CN209881796U - Optical signal amplification equipment and PON network system - Google Patents

Abstract

The application discloses optical signal amplification equipment and PON network system, equipment includes: an OLT interface, an ONU interface, a protection module, an ONU optical module, an OLT optical module and a data processing module which form a signal transmission link; the protection module includes: first to fourth ports; the first port is used for being in communication connection with the OLT interface, and the second port is used for being in communication connection with the ONU interface; the third port is connected with an ONU optical module; the fourth port is connected with an OLT optical module; the problem that a suspended user terminal is disconnected due to faults of PON amplifying equipment in the prior art is solved by switching a signal transmission link and a bypass link section of the signal transmission link through a protection module according to abnormal conditions of the equipment; furthermore, the optical signal can be automatically adjusted to proper power by the automatic optical attenuation adjusting module capable of automatically adjusting the attenuation parameter, then enters the optical module and can be shielded by the bypass, and the adaptability of the equipment to different environments is improved.

Description

Optical signal amplification equipment and PON network system

Technical Field

The present application relates to the field of optical communications technologies, and in particular, to an optical signal amplification apparatus and a PON network system.

Background

Under the policy assignment and action deployment of the national 'Internet +' and 'broadband China', the construction of an optical fiber network is accelerated and the speed-increasing and cost-reducing force is increased in recent years. In the broadband construction process, due to factors such as line attenuation, splitter insertion loss and the like, the light receiving power of the user terminals of part of cells is insufficient, and service opening and user perception are influenced; in addition, when broadband coverage is built in rural areas, the OLT is required to be sunk frequently due to the fact that the line distance is long, and the machine room is difficult to select points, investment pressure and maintenance difficulty are large.

An optical signal amplification device (hereinafter referred to as a PON amplification device) of a Passive Optical Network (PON) is positioned on an access optical cable layer between an OLT and an optical splitter, and performs amplification and shaping of a PON signal in an optical-electrical relay manner, so as to improve optical power and signal-to-noise ratio, and improve optical power from end to end and user perception of the PON network.

In the current network environment, the PON amplifying device is generally connected in series to the PON link, and although the problem of insufficient optical power of the current network can be solved, there is a risk. Once the PON amplifying device itself fails or the amplifying device is abnormally powered, the service of all the users hanging down from the PON amplifying device is affected. At this time, not only the user with insufficient optical power in the original link cannot surf the internet, but also the user surfing service with good condition of the original link is interrupted.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present application is to provide an optical signal amplifying device and a PON network system, which solve the problems of the prior art by improving the structure of the optical signal amplifying device of the PON network.

In order to achieve the above and other related objects, the present application provides an optical signal amplifying device for being connected in series in an optical communication link between an OLT device and an ONU device in a PON network; the optical signal amplifying apparatus includes: the OLT interface is used for being connected to one side of the OLT equipment in a communication mode; the ONU interface is used for connecting communication to one side of the ONU equipment; a protection module comprising: a first port, a second port, a third port, and a fourth port; the first port is used for being in communication connection with the OLT interface, and the second port is used for being in communication connection with the ONU interface; the ONU optical module is in communication connection with the third port; the OLT optical module is in communication connection with the fourth port; the data processing module is in communication connection with the ONU optical module and the OLT optical module and is used for signal transmission between the ONU optical module and the OLT optical module; a signal transmission link is formed among the OLT interface, the first port, the third port, the ONU optical module, the data processing module, the OLT optical module, the fourth port, the second port and the ONU interface; the protection module is used for switching the signal transmission link to a bypass link section when the optical signal amplification equipment works abnormally, and the bypass link section is formed by connecting a first port and a second port in the protection module in a communication mode.

In an embodiment of the present application, the optical signal amplifying apparatus further includes: and the automatic optical attenuation adjusting module is integrated in the protection module, is connected between the first port and the third port in series, and is used for outputting an optical signal obtained from one of the first port and the third port to the other port after attenuation processing.

