DE2812970A1 - METHOD AND DEVICE FOR IMAGE GENERATION - Google Patents

Description

The invention relates to a method and a device for generating a stable or constant, satisfactory Image on an image recording material by means of the electrophotographic recording technique.

In the electrophotographic recording technique is the image forming method known as the Carlson method, etc. widely used in which an electrostatic charge image is formed on a photoconductive material is formed which has a layer structure of an electrically conductive layer and a photoconductive layer having. From Japanese Patent Publication No. 50-18782 (US Patent 3,647,271) and Japanese Open

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Legislative specification no. 51-341 is also another process and a device for generating such an electrostatic charge image is known in which the charge image is formed using a photoconductive control grid provided with a plurality of minute openings.

As the development of this electrophotographic Recording technology are procedural measures or Process control techniques to stabilize the obtained image has been developed. For example, a method is known in which the discharge of a corona discharger to charge the photoconductive Material generated electrical current is recorded and controlled or regulated to a constant value, whereby the electrostatic charge image is stabilized in an indirect way. In the case of using the photoconductive control grid A method is used in which an electrostatic charge image formed by modulation is kept constant (Japanese Patent Laid-Open No. 51-1322). Even though This goes unmentioned, these methods involve precise detection and control of the electrical current with the actual imaging cycle is essential for obtaining an optimum condition of the obtained images Meaning.

Regarding the modulator element, which has an ion current and charged By modulating toner particles, it is known from Japanese Patent Laid-Open Nos. 47-33775 and 49-20094, one Electrode in the form of a perforated plate etc. to supply an electrical = signal. However, these publications do not disclose either with regard to such important factors, the appropriate detection and control of the ion current and the charged toner particles. In the case of using the photoconductive control grid system A method is used in which multiple modulations of the corona ion current are carried out with one and the same the control grid formed electrostatic primary charge image are possible so that a variety of reproduced copies can be obtained. With the one with such a control grid

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however, changes in image quality inevitably occur with an increasing number of modulations on. To correct for these changes and to produce reproduced images that are essentially free of such image changes is therefore a correction device for changing the corona ion current for the generation of the electrostatic Secondary charge image required. A method can be considered for such a correction device in which various conditions for image formation depending on the number of Ion current modulations based on predetermined operating states or conditions are changed. In practice, however, it is very difficult to adequately change the image To correct dimensions as a function of constant predetermined operating states or conditions, namely due to various Factors such as the different structure of the control grid in connection with its production-dependent State of execution, changes to the control grid due to its state of use as well as changes in the environment of the Control grid and the like. With a multiple or multiple modulation of the ion current using the electrostatic There is still inevitably a certain restriction in relation to the primary charge pattern. It can therefore be considered be that this number of ion current modulations is given as a limit value and given when it is reached Number of modulations a next electrostatic primary charge image is newly formed. However, as the number of Ion current modulations changes depending on the state of the control grid, is the number of modulations to be specified a little less than the practically possible value. Accordingly, the situation may arise that the modulation in spite of the fact that it is still practicable, stopped in the middle of operation and the electrostatic Primary charge image must be newly formed, which results in a reduction in the image formation speed.

Furthermore, in the electrophotographic recording technology

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nik develops the electrostatic charge image to be formed by means of a developing agent or developer. As a developer color particles known as toner are used. This toner is in most cases in shape a mixture with a carrier material of e.g. glass beads, iron powder, an organic solvent and the like used. Since, in this developing system, the mixing ratio between the toner and the carrier (hereinafter simplified referred to as "toner concentration") affects the image quality to a great extent, is the control of the toner concentration one of the important techniques in the electrophotographic copying or imaging process With regard to the automatic control of the toner concentration, the following methods are known: On the one hand, a method in which the toner concentration is measured and depending on an excess or a shortage of the toner Toner feed mechanism are operated, and on the other hand a Method in which an actually to be consumed or consumed amount of toner is measured or estimated and as a function toner replenishment takes place on the basis of the actual toner consumption. Regarding the first method are so far, however, no satisfactory measures or tools known for performing the measurement, so that the accuracy of the measurement result obtained when taking the measurement Has defects. As for the second method, it is known to adjust the average density of the original image measure or form another charge image besides the one for image reproduction and then this separate charge image and to replenish the amount of toner used for development. However, this procedure is in the Practice far from being realized, in view of the fatigue or aging of the measuring device for determination the average density of the original image as well as the toner due to the development.

In view of the various disadvantages of known imaging techniques described above, it is therefore an object of the present invention

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Invention to provide an imaging method and apparatus which overcomes these problems and difficulties. In particular, a method and a device for image generation are to be created by means of which the state of a Electrostatic charge image can be precisely detected and by means of an improved control system as a function of the state appropriate or corresponding image generation can be carried out for the captured charge image.

It also aims to provide an improved method for appropriate Correction of one to be formed in multiple copying operation for each copying process on the basis of the primary charge image Secondary charge image as well as for the respective correction of a developed image created in multiple copy operation will.

Furthermore, an improved method for the regeneration of the electrostatic primary charge image by suitable differentiation of one to be determined with regard to multiple copying Limit values are created.

This object is achieved according to the characterizing features of the patent application, with advantageous ones in the subclaims Further developments of the invention are characterized. 25th

Preferably used embodiments of the invention are shown in the drawing and are described in more detail below.

Show it:

Fig. 1 is a cross-sectional view of a copier or image generating device, in which the invention can be used,

F i g. 2 is an enlarged partial cross-sectional view of a control grid used in various embodiments of the invention,

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F i g. 3 to 5 are representations to illustrate the generation of the electrostatic primary charge image under Use of the control grid according to Fig. 2,

6 shows a representation to illustrate the generation of the electrostatic secondary charge image using the control grid according to FIG. 2,

7 shows a further representation to illustrate the Generation of the electrostatic secondary charge image using a further embodiment of the control grid,

F i g. 8 to 10 each circuit arrangements for measuring the corona ion current passing through the control grid,

11 is a circuit diagram of a control circuit according to the invention,

12 is a circuit diagram of an error detection circuit;

F i g. 13 is a circuit diagram of a circuit arrangement for generating a reference value,

14 is a signal diagram of the image generation process;

F i g. 15 is a perspective view of a control grid drum unit;

16 shows a graphic representation of the characteristic curve of the corona ion current,
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FIG. 17 is a circuit diagram of a further embodiment of FIG Error detection circuit according to FIG. 12,

Fig. 18 is a circuit diagram of an embodiment of the timing control circuit according to Fig. 11,

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19 and 20 each circuit diagrams for further embodiments the circuit arrangement according to FIG. 11,

FIGS. 21 and 22 each show schematic representations of further Embodiments of the control circuit, 5

23 shows a circuit diagram of an embodiment of the circuit arrangement to automatically change the electrostatic charge image generation,

F i g. 24 is a schematic illustration of a toner supply device for the developing device according to FIG. 1,

25 shows a schematic representation of a further embodiment the invention,

Fig. 26 is a graph showing the relationship between an electrical current IM produced by the modulated quantity of ions and one after the current has been rectified IM illustrates DC voltage VM stored in a capacitor 87,

Fig. 27 is a graphic representation of the input and Output characteristics of a DC amplifier 90,

F i g. 28 is a characteristic of a speed control circuit 92,

Fig. 29 is another graph showing the relationship between the current IM and an amount of toner removed from the image receiving material, and

FIGS. 30 and 31 each show schematic representations of further Embodiments of the invention.

The invention is used in a method and an apparatus to produce a visible image the image

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Procreation conditions (the imaging capabilities of the imaging devices) to control, with an electrostatic primary charge image and then on a chargeable material corresponding to the electrostatic primary charge image, an electrostatic one Secondary charge image are generated, whereupon the electrostatic secondary charge image is developed and depending on the requirements, the image thus developed is transferred to an image receiving material, namely such that by means of one obtained by detecting the visibility or clarity of the electrostatic charge image Detector output signal a visible image of predetermined density can be formed. For example, visibility or Clarity (the ability to form images with respect to a visible image) of the electrostatic primary charge image is determined and on the basis of the result obtained, the image forming conditions for the formation of the electrostatic Secondary charge image and the subsequent processes controlled.

The invention also serves to determine the visibility or clarity of what is formed on the chargeable material electrostatic output charge image, storage of a signal representing the established visibility or a control signal corresponding to the visibility or clarity and control of at least one of the image generating devices e.g., for charge imaging, development, image transfer, etc. in the subsequent further imaging process steps by means of the stored signal and a new detection signal or detector output signal, so that a visible image with a given density can be obtained.

Furthermore, within the scope of the invention, any change in the ion current for controlling the image generation conditions is determined, when the visible image is modulated by forming the electrostatic charge image using the Ion current is to be produced.

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Furthermore, within the scope of the invention, there is a determination of the Visibility of the charge image to control the supply of the developing agent so that a visible image with a predetermined Density can be formed.

For example, when using the photoconductive control grid, the Ion currents flowing through the control grid can be accurately detected in a simple manner, so that an appropriate image can easily be obtained Control of the imaging conditions can be obtained on the basis of such a detection signal. Even if the Modulation repeatedly using one and the same electrostatic primary charge image to determine which of the ion current passing through the control grid in the manner described above is carried out, there is no need to specify or preset the number of repetitions. Also is a Performing constant stable multiple copying using the detection signal to control the image forming conditions possible. Further, since the corona ion current passing through the control grid is to be formed as it is of the electrostatic secondary charge image is developed, the amount of the developing agent to be consumed or consumed can be determined estimate accurately by measuring the amount of ion current passing through the control grid. In the case of multiple copying, a precisely dosed amount of toner can therefore be added and always a visible image with a predetermined one Density can be obtained.

The term "imaging conditions" as used includes the amount of corona discharge and the radiation intensity or intensity. Irradiation amount of the image light at the time of the formation of the electrostatic primary charge image, the corona discharge amount for correcting the potential of the primary electrostatic charge image, etc. and the amount of modulation corona discharge at the time of the formation of the electrostatic secondary charge image, the bias voltage at the time of formation of the electrostatic charge pattern, the corona discharge

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help remove residual charges, bias for development, bias for image transfer, etc. That is, this term denotes those factors which influence the electrostatic charge image when it is formed.

