JPH087494B2 - Detector - Google Patents

Description

The present invention relates to a detection device suitable for application to a developing device of an electrophotographic image forming apparatus, and more particularly to a detection circuit including a piezoelectric vibrator as a sensor. The present invention relates to a detection device that inputs an output level into a differentiating circuit via a connector, inputs the output into an integrating circuit, and detects the presence or absence of toner from the output.

BACKGROUND OF THE INVENTION As a developing device used in an electrophotographic color copying machine or the like, a developing device having a structure shown in FIG. 3 is known.

In the figure, reference numeral 123 is a developing device, and 21 is a housing. In the housing 21, a cylindrical developing sleeve 22 is rotatably accommodated.

Inside the developing sleeve 22, a magnetic roll 23 having N and S8 poles is provided. A layer regulating piece 24 is pressed against the outer peripheral surface of the developing sleeve 22 so that the layer thickness of the developer attached to the developing sleeve 22 is regulated to a predetermined thickness. The predetermined thickness is 10
Within 500 μm, it means a predetermined value.

The housing 21 further includes the first and second stirring members 2
5,26 are provided. The developer D in the developer pool 29 is a first stirring member 25 that rotates counterclockwise and a second stirring member that rotates in the opposite direction to the first stirring member 25 and so as to overlap each other. The developer D is sufficiently agitated and mixed by 26, and the developer D adhered and conveyed to the surface of the developing sleeve 22 by the rotational conveying force of the developing sleeve 22 and the magnetic roll 23 that rotate in opposite directions. .

The electrostatic latent image formed on the image forming body 11 is developed in a non-contact state by the developer D attached on the image forming body 11.

During development, the developing bias signal supplied from the power source 30 is applied to the developing sleeve 22. The developing bias signal is supplied from the power source 30, and the developing bias signal is composed of a DC component selected to have substantially the same potential as the potential of the unexposed portion of the image forming body 11 and an AC component superimposed on the DC component.

As a result, only the toner T of the developer D on the developing sleeve 22 is selectively transferred to the surface of the image forming body 11 where the latent image is formed, so that the toner is adhered onto the surface of the image forming body 11 and the developing process is performed. Become.

Reference numeral 27 is a replenishment toner container, and 28 is a toner replenishment roller. Reference numeral 31 indicates a development area.

A two-component developer is used as the developer, and in the state where the developing bias is not applied, the image forming body 11 and the developer D are used.
The toner T is made to fly under the oscillating electric field due to the application of an AC bias, and selectively adheres to the electrostatic image of the image forming body 11 to be developed in a state where they are not in contact with each other.

When such a non-contact developing method is used, when a multicolor toner image including, for example, a blue toner image, a red toner image, a black toner image, etc. is sequentially developed on the image forming body 11, Has the advantage that it is not damaged by the subsequent development and that thin layer development can be realized.

By the way, in such a developing device, a remaining amount detection sensor is attached to the container 27 in order to detect the remaining amount of the developer (hereinafter referred to as toner) T stored in the container 27.

For example, as shown in FIG. 4, a sensor having a shape as shown so that its sensor surface 35D is exposed inside the container 27 in a window hole 27a formed at an appropriate position on the inner wall of the container 27. 35 is attached.

As the sensor 35, for example, a case where a piezoelectric vibrator (however, unimorph configuration) type sensor is used is shown.

A detection device for detecting the presence or absence of toner from the output of the detection circuit 50 including the sensor 35 is configured as shown in FIG.

First, for convenience of description, the sensor 35 will be abbreviated as illustrated. 35A and 35B are one divided electrode, and 35C is the other electrode.

The divided electrode 35A is directly connected to the power supply Vcc, and the other divided electrode 35B is connected to the power supply Vcc via the resistor 51 forming the circuit 36 and is connected to the base of one Darlington-connected transistor Q1. .

The emitter of the other transistor Q2 is grounded via a pair of resistors 52 and 53 connected in series. The connection middle point q is connected to the other electrode 35C of the sensor 35. As a result, the sensor 35 is positively fed back via the resistors 52 and 53.

Now, as shown in FIG. 4, when the toner T is sufficient, the sensor surface 35D of the sensor 35 is pressed by the toner T, so that the sensor 35 cannot freely vibrate.

Therefore, the transistors Q1 and Q2 remain in the ON state, and a constant detection output (voltage) S is obtained from the emitter of the transistor Q2, and thus from the connector 54 which is a connection portion with the external circuit (FIG. 6B).

However, when the toner T is reduced and the sensor 35 is reduced to such an amount that the sensor 35 can freely vibrate, it vibrates freely, and its sustained energy is transmitted through the transistors Q1 and Q2 to the sensor.
Positive feedback is provided to the other electrode 35C of 35, and oscillation occurs at the natural frequency determined by this sensor 35. for that reason,
As the detection output S, an AC voltage as shown in FIG. 6A is obtained.

