JP3259022B2 - Method and apparatus for measuring charge amount of charged powder particles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for measuring a charge amount of charged powder particles such as a toner used for an electrophotographic developer, for example.

[Conventional technology]

Generally, an electrophotographic toner is known as a charged powder particle that is applied in engineering.

A method for measuring the specific charge (charge amount) of the toner has recently been developed, and the following two methods are widely used as main methods.

(1) A method of intensively introducing a group of toners into one place in a uniform flow, displacing the group under an electric field, reading the position coordinates of the dropped toner, and measuring the specific charge (charge amount) of the toner.

(2) A method of scatteredly creating a flow of a toner group, irradiating the flow with a laser beam, determining the flow velocity of the toner based on the reflected light, and measuring the specific charge (charge amount) from this value.

[Problems to be solved by the invention]

However, the method (1) has a problem in accuracy,
The method (2) calculates the flow velocity of the toner (1).
Although there is a possibility that the accuracy will be higher than the method of
Calibration of the measurement results is difficult, and the use of laser light requires a high level of technology and complicated equipment, and has the disadvantage of high maintenance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus which can measure the charge amount of charged powder particles simply and with high accuracy by inexpensive and simple maintenance.

[Means for solving the problem]

In order to achieve the above object, the method for measuring the charged amount of charged powder particles in the present invention is to guide the charged powder particles into an air stream having a uniform flow rate, to create a charged powder particle flow, and to make the flow perpendicular to the flow direction. A parallel electric field is applied in the direction, the charged powder particle group displaced under the electric field is enlarged by an enlargement optical system, the enlarged image is photoelectrically converted by a photoelectric conversion element into image information, and the image information is processed. Thus, the displacement information and the particle size of the charged powder particles are obtained, and the specific charge of the charged powder particles is thereby calculated.

In order to further improve the measurement accuracy, a rotatable or movable reflecting mirror is provided between the charged powder particle group and the magnifying optical system, and the reflecting mirror is moved in the flow direction of the charged powder particle group. By rotating or moving according to
It is preferable to provide an enlarged image of the charged powder particle group that is stationary in the flow direction on the photoelectric conversion element.

Further, the image information converted by the photoelectric conversion element may be temporarily recorded on a recording medium by an image recording device, and then the image information may be processed while reproducing the image information. This image recording device uses a video tape recorder.

Alternatively, the converted image information may be stored, the information may be processed and processed, and the result may be stored as image information while the video is captured by the photoelectric conversion element.

Further, in order to achieve the above object, a charged amount measuring apparatus for charged powder particles according to the present invention is an apparatus for guiding a charged powder particle into an air stream having a uniform flow rate to create a charged powder particle flow, A device for applying a parallel electric field in a direction perpendicular to the flow direction of the powder particle flow, an image of a group of charged powder particles displaced under the electric field is enlarged by an enlargement optical system, and the enlarged image is photoelectrically converted to obtain image information. And a device for processing the image information to obtain displacement information and the particle size of the charged powder particles, and calculating the specific charge of the charged powder particles based on these values.

In order to further improve the measurement accuracy, the charged powder particle group which is stationary with respect to the flow direction of the charged powder particle flow on the photoelectric conversion element between the charged powder particle group and the magnifying optical system It is preferable to provide a reflecting mirror that is rotatable or movable in accordance with the flow direction of the charged powder particle group so as to give an enlarged image.

[Action]

According to the method and apparatus for measuring the charged amount of charged powder particles of the present invention, image information of a group of charged powder particles that are displaced when an electric field is applied to a charged powder particle stream is obtained, and this information is processed. By calculating the displacement information and the particle size and performing calculations based on these data, it becomes possible to obtain the specific charge of the desired charged powder particles with high accuracy without requiring advanced technology and complicated equipment. .

In addition, when a reflecting mirror is used, the reflecting mirror works so as to give an enlarged image of the charged powder particle group which is stationary in the flow direction, so that the magnification of the magnifying optical system can be increased, and furthermore, Higher accuracy is possible.