In an embodiment of the present application, the optical attenuation automatic adjusting module is configured to attenuate the received optical signal to a pre-optical power normal value/normal range by using an adjustable attenuation parameter.

In an embodiment of the present application, the bypass link segment does not include the light attenuation automatic adjusting module.

In an embodiment of the present application, the signal transmission link includes: the uplink is used for transmitting signals to the OLT interface direction along the ONU interface; the optical signal amplifying apparatus further includes: and the uplink burst optical detection module is connected in series in a first link section from the OLT optical module to the data processing module.

In an embodiment of the present application, the signal transmission link includes: a downlink for transmitting signals along the OLT interface to the ONU interface; the downlink includes: and connecting the data processing module to a second link section of the OLT optical module, wherein the second link section is different from the first link section.

In an embodiment of the present application, the OLT interface and/or the ONU interface are connected to the outside by a flange.

To achieve the above and other related objects, the present application provides a PON network system, comprising: OLT equipment and ONU equipment; the optical signal amplifying device is connected in series in an optical communication link between the OLT device and the ONU device.

In an embodiment of the present application, a first or multiple stages of optical splitters are connected in a downlink from the OLT apparatus to the ONU apparatus in the PON network system, the optical signal amplification apparatus is located at a lower stage of any one of the optical splitters, an OLT interface of the optical signal amplification apparatus is connected to a downlink interface of the optical splitter, and an ONU interface of the optical signal amplification apparatus is connected to a next stage of equipment in the downlink.

As described above, the optical signal amplifying device and the PON network system according to the present application include: an OLT interface, an ONU interface, a protection module, an ONU optical module, an OLT optical module and a data processing module which form a signal transmission link; the protection module includes: a first port, a second port, a third port, and a fourth port; the first port is used for being in communication connection with the OLT interface, and the second port is used for being in communication connection with the ONU interface; the third port is connected with an ONU optical module; the fourth port is connected with an OLT optical module; the data processing module is used for transmitting signals between the ONU optical module and the OLT optical module; the protection module switches a signal transmission link and a bypass link section thereof according to the abnormal condition of the equipment, so that the problem of network disconnection of a hung user end caused by the fault of the PON amplifying equipment in the prior art is solved; furthermore, the optical signal can be automatically adjusted to proper power through an automatic optical attenuation adjusting module capable of automatically adjusting the attenuation parameter and then enters the optical module, and the optical signal can be shielded by the bypass link section, so that the universality of the equipment to different environments is improved.

Drawings

Fig. 1 is a schematic structural diagram of an access network portion of a PON network system according to an embodiment of the present application.

Fig. 2 is a schematic circuit diagram of an optical signal amplifying apparatus according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. The present application is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

Embodiments of the present application will be described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present application pertains can easily carry out the present application. The present application may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present application, components that are not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

Throughout the specification, when a component is referred to as being "communicatively connected" to another component, this includes not only the case of "directly communicatively connected" but also the case of "indirectly communicatively connected" with other elements interposed therebetween. In addition, when a component is referred to as "including" a certain constituent element, unless otherwise stated, it means that the component may include other constituent elements, without excluding other constituent elements.

When an element is referred to as being "on" another element, it can be directly on the other element, or intervening elements may also be present. When a component is referred to as being "directly on" another component, there are no intervening components present.

Although the terms first, second, etc. may be used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first interface and the second interface, etc. are described. Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, steps, operations, elements, components, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions, steps or operations are inherently mutually exclusive in some way.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" include plural forms as long as the words do not expressly indicate a contrary meaning. The term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and/or components.

Terms indicating "lower", "upper", and the like relative to space may be used to more easily describe a relationship of one component with respect to another component illustrated in the drawings. Such terms are intended to include not only the meanings indicated in the drawings, but also other meanings or operations of the device in use. For example, if the device in the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "under" and "beneath" all include above and below. The device may be rotated 90 or other angles and the terminology representing relative space is also to be interpreted accordingly.