This detection output S obtained at the output terminal, that is, the connector 54, is converted by the capacitor 55a forming the rectifier circuit 55 into D
The C component is cut and half-wave rectified by the diode 55b.

The half-wave rectified output is supplied to the A / D converter 57 via the integrator 56, whereby the integrated output is converted into a digital signal having a predetermined number of bits corresponding to the level. The digital signal is fetched by the CPU 60.

Therefore, when there is enough toner T, the integrated output is "0".
Then, when the toner T decreases below a predetermined amount, an integrated output of a predetermined level is obtained, and therefore the CPU 60 detects a difference in digital value corresponding to this.

The output of the CPU 60 is supplied to the display means 61. In this example, when the toner T is below a predetermined level, the display means 61 is controlled to turn on, and the operator is visually informed of the necessity of toner replenishment.

When the toner T is replenished, the free vibration of the sensor 35 is suppressed, so the integrated output becomes "0" again, and the display means 61 is turned off.

[Problems to be Solved by the Invention] By the way, when the toner T is replaced or when the developing device is cleaned, in the developing device thus configured,
The normal power source and the connector 54 are removed to perform the work.

However, when this work is finished, it is necessary to finally connect the power source and the connector 54 to predetermined places, and this is often forgotten.

Since plugging in the power source is particularly careful, the connection is not often forgotten, but the connector 54 may be forgotten.

 This causes the following inconvenient problems.

That is, when the connector 54 is disconnected, the detection output S which is the input of the rectifier circuit 55 is "0".

However, since the DC component of the detected output S is cut by the rectifier circuit 55 and supplied to the integrator 56 at the subsequent stage, there are cases where the toner T is sufficiently contained only by the integrated output and when the connector 54 is disconnected. Then it is indistinguishable at all.

Therefore, no matter how much the toner T is consumed, the display for replenishing the toner does not light up, and the image density decreases.

In view of this, the present invention proposes a detection device which can easily solve such a conventional problem and can accurately determine the detection output when the connector is connected and when it is not connected. It is a thing.

[Technical Means for Solving Problems] In order to solve the above-mentioned problems, in the present invention,
An output level of a detection circuit having a piezoelectric vibrator as a sensor is input to a differentiation circuit via a connector, the output is input to an integration circuit, and the presence or absence of toner is detected from the output. The output of the circuit is input to an integration circuit different from the integration circuit via the connector, and the presence or absence of the connection state of the connector is detected based on the output of the integration circuit.

[Operation] The detection output S obtained from the connector 54 is taken into the CPU 60 through the same path as the conventional one. The detection output S is further taken into the CPU 60 via the following circuit.

That is, when the power of the device is turned on, the detection output S is first supplied to the second integrator 70, and the integrated output is clamped to a predetermined level by the clamp element, for example, the Zener diode 71.

The clamp output is supplied to the A / D converter 57 via the first gate circuit 72, so that the clamp output is converted into a digital signal having a predetermined number of bits.

On the other hand, the integrated output from the rectifier circuit 55 and the first integrator 56 is gated by the second gate circuit 73, and then the A / D
To be converted.

The first and second gate circuits 72, 73 are complementarily controlled, and the first gate circuit 72 is always operated when the power is turned on.
Is controlled to be turned on based on the output of the CPU 60.

In this way, when the power is turned on, the detection output S of the first integrator 70 is first integrated.

When the connector 54 is normally connected and the toner T is sufficiently contained, or when the toner needs to be replenished, a predetermined integral output can be obtained.

On the other hand, when the connector 54 is disconnected, the detection output S is "0", and in this case, the integrated output is "0".

Therefore, when the connector 54 is disconnected, the digital output becomes "0", which causes the display means 61 to operate.

At the same time, when the alarm means 62 provided separately operates and the connector 54 is disconnected, the operator can be notified with an alarm sound. This makes it possible to prevent an accident in which the device is operated without forgetting the connector.

When the connector 54 is properly connected,
That is, when the detected output is not 0 volt, the second gate circuit 73 is switched on by a command from the CPU 60.

[Embodiment] Next, an example of the detection apparatus according to the present invention will be described in detail with reference to FIG. The following example is a case where it is applied to the toner remaining amount detection system of the developing device as described above.

For the convenience of explanation of the present invention, first, an outline of a digital color copying machine having the above-mentioned developing device to which the present invention is applied will be described with reference to FIG.

The document reading unit A is driven by turning on the copy button of the apparatus.

First, the original 82 on the original table 81 is optically scanned by the optical system.

This optical system consists of a halogen lamp (or fluorescent lamp) 86
And a carriage 84 provided with a reflection mirror 87, a V mirror
The movable mirror unit 88 is provided with 89 and 89 '.