In the context of the following description, preferably use ' In certain embodiments of the invention, the electrostatic primary charge image denotes a dependency on the control grid electrostatic charge image formed by the original image, while the electrostatic secondary charge image one on a chargeable material by modulating the image passing through this electrostatic primary charge Ion streams formed electrostatic charge image and under multiple copying the multiple formation these electrostatic secondary charge images from one and the same electrostatic primary charge image for production a large number of reproduced or duplicated and printed copies is understood. With "chargeable Material "means electrically chargeable materials in sheet form such as electrostatic recording paper, etc. as well as in an endless form such as an insulating drum, etc., hereinafter referred to generally as "recording material" are.

Fig. 1 shows schematically in cross section the structure of a copier or image forming apparatus for forming a reproduced Image on uncoated paper or flat paper using a photoconductive control grid and the Process steps for the generation of the electrostatic primary and secondary charge images, development and image transfer onto the image receiving material. Denoted in the figure the reference number 44 an outer wall of the device. A template image to be reproduced such as a literature reference, documents etc. is placed on a master table 4 5 made of transparent material such as glass etc., which is on top of the Outer wall 44 is provided. The template table 45 is firmly attached

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ordered, the image exposure of a control grid 46 being effected by partial movement of the optical device. This optical device is of a known type in which a first mirror 47 and an original illuminating lamp 48 are off their positions indicated by solid lines into the positions shown in dashed lines on the outer right be moved in order to scan the entire distance with the speed V. In addition, a second mirror 49 from his with position indicated by solid lines into the position shown in dashed lines, on the right outer position, at one speed of V / 2 simultaneously with the movement of the first mirror 47 scanning the surface of the original image. The original image guided via the first mirror 47 and the second mirror 49 is then converted by means of an objective system 50 directed at the control grid 46 with a shutter mechanism and a fixed mirror 51. The control grid 4 6 has a drum shape here, for example, so that the electrically conductive material exposed on the outside towards the inside show or can be coated inside. Near the control grid 46, a device for forming a charge image is arranged along the direction of rotation of the control grid 46. Reference numeral 52 denotes a pre-exposure lamp which is used to make use of the control grid 46 forming photoconductive material in a constant, stable, photohysteresis state to enable. The reference number 53 denotes a corona discharger, which is the device for applying the primary voltage and charges the rotating control grid 46 to a sufficient voltage level. The reference number 54 denotes a further corona discharger which represents the device for applying the secondary voltage and via which the Original image occurs while the one on the control grid 46 due to the corona discharge 53 mentioned above electrical charge is removed. For this reason, the corona discharger 54 is constructed so that one on its rear side The shielding plate located is optically open. Numeral 55 denotes an overall exposure lamp which is the control grid 46 evenly illuminates the electrostatic

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To quickly increase the contrast of the primary charge image. By means of the image generation devices described above, thus a primary electrostatic charge image with high electrostatic contrast on the control grid 46 during its rotational movement educated. Corona ions generated by a corona discharger are then removed from the corona ions located on the control grid 46 The electrostatic primary charge image is modulated and the electrostatic secondary charge image is shown in the direction of the arrow rotating insulating drum 57 formed. The insulating drum 57 is constructed in such a way that an electrically conductive substrate 58 is covered by an insulating cover layer 59. With such a construction of the insulating drum, there is a voltage between the electrically conductive substrate and the electrically conductive material of the control grid 46, so that the modulated corona ions on the surface of the insulating layer 59 arrive or be guided. The secondary electrostatic charge image formed on the insulating layer 59 in this way is developed into a toner image by a developing device 60. The toner image is then printed on Image receiving material 6 2 transferred synchronously with the toner image has been transported to an image receiving position. After completing the image transfer step, the insulating drum 57 by a cleaning device 37 of known type for removing the remaining toner on the insulating layer cleaned and also exposed to a corona discharger 64 in order to prepare for the next reproduction step or copying process to maintain a uniform surface potential.

With regard to the developing device 60, both dry development and wet development can be considered will. With regard to the cleaning device 63, too, various embodiments, such as, for example, the blade cleaning sart, the type of brush cleaning, etc. are used.

The image receiving material to be transported to the image receiving station 61 6 2 is located in a storage cassette 65, from which it can be individually sorted by means of a

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roller 66 and a pawl 67 is led out. The image receiving material is transported in such a way that the edge of the transferred image and the edge of the toner image by means of a registration roller 68 must be brought to congruence. The reference number in the figure denotes a corona discharger for image transfer, that for applying a bias to the image receiving material 62 is used at the time of transferring the toner image for the purpose of speeding up the image transfer. To Once the image has been transferred, the image receiving material 62 is detached from the insulating drum 57 by means of a separating pawl 70 and an image fixing device 71, where it is subjected to image fixing by means of a heater 72, whereupon it is it is transported by means of a conveyor belt 73 into a collecting container 74 for the finished image receiving material. in the In the case of multiple copying, the above in relation to the operations described on the optical system for the formation of the electrostatic primary charge image are not carried out, instead, only the process steps take place after the formation of the electrostatic secondary charge pattern, so that the speed of rotation of the control grid can be increased. When performing multiple copying in the above machine Changes in the electrostatic primary charge image occur on the control grid 46, these changes are due to the changes in the corona ion current generated by the corona discharger 56 and passing through the control grid 46 established. The detector device enabling this determination is a circuit arrangement as shown in FIG Fig. 10 is shown. The image quality of the copy produced is determined by using the detection signal kept constant at all times, for example by increasing or decreasing the voltage applied to the corona discharger 56 will. As soon as the repeated use of the electrostatic primary charge image in multiple copying is yours If the limit value is reached, the copying process will be stopped. Duplication process interrupted and a new electrostatic one Generated primary charge image, after which the production of the remaining number of specified copies begins again.

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A toner supply device for the above-mentioned developing device 60 will be described. As can be seen from the drawing, the feed takes place of the toner to be used up during the development process, in that the toner in a toner storage container 75 Toner 76 is further conveyed by means of a screw 78 which can be driven by a motor 77 in such a way that the conveyed toner falls into a toner container 79 of the developing device 60 through an opening 80 formed in the top thereof. With this one By using two stirring screws, the toner that has got into the toner container 79 becomes sufficiently with the structure in use developing agent mixed and is then available for the further development process. Of the Motor 77 is activated, for example, as a function of a corona ion current passing through the control grid received output signal in rotation.

In Fig. 2 is in the form of an enlarged schematic cross section an embodiment of the photoconductive control grid used in the context of the invention is shown. Again Figure is to be removed, the control grid 1 consists of a electrically conductive material 2 with a plurality of tiny openings, such as a metal wire mesh, etc., which is connected to a photoconductive material 3 is coated so that the electrically conductive material 2 is exposed on one surface side to the outside, while on the surface of the photoconductive ähigen material 3 an insulating material 4 is applied, so that the entire arrangement has a layer structure.

In Figs. 3 to 6, an example of a forming process using the control grid 1 is one Electrostatic charge image illustrates its details cannot be described in detail here. As an example, however, consider a case where the used Control grid is designed such that so-called hole electrons or defect electrons into the photoconductive material of the control grid. That is, it will

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assumed that the photoconductive material 3 in the drawing is a semiconductor material such as selenium (Se) or a Selenium alloy, etc., in which the hole or defect electrons represent the main charge carriers. 5

In Fig. 3 the result of applying the primary voltage is illustrated, in which the insulating material of the control grid 1 is uniformly negative (or positive) by means of a known Charging device is being charged. This electrical charge causes the hole or defect electrons (or electrons) injected into the photoconductive material 3 via the electrically conductive material 2 and in the boundary layer in the Trapped near the insulating material 4. In the drawing, reference numeral 5 denotes a corona discharger.

In Fig. 4 is the result of the application of the secondary voltage and illustrates the image irradiation or image exposure taking place at the same time after the application of the primary voltage, in which a corona discharge with a positive superimposed from an alternating voltage and one of the alternating voltage DC bias existing source voltage is used. The voltage to be applied in addition to the alternating voltage can be a DC voltage with the opposite polarity to the above-mentioned primary voltage. If the dark attenuation value of the photoconductive material 3 is small, the above-described operations of voltage application and Image irradiation or image exposure can be carried out not only simultaneously but also successively. In Fig. reference numeral 6 denotes an original image, reference character L a light part, and reference character D a dark part of the image, the reference number 7 light rays and the reference number 8 a corona discharger.

FIG. 5 illustrates the result of the overall exposure or overall illumination taking place according to the processes described above of the control grid 1, in which the surface potential of the control grid 1 changes quickly and one

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the amount of surface charge of the insulating material 4 proportional Assumes potential value, whereby the electrostatic primary charge image is formed. In Fig. 5, reference numeral denotes 9 the light rays emanating from the lamp. 5

Fig. 6 shows a state in which the ion current from the electrostatic primary charge image to form the electrostatic Secondary charge image is modulated, which in turn forms the basis for generating a positive image of the original on the Forms recording material. In the figure, the reference numerals denote 10, a discharge wire of the corona discharger; and reference numeral 15, a recording material made of an insulating layer 12 for holding electrical charge and an electrically conductive substrate 11 consists. The reference numerals 13 and 14 denote current sources by means of which electric fields are formed in the direction in which the corona ion current flows over the corona discharge wire and the reproduction paper 12. The recording material 15 is in the Located near the side of the insulating material 4 of the control grid 1, so that the ion current from the over the control grid - running corona discharge wire 10 to the recording material 15 using the potential difference between the corona discharge wire 10 and the electrically conductive substrate 11 can be supplied. Due to the charge of the on the control grid 1 located electrostatic primary charge image acts at this point in time from the solid line OC shown electric field to block the ion current on the bright part of the image, while one of the solid Line A, the electric field allowing the ion current acts on the dark part of the image, whereby the electrostatic Secondary charge image, which is the positive image of the original, is formed on the recording material 15.

