JPH049968A - Abnormal rotation detecting device for image forming device - Google Patents

Abstract

PURPOSE:To surely detect abnormal rotation and to prevent the damage of a rotor and faults in forming an image by consecutively detecting the vibration of the rotor by plural sensors, Fourier-transforming a signal and checking the change of a difference between the vibration levels of respective spectra. CONSTITUTION:After the detection signals of gap sensors 2a and 2b are respectively A/D converted, they are inputted in a microcomputer 5 and stored in a RAM 51. The data are individually Fourier-transformed by an arithmetic means 52 so as to calculate the vibration levels A(nu) and B(nu) of every frequency. A discrimination means 53 calculates the square of the difference between the vibration levels D(nu). By judging that abnormal vibration occurs when an area Ds exceeds a reference value Dso at a normal time, the display of abnormality is performed by a display means 6 and the driving of a photosensitive drum 12d or the driving of an entire copying machine is stopped by a driving stop means 7, thereby preventing the damage of the rotor and the large number of faults in forming the image.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is intended to prevent abnormal rotation of rotating bodies such as photosensitive drums, developing sleeves, and optical system drive pulleys in image forming apparatuses such as copying machines, facsimiles, and printers. The present invention relates to a rotation abnormality detection device that can easily detect abnormal rotation.

<Prior Art> Conventionally, in image forming apparatuses such as copying machines, abnormal vibrations of rotating bodies such as the photoconductor tram, developing sleeve, and optical system drive pulley cause blurring and density in the image transferred from the photoconductor tram. Image formation defects such as unevenness may occur.

Conventional image forming apparatuses are not equipped with means for detecting such abnormal vibrations of the rotating body. For this reason, abnormal vibrations of the rotating body can be detected by visually evaluating the formed image, by listening to the noise generated due to abnormal vibrations, or by attaching a vibration sensor to the main body of the image forming apparatus to detect the vibrations and outputting the output signal. It was detected by reading and evaluating.

<Problem to be Solved by the Invention> However, when visually judging an image, if the density of the image is low or the difference in density is small, it may be difficult to judge whether the image is good or bad. Furthermore, when distinguishing between the noises generated by abnormal vibrations or when detecting vibrations using an attached vibration sensor, the noises generated by the abnormal vibrations may be canceled out by surrounding noise. Furthermore, since the vibration sensor has a complicated structure and is large in size, the problem of installation location arises.

Furthermore, in any of the above cases, the abnormality cannot be detected until the abnormality has progressed to a certain extent. As a result, the rotating body may be damaged due to a delay in detecting an abnormality, affecting the developing section, bearings, cleaning section, etc. around the rotating body, or causing a large number of defective image formations. there were.

In particular, the higher the speed of the machine, the more susceptible it is to vibrations.
The above problems were serious.

This invention was made in view of the above-mentioned problems, and involves illuminating and scanning an original placed on a document table, guiding the reflected light from the original to a rotating photoreceptor, and forming a photoreceptor on the photoreceptor. In image forming devices that form images by transferring images onto transfer paper, it is possible to accurately and quickly detect abnormalities in the rotating body, thereby preventing damage to the rotating body or large number of defective image formations. It is an object of the present invention to provide a rotation abnormality detection device that can prevent such occurrences.

<Means and operations for solving the problem> In order to achieve the above object, the rotational abnormality detection device of the present invention includes a plurality of sensors that detect vibrations of the rotating body as the rotating body rotates. a calculation means for Fourier-transforming the output signal from each sensor to calculate the vibration level for each frequency; and a calculation means for determining whether the difference between the vibration levels Fourier-transformed by the calculation means has changed. The apparatus includes a determining means, and a display means for displaying that there is a vibration abnormality in the rotating body when the difference between the vibration levels changes as a result of the determination by the determining means.

According to the rotation abnormality detection device with the above configuration, each sensor continuously detects the vibration of the rotating body, and the read signal is Fourier transformed to check whether the difference between the vibration levels of each spectrum has changed. .

Depending on the relationship between the arrangement of the sensors and vibrations, a significant difference in vibration level may appear in the signals output from each sensor, so the above means can accurately detect abnormal rotational vibrations.

The rotating body may be selected from a photosensitive drum, a developing sleeve, and a pulley for driving an optical system.

In addition to the display means described above, the apparatus may further include a drive stop means for stopping the drive of the rotating body. According to this, when an abnormality in the rotating body is detected, the rotation can be immediately stopped.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows the internal structure of a copying machine. In the figure, this copying machine has an electrostatic latent image corresponding to an original image on a photoreceptor I/ram as a rotating body. 12d, an image forming section 12 that develops the electrostatic latent image into a toner image by a developing device 12c, and then transfers it onto copy paper; The image forming apparatus includes a transfer paper conveyance section 13 that sequentially passes the transferred transfer paper through an image forming section 12, a conveyance guide 13a, and a fixing device 17, and then discharges it onto a paper discharge tray 16.

FIG. 1 is a block diagram showing a device for detecting abnormal rotation of the photoreceptor tram 12d.
cap sensors 2a, 2 facing both ends of the outer peripheral surface of d;
b is attached, and these gap sensors 2a, 2
The signal from b is filtered to remove unnecessary signals by filters 3a and 3b, and is input to the microcomputer 5 via the A/D converter 4. The gap sensors 2a and 2b are of a type that uses the directional angle of the projected light to detect the amount of reflected light that changes depending on the distance, a type that uses magnetic induction to detect changes in impedance due to the approach of a metal object, and a type that uses ultrasonic waves. It is possible to use a well-known method such as one that examines the reflection time of .

