JP3142034B2 - Apparatus and method for charging photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device in an electrophotographic apparatus for charging a belt-shaped or drum-shaped photosensitive member by particle charging, and a charging method thereof.

[0002]

2. Description of the Related Art Conventionally, respective process means of exposure, development, transfer, cleaning (removal of residual toner), charge elimination and charging are arranged on the outer peripheral surface of a photosensitive drum, and an image is formed by a predetermined electrophotographic process. Image forming apparatuses based on the so-called Carlson process are well known.

In recent years, a photoconductive drum is formed by laminating a light-transmitting conductive layer and a photoconductive layer on a cylindrical light-transmitting support, and a light output corresponding to image information is formed in the drum. Exposure means (for example, an LED head) to be generated is interpolated, and the light output of the exposure means is exposed on a photosensitive drum charged on the photosensitive drum using a predetermined charging means through a converging lens, or simultaneously or immediately after the exposure. An image forming apparatus configured to form the latent image into a toner image (development) through a developing sleeve facing the photosensitive drum and transfer the toner image to recording paper via a transfer roller or other transfer means; Apparatuses (JP-A-58-153957 and others) are also known.

The charging means used in this type of apparatus is generally a corotron type in which a high voltage is applied to a thin tungsten wire to perform corona discharge, or a charging means in which a conductive roller is charged in contact with a photosensitive drum by applying a voltage of several hundred volts. In addition, there is a type in which a voltage is applied to a conductive brush while being brought into contact with a photosensitive drum to charge the conductive brush. However, the corotron method uses high voltage and generates ozone for safety reasons.
Many environmental problems. Further, the charging roller is unstable in charging because the contact with the photosensitive drum is a line contact. Further, in the brush charging method, the charging of the brush is likely to occur because the drum and the brush are in contact with each other to perform charging.

In order to eliminate such a defect, as shown in FIG. 5, a non-magnetic sleeve 103 having a photosensitive drum 101 and a magnet assembly 102 inserted therein is used, and a charging bias 108 is applied to the sleeve 103. , The sleeve 10
3 is a so-called particle charging method in which a magnetic particle group 104 is adhered to the brush 3 and a brush-shaped magnetic spike is rubbed against the photosensitive drum 101 to apply a charging bias 108 to the magnetic particle group 104 via a sleeve 103 to perform charging. Has been proposed.
(JP-A-59-133569, JP-A-63-18726)
7 others)

In order to uniformly charge the photosensitive drum 101 with the conductive fine particles in such a charging method, the contact area and the contact density between the magnetic particle group 104 and the photosensitive drum 101 in the charged area must be set to sufficient conditions. But,
The contact area of the magnetic brush depends on the photosensitive drum 1 and the magnet assembly 10.
2 is determined by the outer diameter of the non-magnetic sleeve 103 in which the photosensitive drum 101 and the sleeve 1 are inserted.
The smaller the size of 03, the narrower the contact nip and the higher the rotation speed of the photosensitive drum 101, the more easily the contact nip becomes unstable. For this reason, the gap tolerance between the photosensitive drum 101 and the non-magnetic sleeve 103 is strictly set in order to ensure the stability of the contact nip. However, such a configuration increases the number of assembling steps and the like, leading to an increase in cost. In addition, the magnetic force and the magnetic flux density fluctuate due to assembly errors such as eccentricity between the fixed magnet assembly 102 and the non-magnetic sleeve 103 and expansion / contraction due to heat or other environmental factors, and stable charging cannot be performed.

Next, there is a problem that magnetic particles adhere to the photosensitive drum (particle pulling). Further, in the prior art, when the magnetic spikes are formed by the fixed magnet assembly 102, the magnetic field is attenuated in proportion to the square of the distance from the fixed magnet assembly 102. Magnetic particles have the weakest magnetic coercive force. On the other hand, the magnetic particle group 104
Are particles in the charged area or the photosensitive drum 1
And rubs between them to become charged and have electric charge. Therefore, when the photosensitive drum 101 is rotated in this state,
Centrifugal force acts on the surface, and the magnetic particles 104 electrostatically attached to the photosensitive drum 101 are separated from the magnetic chain, that is, the charged area, against the magnetic coercive force (magnetic field) from the fixed magnet assembly 102. The photosensitive drum 101
The particles 104a adhered to the surface adversely affect exposure and development in the next step. However, the above-mentioned disadvantage increases as the particle size of the magnetic particles decreases and as the linear speed of the photosensitive drum 101 increases in order to increase the number of prints per time. For this reason, the prior art is configured to collect the magnetic particles by arranging a blade downstream of the charging area in the photoconductor moving direction. A mechanism for collecting the magnetic particles attached to the blade is required, and the configuration becomes complicated.