〔Example〕

FIG. 1 is a functional configuration diagram of a charge amount measuring apparatus according to a first embodiment of the present invention, which targets toner as charged powder particles, and will be described in detail below.

First, the principle of measuring the charge amount of the toner in this embodiment will be described.

Now, as shown in FIG. 1, it is assumed that the toner group is guided into an air flow having a uniform flow velocity, and a parallel electric field is applied in a direction perpendicular to the flow direction. Here, the toner is approximated as a sphere, the flow direction of the air flow is the z direction, the direction of application of the electric field is the x direction, the speed of the toner in the z direction is Vz, the speed of the toner in the x direction is Vx,
Assuming that the charge amount of one toner particle is q and the radius of the toner particle is r, the following relational expression is obtained by the law (Stokes' theorem) that gives the resistance of the object in the viscous fluid.

Therefore, q / 2r is obtained by obtaining Vx.
Here, since the radius r of the toner is obtained from the measurement and the toner density is also known, the specific charge is calculated. The value of the specific charge is calculated by calculating the mass of one toner particle and calculating q / m from the value of the already obtained charge amount (q) per mass (m) of one toner particle. Is calculated.

 Next, the device configuration will be described.

As shown in FIG. 1, the apparatus of the first embodiment includes a uniform flow creating device 1, an electric field applying device 2, an illumination 3, an enlargement optical system 4,
Photoelectric conversion element 5, physical quantity measuring device 6, and information processing device 7
Consists of The physical quantity measuring device 6 is a device that calculates displacement information and physical quantity of particle size while taking in image information.
This allows real-time measurement.

Further, in the configuration of FIG. 1, a recording / reproducing device and an image information storage device can be substituted for the physical quantity measuring device 6. FIG. 2 shows a second embodiment of the present invention in which such replacement is performed, and FIG. 3 shows a functional configuration thereof, and FIG. 3 shows a partially schematic external configuration thereof.

Hereinafter, the second embodiment will be described in detail with reference to FIG. 2 and FIG. In the drawing, P represents a toner particle as a representative. The uniform flow creating device 1 forms an air flow having a uniform flow velocity, guides a group of toner particles therein, and forms a toner flow. The electric field applying device 2 applies a parallel electric field to the toner flow formed by the uniform flow creating device 1 in a direction perpendicular to the flow direction. The illumination 3 is for generating an image of toner particles, and may be continuous irradiation light or strobe light synchronized with the recording / reproducing device 8. It is preferable to provide the illumination 3 opposite to the image pickup side with respect to the toner so that the transmitted light can be picked up as shown in the figure, since the contrast can be increased. However, the illumination 3 may be provided on the same side as the image pickup side to pick up the reflected light. . The magnifying optical system 4 includes, for example, a microscope, and magnifies the image of the displaced toner group and provides the magnified image to the imaging side. The photoelectric conversion element 5 is formed of, for example, a CCD, and converts an optical signal representing an image of a toner particle into a video signal and outputs the video signal. The recording / reproducing device 8 is composed of, for example, a video tape recorder, and has a function of recording and reproducing a moving image of the toner particle group and a function of controlling the photoelectric conversion element 5 (camera controller). The image information storage device 9 stores the moving image of the toner particle group reproduced by the recording and reproducing device 8 as electronic information. The information processing device 7 can be constituted by a computer, fetches image information from the image information storage device 9, processes the image information, calculates displacement information and physical quantities of particle diameters, and then calculates and totals specific charges. FIG. 3 shows the cables connecting the devices and the directions of the signals passing through the cables.

 Next, the operation will be described.

