US3916146A - Selective fusing - Google Patents

Selective fusing Download PDF

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US3916146A
US3916146A US345384A US34538473A US3916146A US 3916146 A US3916146 A US 3916146A US 345384 A US345384 A US 345384A US 34538473 A US34538473 A US 34538473A US 3916146 A US3916146 A US 3916146A
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time
fuser assembly
signal
energizing
period
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Mark A Hutner
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat

Definitions

  • the fuser assembly is energized for a preestablished minimum period of time when successive portions of the support base are moved therethrough within a first time duration.
  • the fuser assembly is energized for a second pre-established period of time greater than the minimum period of time when a first interval of time has expired since the immediately preceding energization thereof. If a second interval of time has expired since the immediately preceding energization of the fuser assembly, the assembly is energized for a third pre-established period of time when the next successive portion of the support base is advanced thereto.
  • the second interval of time is greater than the first interval of time and the third preestablished period of time is greater than the second pre-established period of time. Further periods of energization may be established in accordance with the amount of time that has expired since an immediately preceding energization.
  • This invention relates to electroscopic fusing techniques and, more particularly, to a method of selectively regulating a fuser assembly and the apparatus therefor.
  • Electrophotographic reproducing techniques of the type described in detail in U.S. Pat. No. 2,297,691 which issued to Chester F. Carlson, form electrostatic latent images of original documents by selectively dissipating a uniform layer of electrostatic charges deposited on the surface of a photoreceptor in accordance with modulated radiation imaged thereon.
  • the electrostatic latent image thus formed is developed and transferred to a support surface to form a final copy of an original document.
  • the development process is effected by applying electroscopic particles, conventionally known as toners, to the electrostatic latent image whereat such particles are electrostatically attracted to the latent image in proportion to the amount of charge comprising such image.
  • the areas of small charge concentration are developed to form areas of low particle density, while areas of greater charge concentration are developed to form areas wherein the particle density is greater.
  • the developed image may be permanently fixed thereto by heat fusing techniques wherein the individual particles soften and coalesce when heated so as to readily adhere to the support surface.
  • selective fusing toner areas admitting of a higher density are preferentially fused leaving low density or background areas unfused. Unfused toner particles comprising background can then beremoved to yield a cleaner, more readable copy.
  • Selective fusing also contemplates the irregular, non-continuous, non-periodic operation of a fuser assembly in response to particular predetermined conditions. In this regard, selective fusing techniques are readily adapted to cooperate with selective xerographic printing techniques.
  • the fuser assembly must be energized each time a developed image of a selected original is transferred to the support surface. It is appreciated that if the support surface comprises a web of suitable material, such as paper, the web will be transported through the fuser assembly in an irregular manner corresponding to the scanning of the unique originals to be reproduced. Consequently, scorching or burning of the web that is stationarily disposed within the fuser assembly must be avoided, while, at the same time, sufficient heat must be accummulated in the assembly to assure an adequate fusingof the toner areas to the Web.
  • a further object of the present invention is to provide a method of fusing electroscopic particles to successive portions of a support base intermittently moving through a fuser assembly, and the apparatus therefor.
  • An additional object of the present invention is to provide apparatus for selectively energizing a heating element that is maintained at a temperature level no lower than a quiescent level for variable time durations such that a substantially equal radiant energy level is attained thereby during each energization irrespective of the length of time that has expired since an immediately preceding energization thereof.
  • Still another object of this invention is to provide a method of rapidly energizing a fuser assembly to permit the fixing of toner particles thereby, while precluding the possibility of scorching a support surface disposed therein, and the apparatus therefor.
  • Yet a further object of the present invention is to provide a method of selectively energizing a fuser assembly, and the apparatus therefor, in accordance with the amount of cooling to which said assembly has been subjected.
  • Another object of this invention is to provide a method of and apparatus for fusing electroscopic particles disposed in image configuration on a support surface in accordance with the intermittent movement of said surface through a fuser assembly.
  • fuser regulating methods and the apparatus therefor wherein the fuser assembly is selectively energized in accordance with the occurrence of preselected conditions such that the fuser assembly rapidly attains an operating energy level sufficient to fuse to a support surface the electroscopic particles supported thereon; said fuser assembly being energized for a preestablished minimum duration of time when the immediately preceding energization thereof occurred within a first time duration; and said fuser assembly being energized for variable durations of time inaccordance with the interval that has expired since the immediately preceding energization thereof.
  • FIG. 1 is a schematic diagram of a typical selective printing apparatus with which the instantinvention may be utilized;
  • FIG. 2A is a schematic diagram of a conventional heating element that may be utilized in the fuser assembly of FIG. 1 and variable supply of energy therefor;
  • FIG. 2B depicts an AC waveform that is helpful in explaining the operation of the electrical circuit illustrated in FIG. 2A;
  • FIG. 3 is a schematic illustration of the logic circuitry that may be utilized to selectively regulate the variable supply of energy depicted in FIG. 2A;
  • FIG. 4 depicts a timing diagram representing the voltage signals produced by the logic circuit of FIG. 3.
