CA1198773A - Corona detection apparatus - Google Patents
Corona detection apparatusInfo
- Publication number
- CA1198773A CA1198773A CA000391140A CA391140A CA1198773A CA 1198773 A CA1198773 A CA 1198773A CA 000391140 A CA000391140 A CA 000391140A CA 391140 A CA391140 A CA 391140A CA 1198773 A CA1198773 A CA 1198773A
- Authority
- CA
- Canada
- Prior art keywords
- corona
- current
- source
- corona source
- conductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Corona Detection Apparatus Abstract The presence (or absence) of corona is detected by inserting an electrical conductor into the path of spatial current produced by said corona and monitoring the conductor current that is produced by corona-generated electric charges impinging on said electrical conductor.
Description
~8'77;3 Description Corona Detection Apparatus Field of the Invention The invention relates to apparatus for detecting 5 the presence of corona, in general, and to apparatus for detecting the presence of corona controlling electrostatic charges on a moving web of charge-retaining material, in particular.
10 Description of the Prior Art The presence of electrostatic charges on charge re~;n-ing materials causes many problems. In photog-raphy, for example, electrostatic charges on film units stacked within a film cassette could cause 15 clin~ing of the film units to one another with such intensity that proper ejection of a film - unit from the cassette may b~ prevented if the effects o, such charges are not controlled. Such electrostatic charges may be controlled by control-20 ling the charge levels on components of the film prior to final film unit assembly.
One technique for controlling electrostatic charges in charge-retaining materials coMprises the establishing a corona between an electrode 25 and a reference surface spaced from said electrode and the passing of the material through the spatial current path produced by the corona. This technique is widely used and is quite effective for regulating electrostatic charges in such materials. However, 30 in order properly to employ corona in this m~nner -- 7.--for electrostatic charge control, it is necessary to provide for a reliable source of corcna to avoid any interruption in the eletrostatic charge controlling process. Current practices for insuring the presence 5 of a corona employ at least two corona sources, one source supplving charge controlling corona to a moving web, for example,the other sourcel spaced from the first corona source in the direction of web movement, being maintained in a deenergized 10 state and capable of supplying the same electro-static charge controlling corona level to the moving web when it is energized. An operator monitors voltmeter and current meter of the power supply of the active corona source. ~eviations in 15 the readings of the voltmeter and/or ammeter from a predetermined range or set of ranges are considered to be an indication of corona-loss.
In such a situation the standby corona source is immediately activated to continue khe process 20 of controlling the electrostatic charge on the moving web, without interruption.
Not only is it an obvious disadvantage to monitor a machine by an operator, but also neither ammeter nor volmeter indications are always 25 reliable indications of corona loss. Sometimes a particular ammeter and/or voltmeter may indicate the presence of an active corona source when, in fact, no corona is present. Not only does this interrupt the charge controlling process, it is 30 also difflcult and costly to determine xeadily which portions of the moving web have not been properly charged, and subsequently to charge these portions, especially in a high-volume, time-oriented production setting.
"7;~
In accordance wlth the present invention there is pro-vided apparatus for assuriny the availability of electrostatic charge controlling corona for controlling the electrostatic charge level on charge-retaining material, comprising: first and second electrically conductive reference surfaces; a first corona source for producing a first stream of electric charges between said first corona source and said first reference sur-face; a second corona source for producing a second stream of charges between said second corona source and said second reference surface;
an electrical conductor in the path of said first stream of elec-tric charges produced by said first corona source wherein an electric current is produced in said conductor as a result of a portion of the said first stream of electric charges impinging on said electrical conductor; and means responsive to the said conductor current in said electrical conductor for energizing said second corona source when the magnitude of the current in said conductor is equal to or less than a prede-termined magnitude as a result of loss of corona from said first corona source where-by the uninterrupted availability of corona produced elec-tric charges for controlling the electrostatic charge level on charge-retaining material is thereby assured for material that is ini-tially passed be-tween said first corona source and said first reference surface, and subsequently between said second corona source and said second reference surface.