When a control grid 1 with the structure described above is used, there is therefore an increase in the electrostatic Contrast due to the amount of electrical charge to a considerably high value possible, since the electrical

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static primary charge image is formed on the insulating material. Since it is still possible to dampen or weaken to reduce the charge of the electrostatic charge pattern, which is as minimal as possible, can be achieved in the Compared to conventional copiers or image forming devices, multiple copying with a much higher number of Make copies. When the polarity of the power sources 13 and 14 is reversed as shown in FIG. 6, negative ions pass through a dem bright part of the image corresponding area through, so that a negative image is formed on the recording material 15 will. Also in the generation of the electrostatic primary charge image occurs when using a semiconductor material such as cadmium sulfide (CdS) and zinc oxide (ZnO) with electrons as the main carriers for the photoconductive material 3 of the Control grid 1 and injection of the electrons into the dark parts of the original image as well as the application of the primary voltage of course with the opposite polarity to the case described above, also taking into account the application of the voltage at the time the generation of the electrostatic secondary charge image is carried out with opposite polarity. The procedure for this case is also shown in FIGS. 2 to 7, with only the polarity of the charge and the Is to reverse voltage sources.

in Fig. 7 is a method of forming the electrostatic Secondary charge image using a control grid 100 that is different from that of the Control grid according to FIG. 2 has a different structure. The generation of the electrostatic primary charge image can take place here by the method in which the control grid according to FIG. 2 is used. In Fig. 7 denote reference number 16 an electrically conductive material, reference number 17 a photoconductive material, reference number 13 an insulating cover layer surrounding the material 16 and the material 17 and the reference numeral 19 for forming a Bias electrode on a "surface side" of the control grid 100 provided electrically conductive material that

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at the time of generation of the electrostatic primary charge image is electrically connected to the electrically conductive material 16. Numeral 20 denotes a corona discharge wire, the reference number 21 an electrically conductive carrier material, the reference number 22 an insulating layer, while the reference numbers 23, 24 and 25 denote power sources, respectively. If, as in the case of the control grid 100 according to FIG. 7, a bias or an electric field is applied between the electrically conductive materials 16 and 19, both by vapor deposition a metal in a vacuum or spraying an electrically conductive paint layer is a fine adjustment an acceleration field and a blocking field for the ion current are possible. For example, if the negative bias for the electrically conductive material 19 is increased according to FIG. 7, the corona ion current flows into the material 19 and causes an extinction or suppression of the due to the charge and fogging occurring in an area of low image density, as well as a reduction in overall image density.

8 to 10, in which embodiments of the invention are illustrated in which an electrical passing through the control grid Current is determined using the control grid 100 described above. In the illustrated embodiments 8 to 10, a control grid is arranged such that its surface side on which the electrically conductive material is exposed, or the side of the electrically conductive material provided for the application of the bias voltage Material facing a modulation corona discharger 26 ". The control grid 29 and the corona discharger 26 are relative arranged movable to one another, that is, by rotating a drum-shaped control grid according to FIG. 1 or by Lateral displacement of a flat control grid and a corona charger in opposite directions.

In Fig. 8, an embodiment is shown in which the

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Control grid 29 is connected to ground. When the modulating Corona-Icsienstrom is generated by the corona discharger 26, part of the generated corona ion current flows in the direction of a shielding plate 28 of the corona discharger 26, while the other part flows in the direction of the control grid 29 and the remaining part passes through the control grid 29. The ion current that has passed through the control grid flows in the direction of a Recording material 30 to which in relation to the control grid a voltage from a bias voltage source 34 to form the electrostatic secondary charge image on the surface of the Recording material 30 is applied. When the side of a corona discharge electrode 27 of the shield plate 28 with the Insulating material is coated, there is no inflow of the ion current in the direction of the shielding plate 28. If this Circuit construction a component for detecting the electric current such as a resistor 35 or the like between Ground and the bias source 34, for which the control grid is switched, remains as flowing through resistor 35 electric current only the current passing through the control grid 29. This means that the one in the control grid 29 or the shielding plate 28 is removed electrical current which has flown. By measuring the potential across the resistor 35 it is thus possible to measure the electric current which actually forms the electrostatic secondary charge image is effective. In the present embodiment, reference numeral 31 denotes an insulating layer, the Reference number 32 an electrically conductive carrier layer and reference number 33 a power source for the corona discharge electrode.

In Fig. 9, a further embodiment is shown in which the control grid 29 is supplied with a bias voltage while the recording material 30 is grounded. In this embodiment, the component 38 for detecting the through the Control grid passing electrical current also between the bias source 37 for the control grid and Be connected to ground. As can be seen from the figure, a

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Constant voltage element 39 can be connected between the shielding plate 28 and the control grid 29 if it is necessary a potential difference between the shield plate 28 and the Manufacture control grid 29. The presence of this component 39 in no way affects the measurement of the above mentioned electric current. Reference numeral 26 in the figure denotes a power source for the corona discharge electrode. Otherwise, the same components as in the circuit arrangement according to FIG. 8 have the same reference numbers designated. In addition, the above explanations also apply in this case, even if the detector element 38 and the grounded side of the electrically conductive carrier 32 directly electrical via a connecting wire are connected to each other.

In Fig. 10 a further embodiment is illustrated, in which the bias for the control grid from a constant voltage element 41 or a resistance element 42 is not used the above-described bias sources 34 and 37 for the control grid is formed. The detector signal can be picked up by means of an electrode which, due to the rotary movement of the control grid drum, is connected to the Control grid connected slip ring slides. In this circuit construction is also a measurement of the by the control grid passing through ionic current caused electrical current possible. That is, by capturing and Measurement of the electric current enables the state of the electrostatic secondary charge to be determined. while normal imaging is performed at the same time. To measure the amount of electrical charge of the electrostatic Secondary charge image, it can be expedient to use the electrically conductive carrier of the recording material To keep the measurement of the current flowing in the carrier body floating. As mentioned above, there are various physical methods of controlling the essentially determined state of the electrostatic secondary charge image. Single 7, angular use of such

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Methods is described in more detail below.

The first effective measure is to prevent the occurrence of image changes during multiple copying. For this purpose, the electrostatic secondary charge image in the state of the output modulation is stored in a storage element, so that later, after the occurrence of changes as the number of modulations increases, the image forming conditions can be controlled in such a way that the charge image is stored in the same state as that stored in the storage element Initial state is. It is of course not necessary that one measured at the time of multiple copying Value is exactly identical to the value measured at the beginning. Depending on the situation that arises, better results may be obtained can be obtained by merely specifying a predetermined value with respect to the expected value depending on the number of copies is changed when making multiple copies. With regard to the measured value to be stored at the beginning, either a integrated value of the value used to form the electrostatic secondary charge image in the image generation according to FIG electrical current or peak values to be picked out at the time of generation of the electrostatic charge image or mean values of this current are used. Incidentally, depending on the control grid, the one formed first has electrostatic secondary charge image does not always have the best image state. In such a case, the for The number of modulations to be stored for the generation of the electrostatic secondary charge image are specified in such a way that that the electrostatic primary charge image stabilized better during the repeat process or multiple copying State is maintained. A combination can also be used as a further example of the value to be stored in the memory element may be considered in the one after a few or a few tens of modulations in stable picture states selected value is used and the initial conditions for image generation depending on the given or previously set up program can be changed. For that too

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changing image generation conditions, for example, an amount of the Corana ion current flowing from the modulation corona discharger to the control grid can be efficiently changed. For this purpose, one can be fed to the modulation corona discharger Tension or tension on the side of the recording material can be changed or there can be a change in the opening. voltage width of the corona discharger or 'a distance between the corona discharge electrode and the control grid. Measures such as a

TQ Change in the amount to be supplied to the shielding plate 28 of the corona discharger Voltage or with respect to the bias voltage source 37 of the control grid, etc. shown in FIG. 9 as effective prove. In addition, in the manner shown in FIG when using the electrically conductive material 19 with.

the control grid showing the bias voltage electrically conductive material 19 applied voltage can be changed.

A method for keeping the electrostatic secondary charge image constant has been described above. However, it is also possible to carry out multiple copying with minimal changes in the electrostatic secondary charge image by forming the electrostatic secondary charge image under certain defined conditions, then changes in the electrostatic secondary charge image generated in this way by measuring the ion current passing through the control grid as described above generated electric current can be detected, on the basis of the determined results, the image forming conditions according to 3Q: the modulation _T such as the bias voltage, the developing electrode, etc. _t can be controlled .

Although it is possible to keep the _f obtained in the multiple copying Bildztistand means of the measures described above constant at a certain, defined value _r when the number of produced copies in the multi-copy each to fifty / vein hundred copy sheets or more departure

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increases, the situation occurs that image changes are inevitable are, in which way the above-described image generation conditions are also specified and specified. Even if the image forming conditions are determined by increasing the voltage, there is a risk that the On the high voltage side, a change in the power of the power source, a spark discharge between the components and the like may occur. Due to this fact, there may therefore be a restriction within the limits of which a Voltage rise with an increase in voltage is permissible and the specification of such a critical voltage for the Makes circuitry for controlling the imaging conditions required. There are also other measures certain limit values within the range of which a correction is permitted. The number of copies that can be made when making multiple copies becomes therefore usually ranked a little below the desired number, with reaching this number of copies in the case of multiple copying the mastering processes for the new formation of the electrostatic primary charge image are interrupted. In the case of the invention, in which the state of the formed electrostatic secondary charge image can be continuously determined, however, it is possible to automatically regenerate the electrostatic primary charge image without doing the above Way, the possible number of copies that can be produced in multiple copy mode Preset copies by adding a value as critical Number for the copies that can be made in multiple operation is specified or set, for which see B. the image quality of the electrostatic secondary charge pattern has decreased by a certain ratio of e.g. 2G%. This lets multiple copying can be performed with excellent image quality and the maximum possible number of copies, although the number of copies that can be made varies depending on the tiredness and! the conditions of the Control grid can change »even if only one and the same template image is used.

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_ 31 - ^{B 8823}

The second efficient measure is to determine whether the monitored electrostatic secondary charge image is present is in a reasonable condition or not and the result obtained on the production conditions for the feed back electrostatic primary charge image. In this case, since there is a delay in the imaging speed If the electrostatic primary charge image is newly formed, a method can be considered in which the control on the primary side before the start of the image generation process at the beginning of a day or takes place once every few hours or at the time of the heating process of the image forming device.

Even with the second type of application described above, an optimal image can be obtained without the formation of an electrostatic Primary charge image can be obtained by the conditions for the generation and development of the electrostatic secondary charge image changed automatically. A specific example of this is a control of a corona discharge voltage or an amount of light at the time of the image irradiation or image exposure during the generation of the electrostatic primary charge image or a bias voltage, a corona discharge voltage or a developing electrode voltage of the developing device etc. at the time of formation of the secondary electrostatic charge image to prevent a Influencing the image finally obtained by any Changes can be made. In addition, it is also possible to record or monitor the electrical current automatically unusual conditions such as deterioration differentiate between reduced power of the light source, disturbances in the corona discharge device and the like, so that this monitoring is extremely effective. Instead of a detection or monitoring of the from the unloader during the generation The ion current emitted by the electrostatic secondary charge image can also be provided by a separate corona discharger Detection of changes in the ion current can be provided.