Although not defined differently, including technical and scientific terms used herein, all terms have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms defined in commonly used dictionaries are to be additionally interpreted as having meanings consistent with those of related art documents and the contents of the present prompts, and must not be excessively interpreted as having ideal or very formulaic meanings unless defined.

In the current network environment, the PON amplifying device is generally connected in series to the PON link, and although the problem of insufficient optical power of the current network can be solved, there is a risk. Once the PON amplifying device itself fails or the amplifying device is abnormally powered, the service of all the users hanging down from the PON amplifying device is affected. At this time, not only the user with insufficient optical power in the original link cannot surf the internet, but also the user surfing service with good condition of the original link is interrupted.

In view of the shortcomings in the prior art, an object of the present application is to improve the circuit structure of an optical signal amplifying device to provide a protection switching function.

The optical signal amplifying apparatus may be applied in a Passive Optical Network (PON) system, such as EPON/GPON, etc.

Fig. 1 shows a schematic network structure diagram of an access network portion of a PON network system in an embodiment of the present application.

The access network part of the PON network system includes an OLT device 101 and ONU devices 102, and the OLT device 101 may be connected to a plurality of ONU devices 102 through a passive one-stage or multi-stage optical splitter 103; the OLT apparatus 101 is an Optical Line Terminal (OLT), and is configured to connect to a terminal apparatus of an optical fiber trunk; the ONU device 102 is an optical network unit, and the ONU device 102 may be installed at a user to provide data such as IPTV, voice, etc. to a user terminal.

Therefore, the direction in which the OLT apparatus 101 transmits signals to the ONU apparatus 102 is the downstream direction, and the direction in which the ONU apparatus 102 transmits signals to the OLT apparatus 101 is the upstream direction.

In this embodiment, the optical signal amplifying device 104 may be connected in series with the main path (i.e., the position indicated by a in the figure) in the link, or may be connected in series with the branch path (i.e., the position indicated by B, C in the figure) for amplifying the uplink/downlink optical signal and outputting the amplified optical signal.

Alternatively, at position A, C in the figure, the optical signal amplification device 104 may be located at a lower stage of the optical splitter 103.

Optical signal amplification is particularly important for downstream optical signals. In remote mountainous areas or towns and the like, optical signals are transmitted to the ONU device 102 at the user side, the optical power is weak, and the user in the remote areas can normally surf the internet by amplifying the downlink optical signals.

As shown in fig. 2, a schematic circuit diagram of an optical signal amplifying device 200 in the embodiment of the present application is shown.

The optical signal amplifying device 200 is connected in series in an optical communication link between the OLT device 207 and the ONU device 208 in the PON network.

The optical signal amplifying device 200 includes: an OLT interface 201, an ONU interface 202, a protection module 203, an ONU optical module 204, an OLT optical module 205, and a data processing module 206.

The OLT interface 201 is configured to be communicatively connected to one side of the OLT device 207. In one or more embodiments, the OLT interface 201 is used to connect the OLT apparatus 207 in the upstream direction or to connect to the OLT apparatus 207 via other optical communication equipment in the link (e.g., optical splitters, other optical signal amplification apparatus 200).

The ONU interface 202 is configured to be communicatively connected to an ONU device 208 side. In one or more embodiments, the OLT interface 201 is used to connect the OLT apparatus 207 in the upstream direction or to the ONU apparatus 208 via other optical communication equipment in the link (e.g. optical splitters, other optical signal amplification equipment 200).

In one or more embodiments of the present application, the OLT interface 201 and/or the ONU interface 202 are connected to an external device by a flange.

For example, any type of flange connection structure, such as SC, FC, SC and FC converters, SC and SC converters, FC and FC converters, etc., may be used to implement the communication connection between the OLT interface 201 and/or the ONU interface 202 and the external device.

The protection module 203 comprises: a first port 231, a second port 232, a third port 233, and a fourth port 234; the first port 231 is communicatively connected to the OLT interface 201, the second port 232 is communicatively connected to the ONU interface 202, the third port 233 is communicatively connected to the ONU optical module 204, and the fourth port 234 is communicatively connected to the OLT optical module 205.