First, a uniform flow of air is formed in the uniform flow creating device 1, and a group of toner particles is guided into the air to form a toner flow. This toner flow is displaced on the way as shown in FIG. 3 by a parallel electric field perpendicular to the flow direction applied by the electric field applying device 2. At this time, the illumination 3 provided on the side opposite to the imaging side
Illuminates the toner flow, and an image of toner particles is obtained by the transmitted light. This image is enlarged by the enlargement optical system 4 and forms an image on the element surface of the photoelectric conversion element 5. The photoelectric conversion element 5 photoelectrically converts the optical signal of the image of the toner particles under the control of the recording / reproducing device 8 and outputs it to the recording / reproducing device 8 as a video signal. At this time, the recording / reproducing device 8 is manually set to the recording mode, and the moving image of the toner particle group is recorded. When the recording is completed, the tape is rewound and the information processing device 7
Switch to automatic control by. Then, the information processing device 7 controls the recording / reproducing device 8 to perform the normal or slow (still) mode reproduction properly, and causes the image information storage device 9 to capture the information of the screen reproduced by the recording / reproducing device 8. . Then, the information processing device 7 processes and processes the image information stored in the image information storage device 9, calculates source data necessary for calculating the value of the specific charge of the toner, and stores the result. When the processing of the image information of one screen is completed, the image information of the next screen after a lapse of a predetermined time is similarly processed, and the processing of the image information of all the screens is performed in the same manner. When the primitive data is obtained, the specific charge q / m is calculated based on these, and these are totaled.

Next, the information processing apparatus 7 will be described with reference to the flowchart of FIG.
The procedure for obtaining source data will be described in detail.

First, the information processing device 7 fetches the image information of the first screen from the image information storage device 9 (step S1).
Perform pre-processing such as binarization processing and noise removal (steps S2, S
3). After performing these processes, the particle diameter d of one toner particle is obtained, and the radius r is obtained therefrom (step S4). Next, the central coordinates and velocities Vx and Vz of the toner particles are derived (steps S5 and S6), and the results are stored (step S7). When the above processing is completed, the image information of the next screen is fetched from the image information storage device 9, and the same routine as described above is performed on the image information of all the screens. When the accumulation of the primitive data is completed, an operation is performed on the basis of these data in accordance with the above-mentioned relational expression, a specific charge q / m is obtained, and a total result is obtained.

In the above embodiment, the image information storage device 9 and the information processing device 7
Are provided separately, but the image information storage / information processing apparatus may be integrated with a single computer by integrating the two apparatuses. In this case, the functions of the image information storage device 9 of the above embodiment are incorporated in the computer.

In the above embodiment, up to the recording in the recording / reproducing device 8 is manually performed. However, it is needless to say that automatic control by the information processing device 7 is also possible.

If the recording speed of the recording / playback device 8 is insufficient,
A recording device for recording the flow toner image and a recording and reproducing device for controlling and reproducing the tape recorded by the recording device with the information processing device 7 may be used. In this case, recording on the tape in the recording device and loading the tape into the recording / reproducing device are performed manually.

 Next, a third embodiment according to the present invention will be described.

FIG. 5 shows a functional configuration of the charge amount measuring device according to the third embodiment of the present invention. In this figure, the same elements as those in FIG. 1 are denoted by the same reference numerals. In the figure, 10 is a guide tube, 11 is a slit, 12 is a rotatable reflecting mirror, and a uniform flow creating device and an electric field applying device are not shown. The reflecting mirror 12 rotates so that the flow velocity of the toner flow in the guide tube 10 and the moving speed of the optical image by the reflecting mirror 12 become equal.

