JPH0554955B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a wet development multicolor image forming apparatus,
More specifically, the present invention relates to a wet development multicolor image forming apparatus that can be applied to a so-called color electrophotographic apparatus.

(Prior Art) Conventionally, as an image forming apparatus using a wet development method, an apparatus that performs development formation through the following process is known.

The process involves uniformly charging a latent image carrier that rotates in a certain direction in the dark, and then exposing the original light image on the latent image carrier to form an electrostatic latent image. This electrostatic latent image is visualized with a liquid developer and then transferred to recording paper, and this transferred image is fixed to obtain a desired recorded image. The remaining toner is removed by a cleaning device in preparation for the next image formation.

In such an image forming apparatus, as a means to obtain a multicolor image with a simple operation, liquid developer of a desired color is supplied to a single developing device by switching appropriately from each developer tank. A method has been proposed in which the developer is collected in a developer tank.

A first technique related to the above method is to clean the cleaning device and the developing device at the time of color switching using a cleaning liquid stored in a single dedicated cleaning tank, and to collect the cleaning liquid into the cleaning tank again. However, with this technique, colored toner from the developing device and the cleaning device is mixed into the liquid collected into the cleaning tank as a result of cleaning. This mixed toner often comes from cleaning equipment,
There is a problem that the cleaning liquid is contaminated and is wasted without being recovered.

Further, in the second technique according to the above method, a dedicated cleaning tank is not used, and the cleaning of the cleaning device is performed exclusively with the black developer stored in the black developer tank, and the black developer is collected into the black developer tank. Note that cleaning of the developing device is not particularly performed at the time of color switching, and while development is continued with the developer of the color after color switching, the previous remaining toner is consumed and the color gradually stabilizes to the color after switching.

However, although color mixing in the black developer tank is not a problem with this technology, it is not possible to avoid color mixing in color developer tanks other than black, and especially when changing colors frequently, it is difficult to avoid color mixing in the black developer tank. This may be a problem depending on the situation.

(Objective) Therefore, an object of the present invention is to provide an improved wet-type multi-color developing method that can minimize wasteful consumption of toner collected in a cleaning tongue and prevent color mixing in a color developer tank. An object of the present invention is to provide an image forming apparatus.

(Structure) In order to achieve the above object, the present invention includes: a first supply and recovery means for supplying the black developer stored in the black developer tank to the developing device and then recovering it to the black developer tank; and a black developer. a second supply and recovery means for supplying the black developer stored in the developer tank to the cleaning device and then recovering it to the black developer tank; a third supply and recovery means for supplying the cleaning liquid stored in the cleaning tank to the developing device and then recovering it to the cleaning tank; The present invention is characterized in that it is equipped with a toner processing means for separating the collected developer from the cleaning liquid.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

In FIG. 1 showing the overall structure of an electrophotographic apparatus to which the present invention is applied, reference numeral 1 indicates a transparent original placing plate, and reference numeral 2 indicates a pressure plate that covers the original. Further, reference numeral 3 indicates a photosensitive drum having a latent image carrier attached to its circumferential surface. The photosensitive drum 3 is rotated in a fixed direction indicated by an arrow during image formation.

As is well known, on the circumferential surface of the photoreceptor drum,
A main charger 4, a developing device 5, a paper feed guide plate 6, a transfer charger 7, a separation unit 8, a cleaning device 9, etc. are arranged in the order of rotational direction.

In addition, among the above, the circumferential surface of the photosensitive drum 3 located between the main charger 4 and the developing device 5 is called an exposure section, where the optical image of the original placed on the original placing plate 1 is formed. It is designed to be image exposed. This imaging exposure optical system includes an exposure lamp 10, a first mirror 11,
Second mirror 12, third mirror 13, imaging lens 1
4, a fourth mirror 15, etc.

Next, reference numeral 16 indicates a paper feed cassette containing a large number of recording papers. The recording paper is fed out by a paper feed roller 17 in response to a recording signal, then separated into one sheet by a separation pair roller 18, passes through a guide plate 19, a feed roller 20, and a guide plate 21, and waits at a registration pair roller 22. It's becoming like that.