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In addition, the measured current value can be due to various factors can be influenced, for example by the potential of the charge image, the performance of the corona discharger for the generation of the electrostatic secondary charge image, an acceleration voltage for preload and the like. In a situation where there are different gradations for an area with a certain density or concentration, such as a white sub-area, a sub-area of low density Intermediate area and a high-density portion, etc. occur, and an electrical one corresponding to each portion Current by means of, for example, a pulse height analyzer or the like is compared with a predetermined value, it is possible to determine which factor is to be changed can. Since these factors are interrelated, it is also possible to determine the number of Reduce factors, thereby reducing the objective of control to preventing fogging in the manufacture of the Image, which is the most serious problem in this regard. When an electric current of the density value is determined in the manner described above in a plurality of gradations to keep the image density constant, is the intensity of the secondary voltage to be applied simultaneously with the image irradiation or image exposure in the event of an increase of the current increased in areas of low density of the original image. In contrast, the intensity of the Primary voltage increased when the current is reduced in high-density sub-areas of the original image. Furthermore, the Generation of the charge image when the current increases in image areas of medium density with a wide open aperture for Increase in the amount of exposure light is carried out so that the current value is automatic at each density range of the original image can be controlled to a control value.

Since the amount of electric current and the amount of electric charge generated by the in conjunction with FIGS. 8 to 10 measures and process steps described can be measured, the amount of electrical charge for the formation of the electrical

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static secondary charge image is proportional to the The amount of toner consumed in development is substantially proportional to that based on the measurement described above amount of charge obtained, although to some extent a difference due to an absolute value of the potential of the electrostatic secondary charge image, image states such as such as thin lines, solid, solid black, etc. occurs. Therefore, when the toner of the developing device is obtained according to the measurement obtained from the above Amount of charge is supplied, the toner concentration of the developing agent in the developing device can be constant be kept at a certain predetermined value. It is of course possible to adjust the amount of toner supplied due to of the ion current passing through the control grid To keep the amount of charge not only exactly proportional, but also a non-linear dependence according to the To bring about characteristic values and properties of the development facility. In the event that there is an extremely small amount of electrical current in the background area and that Electrostatic secondary charge image cannot be developed as an image due to this current, it may be permissible that only a certain threshold value or a higher amount exhibiting current of the detection is made accessible. Or it can be considered that with low toner consumption and an image with a strong black area and high edge effect, the amount of toner supplied is not increased too much, namely not even if the amount of the current exceeds a certain predetermined value. The compared to that The amount of toner supplied depends on the developing device, the developing agent, or whether the residual toner after image transfer in the case of a copier of the plain paper type should continue to be used or not, the optimum value being determined empirically.

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There are numerous practical methods of delivering the toner depending on the amount of charge measured in the manner described above, that is, there can be various devices and mechanisms in conjunction with the toner supply device. The various methods known in relation to the toner supply can essentially be classified as follows: continuous feed process, process for feed a constant amount and method of supplying a variable amount. In the case of a feeding device in which a solenoid, etc. is used to intermittently supply a certain amount of toner, a method may be considered in which the amount of charge passing through the control grid is integrated, the supply device is operated when the amount of charge reaches a certain predetermined value for the aforementioned Integration charge used is discharged at the same time, and then the integration of the charge is started again. the Realization of "this toner supplying method using the integration described above is practical usually in such a way that the charge obtained by the aforementioned measurement is stored in a capacitor or through a to counting pulse signal is replaced, etc. On the other hand, if a mechanism with a profiled roller or grooved roller such as a Screw, etc. is used, and the toner supply speed is continuously changed by the number of revolutions or the amount of revolution of the roller member is changed, such a rotatable member becomes each time the electrostatic is generated Secondary charge image rotated constant or evenly, in such a way that the number of revolutions to the electrical current passing through the control grid are proportional and thereby achieve the intended purpose will. A separate device for measuring the toner concentration on the basis of different methods can also be used a common use with the rolling element provided will. For example, the method described below is believed to be efficient in increasing the overall reliability in

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_ 35 - ^{B 8823}

Viewed in connection with a toner concentration measuring device, which cannot be regarded as perfect in terms of its performance. That is, the procedure is based on a change in the relationship between the amount of charge passed through the control grid and that on the obtained from the toner concentration measuring device based result based toner supply amount, in the case of too high Measured value of the toner concentration the amount of toner supplied for a certain predetermined amount of charge is reduced and vice versa in the case of a too low measured value of the toner concentration the toner supply amount is increased for a certain predetermined amount of charge. Even if the toner concentration measuring device ' is subject to a malfunction or is no longer operational, this procedure can, on the one hand, involve the required minimum amount of the toner can be supplied without failure or failure and, on the other hand, excessive toner supply can be prevented from rendering the reproduced image unsuitable for practical use.

Furthermore, in an image forming apparatus provided with a microcomputer, the application of the invention is due to its operational functions and storage functions are very simple and the methods in practice become redundant or superfluous. In addition to the practical examples described above Various others may also be envisaged of the invention, such as a method in which a The amount of electric current carried during an imaging cycle is integrated, then a calculation is made to determine which multiple of a given

3Ό level or preset amount of charge of this integrated Represents the value and then the toner supply device is actuated several times in accordance with the numerical value obtained by this calculation process. For operating the toner supply device, a method can be considered at the toner supply device in that described above Way is operated in a pulsed manner or in which this multiple numerical value is converted into their actuation time.

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B 8823

The operating system based on a computer program control can also be used in the event that the generation conditions for the electrostatic secondary charge pattern etc. according to specified conditions or operating states being controlled.

A control system which prevents changes in the image to be formed during multiple copying will now be explained and is able to automatically calculate the possible number of copies that can be made in the multiple copying mode as a function of the state of the control grid itself or a state to which the control grid is exposed. Furthermore will in this connection, a copier or image forming apparatus is explained which has such a control system.

11 is a circuit arrangement for a specific device for performing the method according to the invention shown, in which the electrostatic secondary charge image is saved at the time of initial reproduction and then the voltage of a high voltage source for generating the electrostatic secondary charge image is changed in this way that the electrostatic secondary charge image to be formed thereafter has the same state as the stored charge image having. In this circuit arrangement, a component for detecting or monitoring the corona current is used Generation of the electrostatic secondary charge image arranged in a position as described in connection with FIG has been. A high-voltage source 36 of the modulation corona discharger 26 is used as the high-voltage source, whose output signal can be controlled by an input signal, as can be done by a high-voltage output unit 13A is illustrated in FIG. Before describing the circuit arrangement in its entirety, each Circuit components are described individually. First, an impedance converter circuit 1A in Fig. 11 will be discussed. which is a common voltage follower circuit and such for an impedance conversion is used that is no uncommon

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Influence on the actual image reproduction process is exerted when a voltage occurs between the terminals of the resistor of a corona current detector element 38 (hereinafter referred to simply as "resistor"). A low pass filter circuit. 2A has a generally customary structure , its mode of operation being such that it merely forwards a regular or normal signal of a voltage to be measured to the subsequent stage and thereby prevents the circuit arrangement from operating incorrectly due to interference signals, noise, etc. A special circuit diagram of the filter circuit 2A is therefore not shown. A direct current amplifier circuit 3A serves to amplify a very low measuring voltage, so that the circuit arrangement following the amplifier circuit can easily be activated for control purposes. Since the amplifier circuit has a generally customary structure, no special circuit diagram is shown. An analog logic circuit 4Ά, sampling / storage circuits 5A, 6A and an error detection circuit 7A are connected to one another in the manner shown in FIG. 12 and will be explained in more detail below. The analog logic circuit 4A consists of two relays 4A-6 and 4A-11, which have normally open contacts 4A-1 and 4A-2, respectively. The circuit 4A controls the transfer of a signal voltage at a point a of the circuit diagram to the sample / store circuits 5A and 6A. If a logic signal of the value "1" for switching on a transistor 4A-7 is fed to a point b of the circuit diagram and the relay 4A-6 is energized, the normally open contact 4A-1 closes and the signal at point a becomes the following circuit arrangement 5A transfer.

When a logic signal of the value "1" for switching on a transistor 4A-12 is fed to a point c of the circuit diagram and the relay 4A-11 is energized, the normally open contact 4A-2 is used in a similar manner to transmit the signal to the Point a closed to the following circuit 6A. The in-circuit diodes 4A-3 and 4A-8 serve, respectively for blocking or absorption "one of the relay 4A-6 resp. 4A-11 generated back emf. Furthermore, the reference numerals denote

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4A-4, 4A-5, 4A-9, and 4A-10 resistors, respectively. The scanning / Memory circuit 5A consists of a capacitor 5A-2, an N-channel MOS field effect transistor 5A-4, a resistor 5A-5, a relay 5A-9 and a constantly open normally open contact 5A-3 for the relay. A sampling signal is in the capacitor 5A-2 saved. The MOS field effect transistor 5A-4 has the construction of a source follower circuit. One of the applied to the gate electrode of the MOS field effect transistor 5A-4 Voltage proportional to the voltage drops between the terminals of the resistor 5A-5 connected to its source electrode away. The signal sampled and stored in the capacitor 5A-2, that is to say the charging voltage of the capacitor 5A-2, can can be maintained for a long period of time because the gate impedance of the MOS field effect transistor 5A-4 is very large.

To reset this storage voltage, the constantly open normally open contact 5A-3 of the relay 5A-9 can be used to short-circuit of the connections of the capacitor 5A-3 are closed, which is achieved by applying a logic signal of the value "1" for connection of a transistor 5A-10 at point d in the schematic and energizing the relay 5A-9 can be achieved. The sample / store circuit 6A performs exactly the same operations as the sample / store circuit 5A, so that a more detailed description can be dispensed with. A diode 5A-6 connected to the relay 5A-9 corresponds to the diode 5A-3.