In operation, first, a uniform flow of air is formed in a uniform flow creating device (not shown), and a group of toner particles is guided into the air flow, becomes a toner flow, and is introduced into the guide tube 10. When the toner flow passes through the guide tube 10, each toner particle is displaced by an electric field applied by a pair of electrodes of an electric field applying device (not shown). At this time, the image of the toner particles generated by the irradiation light from the illumination 3 strikes the reflecting mirror 12 via the slit 11. The reflecting mirror 12 is rotated by a driving unit (not shown) so that the flow velocity of the toner flow and the moving speed of the image by the reflecting mirror 12 become equal. Therefore, the toner particles of interest can be grasped in a wide range, and the image of the toner particles reflected on the photoelectric conversion element 5 becomes stationary in the flow direction. That is, the photoelectric conversion element 5
In other words, the movement of the image of the toner particles on the monitor screen is only a movement in the horizontal direction (x direction) as shown in FIG. FIG. 6 shows the n-th screen and the (n + 1) -th screen at the same time. Furthermore, in this case, since the image of the toner particles is relatively stationary in the flow direction, there is an advantage that blur is eliminated and an image with high definition can be obtained. Therefore, even with a high-speed toner flow, movement of a large number of toner particles on the screen can be captured.

The image information converted into electrical information by the photoelectric conversion element 5 enters the physical quantity measuring device 6, where the velocity Vx of the toner in the x direction, that is, the electric field application direction is calculated. The speed Vx is calculated according to the following equation after obtaining a time t _{O at} which one screen is changed to the next screen and a moving distance 1 during the time t _O.

The calculation result of Vx is immediately sent to the information processing device 7, where the q, d, q / m
Are calculated and totaled. When one process is completed, one measurement is completed, and a final calculation result is obtained.

FIG. 7 shows a physical quantity measuring device 8 of the third embodiment (FIG. 5).
Is an embodiment (fourth embodiment) in which the recording and playback device 8 and the image information storage device 9 are replaced. The operation of both devices is the same as that of the second embodiment, and once the video is recorded and reproduced. In the meantime, physical quantities are determined and tabulated.

FIG. 8 is a specific configuration diagram of the fourth embodiment shown in FIG. 7, and here, a point different from the device configuration of the second embodiment shown in FIG. 3 will be described. A uniform flow is formed in the guide tube 10 by the device shown in the left box and the device shown in the right box, and toner is guided from the device shown in the left box. A pair of electrodes 13 for applying a parallel electric field are provided above and below the guide tube 10. Irradiation light from the illumination 3 is applied perpendicular to the toner flow. This irradiation light may be continuous light or strobe light as described above. The light image, which is illuminated and shines on the toner group and bears a silhouette, meets the slit 11, hits the reflecting mirror 12, and is guided to the photoelectric conversion element 5. A portion of the guide tube 10 through which the light image passes is a flat surface 14. Also reflector 12
As described above, the motor 15 is rotated at a predetermined rotation speed by the motor 15 so that the movement in the flow direction of the toner particles on the photoelectric conversion element 5, that is, on the monitor screen is stopped. The device configuration downstream of the photoelectric conversion element 5 is the same as that of the second embodiment.

In the third and fourth embodiments described above, the rotary reflecting mirror is used. However, it is needless to say that a parallel moving reflecting mirror of a type that moves in parallel with the direction of toner flow may be used.

Further, the shape of the reflecting mirror may be a mirror having a mirror surface on both sides as shown in FIG. 9 (a), or a mirror having an outer surface of a polyhedron as shown in FIGS. 9 (b) and 9 (c). May be. Note that the hatched portion in the figure indicates the mirror surface.

According to the third and fourth embodiments described above, the following effects can be obtained in addition to the effects of the first and second embodiments.

In the first and second embodiments, the magnification of the magnifying optical system must be increased in order to further increase the accuracy of the particle diameter and the like. If the magnification is increased, the time response of the imaging system may not be able to keep up. That is, one charged powder particle cannot be grasped on a plurality of frames, and immediately comes out of the screen. On the other hand, in the third and fourth embodiments, even when the magnification of the magnifying optical system is increased by using the reflecting mirror, the mirror does not immediately go out of the screen, and more accurate measurement is possible. Becomes Further, since the image of the toner particles becomes stationary in the flow direction, there is an advantage that the toner particles can be captured over a long moving distance, and thus a large number of particles can be captured clearly.

