of the device until the toner is replenished when the device is stopped, and releases the device activation inhibition state without delay when the toner is replenished. ing.

FIG. 2 is a block diagram showing the functional arrangement of the image forming apparatus of this embodiment. This image forming apparatus includes a developing device 4 that visualizes the electrostatic latent image formed on the photosensitive drum 1, and a density detection sensor 7 that detects the density of the developed image visualized by the developing device 4. And a toner replenishing device 11 for replenishing toner corresponding to the density detected by the density detecting sensor 7, and a toner replenishing toner from the toner replenishing device 11 to the developing device 4 according to the density detected by the density detecting sensor 7. The toner density control means 2 for controlling the amount of the toner density and detecting the density when the density detected by the density sensor 7 becomes lower than a preset value.
0, a first device stopping unit 21 that stops the device when a low density state is detected by the toner density control unit 20, and a toner absence detection sensor 12 that detects the presence or absence of toner in the toner replenishing device 11. A low density detection level changing means 22 for changing the value of the low density detection level in the toner density control means 20 to a higher value than in the normal case when the toner empty state is detected by the toner absence detection sensor 12. A second method of stopping the apparatus when the toner-absence detection sensor 12 detects the toner-absence state and the toner-concentration control unit 20 detects a low-concentration state.
When the device stopping means 23 and the second device stopping means 23 are operated, and at the same time, the display means 24 for displaying a message prompting the toner replenishment and the second device stopping means 23 stop the device, The device activation control means 25 prohibits the activation of the device until the toner is replenished and releases the activation prohibition when the toner is replenished.

Next, the operation of the image forming apparatus will be described with reference to the flow charts shown in FIGS.

First, the control section 13 receives the output signal of the toner-free detection sensor (SNR) 12 to constantly monitor the presence / absence of toner (FIG. 3, steps S100, 10).
1). When the output signal of the toner-free detection sensor 12 becomes high level, it is determined that there is no toner (step S101; Y), and a message "toner supply" is displayed on the console panel (step S102). , The device (M / C) stop program shown in FIG. 4 is started.

At this time, the control unit 13 always monitors the presence or absence of toner in the toner replenishing device 11 by the output of the toner-free detection sensor 12 (step S103), and when the state with toner continues for 3 seconds (step S104; In Y), the device (M / C) stop program shown in FIG. 4 is canceled (step S105), and the display of "toner supply" on the console panel is turned off (step S106).

On the other hand, when the apparatus stop program of FIG. 4 is started, the control unit 13 firstly causes the normal low-concentration detection level of the concentration detection sensor 7 (for example, SAD (solid.
Area density) of 0.6) is added to B (for example, 0.3) to change the low-density detection level A to a higher-density value (0.9) (step S20).
0).

Further, the control unit 13 periodically detects the density (PCH) of the density control pattern by the density detection sensor 7 (step S201) and compares this detected density (PCH) with the low density detection level A ( Step S202).
When the detected concentration (PCH) is lower than the low concentration detection level A, that is, when the concentration is lower than the low concentration detection level A (step S202; Y), the apparatus is stopped and " A message stating "Printing is complete" is displayed (step S203).

Even in this state, the control unit 12 continues to monitor the presence or absence of toner in the toner replenishing device 11 by the output of the toner absence detection sensor 12 (steps S204, 205), and when the state with toner continues for 3 seconds, that is, Unless it is recognized that the toner has been replenished, the apparatus is not activated (step S205; N). In this state, when it is determined that the state with toner continues for 3 seconds (step S20).
5) Y), the control unit 13 releases the stoppage of the apparatus, releases the start prohibition state, and releases the apparatus stop program. Further, the display on the console panel is changed to a message "printing data", the toner supply message is turned off, and the normal state (FIG. 3, step S10).
It returns to 0) (step S206).

As described above, in the image forming apparatus of this embodiment, when the toner-absence detection sensor 11 detects the toner-absence state, the low-density detection level changing means 22 causes the low-density detection level in the toner density control means 20. The value of is changed to a higher value than usual. Therefore, the detection of the low density state by the toner density control means 20 becomes faster than in the conventional case, and the automatic stop of the apparatus by the first apparatus stop means 21 is quickly performed. Therefore, between the time when the toner-free condition is detected and the apparatus is stopped, a developed image with a high image density is continuously printed, and the density does not drop sharply and a poor quality copy is not discharged. .