Further, in the above-mentioned prior art, in order to adopt a configuration in which a magnet assembly or a charging sleeve containing the assembly is disposed so as to be opposed to the photosensitive drum, a charging device portion is protruded largely on the photosensitive drum. For this reason, even if the size of the photosensitive drum is reduced, the size of the entire apparatus is not reduced.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, it is an object of the present invention to provide a charging device capable of effectively securing a charging area and a charging density even when the diameter of a photosensitive drum is reduced. Another object of the present invention is to stably maintain the charging ability even when the magnet assembly or the charging sleeve containing the assembly is removed so as to face the photoconductor drum. It is an object of the present invention to provide a charging device that can maintain a stable charging ability without being affected by the fluctuation of the charging gap, an assembly error, and the like even when the charging device is disposed facing the upper side. Another object of the present invention is to provide a charging device which can effectively prevent magnetic particles from leaking out of the charging region with a simple configuration.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above technical object, a photoreceptor is structured such that the photoreceptor can be charged by magnetic force via magnetic particles held on a charged area of the photoreceptor. In the apparatus, on the back side of the charged area of the photoconductor,
Two magnetic bodies having different polarities along the photoconductor moving direction or two magnetic field generating means composed of a combination of a magnet and a magnetic substance are arranged adjacent to each other, and a horizontal magnetic field mainly formed between the two magnetic field generating means is used. The magnetic particles are charged while being brought into close contact with the photoreceptor. As a result, due to the horizontal magnetic field, the magnetic particle group can be brought into close contact with the photoreceptor by only the two magnetic field generating means disposed on the back side of the photoreceptor, irrespective of the fixed magnet body and the like arranged opposite to the photoreceptor drum. . Even when the diameter of the photoconductor drum is reduced, not only can the charging contact area and the charging density with which the magnetic particles are effectively contacted be ensured, but also the case where the magnet assembly or the charging sleeve is removed in opposition to the photoconductor drum. Can also maintain stable charging ability. As a result, the charging device section does not protrude largely on the photosensitive drum, and therefore, the size of the photosensitive drum and the size of the entire apparatus can be easily reduced.

However, when the above configuration is adopted, the configuration is such that the magnetic particles are held only by the magnetic force on the back side of the photoreceptor, so that leakage of the magnetic particles from the charged area cannot be avoided.
Therefore, the present invention provides a repulsive magnetic field composed of a pair of adjacent magnetic poles of the same polarity on the back side of the photoconductor located downstream of the charging area,
The repelling magnetic field forms a non-magnetic force zone at the downstream end of the charged area on the photoconductor, thereby preventing leakage of the magnetic particles. Of course, such a configuration is also effective when a magnet assembly or a charging sleeve is provided so as to face the photoconductor drum, but in this case, a perpendicular magnetic field in which the magnetic field lines extend in the normal direction of the photoconductor downstream of the photoconductor charging area. It is good to take the structure which forms. As such a vertical magnetic field forming means, specifically, of the two magnetic field generating means located on the back side of the photoconductor charging area, the first magnetic field generating means located on the downstream side in the photoconductor moving direction is substantially opposed to the first magnetic field generating means. This can be achieved by arranging a vertical magnetic field forming means made of a magnetic material or a magnet having a polarity opposite to that of the first magnetic field generating means at a position above the photoconductor.