The invention will n()w be described in greater detail with reference to the accompanying drawings, in which:
,1 "73 --4a-Figure 1 is a schema-tic dlagram, in eleva-tion, of a moving web being subjected to electrostatic charge controlling corona in accordance with the prior art.
Figure 2A is a schematic diagram, in eleva-tion, of the corona detec-tion apparatus of the present invention which includes means for automatically providing an alternate corona source whenever a loss of corona is detected.
F`igure 2B is a top view of a portion of the corona source and moving web of Figure 2A, and a corona sensing conduc--tor positioned near the edge of the spacial current path produced by said corona source.
Figure 3A is a schematic of a corona sensing conductor similar to that in Figure 2A except that the conductor is posi--tioned between -the corona source and the moving web whose charge is being controlled.
~;
--5~
Fig. 3B shows a corona sensing conductor positioned between a corona source and a moving web whose charge is being controlled by said corona source, that is physically supported at two points 5 rather than at one point as in Figs. 2B and 3A.
Fig. 3C is the same as Fig. 3B except that the corona sensing conductor is positioned near the edge of the spacial current path produced by the corona source.
10 Description of the Preferred Embodiments In Figure 1, numeral 10 indicates corona-type electrostatic charge controlling apparatus for controlling charges on a moving web of charge-retaining material constructed in accordance with 15 the teachings of the prior art.
Web support or backing rollers 12 and 14 are cylindrically shaped~ are electrically conductive and are mounted for rotation about axes 16 and 18, respectively. ~rive means (not shown) move a 20 charge-retaining web 20 in the direction of arrow 22 over backing rollers 12 and 14. As the web 20 is moving the rollers 12 and 14 rotate about axes 16 and 13, respectively, as a result of the fric tional engagement of the surace of web 20 with 25 the surface of the rollers 12 and 14~
The input of a primary high voltage power supply 24 is connected to a relatively low voltage source (not shown) at terminal 26 through a path 28. The high voltage output of the power supply 30 ~4 is connected to a corona electrode 30 ~lrough a path 32. Normally several corona sources are employed per web charging station, but one corona source only has been shown. Power supply 24 is energized by the manual act~ation of a switch 34, 7~
~, and the level of the voltage at corona source or electrode 30 is manually adjusted to the desired corona voltage level by knob 36.
Similarly, the input of an alternate high 5 voltage power supply 38 is connected to a rela-tively low power source (not shown) at terminal 40 through path 42. The high voltage output of said alternate power supply 38 is connected to alternate corona source elec~rode 44 through lO path 46. Alternate power supply 38 is energized by the manual actuation of switch 48, and the level of the voltage at alternate corona source or elec-trode 44 is manually set to the desired corona voltage level by a knob 50.
~en the power supply 2a is energized by actuating the switch 34 a high voltage is produced at its output; this produces a corona at corona source 30 and a current or stream of electric charges 51 between said corona source 30 and 20 grounded backing roller 12. The desired corona level is controlled by rotating knob 36 while monitoring voltmeter 52 and/or ammeter 54.
Alternatively, the corona levels can be deter-mined empirically by measuring the charge le~els 25 on charge-retaining materials after said materials have been subjected to the electric charges 51.
When web 20 is passed between electrode 30 and grounded backing roller 12 through current 51 ha~ing a predetermined magnitude, the desired 30 electrostatic charge level will be produced on said web 20.
Web 20 is moved between corona source or electrode 44 and grounded backing roller 14 after moving between electrode 30 and backing roller 12.
35 While corona current is present between corona ~ 9~7~7;~
source or electrode 30 and roller 12 no electro-static charge-controlling corona is present between alternate source 44 and backing roller 14.