The carriage 84 and the movable mirror unit 88 are caused to travel on the slide rail 83 at a predetermined speed and direction by a stepping motor 90.

That is, the rotational force transmitted from the stepping motor 90 is transmitted by the belt 95 laid between the rollers 92, 93 and the pulley 111, whereby the carriage
The 84 and the movable mirror unit 88 are moved.

The optical information (image information) obtained by illuminating the original 82 with the halogen lamp 86 reflects the reflection mirror 87 and the V mirrors 89, 89 '.
Through the optical information conversion unit 100.

A halogen lamp is used as the light source, and an IR cut filter is used in front of the lens.

When optically scanning a color original, a commercially available warm white fluorescent lamp may be used when a fluorescent lamp is used in order to prevent emphasis or attenuation of a specific color based on optics.

In this case, in order to prevent flicker, the fluorescent lamp is lit and driven by a high frequency power supply of about 40kHz.

Also, in order to keep the temperature of the tube wall constant or to promote warm-up, it is kept warm by a heater using a posistor.

A standard white plate 97 is provided on the upper surface side of the left end portion of the platen glass 81. This is because the image signal is normalized to a white signal by optically scanning the standard white plate 97.

The optical information conversion unit 100 includes a lens 101 and a prism 10.
2, dichroic mirror 103 and CCD 104 that projects a red color separation image, and CCD 105 that projects a cyan color separation image
Composed of and.

Optical signals obtained from the optical system are aggregated by the lens 101, and color-separated into red optical information and cyan optical information by the dichroic mirror 103 provided in the prism 102 described above.

By forming the respective color separation images on the light receiving surfaces of the CCDs 104 and 105, image signals converted into electric signals can be obtained. The image signal is processed by the signal processing system, and then each color signal is output to the writing unit B.

The signal processing system is assumed to include various signal processing circuits such as a color separation means and a multi-value conversion means in addition to the A / D conversion means.

The writing unit B has a deflector 935. As the deflector 935, in addition to a galvanometer mirror, a rotary polygon mirror, or the like, a deflector including an optical deflector using crystal or the like may be used. The laser beam modulated by the color signal is deflected and scanned by the deflector 935.

When the deflection scanning is started, the beam scanning is detected by the laser beam index sensor (not shown), and the beam modulation by the first color signal (for example, blue signal) is started. The modulated beam is made to scan the image forming body (photosensitive drum) 11 to which uniform charging is applied by the charger 121.

Here, an electrostatic image corresponding to the first color signal is formed on the image forming body 11 by the main scanning by the laser beam and the sub-scanning by the rotation of the image forming body 11.

This electrostatic image is developed by the developing device 123 containing blue toner. A predetermined bias voltage from a high voltage source is applied to the developing device 123. A blue toner image is formed by the development.

The toner replenishment of the developing device 123 is such that toner is replenished when necessary by controlling the toner replenishing means (not shown) based on a command signal from a CPU (not shown) for system control. become.

The blue toner image is rotated with the cleaning blade 127 being released from the pressure contact, and an electrostatic image is formed on the basis of the second color signal (for example, a red signal) in the same manner as in the case of the first color signal. Is developed to form a red toner image.

It goes without saying that a predetermined bias voltage is applied to the developing device 124 from a high voltage power source.

Similarly, an electrostatic image is formed on the basis of the third color signal (black signal), and by the developing device 125 filled with black toner,
It is developed in the same way as the previous time.

Therefore, the multicolor toner image is written on the image forming body 11.

It should be noted that although the formation of a multicolor toner image of three colors has been described here, it goes without saying that a two-color or single-color toner image can be formed.

As the developing process, as described above, in the state where the AC and DC bias voltages from the high voltage power source are applied,
An example of so-called non-contact two-component jumping development, in which each toner is made to fly toward the image forming body 11 for development, has been shown.

On the other hand, the recording paper P fed from the paper feeding device 141 via the feeding roll 142 and the timing roll 143 is conveyed onto the surface of the image forming body 11 in a state of being synchronized with the rotation of the image forming body 11. To be done. Then, the multi-color toner image is transferred onto the recording paper P by the transfer pole 130 to which a high voltage is applied from the high voltage power source, and separated by the separation pole 131.

The separated recording paper P is conveyed to the fixing device 132 to be subjected to a fixing process and a color image is obtained.

The image forming body 11 that has completed the transfer is cleaned by the cleaning device 126, and is prepared for the next image forming process.

In the cleaning device 126, in order to facilitate collection of the toner cleaned by the blade 127,
A predetermined DC voltage is applied to the metal roll 128 provided on the 127. The metal roll 128 is arranged in a non-contact state with the surface of the image forming body 11.