  • FIG. 1 For a general understanding of selective printing apparatus in which the instant invention may be incorporated, reference is made to FIG. 1 in which some of the various system components for the apparatus are schematically illustrated. Like component parts are identified by like reference numerals throughout and primed reference numerals identify the waveforms produced by corresponding component parts identified by unprimed reference numerals.
  • the printing apparatus illustrated herein employs electrophotographic concepts originally disclosed in U.S. Pat. No. 2,297,691, which issued to Chester F. Carlson. Accordingly, the selective printing apparatus comprises an electrostatic system wherein a light image of an original to be reproduced is projected onto the sensitized surface of a photosensitive plate to form an electrostatic latent image thereon.
  • the latent image is developed with an oppositely charged developing material comprising electroscopic particles, known as toner particles, to form a powder image corresponding to the latent image on the photosensitive surface.
  • the powder image is then electrostatically transferred to a support base to which it may be fixed by a fusing assembly whereby the powder is caused to adhere permanently to the support surface.
  • visible document information is provided on each of the data cards 1 that are successively transported from'a feeder tray 2 to a restack tray 49.
  • the data cards are transported in timed sequence with respect to the operation of the remaining apparatus illustrated herein, and are caused to traverse detecting station A, scanning station B and slit exposure device 34 in successive order.
  • Each data card is additionally provided wtih precoded information thereon, which precoded information is determinative of the selective printing of the visible document information carried by the card. More particularly, if the precoded information scanned from the card by scan ning station B admits of a particular precondition, additional logic circuitry, not shown, responds to such scanned information to derive a print signal. The thus derived print signal is operated upon in a timed sequence to provide a direct correspondence between the sequential manipulation of such print signal and the particular operation performed by the apparatus illustrated in FIG. 1.
  • the sequential passage of data cards from the scanning station B through the projection system 33 to the restack tray 49 will cause optical images of the visible document information on each of the data cards passing through the slit exposure device 34 to be sequentially projected upon the surface of photosensitive drum 20.
  • the projected images may admit of magnification.
  • the photosensitive drum 20 is continuously driven at a constant angular velocity such that the surface thereof is moving at a velocity equal to that of the data cards moving past the exposure device 34. In moving in the direction indicated by the arrow, prior to reaching the exposure station C, that portion of the photosensitive drum being exposed is uniformly charged by a corona discharge station G.
  • the exposure of the photosensitive drum surface to the light image selectively dissipates the electrostatic charge on the surface thereof in the areas struck by light, thereby forming an electrostatic latent image in image configuration corresponding to the light image projected from the visible document information on the data card transported through the slit exposure device 34.
  • the electrostatic image passes through a developing station D in whichthere is positioned a de veloping apparatus generally indicated by the reference numeral 13.
  • the electrostatic latent image passing through development station D is derived from a data card having a print signal associated therewith, such print signal is utilized to activate the developer motor 24 such that the developing apparatus may be operated to develop such electrostatic latent image.
  • the,developer motor 24 is not activated and such electrostatic latent image is not developed. It is therefore appreciated that thedevel oping apparatus 13 is operated in an intermittent manner wherein only those electrostatic latent images derived from data cards having print signalsassociated therewith are developed at station D.
  • the photosensitive drum 20 continues to rotate in the direction indicated by the arrow, successive areas thereof will be provided with image information distributed thereon in the form of a distributed electrostatic charge pattern. However, only selected ones, of successive areas will be developed.
  • the developing apparatus 13 may typically be provided with electroscopic particles that are cascaded across the surface of photosensitive drum 20, which particles are attracted electrostatically to the distributed charge pattern to form powder images.
  • the developed electrostatic image is transported by the photosensitive drum 20 to a transfer station E located at a point of tangency on the photosensitive drum whereat a support base 9 is intermittently moved at a speed in synchronism with the moving drum in order to accomplish transfer of the developed image.
  • the supportbase 9 is here depicted as a web comprised of suitable material such as paper, plastic or the like, that is driven from a supply 13 through selective transfer mechanism 25, through fuser assembly 40, about strip driving means 16 and into a strip receiving tray 14.
  • the associatedprint signal is operated upon to cause the web driving means 16 to be activated, thereby transporting the support base 9 at a velocity equal to the surface velocity of the photosensitive drum 20.
  • the print signal is used to operate the selective transfer mechanism 25 whereby the support base 9 engages the photosensitive drum 20 in an arc of contact.
  • charging means 30 may be energized to provide a charge on the support base 9 prior to its engagement with the photosensitive drum so that the developed image may be electrostatically transferred from the surface of ,drum 20 to the adjacent side of the support base as such support base is brought into contact therewith.