Further, when the absence of toner is detected, the display means 24 displays a message prompting the replenishment, so that the toner can be replenished even if the toner-free detection state is erroneously canceled due to chattering of the sensor or the like. .

Further, when the apparatus is stopped by the second apparatus stopping means 23, the activation of the apparatus is prohibited until the toner is replenished, and when the toner is replenished, the activation prohibition is automatically released. To be done. Therefore, the user can restart the printing operation without waiting for the maintenance by the service person.

[0030]

As described above, according to the image forming apparatus of the first to third aspects, when the absence of toner is detected by the second detecting means, the toner density control is performed by the low density detecting level changing means. Since the low density detection level value of the means is changed to a higher value than in the normal case, the toner density control means can detect the low density state faster, and the apparatus stop means can automatically stop the apparatus quickly. Be seen. Therefore, between the time when the toner-free condition is detected and the apparatus is stopped, a developed image with a high image density is continuously printed, and the density does not drop sharply and a poor quality copy is not discharged. Has the effect.

Particularly, according to the image forming apparatus of the third aspect, when the apparatus is stopped by the second apparatus stopping means,
The device is prohibited from starting until toner is replenished, and when toner is replenished, the start prohibition is automatically released, so the user can resume printing without waiting for maintenance by a service person. can do.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of the image forming apparatus in FIG.

3 is a flowchart showing a toner-free detection sensor program for explaining the operation of the image forming apparatus of FIG.

FIG. 4 is a flowchart showing an apparatus stop program for explaining the operation of the image forming apparatus of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 4 ... Developing device, 7 ... Density detection sensor, 11 ... Toner supply device, 12 ... Toner-free detection sensor, 13 ... Control part.

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Claims (3)

[Claims] 1. A developing unit that visualizes an electrostatic latent image formed on an image carrier, a first detecting unit that detects a density of a developed image visualized by the developing unit, and Toner replenishing means for replenishing toner to the developing means, and controlling the amount of toner replenished from the toner replenishing means to the developing means according to the density detected by the first detecting means. The toner density control means for detecting when the density detected by the detection means becomes lower than a preset value, and the apparatus is stopped when the low density state is detected by the toner density control means. Device stopping means, second detecting means for detecting the presence / absence of toner in the toner replenishing means, and when the second detecting means detects the absence of toner, the toner concentration controlling means detects a low concentration. An image forming apparatus, comprising: a low-density detection level changing unit that changes a value of a degree detection level to a value higher than a normal value. 2. A developing unit for visualizing an electrostatic latent image formed on an image carrier, a first detecting unit for detecting a density of a developed image visualized by the developing unit, Toner replenishing means for replenishing toner to the developing means, and controlling the amount of toner replenished from the toner replenishing means to the developing means according to the density detected by the first detecting means. The toner density control means for detecting when the density detected by the detection means becomes lower than a preset value, and the apparatus is stopped when the low density state is detected by the toner density control means. A first device stopping means for controlling the toner concentration, a second detecting means for detecting the presence or absence of toner in the toner replenishing means, and a toner concentration control means for detecting the absence of toner by the second detecting means. Oke Low density detection level changing means for changing the value of the low density detection level to a higher value than in the normal case, and the second detection means detects the toner-free state,
Also, a second device stopping device for stopping the device when the low density condition is detected by the density controlling device, and a display device for displaying that the second device stopping device is actuated and toner replenishment is prompted at the same time. An image forming apparatus comprising: 3. A developing means for visualizing an electrostatic latent image formed on an image carrier, a first detecting means for detecting a density of a developed image visualized by the developing means, Toner replenishing means for replenishing toner to the developing means, and controlling the amount of toner replenished from the toner replenishing means to the developing means according to the density detected by the first detecting means. The toner density control means for detecting when the density detected by the detection means becomes lower than a preset value, and the apparatus is stopped when the low density state is detected by the toner density control means. A first device stopping means for controlling the toner concentration, a second detecting means for detecting the presence or absence of toner in the toner replenishing means, and a toner concentration control means for detecting the absence of toner by the second detecting means. Oke Low density detection level changing means for changing the value of the low density detection level to a higher value than in a normal case, and the second detection means detects a toner-free state,
Also, a second device stopping device for stopping the device when the low density condition is detected by the density controlling device, and a display device for displaying that the second device stopping device is actuated and toner replenishment is prompted at the same time. And when the device is stopped by the second device stopping means,
An image forming apparatus comprising: an apparatus activation control unit that prohibits activation of the apparatus until toner is replenished and releases activation prohibition when toner is replenished.