The blade 127 is released from the pressure contact after the cleaning is completed, but when releasing the blade 127, an auxiliary cleaning roller 129 is further provided in order to remove the unnecessary toner left behind, and the roller 129 is rotated in the direction opposite to the image forming body 11 and pressure bonded By doing so, the unnecessary toner is sufficiently cleaned and removed.

The sheet feeding device 141 is provided with a sensor 65a, and its detection output is sent to the CPU.

Next, FIG. 1 shows an example of the toner T remaining amount detection system of the above-described developing device.

The parts corresponding to those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

The detection output S obtained from the connector 54 which is the output terminal of the detection circuit 50 is supplied to the second gate circuit 73 via the rectifier circuit 55 and the first integrator 56.

The gate output is digitally converted by the A / D converter 57 and taken into the CPU 60.

The detection output S is further supplied to the second integrator 70, and its output is clamped to a predetermined operation level by the Zener diode 71 which is a clamp element, and this is A / D converted through the first gate circuit 72. . The A / D converted digital signal is fetched by the CPU 60 as described above.

The first and second gate circuits 72 and 73 are complementarily controlled by a control signal from the CPU 60, and the priority operation is always performed so that the first gate circuit 72 is always turned on when the device power is turned on. It shall be decided.

It is assumed that an alarm means 62 such as a buzzer in this example is provided together with the display means 61 in association with the CPU 60, and the alarm means 62 is driven when the connector 54 is forgotten to be connected.

Now, when the device is powered on, the first gate circuit 72
Only turn on. In this state, the detection circuit 50
Detection output S corresponding to the presence / absence of connection of 54 and the remaining amount of toner T
Is obtained.

The detection output S is integrated by the second integrator 70. When the toner T is sufficient, the detection output S having the predetermined DC level shown in FIG. 6B is obtained. When toner supply is required, the detection output S of the AC signal shown in FIG.

In the case of such a detection output S, each is integrated to a predetermined level, and this is clamped by the Zener diode 71. Therefore, when the connector 54 is connected, a predetermined clamp output is obtained.

On the other hand, when the connector 54 is disconnected, the detection output S is "0" (FIG. 7C), so the integration result is also "0" and the clamp output is also "0". Therefore, the presence or absence of the connection state of the connector 54 can be clearly identified by determining the clamp output.

This determination is performed by loading the A / D conversion output into the CPU 60. If it is determined that the connector 54 is not connected, the alarm means 62 is driven and an alarm is issued.

As a result, the operator can more reliably know that the connector 54 has been forgotten to be connected. At this time, CPU60
In response to a command from, acceptance of the copy button is prohibited.

On the other hand, when the connector 54 is connected, the CPU60
The control signal from is inverted, and this time the second gate circuit
73 is controlled to the ON state.

Then, the normal toner remaining amount detection mode is set, and when the toner supply is required as described above, the display means
The fact will be displayed on 61.

[Effects of the Invention] As described above, according to the present invention, the output level of the detection circuit having the piezoelectric vibrator as a sensor is input to the differentiating circuit via the connector, and the output is input to the integrating circuit. In the detection device that detects the presence or absence of toner from the output, the output of the detection circuit is input to an integration circuit different from the integration circuit via the connector, and based on the output of the integration circuit, Since the presence or absence of the connection state is detected, the detection output when the connector is connected and when it is not connected can be accurately determined.

Therefore, it is possible to reliably prevent fluctuations in image density caused by forgetting to connect the connector.

Further, since the detection circuit for detecting the presence / absence of toner is also used as the circuit for detecting the connection of the connector, the structure is simplified.

Therefore, the present invention is extremely suitable for application to a developing device of an electrophotographic image forming apparatus, particularly an electrophotographic color image forming apparatus.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a detection device according to the present invention,
FIG. 2 is a block diagram of an essential part showing an example of an electrophotographic color copying machine to which the present invention is applied, FIG. 3 is a block diagram showing an example of a developing device used therein, and FIG. FIG. 5 is an explanatory view of an example of arrangement of sensors, FIG. 5 is a system diagram showing an example of a conventional detection device, and FIG. 6 is a waveform diagram used for explaining the operation thereof. 27 …… Toner container 35 …… Detection sensor 35A to 35C …… Electrode 50 …… Detection circuit 54 …… Connector 56,70 …… Integrator 57 …… A / D converter 60 …… CPU 61 …… Display means 62 …… Alarm means 72,73 …… Gate circuit 123,124,125 …… Developer S …… Detection output T …… Developer

Claims (1)

[Claims] 1. A detection method in which an output level of a detection circuit equipped with a piezoelectric vibrator as a sensor is input to a differentiating circuit via a connector, its output is input to an integrating circuit, and the presence or absence of toner is detected from the output. In the apparatus, the output of the detection circuit is input to an integration circuit different from the integration circuit via the connector, and the presence or absence of the connection state of the connector is detected based on the output of the integration circuit. .