During image formation, the photosensitive drum 3 rotates, and the latent image carrier passes through an exposure section while being uniformly charged by the main charger 4 in the dark. In synchronization with this, the exposure lamp 10, first mirror 11, second mirror 12, third mirror 13, etc. move in the direction of arrow A, and the optical image of the document is formed on the exposure area on the photoreceptor drum. An electrostatic latent image is carried by a slit exposure method.

This electrostatic latent image is produced by a developing device 5 using a liquid developer.
While passing through, a developer is supplied and a visible image is created using the principle of electrostatic phenomenon.

On the other hand, the recording paper that has been waiting at the resist roller 22 section is fed out from the resist roller 22 at a timing that coincides with the visualized toner image at the transfer charger 7 section. In this way, the toner image is transferred to the recording paper, and then the recording paper is transferred to the separation unit 8.
It is separated from the photoreceptor drum 3 and sent over a guide plate 23 to reach a fixing device 24, where it is subjected to a fixing operation, and is then discharged onto a tray 27 via a guide plate 25 and a feed roller 26. Ru.

Although residual toner adheres to the latent image carrier after the recording paper is separated, this residual toner is removed while passing through the cleaning device 9 and prepared for the next image formation.

By the way, the developing device 5 has a socket 28 for introducing the developer, and an outlet 29 for discharging the developer introduced from the socket 28.

For example, five sockets 28 are provided. As shown in FIG. 2, one socket 28B is connected via a feed pipe 32B to a discharge port of a pump 31B that discharges black developer 30B stored in a developer tank 29B. Similarly, another socket 2
8M is connected via a feed pipe 32M to a discharge port of a pump 31M that discharges magenta developer 30M stored in a developer tank 29M. Similarly, another socket 28C is connected to a discharge port of a pump that discharges cyan developer stored in a cyan developer tank (not shown). Similarly, another socket 28Y is connected to a discharge port of a pump that discharges yellow developer stored in a yellow developer tank (not shown). Similarly, another inlet is connected via a feed pipe 103 to a discharge port of a pump 102 that discharges a dedicated cleaning liquid 101 stored in a cleaning tank 100 . As this cleaning liquid 101, for example, a mother liquid, which will be described later, is used.

Each of the above-mentioned developers is composed of a colored toner dispersed in a highly insulating mother liquor. That is, the developer 30B is composed of the black toner in the toner bolt 34B and the mother liquor in the mother liquor bottle 35, and similarly the developer 30M is composed of the magenta toner in the toner bottle 34M and the mother liquor in the mother liquor bottle 35. has been done. The above examples also apply to the yellow developer and cyan developer.

Next, an outlet pipe 36 is led out from the outlet 29 of the developing device 5, and is connected to an electrically driven four-way switching valve 37.

One outlet of this four-way switching valve 37 is connected to a recovery pipe 38B that opens onto the developer tank 29B.

Similarly, another outlet is connected to a recovery pipe 38M that opens onto the developer tank 29M.
Similarly, the other two outlets are connected to recovery pipes opening onto the cyan developer tank and the yellow developer tank, respectively, but these are not shown.

Furthermore, another outlet of the four-way switching valve 37 is connected to a recovery pipe 104 that opens onto the cleaning tank 100.

Next, focusing on the cleaning device 9, there is a drain socket 40 for introducing cleaning liquid (developer 30B is used in this example), and
It has an outlet 41 for discharging the introduced cleaning liquid.

As shown in FIG. 2, the socket 40 is
A pump 4 that discharges a black developer 30B as a cleaning liquid stored in a developer tank 29B.
It is connected to the discharge port of No. 2 via a feed pipe 43.

Further, the outlet 41 is connected to a recovery pipe 44 that is open above the developer tank 29B.

In each of the above piping systems, the pump 31B, the feed pipe 32B, the collection pipe 38B, etc. are used as a first supply for supplying the black developer stored in the black developer tank to the developing device 5 and then collecting it to the black developer tank. It is an example of the main structural members of a collection means. Similarly, the pump 42, the feed pipe 43, the recovery pipe 44, etc. are the main components of a second supply and recovery means that supplies the black developer stored in the black developer tank to the cleaning device and then recovers it to the black developer tank. This is an example of a component. Similarly, pump 31M,
The feed pipe 32M, the collection pipe 38M, etc. are the main components of a third supply and collection means that supplies the developer from the color developer tank storing developer other than black to the developing device and then collects it into the color developer tank. This is an example of a member.