Reference numerals 5A-7 and 5A-8 denote resistors, respectively. The error detection circuit will now be described in more detail below will. This circuit arrangement consists of a built up using a conventional operational amplifier Differential amplifier. When a source voltage e .. des MOS field effect transistor 5A-4 of the front stage an inverting Input terminal of an operational amplifier 7A-4 via a resistor 7A-1 and a source voltage e "des MOS field effect transistor 6A-4 of the front stage to a non-inverting input terminal of the operational amplifier 7A-4 are fed through a resistor 7A-2, one occurs

the value e ₂ - e .. proportional voltage at the output terminal f of the operational amplifier 7A-4 when the resistors in

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the circuit arrangement can be selected such that the resistance value of the resistor 7A-1 is equal to the resistance value of the resistor 7A-2 and the value of the resistor 7A-3 is equal to the value of the resistor 7A-5.
5

The high-voltage output unit 13A will be explained in detail, the reference value generating circuit 8A of which will be described with reference to FIG. This circuit arrangement consists of a resistor 8A-1 and a constant voltage diode 8A-2 and is an output signal constant voltage determined by the constant voltage diode. Then refer to a high voltage correction circuit 9A entered into more detail. This circuit arrangement consists of one constructed using an operational amplifier 9A-3 Adding circuit and an inverting amplifier circuit constructed using an operational amplifier 9A-8. The signals to be added consist of an output signal e., the high voltage reference value generating circuit 8A and an output signal.1 e. the error detection circuit 7A (circuit point f). These signals are sent to an inverting input terminal of the operational amplifier 9A-3 via the associated Resistor 9A-1 or 9A-2 supplied. By appropriate choice of the resistors such that the resistance of the Resistor 9A-1 is equal to the resistance of resistor 9A-2, is applied to the output terminal of operational amplifier 9A-3 a voltage proportional to the value e, + e_ is output, which inverts will. In this circuit arrangement, reference numeral 9A-5 denotes a bias resistor for the not inverting input terminal of operational amplifier 9A-3, while reference numeral 9A-4 is a feedback resistor designated. The output signal · of the operational amplifier 9A-3 is applied to the inverting input terminal through a resistor 9A-6 of the operational amplifier 9A-8 and output by this as an amplified and inverted output signal. Reference numeral SA-7 denotes a bias resistor for the non-inverting input terminal of the "Operational amplifier? ~ -8, while reference numeral 9A-9

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12970

denotes a feedback transistor.

A high voltage output circuit 12A consists of one DC / DC converter or rectifier. In this circuit, one of the emitter voltage of a transistor 12A-1 can be obtained through one of transistors 12A-3, 12A-4, a resistor 12A-2, a base winding 12A-5 and a transformer 12A-9 existing converter section of the freely oscillating or self-exciting type, and one of capacitors 12A-10, 12A-13 and diodes 12A-11, 12A-12 existing multiple voltage rectifier circuit. Since the transistor 12A-1 is connected in the form of an emitter follower the output high voltage can be varied by changing its base voltage. The ON-OFF control of the high voltage output depends on whether a current source + V by the ON-OFF switching action of one to the collector of the transistor 12A-1 connected transistor 12A-16 to the converter section connected or not. It is thus controlled by an output control signal controlled that is the base of transistor 12A-16 via a resistor 12A-15 (node g) as an input signal is fed. Numeral 12A-14 denotes a bias resistor for transistor 12A-16. Below now be closer to voltage / current limiting circuits 10A, 11A received. This circuit arrangement consists of voltage / current detector windings 12A-12, 11A-17 for the high voltage output, a comparator circuit having a rectifier circuit and an operational amplifier and a transistor 11A-1 for turning off the transistor 12A-1. One Voltage appearing on the voltage detector winding is applied to a non-inverting input terminal of the operational amplifier 11A-4 fed through a diode 11A-18 after it by means of a diode bridge 11A-11 and a capacitor 11A-10 has been converted into a direct current. Similarly, a current corresponding to the output high voltage is supplied by means of the current detector winding converted into a voltage, after which it by means of a diode bridge 11A-16 and a capacitor

809840/0921

B 8823

11 A-15 further converted into a direct current and finally through a diode 11A-13 to the non-inverting input terminal of the operational amplifier 11A-4 is supplied. The inverting input terminal of operational amplifier 11A-4 is due to a voltage of a certain predetermined value / which results from the division of the source voltage + V by the resistors T1A-5 and 11A-7 result. When this voltage is on limits of voltage and current for the output high voltage is held, is that detected by the voltage detector winding 11A-12 and the current detector winding and the non-inverting one Input terminal of the operational amplifier 11A-4 to be supplied voltage value lower than a voltage at a Switching point a. Accordingly, the output signal of the operational amplifier 11A-4 has a logic signal "0" corresponding value by which the transistor 11A-1 does not is switched through. However, if the output high voltage exceeds the limit value either in the form of a voltage value or a current ' exceeds the value, this change is passed through diode 11A-8 or diode 11A-13 to the non-inverting input terminal of the operational amplifier 11A-4. At this time the output of the operational amplifier 11A-4 goes to the logic value "1" and thus turns on the transistor 11A-1 via the resistor 11A-3, while on the other hand the high-voltage output is interrupted or interrupted by blocking the transistor 11A-1 of the high-voltage output circuit 12A. is switched off. Reference numerals 11A-9 and 11A-14 denote Load balancing resistors, while reference numeral 11A-12 denotes a bias resistor for transistor 11A-1. In this context, it should be mentioned that even when the transistor 11A-1 is switched through, that supplied to its collector Output of operational amplifier 9A-8 generally limits its short circuit current, so in this regard no problems arise.

5 The function and mode of operation of the entire circuit arrangement will now be described in more detail below with reference to FIG. 14, which set the time schedule for the

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shows generation of the electrostatic primary charge image and the electrostatic secondary charge image as well as ^{signals occurring at the respective circuit points b, c, d, d 1} and g.

As soon as the first method step (t .. -t-) of the entire copying or image generation steps comprising the generation of the electrostatic primary charge image is completed, a signal of the logic value "1" is _{fed to the circuit point d at the time t o} , whereby the Capacitors 5A-2 and 6A-2 of the sample / store circuit, old data held or stored are reset. The first step for the formation of the electrostatic secondary charge image then begins at the point in time t- ,, at which an output voltage value emitted by the high voltage squel Ie 13A for the generation of the electrostatic secondary charge image generates a reference value. This is because, due to the fact that the capacitors 5A-3 and 5A-3 of the sample memory circuit 5A are both reset and discharged, the output signals obtained therefrom have the same value and the output signal given by the error detection circuit 7A (node f) has the value zero »An output signal emitted by the high-voltage correction circuit 9A therefore becomes a reference value to be determined by the high-voltage reference value generator circuit 8A. If a signal of the value "1" is present at node g in this state, the high-voltage source is switched on and the high-voltage output forms the reference value. In addition, in this state, one corresponds to a terminal A of the detector element 38 for determining the between time t ₃ and time t. the corona current passing through the control grid to the corona current due to an electrostatic reference charge image generated at the front end part of the image, etc. Since the switching signals at nodes b and c of the logic element also have the logical input signal value "1", the capacitors 5A-2 and 6A store -2 of the sample / store circuits 5A and 6A, data which the first electrostatic secondary reference charge

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picture match. Here, the output signal indicates the error detection switching continues to the value zero. The output signal also does not change after the logic switching signal at time t. passes to the value "O" until the second step for the formation of the electrostatic secondary charge image begins, if at time t, again a logic signal of the value "1" to the circuit point b for the Link switching signal is supplied and new data is stored in the sample / storage circuit 5A. aside from that the high voltage source 13A is switched off because the signal at switching point g at time t, - to the value "0" transforms. During the first step (t-. To t ^) to training of the electrostatic secondary charge image, the high-voltage source 13A thus gives a value corresponding to the reference value Output voltage.

If then, in the second step (t, to 6 _Q ) for training

D O

of an electrostatic secondary charge pattern, the corona current to generate the electrostatic reference charge pattern is measured and a signal of the value "1" is only _{fed to circuit point b for the logic switching signal from time t to time t 7} for sampling and storing the data, only stores the sampling / storage circuit 5A receives the new data while the sample / store circuit 6A continues to store the initial data. In this state, if the data held in the sample / store circuit 5A is different from the initial data previously obtained, this difference appears at the node f in the form of an output signal from the error detection circuit. The signal value present at the node f "is fed to the subsequent high-voltage correction circuit 9A and there added to or subtracted from the output signal of the high-voltage reference value generator circuit 8A, as a result of which the high-voltage output value is determined This means that if the current to be measured is smaller than the initial value, a correction is made to the effect that

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that the output high voltage can be increased. Conversely, when the output signal assumes a negative value, that is, when the corona ion current exceeds the initial value, a correction is made so that the output high voltage can be reduced. In this way, the output high voltage is corrected so that the corona current is equal to the initial value, the step for generating the electrostatic secondary charge image being _{carried out from the time t 7} to the time t 1 using this output voltage value. Thereafter, when the step of forming a secondary electrostatic charge image is to be performed n times, the above-described operations and processes are repeated and control is performed so that an image having the same image quality as the initial image is constantly obtained. If the voltage value of the high output voltage or the associated current value exceeds the reference value during these processes, the output signal at B is interrupted by the voltage / current limiter circuit 11A or limited to the safe range.

In the embodiment described above, the corona ion current is used to form the secondary electrostatic reference charge image used as the data in the leading end part of the image, etc. However, if an integrated value of the zur Generation of the electrostatic secondary charge image used for the first image transfer process is to serve as a data value, this can easily be realized by using a resettable integration circuit general design between the DC amplifier circuit 3A and the analog logic circuit 4A of the circuit arrangement is inserted according to FIG. 11 to precisely change the timing of the logic switchover signal. In Fig. 19, such a circuit structure is shown, in which the reference numeral 192 is a capacitor having a large storage capacity which together with a resistor 191 forms the integration circuit. In this case it is

809840/0921

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expedient that a signal b as an output signal before the start of Generation of the secondary charge image in the case of an even number and a signal c as an output signal just before the start of the second secondary charge image can be set. A contact 193 closes briefly immediately after the output of the Signal b, that is, an odd-numbered secondary charge image is compared with the initial charge image. If the maximum value of the corona current used to generate the first secondary charge image are used as the data value a resettable peak detector circuit of a general type is inserted between the DC amplifier circuit 3A and the analog logic circuit 4A in the circuit arrangement according to FIG. 10 to achieve an appropriate Change of the timing of the logic switching signal switched and thereby the required in a simple manner Control achieved. In Fig. 20, an embodiment of such a circuit is shown in which the Reference numeral 202 denotes a capacitor with a small storage capacity, which together with a diode 201 forms a peak value detection circuit forms. In this case too, signals b and c and a contact 203 can have the same timing as in the case of the circuit arrangement according to FIG. 19. Both of these cases can be used when detecting an object in which the surface potential of the primary charge image or secondary charge image is measured or determined directly by means of a potential probe.