An operator monitors meters 52, 54 to insure a 5 predetermined range of values. If the meter read-ings deviate from the predetermined range, it is assumed that the corona source has failed. When this happens the operator energizes alternate power supply 38 by actuating power control swltch 10 48 to its ON position. When power supply 38 is energized corona source 44 produces a corona current or a stream of electric charges 56 e~ual to current 51 produced by electrode 30; the desired corona level produced by electrode 44 is established lS by the rotation of knob 50 and the monitoring of meters 58 and 60 on alternate power supply 38. If alternate power supply 38 is energi~ed promptly after loss of corona occurs at electrode 30, there is no interruption in the level of charge 20 on moving web 20 as long as the web 20 moves between corona source 44 and backing roller 14 after it moves between corona source 30 and backing roller 12. A problem with the prior art charge controlling apparatus of Fig. l is that the corona-25 loss indication provided by meters 52, 54 on powersupply 24 are not consistently accurate. In many instances a meter reading will be well within a predetermined range of values indicating the pres-ence of charge-controlling corona when, in fact, 30 a corona is not present. The apparatus of the present invention avoids any interruption of charge controlling corona by consistently indicating its presence or lack thereof.
Turning now to Fig. 2, the numeral 62 generally lndicates corona-type apparatus for controlling electrostatic charges on a moving web. Web support or backing rollers 64 and 66 are electrically 5 conductive and are mounted for rotation about axes 68 and 70, respectlvely. Drive means (not shown) are provided to move a web 72 in the direction of arrow 74. As the web 72 is moving, rollers 64 and 66 rotate as a result of the fric-10 tional engagement with ~he surface of web 72.
A high voltage power supply 76 is connectedto a voltage source (not shown) at terminal 78 through path 80. The output of the power supply 76 is connected to electrode 82 through path 84.
15 Power supply 76 is energized by the actuation of switch 86, and the voltage level at corona source or electrode 82 is set by a knob 88. Similarlyt an alternate high voltage power supply 90 is con-nected to a power source (not shown~ at terminal 20 92 through path 94. The output of the alternate power supply 90 is connected to alterna~e corona electrode 96 ~hrough path 98~ The alternate power supply 90 is energized by a switch 100, and the voltage level at alternate corona electrode 25 96 is set by a knob 102.
The alternate high voltage power supply-90 may also be energized by switch means 104. When a predetermined current i5 produced in conductor 106 by impinging current or stream of electric 30 charges 108, switching mPans 104 has no effect on the energization of alternate power supply 90.
~Iowever, if the current level in conductor 106 drops below a predetermined level (normally to zero), current amplifier 110 coupled to the conductor 106 '7~73 g generates a signal. This signal is routed to switch means 104 through path 112 causing the switch means 104 to energlze power supply 90 through an alternate energization path internal of the power supply.
The power supply 76 is energized by actuating switch 86 to produce a high voltage, a corona at electrode 82 and a current or streami of electric charges 108 between the corona source 82 and grounded backing roller 64. The desired corona level is 10 established by the knob 88 while monitoring volt-meter 114 and/or ammeter 116. When the web 72 passes between electrode 82 and grounded backing roller 64 through the current 108, ~he desired electrostatic charge level is produced on the web 15 72.
When the power supply 90 is energized, corona electrode 96 produces a corona current or stream of electric charges 118 equal to the current 108;
the desired corona level produced by electrode 20 96 having previously been established by the moni-toring of voltmeter 120 and ammeter 122 on alternate power supply 90.
The web 72 is moved between the corona elec~
trode 96 and the grounded backing roller 66 after 25 it has moved through electrode 82 and backing roller 64. As lony as a corona curxent is present between the electrode 82 and the roller 64 no current flows between the alternate corona source 96 and the ba~king roller 56. The presence of a corona between 30 the electrode 82 and the roller 64 is detected hy the conductor 106 positioned in the stream of elec-tric charges 108. If the charges 108 impinging on ~- the conductor 106 drop below a predetermined lével, the current amplifier 110 causes the switch means 35 104 to energize power supply 90. Alternate power-supply 90 is energized as soon as the loss of corona current 108 is detected and, therefore, no interrup-tion in the charge level on moving web 72 occurs as long as the moving web 72 moves between the corona 5 source 96 and the backing roller 66 aft:er it has moved between the corona source 82 and the backing roller 64.