  • the fuser assembly 40 may comprise conventional apparatus capable of carrying out various fusing techniques such as oven fusing, hot air fusing, radiant fusing, hot and cold pressure roll fixing and fusing and flash fusing.
  • fusing techniques such as oven fusing, hot air fusing, radiant fusing, hot and cold pressure roll fixing and fusing and flash fusing.
  • the fuser assembly 40 is comprised of one or more quartz lamps connected in parallel relationship and shaped to emit a suitable amount of heat when energized.
  • the dimensions of the assembly may be such as to admit of a plurality of transferred images to be disposed therein.
  • the fuser assembly is maintained at a quiescent operating temperature when not energized, said quiescent operating temperature being slightly less than the temperature normally required to fix the powder image to prevent scorching to the support base.
  • the fuser assembly 40 must not be continuously energized in order to avoid the scorching of the support base that is maintained in a temporary stationary relationship with respect thereto. Nevertheless, as an immediately succeeding portion of the support base is advanced to the fuser assembly, the latter must be rapidly energized to an operating level capable of fixing the electroscopic powder image upon the support base.
  • the manner in which the fuser assembly 40 is regulated to provide the just-mentioned selective fusing is described in detail hereinbelow.
  • the excess electroscopic particles remaining as residue on the developed images, as well as those particles not otherwise transferred therefrom, are carried by the photosensitive drum 20 to a cleaning station F on the periphery of the drum adjacent the charging station G.
  • the cleaning station may comprise a rotating brush and a corona discharge device for neutralizing charges remaining on the nontransferred electroscopic particles.
  • the selective fusing techniques described hereinbelow are readily adapted to fix powder images to a support base therefor on an irregular basis in accor' dance with the occurrence of preselected conditions.
  • the selective fusing techniques of the present invention may be employed for the preferential fusing of dense image areas while leaving low density or background areas unfused.
  • FIGS. 2A and 28 there is schematically illustrated a conventional heating ele ment 105 that may be typically included in the fuser as sembly 40 of FIG. 1.
  • the heating element 105 which may comprise a plurality of quartz lamps connected in parallel relationship, is coupled to a variable supply of voltage, generally designated by the reference numeral 100, the latter being adapted to supply the heating element 105 with energy.
  • the variable supply may be a conventional voltage regulator such as model 9T68Y7001 manufactured by General Electric, and therefore need not be described in detail herein.
  • variable supply 100 includes bi-directional current conducting means 101 which may be a silicon bi-directional triode device, such as a triac, capable of conducting relatively high AC current in both directions and whose time of initial conduction during a half cycle is dependent upon the magnitude of a control voltage applied to the trigger input 101a thereof.
  • the bi-directional current conducting means 101 may function as a triggerable switch that is rendered conductive during a half cycle of an AC voltage applied thereto when the voltage exceeds a threshold or firing level.
  • the bi-directional current conducting means may be a conventional thyrister. Once rendered conductive, the bi-directional current conducting means 101 is adapted to remain conductive until the voltage applied thereto commences a successive half cycle.
  • control voltage applied to the trigger input 101a of bi-directional current conducting means 101 is derived from a voltage dividing means that comprises series connected resistance means 102, 103 and 104.
  • Trigger input 101a is coupled to the junction formed by the series connection of resis tance means 102 and 103.
  • the value of the resistance of resistance means 102 is, to some degree, determined by the intensity of radiant energy emitted by lamp 108 and, therefore, is precisely regulated.
  • the threshold level at which the bi-directional current conducting means 101 is tendered conductive is decreased by selectively reducing the voltage derived by the illustrated voltage dividing means.
  • Adjustable resistance means 106 is capable of being selectively connected in parallel relationship with resistance means 102 by energizable switch 107. It should be appreciated that the effective resistance of the first stage of the illustrated voltage dividing means is'lde'creased when adjustable resistance means 106 is connected in parallel with resistance means 102. Consequently, the threshold or firing level voltage applied to the trigger input 101a of bi-directional current conducting means 101 is correspondingly increased. Thus, the time of initial conduction during a half cycle is advanced and the duration of conductivity of the bidirectional current conducting means 101 is increased. With adjustable resistance means 106 connected in parallel with resistance means 102, the root mean square (RMS) voltage applied to heating element 105 is decreased, resulting in a decrease in the amount of heat radiated therefrom.
  • RMS root mean square
  • Adjustable resistance means 106 may comprise a conventional potentiometer, rheostat or the like whereby an adjustment of the resistance value thereof enables a corresponding adjustment in the threshold or firing level of bi-directional current conducting means. Hence, a suitably wide range in the RMS voltage applied to heating element 105 may be obtained.
  • variable supply 100 is utilized to regulate the heat radiated by heating element 105
  • the heating element 105 is maintained at a quiescent level of energization to radiate an amount of heat that is not quite sufficient to fuse electroscopic material to a support base. Nevertheless, this quiescent energization enables the radiant energy emitted by the heating element to be rapidly increased to a proper fusing level when the voltage applied to said heating element is increased.
