JPH03289688A - Developer concentration detecting device - Google Patents

Abstract

PURPOSE:To always detect developer concentration by a normal developer concentration sensor by generating concentration data based on the output of plural developer concentration sensors and the discriminated result by a discriminating means. CONSTITUTION:The respective outputs from plural developer concentration detecting sensors 12 and 13 are compared to discriminate whether the actuated states of the sensors 12 and 13 are normal or abnormal by the discriminating means 15. Based on the output of the plural sensors 12 and 13 and the discriminated result by the discriminating means 15, a concentration data generating means 18 generates concentration detecting data from the output of the normal developer concentration sensor. Thus, the normal detection of the developer concentration is always executed, and the stable image density is secured even when some abnormality occurs in the sensors 12 and 13, thereby improving the image quality of a copying machine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer concentration detection device for detecting the concentration of developer in a developing device in an image forming apparatus such as a copying machine.

[Prior Art] Conventionally, in image forming apparatuses such as copying machines, the density developed by the developing device is controlled in response to changes in the concentration of the developer in the developing device, thereby obtaining a stable image density. Such image forming apparatuses are provided with a developer concentration detection device that detects the concentration of developer.

An example of a conventional developer concentration detection device of this type is shown in FIG. 3.4. This device is equipped with a developer concentration sensor 3 having a light emitting element part 1 that emits a constant amount of light and a light receiving element part 2 that receives the light from the light emitting element part 1, as shown in FIG. , when the developer (toner) flows in a predetermined direction between the light emitting element section 1 and the light receiving element section 2, the light receiving element section 2 outputs a signal corresponding to the change in the amount of light received, and from this output signal, the developer The concentration is now detected.

[Problem to be solved by the invention]

However, in such a conventional developer concentration detection device, since the developer concentration is detected by a single developer concentration sensor 3, some abnormality may occur in this developer concentration sensor 3. In some cases, there is a problem in that normal developer concentration cannot be detected and stable image density cannot be obtained, and furthermore, it is not possible to even detect that an abnormality has occurred in the developer concentration sensor 3. There was a problem.

[Object of the Invention] Therefore, an object of the present invention is to compare the outputs of a plurality of developer concentration sensors so that the developer concentration can always be detected by a normal developer concentration sensor. The object is to be able to detect when an abnormality occurs in the developer concentration sensor.

[Means to solve the problem]

In order to achieve the above object, the present invention compares a plurality of developer concentration sensors that respectively detect the concentration of developer contained in a developing device of an image forming apparatus, and compares the outputs of the plurality of developer concentration sensors. A determination means for determining whether the operating state of the developer concentration sensor is normal or abnormal, and a concentration data generation means for generating concentration data based on the outputs of the plurality of developer concentration sensors and the determination results of the determination means. The present invention is characterized by further comprising a display means for displaying that an abnormality has occurred in the developer concentration sensor based on the determination result of the determination means.

Hereinafter, the present invention will be explained based on examples.

FIG. 1.2 is a diagram showing an embodiment of the present invention.

First, the configuration will be explained.

In Figure 1.2, 11 is a developer concentration detection device, 12
．． 13 is a plurality of units attached to a developing unit of a copying machine (not shown);
For example, two developer concentration sensors. The developer concentration sensors 12 and 13 detect the concentration of the developer (toner) contained in the developing device, and for example, the third.
This sensor is similar to the conventional developer concentration sensor 3 shown in FIG. The output signals of these developer concentration sensors 12 and 13 are sent to the CP as digital signals via the I/○ boat 14, respectively.
It is read into U15 (discrimination means) and stored in RAM16. Reference numeral 17 denotes a ROM, and the CPU 15 executes processes to be described later in accordance with a predetermined program stored in the ROM 17 in advance to generate density detection data. That is, C.P.
U15, RAM16, and ROM17 store the outputs of the plurality of developer concentration sensors 12.13 and the CPU1, which is a determining means.
A density data generating means 18 is configured to generate density data based on the determination result of step 5.

In this embodiment, there are two developer concentration sensors, but the number may be greater than this.

Further, a display means (not shown) is connected to the ■/○ port 14, and this display means is connected to the developer concentration sensor 12.1.
If an abnormality occurs in any of the above items, this is displayed on the operation panel of the copying machine.

Next, the effect will be explained.

FIG. 2 is a flowchart showing a program executed by the CPU 15.