Similarly, the pump 102, the feed pipe 103, the collection pipe 104, etc. are examples of main components of a fourth supply and collection means that supplies the cleaning liquid stored in the cleaning tank to the developing device and then collects it into the cleaning tank.

In the above example, as a modified example of distributing the outlet pipe 36 of the developing device 5 to the recovery piping system, there is a mechanism in which a rotary solenoid 45 and a rotation joint 46 are combined, as shown in FIG. 3, for example. In this example, a rotating tube 47 communicating with the outlet tube 36 is configured to rotate, and the recovery tube 38B,
38M, 104, etc., and the openings of the respective recovery pipes to the cyan developer tank and the yellow developer tank are arranged.

In addition, as another modification, as shown in FIG.
A plunger 49 is provided and biased by a compressible spring 48, and moves in and out in a direction opposite to the biasing direction.
It is also possible to have a configuration in which it is connected to. The stroke of the plunger 49 is controlled in stages by a solenoid 50 that uses a click stop mechanism, for example. Below each stop position of the rotation pipe 47' is a collection pipe 3.
8M, 104, etc., and the recovery pipes and developer tank 29B to the cyan developer tank and the yellow developer tank are left open.

When forming an image in any desired color,
Switching of the reflux route using the four-way switching valve 37 or the rotary solenoid 45 or solenoid 50
The reflux route is switched by operating a knob on the operation panel of the electrophotographic apparatus in conjunction with selective operation of each pump 31B, 31M, etc.

The switching position of the knob on the above operation panel is, for example,
It has four selection positions: black image mode, cyan image mode, magenta image mode, and yellow image mode.

The operating conditions when each selected position is selected will be explained below.

(1) Black image mode This can be switched by specifying the black image mode position with the knob on the operation panel. The main point of this mode is that when the four-way switching valve 37 opens a recovery path to the recovery pipe 38B, the pumps 31B and 42 start operating in the same way.

Therefore, the black developer 30B flows back between the developing device 5 and the developer tank 29B and is used for development. Also, black developer 30 is used as a cleaning liquid.
B is used and refluxed between the cleaning device 9 and the developer tank 29B.

In this mode, a black recorded image can be obtained regardless of the color of the original. Note that appropriate amounts of toner in the toner bottle 34B and mother liquor in the mother liquor bottle 35 are automatically replenished according to the degree of consumption of the developer 30B.

(2) Color image mode The mode can be switched by setting the knob on the operation panel to, for example, the magenta color image mode. In this mode, it is possible to obtain a recorded image in magenta, which is the switched mode, regardless of the color of the original. If a mode for developing with a developer of another color was being executed before switching to this mode, there would naturally be some developer of a color other than magenta remaining in the developing device 5, and this would be in the collection tube. Since it is refluxed to the developer tank 29M through 38M, color mixture occurs. Therefore, in order to avoid such color mixing, before entering the magenta color image mode, the four-way switching valve 37 is switched to the recovery pipe 104, and the pump 102 is driven to run the cleaning liquid 101 for a certain period of time. The residual developer in the developing device 5 is washed away and returned to the cleaning tank 100 via the recovery pipe 104.

Thereafter, the four-way switching valve 37 opens a recovery path in the recovery pipe 38M, and at the same time, the pumps 42 and 31M start operating, and the magenta color image mode is executed.

Therefore, the magenta developer 31M flows back between the developing device 5 and the developer tank 29M and is used for development. Further, residual toner on the photosensitive drum 3 is removed by a cleaning device 9 supplied with a black developer 30B.

The above example also applies to the cyan color image mode and the yellow image mode. That is, when switching to each mode, first, the developing device 5 is cleaned with the cleaning liquid 101 for a certain period of time, and then the original color image mode is automatically changed. enter. While the color image mode is being executed, the cleaning device 9 is cleaned with the developer 30B regardless of the designated color.

Therefore, each time the mode is switched, toner of the color before the mode is mixed into the cleaning tank 101. However, the amount of mixed toner is smaller than the toner collected by the cleaning device 9.