The microcomputer 5 operates the gear source 2a for a predetermined period of time (for example, one rotation time of the photoreceptor drum 12d).
, 2b, and a RAM 51 that stores signals from R
, A, M The data stored in 51 are each subjected to Fourier transform, and the vibration values △ and Le are calculated for each vibration frequency. Calculating means 52 for calculating the difference between novels, the difference in vibration and ＼le stored during normal rotation, and calculating means 52
and a determining means 53 that compares the difference in the vibration level of the signal of each sensor 2a2b calculated by the above method and determines whether the comparison result exceeds the W quasi-value or is old.

More specifically, the calculation means 52 calculates the vibration level A(ν) of the gear/knob sensor 2a for each frequency and the vibration level B(ν) of the cap sensor 2b for each frequency, and calculates the difference A(ν) between them. -B(v)-〇(v) is calculated. Then, the discriminating means 53 stores C(ν) during normal rotation as Co(ν) in its own storage area, and calculates the C(ν) from the calculating means 52.
(Receiving Shin as data, calculate the square of the difference from Co(ν), D(ν) = IC(ν) - Co(ν), and calculate the area of D(ν) Ds = 5D(ν) dν ν Wa is determined. Based on whether or not this area Ds exceeds the reference value Dso, an abnormality in the vibration of the rotating body is determined. A display means 6 for displaying an abnormality when it is determined that the condition has occurred is connected to a drive stop means 7 for stopping the drive of the photoconductor tram 12d or the drive of the entire copying machine.

With the above configuration, the detection signals of the gap sensors 2a and 2b are A/D converted by the A/D converters 4a and 4b, and then manually stored in the RAM 51 by the microcomputer 5. are individually Fourier-transformed by the calculation means 52 to obtain the vibration level A(ν) for each frequency.
, B(ν) are calculated. Figure 3(a), (
b) is ^(ν) during normal rotation.

It is a graph showing B(v). FIG. 4 is a graph showing the waveform of A(ν) when abnormal vibration appears in the output of the gear/knob sensor 2a (the waveform of B(ν) is normal and is not shown). Looking at Figure 4, it can be seen that the vibration level is high in the low frequency region.

Therefore, the difference C(ν) between A(ν) and B(ν) increases especially in the low frequency region when compared with the difference Co(ν) during normal rotation. Therefore, the discriminating means 53 calculates the above D(ν) and determines whether the area Ds of D(ν) or the reference value Dso
Determine whether or not it exceeds [7, standard value Ds.

If it is determined that the photosensitive tram 12d has been exceeded, the display means 6 displays an abnormality, and the drive stop means 7 stops the driving of the photosensitive tram 12d or the entire copying machine.

In this way, according to the above-mentioned copying machine, 1. By Fourier transforming the vibration data from the gear/knob sensor 2a2b (2) and taking the difference, even if the level of the vibration component of the photoconductor tram 12d included in each vibration data changes slightly,
The vibration can be detected with good sensitivity. Therefore, it is possible to detect rotational abnormalities in the photoreceptor drum 12d at an early stage before 1f and take countermeasures. It is possible to prevent this from happening.

Furthermore, it is possible to accurately determine whether the rotation of the photoreceptor tram 12d is good or not, while excluding the influence of other vibration sources.

It is preferable that the photosensitive tram 12d be vibrated repeatedly for a certain period of time while the photosensitive tram 12d is being rotated, or that the rotational state of the photosensitive tram 12d can be constantly monitored.

Further, instead of the cap sensor, an acceleration sensor is attached to the inner peripheral surface of the photoreceptor tram 12d, and the photoreceptor drum 12d is provided with an acceleration sensor.
2d vibration may also be detected.

In the above embodiment, abnormal vibrations of the photosensitive drum 12d are detected, but it is of course possible to detect vibrations of other rotating bodies such as the developing sleeve of the developing device 12c or the pulley for driving the optical system.

Furthermore, if the signals output from the gap sensors 2a and 2b are immediately subjected to Fourier transform, the RAM 51 is unnecessary.

Various design changes can be made without changing the gist of the invention.

<Effects of the Invention> As described above, according to the rotational abnormality detection device in the image forming apparatus of the present invention, each sensor continuously detects vibrations of the rotating body, and Fourier transforms the read signals.
By checking whether the difference between the vibration levels of each spectrum has changed, abnormal rotation of the rotating body can be reliably detected.

In particular, compared to the case where only one sensor is attached to the rotating body, since the difference in vibration levels related to the outputs of two sensors is investigated, detection can be made more sensitive.

Therefore, it is possible to prevent damage to the rotating body and occurrence of a large number of defective image formations.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the rotation abnormality detection device, Fig. 2 is a schematic diagram showing the internal configuration of the copying machine, Fig. 3 is a diagram showing the waveform after Fourier transform of the signal of each gap sensor, Fig. 4 FIG. 2 is a diagram showing a Fourier transform waveform when there is rotation abnormality. 2a, 2b...Gap sensor, 6...Display means, 7...Drive stop means, 12d...Photosensitive drum, 52...Calculation means, 53...Discrimination means

Claims (1)

[Claims] 1. By illuminating and scanning a document placed on a document table, guiding light reflected from the document to a rotating photoconductor, and transferring the image formed on the photoconductor to a transfer paper. In an image forming device that forms images, multiple sensors are placed at multiple locations on the rotating body to detect vibrations of the rotating body as the body rotates, and output signals from each sensor are Fourier-transformed to detect the vibrations. a calculation means for calculating the vibration level for each number; a determination means for determining whether the difference between the vibration levels Fourier-transformed by the calculation means has changed; and as a result of the determination by the determination means, the difference between the vibration levels has changed. 1. A rotation abnormality detection device for an image forming apparatus, comprising: a display means for displaying that a vibration abnormality exists in a rotating body when the rotating body is abnormal.