It can also be seen that with a fixed output voltage of the high voltage source for generating the electrostatic secondary charge image the limit of the number of copies that can be produced in multiple copy operation at one point in time or one Number is set in which or the electrostatic secondary charge image with regard to its initial state in has decreased or deteriorated to a certain extent / with the formation of the electrostatic primary charge image takes place automatically at this point in time, the output signal of the high-voltage output unit 13A of the circuit

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" ⁴⁶ " B 8823

Order is set as shown in Fig. 11 and a certain set voltage as the input voltage of a reference input unit a circuit arrangement for determining the output signal of the error detection circuit 7A (a conventional comparator, in which an input is formed by the node f) is supplied, as illustrated in FIG. 23 is.

When both the output voltage and the current of the high voltage output circuit exceed their respective limit values, a warning signal can be passed through in a simple manner generate the output of the current / voltage limiter circuit 11A shown in FIG. 11, interrupt the copying process, or take a similar action.

The circuit designs described above are used to over the in the control grid due to 'the by the control grid Corona ion current passing through the electric current directly changes the state of formation of the flowing electric current Electrostatic secondary charge pattern due to changes in the control grid over time and changes of the secondary charge image in connection with the modulation. According to these embodiments it is possible copies made constantly uniformly in accordance with the state of formation of the secondary electrostatic charge image to be maintained even in the event of changes in the control grid status over the course of time. It is also possible to use multiple copying consistently produce even copies.

Another example of the procedure for changing the initial value on the side of the high voltage source consists in feeding the output voltage or the output signal to the Developing device, wherein the bias of the developing electrode of the developing device is changed while the generation conditions for the primary charge image or the secondary charge image remain unchanged, whereby constant uniformity Copy operations can be achieved. The expression "develop

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Lung electrode "here refers to a trough or bowl-shaped Device for applying the toner powder or a developing liquid to the charge image. In the case of the Cylinder development system is a control of the cylinder supplied bias possible in the manner described above.

Multiple copying can also be carried out by regulating the number of made copies depending on the state of the control grid to the maximum possible extent will. As the value acquisition and control using a scanning / storage technique can be carried out, not only a simple change of the electrostatic secondary charge image but also changes in the control grid status that occur over time can be determined, which is in advantageous contrast to a case which a predetermined value is determined and this predetermined value essentially with the potential of the in this way The electrostatic secondary charge image formed is compared for image generation. By the above-described Control technology is therefore an extremely fine and precise setting or regulation of the generation of electrostatic charge images possible. If, in the case of the embodiments according to FIGS. 19 and 20, the image development and image transfer after the formation of the electrostatic secondary charge image is to be carried out, such a Secondary charge image at any time to control development and image transmission monitored so that the visible image can be stabilized at any time. It does not need special mention that the invention is also applicable to a case in which a result from a comparison of a predetermined reference voltage with a determined potential resulting difference is obtained from those described above Can contribute to tax operations.

Here, the reference charge image can be on a part 151 of the Control grid 46 are formed, as shown in FIG.

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is set. This charge image can be generated by first a field 152 of uniform density provided at the end of a plate 45 is exposed or illuminated with a lamp 48 and then the image exposure then takes place. In Fig. 15, the state is shown in which the electrostatic Primary charge image is to be generated. The link switching signal b can at the time of generation of the primary charge pattern by means of a cam (to be provided on a control grid drum) for switching on and off of a switch in a time interval at which a detector signal can be obtained, namely then, when the portion 151 reaches and passes through a loader 56. As a further example, in the event that the device is responsive to a control grid motor and due to the rotation of the control grid generates a pulse train generating generator and a counter for counting the generated pulses is provided, the logic switching signal b generated by a count value of the pulses by the pulse count is started when the front end 153 of the control grid reaches the control grid holding position (i.e., the position the lamp 52) passes through.

The signal c represents a selection value from the above described signal b at its first, delivery. The reset signal d can be generated by means of a cam (provided on the control grid drum) for switching on a switch when the control grid completes one revolution and the position shown in FIG. 15 is reached. As another example may be a signal indicating the generation of the primary charge image such as an operation command signal, etc. for the Loader 53 or one indicating the completion of multiple copying Signals such as the signal indicating the zero value of the signal g at time η and the like can be used.

In Fig. 18 an embodiment of a more effective automatic control of the corona ion flow is illustrated, when the amount of the ion current changes, the

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16, that is, the corona ion current first increases and then decreases with respect to the number of copies made in the multiple copying operation or the number of secondary charge images. That is, instead of the sample / store circuit 5A according to FIG. 12, a circuit arrangement 5A 'shown in FIG. 17 is used, and by forming the reset signal d "according to FIG This reset ^{signal d 1} can be generated by detecting or monitoring the rise of the control signal g. Another possibility is to generate the reset signal d ¹ by counting the above-mentioned pulse at a predetermined count value n3.

In the embodiment according to FIG. 18, the reference symbol RC denotes a signal of the value "1" in which the primary charge image is not formed, the reference symbol CL the above-mentioned pulse, the reference symbol CT a counter, the reference numbers 181 to 185 AND gates, the reference numbers 186 to 190 inverters, the reference symbol EX a signal for timing a lamp 48 and a charger 54, the reference symbol DC a signal for the timing of a lamp 52 and a charger 53, the reference symbol FDHP a die Detector signal indicating drum holding division for resetting of the counter CT (by means of a drum cam and a switch) and the reference symbol START a copy start signal (by means of which the control grid drum is set in rotation from its holding or rest position). When the by-exposure lamp 52 and the primary DC charger 53 switched on synchronously with the start of the rotary movement of the control grid drum and the number of pulses reaches the value n4, i.e. when the front end of the control grid reaches the exposure position, the image exposure lamp 48 and the AC charger 54 are turned on at the same time and at the same time the optical system is advanced to initiate the generation of the primary electrostatic charge image. If then the

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When the number of pulses reaches n5, there is a general shutdown to return the optical system. Then reach the If the number of pulses has the value n6, the RC signal changes to the value "1", which is retained or stored until the multiple copy operation is finished. As soon as the front end of the control grid reaches the holding or rest position, the Counter CT is reset for renewed pulse counting and outputs the logic switching signal b and that as output signals High voltage signal g at the time of n1, reducing the electrostatic Secondary charge image is formed. In this case, the output signal b is emitted at time n1, while the output signal g is generated at a point in time between η and n3. By repeating the above Processes can thus receive the maximum possible number of copies in multiple copy operation.

The following is to start again the generation of the primary electrostatic charge image will be described with reference to FIG. A comparator 231 determines whether the signal f is above its limit value or not. If the signal exceeds its limit value, a OR gate 235 emits an output signal sTOP, by which the operation of the image receiving material supply and the modulation corona charger is terminated. The reference number KSTOP denotes a switching signal for manually stopping or switching off the image generation device. After that, after expiration A timer 233 emits an output signal STAT via an OR gate 234 at a certain time interval, by the def primary charger, the AC charger, the optical system, lamp, etc. carry out their operations and operations with the timing described above resume to generate the electrostatic primary charge image. The reference symbol COPY denotes a switching signal for manual start of the imaging device.

In Fig. 21 is an embodiment of the image forming apparatus to produce a satisfactorily developed image

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illustrates, in which the potential of the electrostatic charge image on the control grid is detected or monitored directly by a surface potential probe 110 for controlling a high voltage at the modulation charger 27 and / or a developing roller 210. In the figure, the reference symbols 1A ¹ to 7A ^{1 designate} the circuit arrangements 1A to 7A already described above, in which only the reference values are different. The circuit 13A ¹ is coordinated with the timing switching control of the circuit 13A when the part 151 passes the position of the probe 210, while the circuit 13D ¹ differs from the circuit 13A with regard to its output voltage value.

In Fig. 22 is an embodiment for achieving a satisfactory final image transfer by controlling at least either the voltage of a modulation charger 27, the voltage of a charger 220 for the correction of the electrostatic primary charge image, a voltage of a charger 64 for applying a potential to the insulating material 59, a bias of a developing roller 211 or a Voltage of an image transfer charger 6 9 by means of an ion current detector resistor 38. That is, any possibly in the formation of the electrostatic secondary charge image, Disturbance or image impairment occurring during image development and image transmission can be corrected. Here, in the apparatus of Fig. 21, for example, a selenium type photoconductive control grid is used as the primary recording medium used.

In the following, the control of the toner supply will now be dependent on can be described in more detail by the formed electrostatic charge image.

Referring to Fig. 24, there is an embodiment of a related one A circuit structure is shown in which a reference numeral 258 denotes a capacitor for ion current detection by which is an average of a positive and negative current

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can be held. Reference numeral 240 denotes a transformer for generating a voltage for a wire 27, while the reference number 241 a transformer for generating a bias for a control grid 29 denotes. The reference numerals 24 2 and 243 each denote a diode for Rectification of the output voltage of each transformer as well as a capacitor. The amount of electrical charge due to the corona passing through the control grid 29 Negative polarity ion current can be determined by measuring the potential of capacitor 258. The amount of charge is turned into a by means of a control circuit unit 243 Output signal for rotating a motor 77 converted.

Another example of the toner supply according to the invention will be explained in more detail below. In Fig. 25 A circuit arrangement of one embodiment is illustrated in which a bias is applied to the control grid 27 while the recording material is grounded. A detector element 275 is located between a control grid bias source 76 and ground for detection or monitoring the amount of charge switched due to the corona ion current passing through the control grid. Like the drawing As can be seen, the electric current flowing through the charge amount detecting element 275 is different from that on the Control grid 29 formed electrostatic primary charge image modulated. That is, in the illustrated embodiment, a negative high voltage (or positive high voltage) the Modulatxonscoronaentlader 77 supplied, whereby a positively charged area and a negatively charged Area are arbitrarily present together on the control grid 29 in the form of an electrostatic charge image. By doing positively charged area on the control grid 29 occurs, for example, those generated by the discharger 27 mentioned above negative corona ions pass through a gap or space in the control grid 29 and are removed from the recording material 30 tightened. In the negatively charged area on the control grid 29, however, are those of the

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Discharger 27 generated negative corona ions from the control grid absorbs and cannot reach the insulating layer 31 of the recording material 30. Accordingly, will be due the negative charge on the insulating layer 31 of the electrically conductive substrate 32 to lying under the control grid and the locations corresponding to the positively charged area of the control grid are formed.