As a further preferred magnetic particle leakage preventing means, of the two magnetic field generating means located on the back side of the photosensitive member charging area, the first magnetic field generating means located on the downstream side in the photosensitive member moving direction is formed by a magnet. On the other hand, a second magnet body having a polarity opposite to that of the first magnetic field generating means is arranged at a position above the photosensitive member so as to substantially face the first magnetic field generating means, and
A magnetic substance is disposed adjacent to the magnetic field generating means or the second magnet body on the downstream side in the charging direction, and a magnetic field is further prevented by forming a closed circuit of a vertical magnetic field between any one of the magnet bodies and the magnetic body. Becomes effective. In addition, the magnetic particles may be formed of conductive magnetic particles or a mixed particle of conductive particles and magnetic particles, and the linear velocity of the photoconductor may be reduced by applying a charging bias to the particles. Sufficient charging can be ensured even when the charging speed is increased and the charging area is reduced due to the reduction in the diameter of the photosensitive drum.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just. FIG.
The configuration of the charging device according to the first embodiment of the present invention will be described based on FIG. This embodiment shows an embodiment in which a charging sleeve and a fixed magnet assembly are not arranged on the photosensitive drum but opposed to each other, and are arranged only on the back side of the photosensitive drum. Reference numeral 1 denotes a photosensitive drum which rotates clockwise. On the back side of the drum corresponding to the charged area, an N-pole first magnet body 5B and a downstream side are provided on the upstream side so as to substantially divide the charged area into two. And a second magnet body 5A having an S pole having the opposite polarity is disposed adjacent to the second magnet body 5A.
A horizontal magnetic field 6A is formed on the photosensitive drum 1 between A and 5B. At a position adjacent to the second magnet body 5A and beyond the downstream end of the charging area in the rotation direction of the photosensitive drum 1, a repulsion magnet body 5C having the same polarity as the second magnet body 5A and having the S pole is disposed. And a non-magnetic force zone 6D formed by the repulsive magnetic field 6C formed therebetween is located at the downstream end of the charging area.

The magnetic force of each of the magnet bodies is set to 800 gauss at the end face of the magnetic pole on the photosensitive drum 1 side, for example, when magnetic particles described later are used.
It is preferable that a magnetic force of about 300 to 400 Gauss be obtained on the surface of the photosensitive drum 1 immediately above. The conductive magnetic particles 4 interposed on the charged region are not particularly limited as long as they are conductive, but are formed of conductive magnetic particles having a magnetic resin surface coated with a conductive resin such as ferrite, iron powder, or magnetite. Alternatively, it may be composed of a mixed particle group 4 of conductive particles and magnetic particles. For example, if the average particle size is 30
A mixture of a magnetic particle base material having a particle size of about 15 μm and a conductive particle material having an average particle size of about 15 μm at an appropriate ratio may be used.
In this example, ferrite core particles having an average particle diameter of 20 to 35 μm and a resistivity of 10 ³ to 10 ⁶ Ω · cm are used, and magnetic characteristics set to 60 to 70 emu / g (1 k Oe) are used. . Reference numeral 8 denotes a bias power supply for applying a charging bias to the conductive magnetic particle group 4 via the linear electrode.

FIG. 2 shows the magnetic action of the vertical magnetic field 6B and the horizontal magnetic field 6A in the above-described magnetic pole layout. As can be understood from FIG. 2, the vertical magnetic field 6B is formed immediately above each magnetic pole, and the charged area is formed. A strong horizontal magnetic field 6A is located between the N-pole and S-pole magnet bodies 5A and 5B located between the S-pole and the S-pole second magnet body 5A and the repulsion magnet body 5C at the lower end of the charged area. A repulsive magnetic field 6C in which the two horizontal magnetic fields 6A are separated is formed, and as a result, a non-magnetic force zone 6D is formed between the two magnetic poles 5A and 5C.