In this way, even if the amount of contamination per batch is small,
Cleaning liquid 101 is used while switching modes repeatedly.
gradually becomes dirty. Therefore, cleaning liquid 1
Toner processing means is attached to the cleaning tank 100 in order to separate and remove mixed toner components from the cleaning liquid 101 and maintain the cleaning liquid 101 in a clean state.

This toner processing means has the following three aspects.

(1) Use an electrode roller to which a via is applied for toner electrodeposition. Examples of this are shown in Figures 1 and 2,
The toner adhering to the electrode roller 105 is scraped off by a scraper 106 and collected in a collection container 107. The toner collected in the collection container 107 can be reused as needed.

(2) A porous member is provided at the bottom of the cleaning tank 100. For example, when an open-cell sponge is used, the toner that has settled in the cleaning liquid 101 enters the pores of the sponge and is no longer affected by the liquid flow, so that the toner remains settled. Therefore, the developer can be obtained by appropriately collecting the sponge and kneading it in the mother liquor. However, this developer is generally considered to be a black developer due to color mixing.

Instead of a sponge, a brush-like cloth such as Magic Tape (trade name) can also be used.

(3) Provide a filter member. For example, a filter member such as filter paper or activated carbon is provided at the outlet of the recovery pipe 104 to capture the toner before it reaches the cleaning tank 100.

By appropriately using these toner processing means, the cleaning liquid 101 in the cleaning tank 100 is kept clean. Since residual developer from the previous mode is also removed from the developing device 5, color mixing in the color developers is avoided.

Next, focusing on the cleaning device 9, the residual toner of each color image mode adhering to the latent image carrier is removed by washing away with the black developer 30B, and the remaining toner is removed from the developer tank 2 through the collection pipe 44.
There is a concern about color mixing with the developer 30B, but in this case, since the color is mixed with the black developer 30B, there is no problem with black reproducibility when switching to the black image mode. Does not occur.

Note that a portion of the developer 30C flows into the developer tank 29B via the recovery pipe 44, so it is conceivable that the developer tank 29B that continues in this mode may overflow with developer and stain the surrounding area. Therefore, as a countermeasure, for example, an auxiliary tank (not shown) is attached to accommodate the overflowing liquid. When this auxiliary tank is full, a sensor detects its condition, issues a warning, and shuts down the device. Then, the auxiliary tank may be emptied and image formation may be continued again. In this example, developer tank 2
There is an advantage that the size of 9B can be reduced. Alternatively, a liquid level gauge may be provided in the developer tank 29B or the auxiliary tank for display.

By switching each color image mode, black,
A single color image can be obtained for any color selected from the four colors cyan, magenta, and yellow.

Furthermore, by making changes to the other paper passing paths mentioned above, interposing a filter in the exposure optical path, and linking it with the switching of each of the image modes mentioned above, it is configured to obtain a full-color image, a two-color image, etc. You can also do that.

In order to obtain a full-color image, as shown in FIG. 5, the paper passing path is a cycle in which the recording paper leaves the pair of feed rollers 26, wraps around in a loop as shown by reference numeral 51, and waits again at the pair of registration rollers 22. is configured. Also, a filter 5 is installed between the fourth mirror 15 and the photosensitive drum 3 in FIG.
2 is placed on the optical path so as to be freely accessible.

This filter 52 includes a red filter RE that passes red and white colors, and a green filter RE that passes green and white colors.
It consists of a blue filter BL that passes GR, blue, and white, and can be rotated about an axis O to selectively position each color filter on the optical path.

For the first time, a full-color original is exposed with a red filter RE, and the electrostatic latent image is developed into cyan color in cyan image mode.The second time, the same recording paper is exposed using a green filter GR and a magenta color image. In combination with the mode, the image is developed in magenta color, and for the third time, the same recording paper is developed with a blue filter.
A combination of BL and yellow image mode produces full-color development by developing yellow.

Furthermore, a two-color image is also possible according to the above process.

Alternatively, images can be obtained on both sides of the recording paper by using a switchback type for the paper passing path as shown by reference numeral 53 in FIG.

Next, one embodiment of the developing device 5 will be described based on FIG. A first developing roller 6 is provided in the developing container 60.
1. Second developing roller 62 and squeeze roller 63
are each rotatably supported. Each roller is made of metal, is positioned at a predetermined gap from the photosensitive drum 3, and is driven to rotate in the direction of the arrow by a drive device (not shown).