As in the embodiment described above, the positively charged toner of the developing agent adheres to the negatively charged one charged area of the aforementioned insulating drum due to the magnetic brush development process. This adhering toner is then transferred to the image receiving material and heated to produce the finished product Copy fixed image-wise. The electric current IM flowing through the charge amount detecting element 275 is therefore a Current, the amount of charge modulated by the electrostatic primary charge image formed on the control grid is equivalent to. The embodiment described above enables thus a determination of the toner consumption in the development device by integrating the current IM per unit of time and supplying an amount of toner corresponding to consumption, thereby obtaining a more stable image. aside from that can in an image forming apparatus which, like the apparatus of FIG. 1, is provided with a multiple copying mechanism which Total consumption of toner for a given number of copy sheets by measuring the current IM for the first copy sheet can be estimated from which then the amount of toner supplied can be determined. If the copying performance or copying quality drops in the case of multiple copying, the current IM is used to correct the Amount of toner supply per copy sheet measured intermittently. These operations and functions are explained below.

The current IM obtained by the modulation flows through the detector element 275, whereby a voltage can be obtained. Since the current IM has a small amount, it is amplified by an amplifier 281 and then by means of a DC

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converter circuit 28 2 converted into a direct current, after which it is stored in a memory circuit 283 connected in cascade fashion. As a result of the positive pulse signal rectified in the rectifier circuit 28 2, a diode 284 becomes conductive. However, since a reverse-biased diode 285 blocks ₇ , capacitors 286 and 287 are charged via diode 284. The capacitor 286 discharges when the positive pulse signal returns to zero potential while the pulse signal is stored in the capacitor 28 7 in a cascade fashion.

The charge stored in this way is fed to the gate electrode of a field effect transistor 288 as an input signal. Of the There is a reason for using a field effect transistor in that an undesired or unexpected discharge of the charge stored in the capacitor 28 7 is to be prevented and therefore a transistor with a very high input impedance Should be used. With the source electrode of the field effect transistor a resistor 289 is connected to dissipate the charge described above. The one in this resistance The voltage drop caused by 289 is substantially equal to the charge stored in capacitor 287 and becomes amplified by a DC amplifier 290 and a speed control circuit 292 of a motor 291 for the toner supply fed. The speed control circuit 292 generates an output voltage proportional to an input voltage, through the Changes the rotational speed or speed of the DC motor is changed. With the DC motor 291 is e.g., a toner supply screw as in the apparatus 43 shown in FIG. In the event that the in the capacitor 287 stored charge is low, so is the rotational speed or the speed of the DC motor 291 is low, and thus the amount of toner supplied is small. If, on the other hand, the stored charge is large, is the speed of the DC motor high so that the toner supply amount is increased. Thus, when the toner consumption is high, the current IM decreases high values, so that the stored amount of charge and thus the amount of toner supplied increase. The relay shown 293 is through regarding its ON-OFF switching operations

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the above-mentioned control switch 294 is controlled so that the toner supply only during a certain period of time can be done. When the relay 29 3 is actuated to close the contact 295 and the control of the rotational speed or speed of the direct current motor 291 with one of the amount of charge stored in the capacitor 287 proportional When voltage begins, a contact 296 assigned to the relay 29 3 is switched off, whereby the storage of the current IM in the capacitor 287 is interrupted or terminated. If the

TO toner supply time ends, the relay 29 3 immediately gives a signal to the base 298 of the transistor 297 and switches it through, whereby the charge stored in the capacitor 287 is discharged. In an image forming apparatus having a multiple copy mechanism an electrostatic charge image formed once on the control grid 29 becomes multiple or multiple used for modulation. The toner consumption per copy sheet can therefore be estimated by previously checking the current IM at the first modulation by means of the circuit arrangement according to FIG. is measured, so that a measurement of the current IM is not necessary for each modulation. If in this case the discharge time of the capacitor is long, only a single capacitor can be provided. A suitable temporal For example, control can be obtained by closing contact 296 during the formation of the first secondary charge image and from the second image generation onwards continuously open confused! or by contacting 295 during a certain predetermined period of time after the end of the generation of each secondary charge image is closed or by the Transistor 297 is turned on before the generation of the first secondary charge image begins. When the copy performance or the copy quality in the case of multiple copying as a result of multiple modulation processes with one and the same electrostatic The charge image decreases and image changes occur as a result, the current IM also becomes intermittent Correction of the toner supply amount measured. In this case, appropriate timing can be obtained by using the Contacts 295 and 296 are coupled together such that

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they open or close when the secondary charge image is generated is finished and charge imaging is started again.

The graphical representations according to FIGS. 26 to 28 show the characteristics of each unit shown in Fig. 25. Fig. 26 is a graph showing the relationship between that of the modulating Ion amount corresponding to current IM and a DC voltage VM, to which the capacitor 287 is after the rectification of the current IM is charging. It can be seen from the diagram that at a high value of the current IM, the charger direct voltage VM is great. Fig. 27 is a graph showing the input and output characteristics of the DC amplifier 290, from which it can be seen that the input voltage of the DC amplifier 290 one with the voltage VM essentially assumes an identical value. As can be seen from the diagram, the known and commonly used amplifier such characteristic values that a voltage proportional to the input voltage is output as an output signal. The reason for the amplification of the voltage by the DC amplifier 290 is that the one at the source electrode of the field effect transistor 288 connected resistor 289 has a relatively small amount. Fig. 28 illustrates the characteristics of the speed control circuit 292. That is, the speed control circuit is used to drive the DC motor 291, the DC motor has the property that its speed of rotation is proportional to the applied voltage. The speed control circuit 292 is therefore used to control a DC voltage (a voltage to be supplied to the motor) which is a boosted DC voltage Vo is proportional, so that a voltage proportional to the input voltage is output as an output signal will. Fig. 29 is a graph showing the relationship between the current IM and an amount of toner produced by the Image receiving material is used up. From this illustration it can be seen that the toner consumption increases with the current IM becomes larger due to the image receiving material.

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In Fig. 30, an embodiment is illustrated in which a stepping motor as a drive source for the toner supply device is used. Since in this circuit arrangement, the circuit for generating the output voltage V with that 25 is identical, a more detailed description is unnecessary. One amplified by the DC amplifier 290 The signal is converted into a pulse signal by means of an analog-to-digital converter 300, which drives a stepping motor 301 will. That is, - depending on the amount of the stored amount of charge is made by the analog-digital converter 30 0 a pulse cycle or a pulse period or a pulse width or duration changed and thus a control the rotational speed of the stepping motor 301 allows. An arrangement is also possible in which, at a point in time, to which the output signal · of the DC amplifier 290. a Assumes a certain value, the drive time or drive size of the stepping motor 301 is kept constant and at the same time the Charge of the storage capacitor is discharged.

In Fig. 31, there is illustrated a developer supply system whose Characteristic features consist in the fact that a method of storing the information passed through the control grid modulating ionic current generated electrical current amount is applied, in which the current alternately in a first and second memory means and the toner supply means from an output signal of one of the both storage devices is actuated, the storage device being switched over at the same time. A more accurate one Description will be given below in connection with FIG. There is a difference from the arrangement according to FIG ■ in that two units of the storage device are provided for the modulated ion current quantity IM. That is, at the arrangement according to .Fig.31 the current IM from the amplifier 281 amplified and through the rectifier circuit 28 2 rectified. When a positive pulse is generated, the diode 307 becomes conductive via the capacitor 305 and thereby charges capacitor 310, while contacts 308 and 309

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of a relay 319 are in contact with the respective sides c and a. When the current IM assumes the value zero, the in The charge stored in the capacitor 305 is discharged through the diode 306, while the charge stored in the capacitor 310 is not discharged. When a certain sampling time ends or expires, the contact 320 is closed and the relay 319 switched on, whereby the contacts 308 and 309 are switched. When the charging voltage of the capacitor 310 is higher than the zener voltage of a zener diode 312, becomes the diode 312 conducting and the stored in the capacitor 310 Charge is discharged through resistor 313 and this discharge continues until the charge voltage drops below Sener voltage value drops. This has the consequence that an output voltage is applied during the continued discharge the resistor 315 drops, which is amplified by the amplifier 316 and via the motor drive circuit 317 the DC motor 318 drives, whereby a Tpnerzufuhr takes place. When the voltage stored in capacitor 310 is lower than the sener voltage, the motor does not turn.

That is, the toner supply time will depend on the The amount of charge of the capacitor 310 is controlled. When capacitor 310 is connected to side c of contact 309, is it is of course coupled to the a side of the contact 308, so that the capacitor 310 is charged. If then the sampling time begins, the contact 308 to switch off the relay 319 is opened and the contacts 308 and 309 is switched, thereby repeating the same operations as described above. By switching of the contact 320 after a certain sampling time, it is therefore possible to continuously measure the current IM and the To control rotation of the motor 318 so that the toner supply takes place as a function of the measured value of the current IM. Although in the circuit arrangement according to FIG Discharge resistor 313 is used, it is evident that the discharge transistor 197 according to FIG. 25 can also be used instead of the discharge resistor 313 can be used. Regarding the method for controlling the rotational movement of the motor, the

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Use of the analog-to-digital converter and the stepper motor should be considered. As mentioned above, can due to the fact that by means of the arrangement according to Fig. 31 the electric current is continuously sampled, a stable, regular toner supply can be achieved. When the ON-OFF switching operations of the switch 3 20 each at the beginning of the If the electrostatic secondary charge image is generated, a suitable timing control can be obtained.

Another effect is that the state of the secondary electrostatic charge image upon image formation without processing a high voltage or a corresponding current can be determined by the above-described Detector device is inserted into the circuit arrangement at the position shown in the drawing. Since it is not necessary to have a special charge image generation area for recording or monitoring the charge image provided, the space available within the device can also be used effectively. More important is, however, that by the method according to the invention an easy, simple detection of the amount of the total Corona ion current passing through the surface of the control grid is possible, which also means that not only the Changes in the charge image potential at part of the area on the control grid but also an average Change in the electrostatic primary charge pattern can be determined over the entire surface of the control grid.