  • adjustable resistance means 106 is connected in parallel with resistance means 102, a quiescent threshold level is applied to trigger input 101a of bi-directional current conducting means 101. As illustrated in FIG.
  • this quiescent threshold level renders the bi-directional current conducting means conductive at a point on the positive half cycle of the AC voltage applied to the bi-directional current conducting means defined by the intersection of broken line 121a and AC waveform 120.
  • the bi-directional current conducting means 101 is rendered nonconductive at the conclusion of a positive half cycle. However, at a point on the negative half cycle defined by the intersection of broken line 121b and AC waveform 120, the bi-directional current conducting means is again rendered conductive. It is appreciated that when the quiescent threshold level is applied to trigger input 101a of bi-directional current conducting means 101, the bi-directional current conducting means is rendered conductive for only a relatively small portion of an AC cycle.
  • adjustable resistance means 106 When energizable switch means is energized so as to assume an open state, adjustable resistance means 106 is thereby disconnected from resistance means 102. It may be recognized that switch means 107 may comprise the movable contact of a conventional relay, an electronic switch or the'like. The disconnecting of adjustable resistance means 106 from resistance means 102 alters the ratio of division of the voltage dividing means to thereby alter the threshold level applied to trigger input 101a. Accordingly, the point at which the bi-directional current conducting means 101 is rendered conductive during the positive half cycle of the AC voltage applied thereto is defined by the intersection of line 122a and AC waveform 120 illustrated in FIG. 2B. The conductivity of the bi-directional current conducting means is maintained until the conclusion of the positive half cycle.
  • bi-directional current conducting means 101 is rendered conductive at the point of intersection of line 122b and AC waveform 120.
  • the relatively large duration of conductivity during each cycle is effective to apply an increased RMS voltage to heating element whereby the heat radiated by the heat ing element is sufficient to fuse the electroscopic material.
  • energizable switch means 107 is energized for a plurality of AC cycles, the amount of heat radiated by heating element 105 is proportionally increased. Therefore, the total amount of heat radiated by the heating element and, consequently, the increase in temperature obtained thereby, is a function of the duration of energization of energizable switch means 107.
  • FIG. 3 An exemplary embodiment of apparatus that may be utilized to energize energizable switch means 107 is schematically illustrated by the logic circuit of FIG. 3 and comprises storage means 200, gating means 203, 204 and 206, selective gating means 209 and driver means 21 1.
  • Storage means 200 is adapted to store a history of the preceding energizations of the heating element included in the fuser assembly 40 illustrated in FIG. 1 and, therefore, may comprise a plural stage shift register means including an input terminal for receiving an irregularly occurring selective energizing signal and a shift terminal for receiving a periodic shift signal.
  • the selective printing apparatus with which the present invention may be utilized is adapted to develop and transfer an image of a given data card when said card is provided with scanning information from which is derived a print signal.
  • a derived print signal is shifted through shift register means in timed relation with the rotation of image information obtained from a corre sponding data card.
  • the image information is distributed on the surface of a rotating photosensitive drum in the form of a distributed electrostatic charge pattern. Accordingly, the relative position of the image information at any given time may be determined by the particular position occupied by the print signal as said print signal is shifted through the shift register means.
  • the movement of that portion may be represented by a corresponding shifting of the print signal through the shift register means. It should, therefore, be readily apparent that a print signal will be shifted to a predetermined position within the shift register means when a portion of the support base is advanced to the fuser assembly. Hence, electroscopic particles that are disposed in image configuration on the support base are to be fused to the support base when a print signal occupies said predetermined position. As will soon become apparent, the print signal occupying the predetermined position need not be associated with that particular portion of the support base that is advanced to the fuser assembly.
  • Storage means 200 may, therefore, comprise a portion of the aforementioned shift register means having a first stage corresponding to the predetermined position and including a plurality of succeeding stages.
  • the storage means 200 may comprise an individual plural stage shift register means having a first stage corresponding to the aforementioned predetermined position and including a plurality of succeeding stages.
  • the storage means is illustrated in FIG. 3 as comprising a plural stage shift register means wherein only stages 1-8 have been designated as only these stages are of interest here.
  • a conventional shift register is adapted to shift an input signal applied thereto consecutively through the stages thereof in accordance with a transition in the shift signal applied.
  • the shift register may, therefore, comprise a counter capable of representing timing information relating to the times of occurrence of successive input signals in accordance with the particular stages occupied thereby.
  • the input terminal of storage means 200 is coupled to terminal 201 to which is applied a preselected information signal such as the aforementioned print signal.
  • the shift terminal of storage means 200 is coupled to terminal 202 to which is applied a periodic shift signal.