As a result, the magnetic particle group 4 adhered to the charged area adheres closely to the photosensitive drum 1 on the horizontal magnetic field 6A between the N-pole and S-pole magnets 5A and 5B. The vertical magnetic field 6B on the downstream side of the charged area deviating from the horizontal magnetic field 6A
Above, it is attached so as to stand in the normal direction of the photosensitive drum 1 in a rough state. When the photoconductor drum 1 rotates in this state, the photoconductor drum 1 moves from the horizontal magnetic field 6A to the vertical magnetic field 6B while charging the photoconductor drum 1 on the horizontal magnetic field 6A, and the magnetic particles are formed by the repulsive magnet 5C. Without being transported downstream by the non-magnetic force zone 6D.
B has to escape in the vertical direction. The magnetic particle group oriented in the vertical direction is composed of the first and second magnet bodies 5A, 5A,
The magnetic field is returned to the magnetic field composed of B, and then returned to the horizontal magnetic field 6A side, and thereafter, circulation is repeatedly performed. Therefore, according to this embodiment, smooth charging is performed without leakage of the magnetic particles to the downstream side of the charging area.

FIG. 3 shows another embodiment in which a fixed magnet is arranged to face the photosensitive drum, and a description will be given focusing on differences from the above embodiment. In this embodiment, the vertical magnetic field 6B for preventing leakage is formed by the bar-shaped fixed magnet 2 erected in the normal direction from the photosensitive drum 1 via a predetermined gap without providing the repulsion magnet 5C of the above-described embodiment. In another embodiment described above, the fixed magnet body 2 has an N-pole located on the side facing the photosensitive drum 1, and the second magnet body 5B and the fixed magnet body 2 disposed opposite to each other are rotated by the photosensitive drum. Arranged downstream of the charging area in the direction,
The magnetic particle group 4 is magnetically held by a vertical magnetic field 6B between the two magnet bodies 2 and 5B, and the first magnet body 5A is arranged adjacent to the second magnet body 5B and on the upstream side of the charging area. The magnetic particle group 4 is brought into close contact with the photosensitive drum 1 by a horizontal magnetic field 6A mainly formed between the second magnet body 5B and the first magnet body 5A.

In this configuration, the magnetic force of each of the magnets is set to, for example, about 1200 gauss at the end face of the N pole facing the photosensitive drum 1 in the fixed magnet 2, and the second magnet 5A When the end face of the south pole on the body drum 1 side is set to, for example, 800 gauss, the two magnet bodies 2, 5A
A magnetic force of about 300 Gauss could be obtained on the surface of the upper photosensitive drum 1, and it was confirmed that a sufficient magnetic coercive force of the magnetic particles 4 could be obtained on the surface of the photosensitive drum 1. Also the first
It was also confirmed that an effective horizontal magnetic field 6A could be obtained by setting the magnetic force of the magnet body 5A to be substantially equal to that of the second magnet body 5B. Further, a stirring means 11 is arranged in the magnetic particle group 4 in the charging region, and the particle group 4 is replaced by mechanical stirring, and a charging bias power supply 8 is connected to the stirring means.

According to this embodiment, the fine particles whose surface is smoothly charged while the magnetic particles 4 are brought into close contact with each other on the horizontal magnetic field 6A on the photosensitive drum 1 It moves to the position of the vertical magnetic field 6B according to the rotation, where the fine particle group 4 is magnetically sealed by the vertical magnetic field 6B, preventing leakage outside the charged area, and fixed from the photosensitive drum 1 side by the magnetic force difference. The magnetic particle group 4 is attracted to the magnet body side, and is returned to the horizontal magnetic field 6A side while moving to the upstream of the charging area by rotating the stirring means in the direction of the arrow, and the above operation is repeated.

Therefore, the magnetic particles 4 on the charged area are always circulated even if they are in close contact with each other by the horizontal magnetic field 6A,
Even if used for a long time, there is no room for deterioration of the charged particles.
The replacement or circulation is performed by forming the second magnet body 5B or the first magnet body 5A with an electromagnet body, and using a voltage variable device 12 of a DC power supply 13 or the like to perform non-printing or predetermined printing. By appropriately changing the polarity or changing the applied voltage for each sheet, the first magnet body 5A
Alternatively, the replacement and circulation of the particle groups 4 may be performed by appropriately swinging the second magnet body 5B by a predetermined angle. Note that a vertical magnetic field 6B is similarly formed even when a magnetic material is used in place of the fixed magnet body 2. In this embodiment, the same operation as that of the embodiment can be achieved, and the developing bias power supply 8 is connected to the magnetic material. You may connect.