A corona sensing conductor such as conductor 1~6 may take many forms and may be mounted many 10 different ways. In Fig. 2B, for example, the end of current sensing conductor 106 is positioned near the edge of stream of electric charges 108 and does not interfere witX electric charges or ions moving between corona source 82 and web 72. In Fig. 3A, 15 the end of cuxrent sensing conductor 124 is posi-tioned in the stream of electric charges 126 be-tween corona electrode 128 and moving web 130 where it intereres slightly with electric charges moving toward said web 130.
In Figs. 3B and 3C a current sensing conduc~or is shown tautly mounted between a pair of insula-tive support members. In Fig. 3B conductor 132 extends between support members 134A and 134B.
Conductor 132 passes through the path of electric 25 charges 136 moving between corona source 138 and moving web 140. In Fig. 3C conductor 142 extends between support members 144A and 144B, and passes through stream of electric charges 146. In Fig.
3B there is a slight interference with electric 30 charges moving between corona source 138 and web 140. However, in Fig. 3C there is no interference with electric charges moving between corona source 148 and moving web 150.
~98~7;3 --11~
It will be apparent to those skilled in the art from the foregoing description of my invention that various improvements and modifications may be made without departin~ from its true scope.
10 Description of the Prior Art The presence of electrostatic charges on charge re~;n-ing materials causes many problems. In photog-raphy, for example, electrostatic charges on film units stacked within a film cassette could cause 15 clin~ing of the film units to one another with such intensity that proper ejection of a film - unit from the cassette may b~ prevented if the effects o, such charges are not controlled. Such electrostatic charges may be controlled by control-20 ling the charge levels on components of the film prior to final film unit assembly.
One technique for controlling electrostatic charges in charge-retaining materials coMprises the establishing a corona between an electrode 25 and a reference surface spaced from said electrode and the passing of the material through the spatial current path produced by the corona. This technique is widely used and is quite effective for regulating electrostatic charges in such materials. However, 30 in order properly to employ corona in this m~nner -- 7.--for electrostatic charge control, it is necessary to provide for a reliable source of corcna to avoid any interruption in the eletrostatic charge controlling process. Current practices for insuring the presence 5 of a corona employ at least two corona sources, one source supplving charge controlling corona to a moving web, for example,the other sourcel spaced from the first corona source in the direction of web movement, being maintained in a deenergized 10 state and capable of supplying the same electro-static charge controlling corona level to the moving web when it is energized. An operator monitors voltmeter and current meter of the power supply of the active corona source. ~eviations in 15 the readings of the voltmeter and/or ammeter from a predetermined range or set of ranges are considered to be an indication of corona-loss.
In such a situation the standby corona source is immediately activated to continue khe process 20 of controlling the electrostatic charge on the moving web, without interruption.
Not only is it an obvious disadvantage to monitor a machine by an operator, but also neither ammeter nor volmeter indications are always 25 reliable indications of corona loss. Sometimes a particular ammeter and/or voltmeter may indicate the presence of an active corona source when, in fact, no corona is present. Not only does this interrupt the charge controlling process, it is 30 also difflcult and costly to determine xeadily which portions of the moving web have not been properly charged, and subsequently to charge these portions, especially in a high-volume, time-oriented production setting.
"7;~
In accordance wlth the present invention there is pro-vided apparatus for assuriny the availability of electrostatic charge controlling corona for controlling the electrostatic charge level on charge-retaining material, comprising: first and second electrically conductive reference surfaces; a first corona source for producing a first stream of electric charges between said first corona source and said first reference sur-face; a second corona source for producing a second stream of charges between said second corona source and said second reference surface;
an electrical conductor in the path of said first stream of elec-tric charges produced by said first corona source wherein an electric current is produced in said conductor as a result of a portion of the said first stream of electric charges impinging on said electrical conductor; and means responsive to the said conductor current in said electrical conductor for energizing said second corona source when the magnitude of the current in said conductor is equal to or less than a prede-termined magnitude as a result of loss of corona from said first corona source where-by the uninterrupted availability of corona produced elec-tric charges for controlling the electrostatic charge level on charge-retaining material is thereby assured for material that is ini-tially passed be-tween said first corona source and said first reference surface, and subsequently between said second corona source and said second reference surface.