[Effects of the Invention] As described above in detail, according to the present invention, image information of a group of charged powder particles that is displaced when an electric field is applied to a charged powder particle flow is obtained, and charging is performed based on this information. Since the specific charge of the powder particles is obtained, there is an advantage that the charge amount (specific charge) of the charged powder particles can be measured easily and with high accuracy. In addition, since a sophisticated technique and a complicated apparatus such as those using laser light are not required, a desired charge amount can be measured at low cost and with simple maintenance.

Further, a rotatable or movable reflecting mirror is provided between the charged powder particle group and the magnifying optical system, and an enlarged image of the charged powder particle group is given by the reflecting mirror so as to be stationary in the flow direction. By doing so, in addition to the advantages described above,
There is an advantage that measurement with even higher accuracy is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional configuration diagram of a charge amount measuring device according to a first embodiment of the present invention, and FIG. 2 is a function of a charge amount measuring device according to a second embodiment of the present invention. FIG. 3 is a perspective view showing an external configuration of the apparatus shown in FIG. 2, FIG. 4 is a flowchart showing a procedure for obtaining source data in an information processing apparatus, and FIG. 5 is a view showing a third embodiment of the present invention. Functional configuration diagram of such a charge amount measurement device,
FIG. 6 is a diagram showing a toner particle image on a monitor screen, FIG.
FIG. 8 is a functional configuration diagram of a charge amount measuring device according to a fourth embodiment of the present invention, FIG. 8 is a perspective view showing an external configuration of the device of FIG. 7, and FIG. 9 is a diagram showing an example of a reflecting mirror. is there. DESCRIPTION OF SYMBOLS 1 ... Uniform flow creation apparatus, 2 ... Electric field application apparatus 3 ... Illumination, 4 ... Magnification optical system 5 ... Photoelectric conversion element, 6 ... Physical quantity measuring apparatus 7 ... Information processing apparatus, 8 ... Recording Reproduction device 9: Image information storage device, 12: Reflecting mirror

Claims (6)

(57) [Claims] A charged powder particle is introduced into an air flow having a uniform flow velocity to form a charged powder particle flow, a parallel electric field is applied in a direction perpendicular to the flow direction, and the charged powder is displaced under the electric field. The body particle group is enlarged by an enlargement optical system, the enlarged image is photoelectrically converted by a photoelectric conversion element into image information, and the image information is processed to obtain displacement information and particle size of the charged powder particles. A method for measuring a charge amount of a charged powder particle, comprising calculating a specific charge of the charged powder particle. 2. A rotatable or movable reflecting mirror is provided between the charged powder particle group and the magnifying optical system, and the reflecting mirror is rotated or moved in accordance with the movement of the charged powder particle group in the flow direction. The method according to claim 1, wherein an enlarged image of the charged powder particle group that is stationary in the flow direction is provided on the photoelectric conversion element. 3. The image information according to claim 1, wherein the image information converted by the photoelectric conversion element is once recorded on a recording medium by an image recording device, and the image information is processed while reproducing the image information. Method. 4. The method according to claim 1, wherein the converted image information is stored, processed and processed, and the result is stored as electronic information while the video is captured by the photoelectric conversion element.
The described method. 5. An apparatus for producing a charged powder particle stream by introducing charged powder particles into an air stream having a uniform flow rate, and (b) in a direction perpendicular to the flow direction of the charged powder particle stream. A device for applying a parallel electric field, (c) a device for enlarging an image of a group of charged powder particles displaced under the electric field by an optical magnifying system, and photoelectrically converting the magnified image to obtain image information; A device for processing the image information to obtain displacement information and a particle size of the charged powder particles, and calculating a specific charge of the charged powder particles based on these values. measuring device. 6. An enlarged image of a charged powder particle group which is stationary with respect to the flow direction of the charged powder particle flow on the photoelectric conversion element is provided between the charged powder particle group and the magnifying optical system. 6. A reflecting mirror which is rotatable or movable in accordance with the movement of the charged powder particle group in the flow direction.
The described device.