In one or more embodiments, the ONU optical module 204 and the OLT optical module 205 are implemented as optical modules (optical modules), and each of the optical modules includes an optoelectronic device, a functional circuit, and an optical interface, where the optoelectronic device includes a transmitting part and a receiving part.

One of the functions of the optical module is optical/electrical signal interconversion, for example, converting an electrical signal into an optical signal, and transmitting the optical signal through an optical fiber by a transmitting end of the optical module; or, the receiving end receives the optical signal and converts the optical signal into an electrical signal.

The data processing module 206 is communicatively connected to the ONU optical module 204 and the OLT optical module 205, and is configured to transmit signals between the ONU optical module 204 and the OLT optical module 205, as shown in D in the figure.

In one or more embodiments, the data processing module 206 may be configured to recover the electrical signal converted from the optical signal to implement fidelity to the data in the original signal, and the OLT optical module 205 and the ONU optical module 204 are configured to amplify the received electrical signal and convert the electrical signal into an optical signal for outputting, thereby implementing optical signal amplification.

In one or more embodiments, the data processing module 206 may be implemented by a processing circuit, such as an FPGA, a CPLD, or the like.

A signal transmission link is formed among the OLT interface 201, the first port 231, the third port 233, the ONU optical module 204, the data processing module 206, the OLT optical module 205, the fourth port 234, the second port 232, and the ONU interface 202. The signal transmission link comprises an upstream signal transmission link and a downstream signal transmission link.

Specifically, the OLT interface 201, the ONU interface 202, the ONU optical module 204, the OLT optical module 205, the protection module 203, and the data processing module 206 are all bidirectional, and are respectively connected to form an uplink and a downlink through two sets of input/output ends; the downlink refers to a signal transmission link in a signal transmission direction from the OLT interface 201, the first port 231, the third port 233, the ONU optical module 204, the data processing module 206, the OLT optical module 205, the fourth port 234, the second port 232, and to the ONU interface 202; the uplink refers to a signal transmission link in a signal transmission direction from the ONU interface 202, the second port 232, the fourth port 234, the OLT optical module 205, the data processing module 206, the ONU optical module 204, the third port 233, the first port 231, and to the OLT interface 201.

Optionally, the optical signal amplifying device 200 further includes: the uplink burst optical detection module 209 is connected in series in a first link section from the OLT optical module 205 to the data processing module 206; the uplink burst optical detection module 209 is configured to be used during the uplink operation, and the OLT optical module 205 transmits an uplink optical signal to the data processing module 206 through the uplink burst optical detection module 209.

Optionally, the signal transmission link includes: a downlink for transmitting signals in the direction of the OLT interface 201 to the ONU interface 202; the downlink includes: a second link section other than the first link section connecting the data processing module 206 to the OLT optical module 205. For example, in the embodiment of fig. 2, the data processing module 206 is directly connected to the OLT optical module 205.

The protection module 203 is configured to switch the signal transmission link to a bypass link section when the optical signal amplifying device 200 operates abnormally, where the bypass link section is formed by the first port 231 and the second port 232 which are communicatively connected in the protection module 203, and is shown as E in the figure.

Specifically, in the case where the optical signal amplifying device 200 operates normally, the above-described up or down link is used for operation; when the optical signal amplifying device 200 is abnormally operated, for example, when power is abnormally supplied (such as power failure) or fails to normally operate, the first port 231 and the second port 232 of the protection module 203 are communicatively connected to form a bypass.

It is understood that the optical signal amplifying device 200 may be provided with a circuit for detecting an operation state, for detecting a power supply abnormality, a fault signal (for example, containing a fault code) in a fault condition, and generating a corresponding trigger signal to the protection module 203 to trigger the switching bypass operation thereof; of course, in one or more embodiments, the circuit for detecting the operation state of the optical signal amplifying device 200 may also be integrated in the protection module 203.