  • the periodic shift signal may be derived from the system clock which is explained in detail in U.S. Pat. 3,700,324. Accordingly, the periodic shift signal may take the form of clock pulses having a period corresponding to the rate at which the data cards are scanned and imaged.
  • the clock pulse period is thus equal to the interval of time required to transfer successive developed images from the photosensitive drum to support base 9. Consequently, the clock pulse period is also equal to the interval of time required to translate successive portions of the support base 9 to the fuser assembly 40.
  • stage 1-8 of storage means 200 are coupled to the illustrated decoding means, which decoding means is adapted to analyze the sequence of the print signals that have been supplied to storage means 200.
  • the decoding means includes first gating means 203, second gating means 204, third gating means 206 and selective gating means 209.
  • First gating means 203 is comprised of a coincidence means including a first input terminal coupled to the first stage of storage means 200 and a second input terminal coupled to terminal 202.
  • Coincidence means 203 is adapted to produce a signal admitting of a pre-established minimum duration whenever a print signal is applied to terminal 201.
  • coincidence means 203 may comprise a conventional AND gate whereby a binary I is produced at the output terminal thereof when a binary 1 is supplied to each input terminal thereof.
  • a binary l is represented by a positive DC potential and a binary 0" is represented by ground potential.
  • coincidence means 203 may comprise a conventional NAND gate whereby a binary 0 is produced at an output terminal thereof when a binary l is supplied to each input terminal thereof.
  • the second gating means 204 is adapted to sense the expiration of a first interval of time intermediate successive occurrences of a print signal and to produce a signal admitting of a second pre-established duration in response thereto.
  • the second pre-established duration is greater than the aforementioned pre-established minimum duration.
  • gating means 204 is adapted to detect when more than two clock pulse periods have expired since the occurrence of the immediately preceding print signal. Such expiration corresponds to an elapsed time since the previous energization of the heating element included in fuser assembly 40 that the fuser assembly has cooled to a temperature requiring an energization thereof for a duration longer than the minimum duration to attain a suitable accumulation of radiant energy in the assembly.
  • Second gating means 204 includes a first input terminal coupled to a given stage, such as the first stage, of storage means 200 viia inverting means 205, a second input terminal coupled to a second stage of storage means 200 and a third input terminal coupled to a third stage of storage means 200.
  • An output signal is produced by second gating means 204 when the first stage of storage means 200 is occupied by a print signal but the second and third stages, respectively, of storage means 200 are not occupied by a print signal.
  • second gating means 204 may comprise a conventional inverting OR, or NOR, circuit wherein a binary l is produced at the output terminal thereof when a binary 0 is applied to each input terminal thereof.
  • the second gating means 204 may comprise a conventional AND gate, similar to the aforedescribed AND gate 203, wherein a first input terminal thereof is coupled directly to the first stage of storage means 200 and the second and third input terminals thereof are coupled to the second and third stages, respectively, of storage means 200 via inverting means.
  • the inverting means 205 illustrated herein may comprise a conventional logic negation circuit adapted to produce a binary 0 in response to a binary l supplied thereto, and, conversely, to produce a binary l in response to a binary O supplied thereto.
  • the third gating means 206 is adapted to sense the expiration of a second interval of time intermediate successive occurrences of the print signal, the second interval being greater than the aforementioned first interval. More particularly, gating means 206 is adapted to detect when more than six clock pulse periods have expired since the occurrence of the immediately preceding print signal. Should this condition obtain, it is appreciated that the time that has elapsed since the previous energization of the heating element included in the fuser assembly 40 is sufficient to permit cooling of the fuser assembly to a point whereat an extended energization thereof is preferred to achieve a suitable accumulation of radiant energy therein.
  • condition precedent to the activation of gating means 204 comprises a portion of the conditions precedent to the activation of gating means 206.
  • gating means 204 is adapted to produce a signal whenever the gating means 206 produces a signal.
  • the gating means may include a first input terminal coupled to the second stage of storage means 200 via inverting means 207, second through seventh input terminals coupled to stages 3-8, respectively, of storage means 200 and an eighth input terminal coupled to ter minal 202 via inverting means 208.
  • the gating means may comprise a conventional inverting OR, or NOR, circuit similar to NOR circuit 204 or, alternatively, an AND gate similar to the AND gate previously described with respect to gating means 204. It is recognized that if gating means 206 is constructed of commercially available logic components, an eightinput NOR circuit might not be feasible. Accordingly, the NOR circuit may be comprised of a pair of readily available fourinput NOR circuits having output terminals coupled to a conventional AND gate.
  • additional gating means may be provided to sense the expiration of other intervals of time intermediate the successive occurrences of a print signal.
  • the interconnections between gating means 206 and storage means 200 may adopt any suitable configuration to permit the sensing of the expiration of any corresponding interval of time.