The invention will n()w be described in greater detail with reference to the accompanying drawings, in which:
,1 "73 --4a-Figure 1 is a schema-tic dlagram, in eleva-tion, of a moving web being subjected to electrostatic charge controlling corona in accordance with the prior art.
Figure 2A is a schematic diagram, in eleva-tion, of the corona detec-tion apparatus of the present invention which includes means for automatically providing an alternate corona source whenever a loss of corona is detected.
F`igure 2B is a top view of a portion of the corona source and moving web of Figure 2A, and a corona sensing conduc--tor positioned near the edge of the spacial current path produced by said corona source.
Figure 3A is a schematic of a corona sensing conductor similar to that in Figure 2A except that the conductor is posi--tioned between -the corona source and the moving web whose charge is being controlled.
~;
--5~
Fig. 3B shows a corona sensing conductor positioned between a corona source and a moving web whose charge is being controlled by said corona source, that is physically supported at two points 5 rather than at one point as in Figs. 2B and 3A.
Fig. 3C is the same as Fig. 3B except that the corona sensing conductor is positioned near the edge of the spacial current path produced by the corona source.
10 Description of the Preferred Embodiments In Figure 1, numeral 10 indicates corona-type electrostatic charge controlling apparatus for controlling charges on a moving web of charge-retaining material constructed in accordance with 15 the teachings of the prior art.
Web support or backing rollers 12 and 14 are cylindrically shaped~ are electrically conductive and are mounted for rotation about axes 16 and 18, respectively. ~rive means (not shown) move a 20 charge-retaining web 20 in the direction of arrow 22 over backing rollers 12 and 14. As the web 20 is moving the rollers 12 and 14 rotate about axes 16 and 13, respectively, as a result of the fric tional engagement of the surace of web 20 with 25 the surface of the rollers 12 and 14~
The input of a primary high voltage power supply 24 is connected to a relatively low voltage source (not shown) at terminal 26 through a path 28. The high voltage output of the power supply 30 ~4 is connected to a corona electrode 30 ~lrough a path 32. Normally several corona sources are employed per web charging station, but one corona source only has been shown. Power supply 24 is energized by the manual act~ation of a switch 34, 7~
~, and the level of the voltage at corona source or electrode 30 is manually adjusted to the desired corona voltage level by knob 36.
Similarly, the input of an alternate high 5 voltage power supply 38 is connected to a rela-tively low power source (not shown) at terminal 40 through path 42. The high voltage output of said alternate power supply 38 is connected to alternate corona source elec~rode 44 through lO path 46. Alternate power supply 38 is energized by the manual actuation of switch 48, and the level of the voltage at alternate corona source or elec-trode 44 is manually set to the desired corona voltage level by a knob 50.
~en the power supply 2a is energized by actuating the switch 34 a high voltage is produced at its output; this produces a corona at corona source 30 and a current or stream of electric charges 51 between said corona source 30 and 20 grounded backing roller 12. The desired corona level is controlled by rotating knob 36 while monitoring voltmeter 52 and/or ammeter 54.
Alternatively, the corona levels can be deter-mined empirically by measuring the charge le~els 25 on charge-retaining materials after said materials have been subjected to the electric charges 51.
When web 20 is passed between electrode 30 and grounded backing roller 12 through current 51 ha~ing a predetermined magnitude, the desired 30 electrostatic charge level will be produced on said web 20.
Web 20 is moved between corona source or electrode 44 and grounded backing roller 14 after moving between electrode 30 and backing roller 12.
35 While corona current is present between corona ~ 9~7~7;~
source or electrode 30 and roller 12 no electro-static charge-controlling corona is present between alternate source 44 and backing roller 14.