Each roller has its base end connected to a developing container 60.
The free ends 64a, 65a, 66a of the scrapers 64, 65, 66 fixed to the rollers are pressed against each other to scrape off the developer adhering to the roller surface.

The socket 28 is disposed above the developer container 60. The developer supplied from the socket 28 is collected between the scraper 64 and the first developing roller 61, and is applied to the latent image carrier on the surface of the photoreceptor drum 3 by the roller rotating in the direction of the arrow. Supplied.

The developer remaining on the surface of the first developing roller 61 is scraped off by the scraper 64 and collected between the second developing roller 62 and the scraper 65, and is again supplied to the photosensitive drum 3 by the roller 62. be done.

The developer remaining on the surface of the second developing roller 62 is scraped off by the scraper 65, and the developer container 60 is scraped off by the scraper 65.
Flows down to the bottom edge of.

Excess developer remaining on the surface of the photoreceptor drum 3 during the development process is scraped off by the squeeze roller 63 and flows down to the lower end of the developer container 60. The developer that has flowed down to the lower end is discharged from the outlet 29.

In the above example, the roller is used in combination with a refresh roller for squeezing instead of the first developing roller 61, second developing roller 62, squeeze roller 63, etc., and is an elastic roller made of a porous elastic material. A roller (for example, Japanese Patent Publication No. 58-31578) may also be used.

As other embodiments of the developing device 5, it is also conceivable to appropriately utilize examples relating to a cascade developing system (for example, Japanese Patent Publication No. 49-12430) and those relating to a dish developing system (for example, Japanese Patent Publication No. 58-32376).

However, in carrying out the present invention, the former developing device using a metal roller or elastic roller, or the developing device using a developing unit configured in the form of an endless belt (hereinafter referred to as a rotary body developing method) is used. The method is advantageous in various respects.

For example, in the rotary body development system, a scraper or a member having an equivalent function can be attached, so that the developer on the rotary body can be removed more completely. For this reason, even if the color is changed, the amount of residual developer before changing the color mixed into the developer collected in the developer tank is extremely small, and it can be said that the degree of color mixing is even lower.

In addition, in the dish development method, in order to remove the background, there is no means to mechanically remove the developer, which is returned to the dish side by applying a developing bias, using a scraper or the like. However, the developer on the photosensitive drum must be removed by a cleaning device. However, the amount of developer to be removed by the cleaning device is large, and returning this developer to the developer tank 29B not only increases the amount of deteriorated toner due to reverse bias, but also reduces the amount of toner consumed. It will increase.

On this point, in the rotating body development method, a developing bias is applied to collect the developer on the rotating body side, and then this can be removed with a scraper etc. and returned to the developer tank for that color, which reduces color mixing and toner consumption. It's advantageous.

Furthermore, in the case of full-color images, the colors are produced by overlapping colors, so it is necessary to suppress the edge effect as much as possible, and for this purpose it is preferable to place the developing electrode close to the photoreceptor drum. In this method, if the developer is brought close to each other, the developer will not run out properly due to capillary action, and colors will easily mix, and in the end, it will not be possible to bring the developer close to each other.

In this regard, in the rotary development system, as mentioned above, the removal of the developer is good with the addition of a scraper, so it is possible to place it close to the photoreceptor drum, and therefore, it is possible to suppress the edge effect as much as possible and achieve color effects. can be produced.

Next, one embodiment of the cleaning device 9 will be described based on FIG. 7.

The device 9 includes a cleaning container 77 that is detachably attached to the device body 76, a cleaning roller 79 and a cleaning blade 8 that are attached to the device body via a bracket 78.
0, squeezing roller 81, cleaning liquid diffusion plate 8
2. A cleaning liquid socket 40 (described above).

The bracket 78 is swingably supported by a shaft 83, and after the cleaning operation is completed,
It is swung clockwise about the shaft 83 by means not shown.

The cleaning roller 79 is a roller made of an elastic material having liquid absorbing properties, such as sponge, and
It is rotationally driven in the direction of the arrow by a drive mechanism (not shown).

The cleaning blade 80 is made of rubber or a rubber-like material. During the cleaning operation, the blade 80 brings its free end into pressure contact with the surface of the photoreceptor drum 3, and the cleaning roller 79 elastically deforms its peripheral surface and brings it into pressure contact with the surface of the photoreceptor drum 3. There is.