In the figure, each step is represented by Pn, and first, Pl converts the signal from the developer concentration sensor 12.13 to CP.
After reading in U15 and storing in RAM 16, it is determined in P2 whether or not the developer concentration is detected for the first time. At this time, if the determination result is YES (first time), it is determined that there is no abnormality in the developer concentration sensor 12 or 13 in P6, and the read data A from the developer concentration sensor 12 and the read data from the developer concentration sensor 1 are read in P7. Calculate the average value with B and use this as RA
The data is stored in a predetermined area (temporarily referred to as T) of M16, and the current process ends.

If the determination result in step P2 is NO, the process advances to P3, and the data A and B stored in the RAM 16 in P are sent to the CPU 15 in order to determine whether the developer concentration sensor 12.13 is operating normally. Load it into , calculate A-B,
The calculation result is compared with a predetermined value α. This predetermined value α is approximately the maximum value of A-B expected when the developer concentration sensor 12.13 is operating normally, and A-B<α
If the relationship holds true, it is assumed that both the developer concentration sensors 12 and 13 are operating normally, and P6 and P7 are executed.
This process ends.

The determination result in step P3 is No, that is, A−B<
If α is not established, the developer concentration sensor 12.13
Check to see if any abnormality has occurred. In this case, in P4, a value obtained by subtracting A from the previous detection data (hereinafter also simply referred to as data T) stored in area T of the RAM 16 is compared with a predetermined value β. This predetermined value β is approximately the maximum value of data 7-A and data r-B that is assumed when the developer concentration sensor 12 is operating normally. Therefore, if the determination result in P4 is YES (the relationship TA>β holds), it means that an abnormality has occurred in the developer concentration sensor 12, and the process proceeds to P8. On the other hand, if the determination result at P4 is NO, the value obtained by subtracting B from the data stored in area T at P is compared with β. At this time, 7
If the relationship -B>β holds true, it is determined that an abnormality has occurred in the developer concentration sensor 12 at P, and Pl. After A is stored in T, the display means displays that an abnormality has occurred in the developer concentration sensor 12 at pH. At P8, the same determination as P is made, and if the determination result is NO, it is determined that an abnormality has occurred in the developer concentration sensor 12 at P1□, and B is stored in T at PIff. If the determination result at P8 is YES, the developer concentration sensor 12.
It is determined that an abnormality has occurred in the developer concentration sensors 12 and 13, and the abnormality of both developer concentration sensors 12 and 13 is displayed at P15, and the copying machine is stopped.

In this way, in this embodiment, the developer concentration sensor 1
The CPU 1 compares the respective output signals of 2.13 and determines whether the operating state of each developer concentration sensor 12.13 is normal or abnormal.
5, a plurality of developer concentration sensors 12.13
Since the normal data A or B is always stored in the area T of the RAM 16 based on the output of Even if some abnormality occurs, a normal developer concentration can be detected to ensure stable image density, and the image quality of the copying machine can be improved. Furthermore, the occurrence of an abnormality in the developer concentration sensor can be displayed on the display means to immediately notify the operator.

[Effect] According to the present invention, the determining means compares the respective outputs of the plurality of developer concentration sensors to determine whether the operating state of each developer concentration sensor is normal or abnormal, and the concentration data generating means compares the respective outputs of the plurality of developer concentration sensors. Since concentration detection data is generated from the sensor output of a normal developer concentration sensor based on the output of the developer concentration sensor and the discrimination result of this discrimination means, normal developer concentration detection is always performed. Therefore, even if some abnormality occurs in any one of the plurality of developer concentration sensors, stable image density can be ensured, and the image quality of the copying machine can be improved.

Furthermore, since the occurrence of an abnormality in the developer concentration sensor is displayed by the display means, the occurrence of this abnormality can be detected immediately.

[Brief explanation of the drawing]

FIG. 1.2 is a diagram showing an embodiment of the developer concentration detection device according to the present invention, and FIG.
The figure is a flowchart showing a program executed by the CPU. 3.4 is a diagram showing a conventional example, FIG. 3 is a perspective view of a main part thereof, and FIG. 4 is a plan view showing a mounting state of the developer concentration sensor. 11...Developer concentration detection device, 12.13...
...Developer concentration sensor, 15...CPU
(discrimination means), 18... concentration data generation means.

Claims (2)

[Claims] (1) Compare the outputs of multiple developer concentration sensors that each detect the concentration of developer contained in the developing device of the image forming apparatus, and determine the operating status of each developer concentration sensor. a determination means for determining whether the developer is normal or abnormal; a density data generation means for generating density data based on the outputs of the plurality of developer concentration sensors and the determination results of the determination means;
A developer concentration detection device comprising: (2) The developer concentration detection device according to claim 1, further comprising a display means for displaying that an abnormality has occurred in the developer concentration sensor based on the determination result of the determination means.