FIGS. 4A and 4B show another embodiment of the present invention. The difference from the embodiment of FIG. 3 will be mainly described. (0.5
mm) so as to be rotatable in the rotational direction of the photosensitive drum 1 and in the opposite direction (left direction in the drawing), and at the downstream side of the charging area on the back side of the non-magnetic sleeve 3. The N-pole fixed magnet body 2 is arranged to face the second magnet body 5A, and the magnetic body 2a is arranged adjacent to the lower end side of the charged area of the fixed magnet body 2 to form a closed circuit of the vertical magnetic field 6B. . According to this embodiment, the fine particles that smoothly charge the surface of the photosensitive drum 1 while closely contacting the magnetic particles 4 on the horizontal magnetic field 6 </ b> A on the photosensitive drum 1 become vertical as the photosensitive drum 1 rotates. It moves to the position of the magnetic field 6B, where the vertical magnetic field 6B magnetically seals the fine particle group 4 to prevent leakage outside the charged area, and also causes the magnetic force difference to move from the photosensitive drum 1 side to the sleeve 3 side. The magnetic particles 4 are attracted, move toward the upstream side of the charging area while being carried on the non-magnetic sleeve 3 by the against rotation of the non-magnetic sleeve 3, and fall to the photosensitive drum 1 side by the magnetic force of the horizontal magnetic field 6A. Then, the above operation is repeated.

In this case, since the magnetic material is arranged adjacent to the fixed magnet and a closed circuit of the vertical magnetic field 6B is formed, the magnetic shielding effect is further increased. In this case, the same operation is achieved even when the magnetic body is disposed adjacent to the second magnet body 5A on the downstream side in the drum rotation direction, facing the fixed magnet body. Further, in order to promote the circulation of the particles from the developing sleeve 3, a scraper 14 may be provided so that the scraper 14 is mechanically peeled off and falls on the photosensitive drum 1 side on the horizontal magnetic field 6A.

[0023]

As described above, according to the present invention, it is possible to secure a charging area of a predetermined width range by the horizontal magnetic field. Therefore, even when the diameter of the photosensitive drum is reduced, the magnet assembly is opposed to the photosensitive drum. Even when the body or the charging sleeve containing the assembly is omitted, stable charging ability can be maintained. Further, even when the charging sleeve and the like are arranged on the photosensitive drum so as to face each other, stable charging ability can be maintained without being affected by the fluctuation of the charging gap and assembly errors. Further, a uniform magnetic field can always be obtained without being affected by the fluctuation of the charging gap and the assembly error. Further, according to the present invention, it is possible to effectively prevent the leakage of the magnetic particles to the outside of the charged region with a simple configuration utilizing a vertical magnetic field or a non-magnetic force zone. And so on.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention in which a magnet is arranged only on the back side of a photosensitive drum.

FIG. 2 is an operation diagram of the magnetic force lines of FIG.

FIG. 3 is a schematic diagram according to a second embodiment of the present invention.

FIG. 4A is a schematic diagram according to a third embodiment of the present invention,
(B) is an enlarged view thereof.

FIG. 5 is an overall schematic diagram of a charging device according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2 fixed magnet body 5A first magnet body 5B second magnet body 5C repulsive magnet body 2a magnetic body 4 conductive magnetic particle group 6B vertical magnetic field 6A horizontal magnetic field 6C repulsive magnetic field 6D nonmagnetic field

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuo Nishiguchi 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office (56) References JP-A-5-181347 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/02 G03G 15/09

Claims (8)