  • the output terminals of AND gate 203, NOR circuit 204 and NOR circuit 206 are coupled to corresponding input terminals of the selective gating means comprised of series connected inverting OR, or NOR, circuit 209 and inverting means 210.
  • the combination of NOR circuit 209 and inverting means 210 comprises a conventional OR circuit wherein a binary l is produced at the output terminal thereof in response to the application of a binary l to any of the input terminals thereof.
  • the OR circuit comprised of NOR circuit 209 and inverting means 210 is connected to conventional driving means 211 which, in turn, is coupled to the energizing coil 212 of a conventional relay.
  • Driving means 211 is adapted to respond to a switch energizing 'signal applied thereto to supply the energizing coil 212 with ground potential.
  • driving means 211 may comprise a conventional transistor means having a base electrode coupled to the OR circuit comprised of NOR circuit 209 and inverting means 210, a collector electrode coupled to the energizing coil 212 and an emitter electrode coupled to ground potential.
  • the OR circuit comprised of NOR circuit 209 and inverting means 210 is adapted to selectively couple the signal admitting of pre-established minimum duration from AND gate 203 to drive means 211, the signal admitting of a second pre-established duration from NOR circuit 204 to drive means 211 and the signal produced by NOR circuit 206 to drive means 211.
  • the OR circuit acts to combine the signals produced by NOR circuits 204 and 206 to couple a signal admitting of a third preestablished duration to drive means 211. It is, of course, now apparent that the OR circuit is capable of coupling the signals produced by such additional gates that may be provided to drive means 211.
  • this first pulse 201 represents that a portion of the support base 9 has been advanced to the fuser assembly 40, the heating element included in the fuser assembly must now be energized to attain a temperature sufficient to achieve the fixing of theelectroscopic particles to the support base and the heating element has not been energized since the last occurrence of the immediately preceding pulse 20l',not shown.
  • the print signal is shifted into the first stage of storage means 200 and stages 2-8 thereof are not provided with print signals.
  • the storage means 200 may be responsive to the positive transition of the clock pulses 202' applied thereto. Of course, the negative transitions of the clock pulses may be utilized to shift applied signals through the storage means, if so desired.
  • AND gate 203 is supplied with a binary l by the first stage of storage means 200 and with a binary l by clock pulse 1 applied to terminal 202 to produce a first energizing signal admitting of a duration equal to the duration of clock pulse 1 as illustrated by waveform 203'.
  • NOR circuit 204 is supplied with a binary O by the second and third stages, respectively, of storage means 200 and, after the inversion of the binary l stored in the first stage of storage means 200, with a binary 0 by inverting means 205 to produce an energizing signal admitting of a duration equal to the clock pulse period, as represented by waveform 204'.
  • the energizing signal produced by NOR circuit 204 represents that more than two clock pulse periods have expired since the occurrence of the immediately preceding print signal.
  • the OR circuit comprised of NOR circuit 209 and inverting means 210 responds to the energizing signals applied thereto by AND gate 203 and NOR circuit 204 to supply driver means 21 1 with a switch energizing signal admitting of a duration corresponding to that exhibited by waveform 204'.
  • This switch energizing signal represented by waveform 210' and aligned with clock pulse 1, activates driver means 211 which, in turn, energizes the energizing coil 212 for a period of time equal to one clock pulse period. Hence, during-this period, current.
  • switch means 107 of FIG. 2A is activated and thereby opened, for a corresponding period of time.
  • one clock pulse period admits of a duration equal to approximately 332 milliseconds
  • the width of a clock pulse is approximately 230 milliseconds
  • the frequency of the AC waveform 120 illustrated in FIG. 2B is approximately 60hz.
  • the activation of switch means 107 for a duration of approximately 332 milliseconds will enable bidirectional current conducting means 101 to operate upon approximately 20 cycles of the AC voltage applied thereto to supply heating element 105 with a sufficiently high RMS voltage.
  • the electroscopic particles disposed in image configuration upon the support base 9 will, therefore, be fused thereto.
  • the heating element therein has cooled to a lower quiescent temperature. It is, therefore, preferred that the heating element be energized for a further duration to permit the fuser assembly to accumulate additional radiant energy whereby a higher temperature is attained. Accordingly, at clock pulse 2, the print signal stored in the first stage of storage means 200 is shifted into the second stage thereof.
  • This print signal pulse is inverted by inverting means 207 and the first seven input terminals of NOR circuit 206 are each supplied with a binary Clock pulse 2 is inverted by inverting means 208 and the eighth input terminal of NOR circuit 206 is also supplied with a binary 0.
  • the signal thus produced by NOR circuit 206 depicted by the waveform 206' in alignment with clock pulse 2, admits of a duration equal to the clock pulse duration and is applied to driver means 211. It is recognized that the signal produced by NOR circuit 206 represents that more than six clock pulse periods have expired since the occurrence of the immediately preceding print signal. Switch means 107 is thus activated for an additional 230 milliseconds (the approximate clock pulse duration) during the immediately succeeding clock pulse period.