An operator monitors meters 52, 54 to insure a 5 predetermined range of values. If the meter read-ings deviate from the predetermined range, it is assumed that the corona source has failed. When this happens the operator energizes alternate power supply 38 by actuating power control swltch 10 48 to its ON position. When power supply 38 is energized corona source 44 produces a corona current or a stream of electric charges 56 e~ual to current 51 produced by electrode 30; the desired corona level produced by electrode 44 is established lS by the rotation of knob 50 and the monitoring of meters 58 and 60 on alternate power supply 38. If alternate power supply 38 is energi~ed promptly after loss of corona occurs at electrode 30, there is no interruption in the level of charge 20 on moving web 20 as long as the web 20 moves between corona source 44 and backing roller 14 after it moves between corona source 30 and backing roller 12. A problem with the prior art charge controlling apparatus of Fig. l is that the corona-25 loss indication provided by meters 52, 54 on powersupply 24 are not consistently accurate. In many instances a meter reading will be well within a predetermined range of values indicating the pres-ence of charge-controlling corona when, in fact, 30 a corona is not present. The apparatus of the present invention avoids any interruption of charge controlling corona by consistently indicating its presence or lack thereof.
Turning now to Fig. 2, the numeral 62 generally lndicates corona-type apparatus for controlling electrostatic charges on a moving web. Web support or backing rollers 64 and 66 are electrically 5 conductive and are mounted for rotation about axes 68 and 70, respectlvely. Drive means (not shown) are provided to move a web 72 in the direction of arrow 74. As the web 72 is moving, rollers 64 and 66 rotate as a result of the fric-10 tional engagement with ~he surface of web 72.
A high voltage power supply 76 is connectedto a voltage source (not shown) at terminal 78 through path 80. The output of the power supply 76 is connected to electrode 82 through path 84.
15 Power supply 76 is energized by the actuation of switch 86, and the voltage level at corona source or electrode 82 is set by a knob 88. Similarlyt an alternate high voltage power supply 90 is con-nected to a power source (not shown~ at terminal 20 92 through path 94. The output of the alternate power supply 90 is connected to alterna~e corona electrode 96 ~hrough path 98~ The alternate power supply 90 is energized by a switch 100, and the voltage level at alternate corona electrode 25 96 is set by a knob 102.
The alternate high voltage power supply-90 may also be energized by switch means 104. When a predetermined current i5 produced in conductor 106 by impinging current or stream of electric 30 charges 108, switching mPans 104 has no effect on the energization of alternate power supply 90.
~Iowever, if the current level in conductor 106 drops below a predetermined level (normally to zero), current amplifier 110 coupled to the conductor 106 '7~73 g generates a signal. This signal is routed to switch means 104 through path 112 causing the switch means 104 to energlze power supply 90 through an alternate energization path internal of the power supply.
The power supply 76 is energized by actuating switch 86 to produce a high voltage, a corona at electrode 82 and a current or streami of electric charges 108 between the corona source 82 and grounded backing roller 64. The desired corona level is 10 established by the knob 88 while monitoring volt-meter 114 and/or ammeter 116. When the web 72 passes between electrode 82 and grounded backing roller 64 through the current 108, ~he desired electrostatic charge level is produced on the web 15 72.
When the power supply 90 is energized, corona electrode 96 produces a corona current or stream of electric charges 118 equal to the current 108;
the desired corona level produced by electrode 20 96 having previously been established by the moni-toring of voltmeter 120 and ammeter 122 on alternate power supply 90.
The web 72 is moved between the corona elec~
trode 96 and the grounded backing roller 66 after 25 it has moved through electrode 82 and backing roller 64. As lony as a corona curxent is present between the electrode 82 and the roller 64 no current flows between the alternate corona source 96 and the ba~king roller 56. The presence of a corona between 30 the electrode 82 and the roller 64 is detected hy the conductor 106 positioned in the stream of elec-tric charges 108. If the charges 108 impinging on ~- the conductor 106 drop below a predetermined lével, the current amplifier 110 causes the switch means 35 104 to energize power supply 90. Alternate power-supply 90 is energized as soon as the loss of corona current 108 is detected and, therefore, no interrup-tion in the charge level on moving web 72 occurs as long as the moving web 72 moves between the corona 5 source 96 and the backing roller 66 aft:er it has moved between the corona source 82 and the backing roller 64.