(57) [Claims] 1. A charging device for a photoreceptor configured to be able to charge a photoreceptor via a magnetic particle group held on a charging region of the photoreceptor by a magnetic force, wherein a photosensitive element is provided on the back side of the charging region of the photoreceptor. Two magnet bodies having different polarities along the body movement direction, or two magnetic field generating means composed of a combination of a magnet body and a magnetic substance are arranged adjacently, and a horizontal magnetic field mainly formed between the two magnetic field generating means, A charging device for a photoconductor, wherein the magnetic particles are charged while being brought into close contact with the photoconductor. 2. A repulsive magnetic field comprising a pair of adjacent magnetic poles of the same polarity is formed on the back side of the photoreceptor located on the downstream side of the charged area, and a non-magnetic force band is formed at the downstream end of the charged area on the photoreceptor by the repulsive magnetic field. The charging device for a photoreceptor according to claim 1 formed. (3)The belt of the photoconductor downstream of the photoconductor charging area
A first magnetic field generating means is provided on the back side of the
A second surface facing the photoreceptor charged area facing the field generating means;
Magnetic field generating means is arranged, and the first magnetic field generating means is a magnet
And the second magnetic field generating means has a polarity opposite to that of the magnet.
Composed of a magnet or magnetic material  Magnetic field lines along the photoconductor normal direction downstream of photoconductor charging area
2. The charging device for a photoconductor according to claim 1, wherein a vertical magnetic field is formed. 4. A method according to claim 1, wherein said photosensitive member has a charged area on the back side and on the front side.
Two magnetic field generating means are arranged facing each other, and on the back side
The first magnetic field generating means disposed is made of a magnetic material, and the second magnetic field
A field generating means disposed adjacent to the first magnetic field generating means;
As a magnet body of the same polarity as the magnet body, downstream of the photoconductor charging area
A vertical magnetic field with a magnetic field line in the normal direction of the photoconductor
The charging device for a photoreceptor according to claim 1 . 5. A magnetic field generating means, wherein the first magnetic field generating means located on the downstream side in the moving direction of the photoreceptor is formed of a magnet, among the two magnetic field generating means located on the back side of the charged area of the photoreceptor.
And a first position above the photoreceptor substantially opposed to the magnetic field generating means.
A second magnet body having a polarity opposite to that of the first magnetic field generating means, and a magnetic body adjacently arranged on the charging direction downstream side of the first magnetic field generating means or the second magnet body; 4. The charging device for a photoreceptor according to claim 3, wherein a closed circuit of a vertical magnetic field is formed between the body and the magnetic body. 6. The magnetic particle group is formed of conductive magnetic particles or a mixed particle group of conductive particles and magnetic particles, and a charging bias can be applied to the particle group. Photoconductor charging device. 7. A method of charging a photoconductor, wherein the photoconductor is charged by a magnetic force via a group of magnetic particles held on the charged area of the photoconductor. Along
And two magnets with different polarities or a magnet and a magnetic
Two magnetic field generating means consisting of a combination
Said photosensitive member to form a horizontal magnetic field is mainly formed on the charged area of the surface, the magnetic particles with charging while in close contact on the photosensitive member, the photosensitive member back side of the charging area downstream, a pair of the same polarity of
A repulsive magnetic field consisting of adjacent magnetic poles is formed, and
A non-magnetic force zone is formed on the surface of the photoreceptor at the downstream end side of the charging area to prevent leakage of magnetic particles located on the charging area. 8. Holding on a charged area of a photoreceptor by magnetic force
Of the photoreceptor that charges the photoreceptor via the magnetic particles
In the charging method,If two magnets with different polarities along the photoconductor movement direction
Or two magnetic fields consisting of a combination of magnet and magnetic material
Place the raw means adjacent, Mainly in the charged area on the photoreceptor surface
Horizontal magnetic field formed asTo formThe magnetic particle group
While being charged while closely contacting the photoreceptor,A first magnetic field is generated on the photoreceptor back side downstream of the charging area.
Means is disposed and substantially opposed to said first magnetic field generating means.
The second magnetic field generating means is arranged above the photoconductor.
To When the first magnetic field generating means is a magnet, a second magnetic field is generated.
The means is a magnetic material, When the first magnetic field generating means is a magnetic material, a second magnetic field generating means is provided.
The generating means is a magnet body, and the first and second magnetic field generating means are used.
Step by step Mainly on the photoconductor surface at the downstream end side of the charging area
To form a magnetic leakage stop zone consisting of a perpendicular magnetic field.
Area to prevent leakage of magnetic particles located on the charged area
The method of charging a photoreceptor, characterized in that it acts to stop
Law.