  • the switch energizing signal produced by the OR circuit comprised of NOR circuit 209 and inverting means 210, and represented by the waveform 210 is effective to energize the heating element of the fuser assembly for one complete clock pulse period and for one additional clock pulse duration.
  • terminal 201 is not provided with a print signal and, therefore, the fuser assembly 40 need not be energized.
  • the first print signal that had been applied to terminal 201 is shifted into the third stage of storage means 200.
  • that print signal is shifted into the fourth stage of storage means 200.
  • Waveform 201 indicates that the next successive print signal pulse is applied to terminal 201 during clock pulse period 5.
  • the immediately preceding print signal is shifted into the fifth stage of storage means 200.
  • approximately 1328 milliseconds i.e., four clock pulse periods
  • approximately 766 milliseconds have elapsed since the energization of the heating element of the fuser assembly 40 was terminated.
  • the fuser assembly has, therefore, cooled such that the accumulated energy therein has dissipated below the fusing level.
  • AND gate 203 produces a signal illustrated by waveform 203', which signal is applied to the OR circuit comprised of NOR circuit 209 and inverting means 210.
  • NOR circuit 204 responds to each binary 0 applied thereto by the second and third stages, respectively, of storage means 200 and to the binary 0 applied thereto by inverting means 205. It is, of course, appreciated that the print signal occupying the first stage of storage means 200 is subjected to a logic negation by inverting means 205 to produce the last mentioned binary 0. Accordingly, a signal represented by the waveform 204' and admitting of a duration equal to a clock pulse period is also applied to the OR circuit comprised or NOR circuit 209 and inverting means 210.
  • the switch energizing signal represented by waveform 210' is applied to driver means 211 whereby switch means 107 is activated.
  • the activation of switch means 107 results in the energization of the heating element included in the fuser assembly 40 for a duration equal to one clock pulse period.
  • the electroscopic particles disposed on the support base 9 in image configuration are thus fused on the support base.
  • the energizing duration of approximately 332 milliseconds is sufficient to enable the fuser assembly to attain a desirably high temperature, thus accumulating an adequate amount of radiant energy.
  • a print signal is not applied to terminal 201 at the next clock pulse period 6 and, therefore, further movement of the support base 9 is interrupted. Thus, that portion of the support base that was previously advanced into the fuser assembly 40 remains therein and the accumulated radiant energy serves to properly complete the fusing operation.
  • a binary O is shifted into the first stage of storage means 200 and the previous print signal is shifted into the second stage of storage means 200. Accordingly, AND gate 203 and NOR circuit 204 are each disabled and thus do not produce output signals.
  • NOR circuit 206 is also disabled from producing a pulse signal. This, of course, is expected since not more than six clock pulse periods have elapsed intermediate the first and second print signal times of occurrence.
  • the next succeeding print signal is applied to terminal 201 at clock pulse 8 and is shifted into the first stage of storage means 200 as indicated by the waveform 201'.
  • Nor circuit 206 is inhibited from producing an output because the first print signal is applied to an input terminal thereof by the eighth stage of storage means 200.
  • the OR circuit comprised of NOR circuit 209 andinverting means 210 responds to the signalsappliedthereto by AND gate 203 and NOR circuit 204 to apply'a switch energizing signal represented by the waveform 210' to driver means 211.
  • Switch means 107' is, therefore, activated for a duration equal to a clock pulse period, thereby energizing the heating element 105 included in the fuser assembly 40. Consequently, the electroscopic particles disposed in configuration upon the third successive portion of the support base 9 are fused thereto.
  • the first'and secondstages of storage means 200 are each occupied by a print signal
  • the fifth stage of storage means 200 is occupied by a print signal
  • the remaining stages of storage means 200 are not provided with print signalspltis, therefore, appreciated that only AND gate 203is activated to produce an output signal represented by the waveform 203', which signal is applied by the OR circuit comprised of NOR circuit 209 and inverting means 210 as a switch energizing signal 210" to driver means 211.
  • switch means 107 is activated for a duration equal to a clock pulse duration 9 1 thereby energizing the heating element included in the fuser assembly 40.
  • a print signal is applied to terminal 201 and shifted into the first stage of storage means 200 as represented by waveforms 201'.
  • the third stage of storage means 200 is occupied by the immediately preceding print signal
  • the fourth stage of storage means 200 is occupied by the next preceding print signal
  • the seventh stage of storage means 200 is occupied by the third preceding print signal.
  • gate 203 produces an output signal, represented by waveform 203' which, it is appreciated, admits of a duration equal to a clock pulse duration.
  • the signal produced by AND gate 203 is applied as a switch energizing signal to driver means 211 by the OR circuit comprised of NOR circuit 209 and inverting means 210 as represented by the waveform 210. Consequently, switch means 107 is activated for the pre-established minimum duration to thereby energize theheating element included in the fuser assembly 40 for a corresponding duration.