In a state where the cleaning blade 80 and the cleaning roller 79 are in pressure contact with the circumferential surface of the photoreceptor drum 3, the roller 79 is in contact with the aperture roller 81.
It has been greatly transformed by The aperture roller 81 is rotationally driven in the direction of the arrow by a drive mechanism (not shown), and the cleaning roller 79
It is designed to squeeze out the cleaning liquid that has been sucked in.

This squeezing roller 81 is provided with a scraper 8 for scraping off the cleaning liquid adhering to the peripheral surface.
4 are pressed together. Below the socket 40,
There is a cleaning liquid diffusion plate 82 for diffusing the cleaning liquid in the longitudinal direction of the axis of the cleaning roller 79. This diffusion plate 82 is rotatable by a shaft 82a provided at the base edge thereof, and its own weight prevents its freedom. The side edge is brought into contact with the circumferential surface of the cleaning roller 79.

The free side edge 82b is slightly raised to form a pool of cleaning liquid.

During cleaning, the free side edge of the cleaning liquid diffusion plate 82 is lower than its base side edge.

At the lower end of the cleaning container 77, the container 77
There is an outlet 41 for recovering the cleaning liquid supplied to.

Cleaning roller 79 when not cleaning
It has already been mentioned that the cleaning blade 80 swings around the shaft 83, but at this time, the cleaning roller 79 is separated not only from the surface of the photoreceptor drum 3 but also from the aperture roller 81 to prevent deformation. , the cleaning diffusion plate 82 is swung so that its free side edge 82b is higher than its base side edge.

During non-cleaning, the cleaning liquid adhering to and dripping from the cleaning roller 79 and the cleaning liquid diffusion plate 82 falls onto the bottom plate portion 77b of the cleaning container 77, so that no liquid drips on the circumferential surface of the photoreceptor drum 3.

In the conventional method, since the position of the developing device must be moved when changing colors, a certain amount of operation time is required, and therefore, there is a problem that the method is not suitable for rapid image forming processing.

In this regard, in this example, colors can be changed easily and quickly just by operating a knob on the operation panel, and since the cleaning liquid is also used as the developer, there is no need for a dedicated tank for the cleaning liquid, improving space efficiency. can be done.

(Effects) In the present invention, a means for cleaning the developing device when switching modes is provided, and a means for separating and removing toner mixed into this cleaning liquid is also provided, so that color mixing in the color developer tank can be prevented. In addition, it is advantageous in that the separated toner can be collected and reused.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an electrophotographic apparatus that is an embodiment of the present invention, FIG. 2 is a configuration diagram illustrating the piping system shown in the above figure, and FIG. 3 is a perspective view illustrating the swinging mechanism of the outlet pipe. FIG. 4 is a perspective view illustrating a modified embodiment of the same figure as above, and FIG. 5 is a front view illustrating the paper passing path.
FIG. 6 is a sectional view of the developing device, and FIG. 7 is a sectional view of the cleaning device. 31B, 31M, 42, 102...Pump, 3
2B, 32M, 43, 103...Feeding pipe, 38
B, 38M, 44, 104...Recovery pipe, 105...
...Electrode roller.

Claims (1)

[Scope of Claims] 1. A latent image carrier rotating in a fixed direction is uniformly charged in the dark, and then a light image of a document is formed and exposed on the latent image carrier to form an electrostatic latent image. This electrostatic latent image is visualized with a liquid developer, transferred to recording paper, and this transferred image is fixed to obtain a desired recorded image. In an image forming apparatus that has a process in which residual toner on the body is removed by a cleaning device in preparation for the next image formation, the black developer stored in the black developer tank is supplied to the developing device and then collected into the black developer tank. a first supply and recovery means for supplying the black developer stored in the black developer tank to the cleaning device and then recovering it to the black developer tank; a third supply and recovery means for supplying the developer from the developer tank to the developing device and then recovering it to the color developer tank; and supplying the cleaning liquid stored in the cleaning tank to the developing device and then recovering it to the cleaning tank. A wet-type development multicolor image forming apparatus comprising: a fourth supply and collection means; and a toner processing means for separating the developer collected into the cleaning tank from the cleaning liquid.