Furthermore, since the toner depends on the by the control grid passing through charge amount is supplied, that is, depending on an on the electrostatic Secondary charge image-related size, the same amount of toner as that used in the development of the electrostatic secondary charge image can be used used amount of toner can be supplied. As a result, the toner concentration of the developer in the developer device can be kept constant, resulting in a satisfactory image for a long period of time

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is obtained. In addition, the control of the toner supply is extremely precise, so that there is no excess amount of toner is supplied and the device can be operated economically. Due to the fact that the on the through the control grid Passing ion currents based on the amount of charge is determined, the amount of toner supplied can also with a Deterioration or wear and tear of the control grid due to prolonged use or changes in the amount of the modulated ion current in multiple copying can be controlled in accordance with such changes. This represents an essential This differs from the previously customary method in which the amount of toner supplied is specified or preset is. Furthermore, in the present method, the detector signal can be used not only for the toner supply but also for the Control of the imaging conditions can be used. as An example of such a form of use is the method in which the image is changed during multiple copying is prevented. In this case, the electrostatic secondary charge image at the time of the initial modulation is shown in detail stored in a memory element, whereupon the number of changes in the secondary charge pattern increases of the modulations, the imaging conditions can be controlled to be the same as the Show or assume initial state. It goes without saying that this procedure also applies to Generation conditions for the electrostatic primary charge image is advantageously applicable.

Although, in the context of the above description, only the toner supplying operations are described with regard to the developer have been, the method is also applicable to the delivery of carrier particles. That is, if that Carrier material is lost or consumed in proportion to the amount of toner to be supplied for development it can be fed at the same time as the toner.

The developer is not limited to the

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dry developer described in the embodiments described above limited. If liquid developer is used, depending on a detector signal, a concentrated Developer liquid are supplied. That is, the feed line or feed opening of such a concentrated Developer-containing vessel is driven by a drive means such as a plunger or plunger plunger, etc. for Introducing an appropriate amount of developer into the developing device actuated, as has been the case up to now.

In addition, the amount of charge can be determined as a function of the ion current passing through the control grid can be determined in the form of a current or a voltage, while the ionic current consists of particles Contains substances such as charged toner particles, dye particles, etc. In an image forming apparatus that has this Particle substances can be modulated directly, such substances can on the basis of the above-described principle on the side of the generator device for the particle substances be guided. The control grid that can be used in the context of the invention is not limited to the embodiments described above, but various types of Modulator elements such as a control grid with a pre-perforated pattern, a perforated plate and the like are used Find. With regard to the component for generating the electrostatic secondary charge image, either one can be repeated usable insulated drum or sheet can be used. Various types can be used as the image forming apparatus such as a copier or duplicator. a recording device and a printing device.

In a system in which multiple copies or multiple copies are made from one original, it is possible to the toner supply and / or the voltage of a charger according to the scanning method described above as a function of one of the capabilities or the properties of a template corresponding signal, that is, the optically detected

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Contrast of the original _/ to control and thereby achieve an optimal contrast of the copies.

Thus, there are provided an image forming method and an image forming apparatus proposed in which a first and second electrically chargeable material, a first image forming device for forming an electrostatic primary charge image on the first chargeable material, a second image generating device for the formation of an electrostatic secondary charge image on the second chargeable material depending on the electrostatic primary charge pattern, Development of the electrostatic secondary charge image and transfer of the developed image to an image receiving material, a detector device for determining the suitability of the electrostatic charge image with regard to the Generation of a visible image and a control device, which via the detector device at least the first or the second image forming means for forming a developed image with a predetermined image density is provided are.

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Claims (1)

Claims , I J image generating device, characterized by a first (46) and a second (57 to 59) electrically chargeable material, by a first image generating device (47 to 55) for forming an electrostatic primary charge image on the first chargeable material, by a second image generating device (56, 60 to 69) for forming an electrostatic secondary charge image on the second chargeable material on the basis of the electrostatic primary charge image, developing the electrostatic secondary charge image and transferring the image thus developed to an image receiving material, through a detector device (34, 35; 37, 38 ; 40, 42) for determining the suitability of the electrostatic charge image with regard to the generation of a visible image and by a device (1A to 13A) which by means of the detector device at least either the first image generation device or the second image generation device for the formation of a developed Picture with a pre- X / ma Dresdner Bank (Munich) ürlchen) Account 670-43-804 specific image density controls. 2. Image forming apparatus according to claim 1, characterized in that that the second image generating device includes a device (56) for generating an ion current as a function of of the potential of the electrostatic primary charge image and that the detector device determines the ion current. 3. Image forming apparatus according to claim 1, characterized in that the second image forming device comprises a device (13D, 211) regulating the adhesion of toner to the having electrostatic secondary charge image and that the control device controls the control device. 4. Image forming apparatus according to claim 1, characterized in that that the second image generating means includes means (56) for generating an ion current for the second chargeable recording material as a function of the potential of the electrostatic primary charge image and that the control device comprises the device generating the ion current controls. 5. image forming apparatus, characterized by a first (46) and second (57 to 59) electrically chargeable material, by means (47 to 55) for generating an electrostatic primary charge image on the first chargeable material, by means (56) for generating an electrostatic secondary charge image on the second chargeable Material as a function of the electrostatic primary charge pattern, by means (60) for developing the electrostatic secondary charge image, by means of a detector means (7A) to determine a possible limit value for repeated generation of the electrostatic secondary ! charge image based on the electrostatic primary charge image and by a control device (11A) for interrupting the repeated generation of the electrostatic se- 809840/0921 - 3 - B 8823 secondary charge image via the detector device. 6. Image generating apparatus according to claim 5, characterized in that the control device after clor interruption the generation of the electrostatic secondary charge image Performs generation of the electrostatic primary charge image. 7. An image forming apparatus characterized by a material (46) for receiving an original image by a device (56) for repeatedly forming a plurality of charge images on a recording material (57) in dependence from the original image, through a device (60) for developing the charge image, through a detector device (275 to 283) to determine the suitability of the original image with regard to the generation of a visible image and by a Device (289 to 297), which by means of the detector device, the developer supply for_the developing device in such a way controls that a developed image having a predetermined image density can be formed. 8. Image forming apparatus, characterized by an electrically chargeable material (57), by means for Generation of an electrostatic charge image on the chargeable material, which an ion current modulation device (46, 56) for modulating an ion current directed onto the chargeable material to generate the charge image, by means (60) for developing the electrostatic charge image, by one on the modulation means provided detector device (34, 35; 37, 38; 40, 42) for determining the ion current and by a device (1A to 13A), via the detector device at least either the device for generating the electrostatic Charge image or the developing device controls such that a predetermined visible image can be generated. 9. Image generating apparatus according to claim 8, characterized in that the device for generating the charge image 809840/0921 - 4 - B 8823 a charger (56 or 26) for the prior application of a corona charge to the chargeable material and that the Control device controls the loader. 1o. Image forming apparatus according to claim 8, characterized in that that the control device controls the ion current contributing to the modulation. 11. Image forming apparatus according to claim 8, characterized in that that the developing device includes a device (13D, 211) for controlling the adhesion of toner to the charge image and that the control device controls the regulating device. 12. Image forming apparatus according to claim 8, characterized in that that the modulation device has a control grid (46 or 29) with a charge image of the original located thereon and that the detector device is arranged between the control grid and the ground connection of the device. 13. Image generating device, characterized by an electrically chargeable material (5_7), by an image generating device (46 to 69) for the formation of an electrostatic charge image on the chargeable material and production a visible image of the charge image by a detector device (34, 35; 37, 38; 40, 42) to determine the suitability of the electrostatic charge image in terms of the formation of a visible image and by a device (1A to 13A), which by means of the detector device, the image generation device controls in such a way that a visible image with a predetermined density can be generated, the control device a memory device (5A, 6A) for storing signals depending on the suitability of the initial having electrostatic charge image for the generation of a visible image and the image generation device is controlled by the memory device and the detector device for carrying out the subsequent image generation. 809840/0921 " ⁵ " ^{B 8} | fi2970 14. Image forming apparatus according to claim 13, characterized in that that the control means comprises means (13A) which generates an output control signal when the the same charge image is to be generated repeatedly by storing the properties of the initial charge image , then the charge image obtained with each charge image generation is corrected and the corrected signal with the initially stored signal is compared. 15. An image forming apparatus according to claim 13, characterized in that that the detector device detects a sample value of the modulation ion current for the generation of the charge image. 16. The image forming apparatus according to claim 13, characterized in that that the control device has a device (201, 202) for storing a peak potential or a medium potential "of the charge image. 17. A method for image generation, characterized in that in a first process step a first electrostatic Charge image is formed on a first electrically chargeable material that in a second process step the suitability of the first charge image for training tion of a visible image it is determined that in a third process step a second electrostatic charge image generated on a second electrically chargeable material as a function of the first charge image, the second electrostatic charge image is developed and the developed image is transferred to an image receiving material and that in a further method step after the second method step at least either the generation of the second electrostatic Charge image, the image development or the image transfer is controlled so that on the image receiving material an image with a predetermined density can be generated. 809840/0921 - 6 - B 8823 18. A method of imaging in which an electrostatic Charge image formed on an electrically chargeable material by ion modulation and by means of the charge image a visible image is generated, characterized in that in the method for controlling this image generation at least either the generation of the charge image or the generation of the visible image is controlled such that Changes in the ion current generated by a modulation device are determined and visible image with a predetermined Preserve image density. 19. A method for controlling image generation, thereby characterized in that when determining the suitability or performance of an electrostatic charge image for generating a visible image and controlling the image generation process by means of the received detector output signal to produce a visible image having a predetermined density on the basis of that obtained from the initial charge image Detector output signal corresponding signal is stored, whereupon the operating conditions for the image generation by means of the maintained output signal and the obtained Detector output signal can be controlled. 20. A method for image generation, characterized in that that in a first process step a first charge image is formed on a first recording material, that in a second process step, the ability or suitability of the first charge image to generate a visible one Image it is determined that in a third method step a second charge image is repeated as a function from the first charge image on a second recording material is generated and that the generation of the second charge image is ended in a fourth method step, if the performance or suitability of the first Charge image for generating a visible image after repeated image generation reaches its limit value and the new formation of a fresh first charge image is carried out. 809840/0921 21. Process for the preparation of a variety of developed Images from one and the same original image, characterized in that the performance is used to control the image generation or suitability of the original image for generating a visible image is determined and by means of a output signal obtained thereby, the supply of a developing agent is controlled so that the developed image has a predetermined density at all times. 809840/0921