  • NOR circuit 206 is activated to produce an output signal 206, admitting of a duration equal to a clock pulse duration, which pulse is applied as a switch energizing signal to the driver means 211 by the OR circuit comprised of NOR circuit 209 and inverting means 210.
  • Switch means 107 is thus activated for an additional interval during clock pulse period 19 to'effect the required additional energization of heating element 105.
  • the last preceding print signal is shifted into the third stage of storage means 200 and at clock pulse 21 another print signal is applied to terminal 201 and shifted into storage means 200 as represented by the waveform 201.
  • more than two clock pulse periods have elapsed since the occurrence of the immediately preceding print signal and, in addition, more than approximately 434 milliseconds have expired since the immediately preceding energization of heating element 105 has terminated.
  • the proper fusing of the electroscopic particles disposed in image configuration on support base 9 requires slightly more than the pre-established minimum duration of energization of the heating element.
  • storage means 200 stores the time related history of the movement of successive portions of support base 9 through the fuser assembly 40.
  • a variable time interval may elapse between consecutive movements.
  • This is represented by the selected stages of storage means 200 which are occupied by print signals.
  • the selected stages of storage means 200 that are occupied by print signals provide an indication of the length of time that has expired between successive energizations of the heating element.
  • the heating element 105 need not be limited merely to a conventional quartz lamp, but, alternatively, may
  • storage means 200 may comprise any conventional storage device capable of storing a suitable history of the previous operation of the fuser assembly and, therefore, of the intermittently moving support base.
  • NOR circuit 204 may be adapted to produce an output signal if three or more clock pulse periods have expired since the occurrence of the immediately preceding print signal.
  • NOR circuit 206 may be adapted to produce an output signal when any other convenientnumber of clock pulse periods have expired since the occurrence of an immediately preceding print signal.
  • additional gating means may be provided to produce output signals upon detecting the expiration of other clock pulse periods.
  • step of sensing the occurrence of a preselected signal comprises'the steps of:
  • step of energizing said fuser assembly comprises the step of generating a second energizing signal when a preselected information signal is stored in a first position of said'consecutive order and a number of predetermined time'durations are stored in the next successive positions of said consecutive order, said second energizing signal admitting of a period of time that is a function of said number of successively stored predetermined time durations.

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161644A (en) * 1976-09-24 1979-07-17 Ricoh Co., Ltd. Electrophotographic apparatus comprising improved thermal fixing means
US4603245A (en) * 1982-08-23 1986-07-29 Canon Kabushiki Kaisha Temperature control apparatus
US4905051A (en) * 1985-03-12 1990-02-27 Sharp Kabuhsiki Kaisha Fixing means for electrophotographic copier
US5321478A (en) * 1992-03-31 1994-06-14 Canon Kabushiki Kaisha Image forming apparatus which can discriminate frequency of image forming operations
US20050103770A1 (en) * 2003-11-17 2005-05-19 Samsung Electronics Co., Ltd. Fusing system of image forming apparatus and temperature control method thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1068768A (en) * 1975-09-05 1979-12-25 Mark A. Hutner Xerographic apparatus having time controlled fusing
US4121888A (en) 1976-06-29 1978-10-24 Mitsubishi Denki Kabushiki Kaisha Toner image-fixing device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3398259A (en) * 1964-08-12 1968-08-20 Addressograph Multigraph Photoelectrostatic copying machine
US3445626A (en) * 1966-05-02 1969-05-20 Xerox Corp Fusing apparatus with flashlamp circuit

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3398259A (en) * 1964-08-12 1968-08-20 Addressograph Multigraph Photoelectrostatic copying machine
US3445626A (en) * 1966-05-02 1969-05-20 Xerox Corp Fusing apparatus with flashlamp circuit

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4161644A (en) * 1976-09-24 1979-07-17 Ricoh Co., Ltd. Electrophotographic apparatus comprising improved thermal fixing means
US4603245A (en) * 1982-08-23 1986-07-29 Canon Kabushiki Kaisha Temperature control apparatus
US4905051A (en) * 1985-03-12 1990-02-27 Sharp Kabuhsiki Kaisha Fixing means for electrophotographic copier
US5321478A (en) * 1992-03-31 1994-06-14 Canon Kabushiki Kaisha Image forming apparatus which can discriminate frequency of image forming operations
US20050103770A1 (en) * 2003-11-17 2005-05-19 Samsung Electronics Co., Ltd. Fusing system of image forming apparatus and temperature control method thereof
US7109440B2 (en) * 2003-11-17 2006-09-19 Samsung Electronics Co., Ltd. Fusing system of image forming apparatus and temperature control method thereof
CN100437381C (zh) * 2003-11-17 2008-11-26 三星电子株式会社 图像形成装置的熔融系统及其温度控制方法

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