A corona sensing conductor such as conductor 1~6 may take many forms and may be mounted many 10 different ways. In Fig. 2B, for example, the end of current sensing conductor 106 is positioned near the edge of stream of electric charges 108 and does not interfere witX electric charges or ions moving between corona source 82 and web 72. In Fig. 3A, 15 the end of cuxrent sensing conductor 124 is posi-tioned in the stream of electric charges 126 be-tween corona electrode 128 and moving web 130 where it intereres slightly with electric charges moving toward said web 130.
In Figs. 3B and 3C a current sensing conduc~or is shown tautly mounted between a pair of insula-tive support members. In Fig. 3B conductor 132 extends between support members 134A and 134B.
Conductor 132 passes through the path of electric 25 charges 136 moving between corona source 138 and moving web 140. In Fig. 3C conductor 142 extends between support members 144A and 144B, and passes through stream of electric charges 146. In Fig.
3B there is a slight interference with electric 30 charges moving between corona source 138 and web 140. However, in Fig. 3C there is no interference with electric charges moving between corona source 148 and moving web 150.
~98~7;3 --11~
It will be apparent to those skilled in the art from the foregoing description of my invention that various improvements and modifications may be made without departin~ from its true scope.
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for assuring the availability of electrosta-tic charge controlling corona for controlling the electrostatic charge level on charge-retaining material, comprising: first and second electrically conductive reference surfaces; a first corona source for producing a first stream of electric charges between said first corona source and said first reference sur-face; a second corona source for producing a second stream of charges between said second corona source and said second refer-ence surface; an electrical conductor in the path of said first stream of electric charges produced by said first corona source wherein an electric current is produced in said conductor as a result of a portion of the said first stream of electric charges impinging on said electrical conductor; and means responsive to the said conductor current in said electrical conductor for energizing said second corona source when the magnitude of the current in said conductor is equal to or less than a predeter-mined magnitude as a result of loss of corona from said first corona source whereby the uninterrupted availability of corona produced electric charges for controlling the electrostatic charge level on charge-retaining material is thereby assured for material that is initially passed between said first corona source and said first reference surface, and subsequently between said second corona source and said second reference surface.
2. The apparatus of claim 1, wherein said current respon-sive means includes a current amplifier.
3. The apparatus of claim 1, wherein said charge-retaining material is a moving web.
4. The apparatus of claim 1, wherein an end of said elec-trical conductor projects into the stream of electric charges produced by said first corona source.
5. The apparatus of claim 1, wherein said electrical con-ductor is positioned such that it does not interfere with elec-tric charges moving between said corona source and said charge-retaining material passed between said first corona source and said first reference surface.
6. The apparatus of claim 5, wherein said electrical con-ductor is supported between two insulated members.
7. The apparatus of claim 1, wherein said current respon-sive means includes a visual indicator.
8. The apparatus of claim 7, wherein said visual indicator is an electrical meter.
9. The apparatus of claim 1, wherein said current respon-sive means includes an aural indicator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000391140A CA1198773A (en) | 1981-11-30 | 1981-11-30 | Corona detection apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000391140A CA1198773A (en) | 1981-11-30 | 1981-11-30 | Corona detection apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1198773A true CA1198773A (en) | 1985-12-31 |
Family
ID=4121523
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000391140A Expired CA1198773A (en) | 1981-11-30 | 1981-11-30 | Corona detection apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1198773A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4800337A (en) * | 1985-07-01 | 1989-01-24 | Oce-Nederland B.V. | Method and means for determining a measure of the surface potential of a medium charged by means of a corona charging device |
-
1981
- 1981-11-30 CA CA000391140A patent/CA1198773A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4800337A (en) * | 1985-07-01 | 1989-01-24 | Oce-Nederland B.V. | Method and means for determining a measure of the surface potential of a medium charged by means of a corona charging device |
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