For example, when the optical signal amplification device 200 operates in a downlink, if an abnormal operation occurs, the protection module 203 is switched to the bypass link part with a gomper, and the OLT device 207 may perform downlink transmission of the optical signal to the ONU device 208 through the first port 231 to the second port 232; when the optical signal amplification device 200 operates in an uplink, if an abnormal operation occurs, the protection module 203 switches to the bypass link section to operate, and the ONU device 208 may perform uplink optical signal transmission to the OLT device 207 through the second port 232 to the first port 231.

It can be seen that even if the optical signal amplifying device 200 operates abnormally, the normal transmission of the uplink and downlink optical signals can be ensured, and only the abnormally operating device is bypassed.

In one or more embodiments, the protection module 203 may be implemented by an optical transmission component capable of internally switching the port connection mode, such as a controllable optical cross-connect.

In the embodiment of fig. 1, the closer the optical signal amplifying device 200 is to the signal source, the stronger the power of the received optical signal is, for example, the power of the optical signal received from the OLT device 207 side at the a position is stronger than the power of the optical signal at the B position, and since the normal received power of the optical module (for example, the ONU optical module 204 and the OLT optical module 205) is generally about-8 db to-30 db, the power attenuation processing is performed on the optical signal with the power value above the range, for example, -3db, or-5 db.

Accordingly, an optical attenuator is required to attenuate power. However, if an optical attenuator with a fixed attenuation parameter is provided, there is a great limitation in the use of the optical signal amplifying device 200 because the field environment is complicated and varied, and it is impossible to predict the optical power in the field and determine the optical attenuation used. Moreover, due to the bidirectional property of the fixed optical attenuation, when the optical attenuation device is powered off and needs to be bypassed, the fixed optical attenuation is added to the PON link, which causes the optical attenuation of the original link to be increased and the service to be affected.

In view of the above problem, in one or more embodiments, optionally, an optical attenuation automatic adjusting module 210 is provided, which is integrated in the protection module 203, and is connected in series between the first port 231 and the third port 233, and is configured to output an optical signal obtained from one of the first port 231 and the third port 233 after being subjected to an attenuation process to the other.

That is, when the signal goes downstream, the optical attenuation automatic adjusting module 210 can select attenuation or no attenuation depending on whether the power of the optical signal received by the first port 231 from the OLT interface 201 is within a proper range, and then transmit the optical signal to the ONU optical module 204 through the third port 233; alternatively, when the signal goes upstream, the optical attenuation automatic adjusting module 210 can select attenuation or no attenuation depending on whether the optical signal received from the ONU optical module 204 through the third port 233 is within a proper range, and then transmit the optical signal to the OLT interface 201 through the first port 231.

The light attenuation parameter of the light attenuation automatic adjusting module 210 is adjustable; accordingly, the light attenuation parameter can be adjusted according to the power of the actual optical signal, so as to adjust the power value of the optical signal to be within a normal value/normal range, for example, to be between-8 and-30 db suitable for the normal receiving power of the optical module, and for example, to be within a power range suitable for the next-stage device to receive.

In particular, according to the connection structure of the light attenuation automatic adjusting module 210 in the above embodiment, when the bypass link section communicatively connected between the first port 231 and the second port 232 is used, the light attenuation automatic adjusting module 210 is also bypassed; at this time, the optical attenuation parameters of the optical attenuation automatic adjusting module 210 do not affect the communication link between the OLT 207 and the ONU 208, because the optical attenuation of the upstream and downstream optical signals does not need to be performed by the optical attenuation automatic adjusting module 210.

The circuit structure of the optical signal amplifying equipment capable of performing bypass switching is protected, and improvement of a software program is not involved.

To sum up, the optical signal amplification device and the PON network system of the present application, the device includes: an OLT interface, an ONU interface, a protection module, an ONU optical module, an OLT optical module and a data processing module which form a signal transmission link; the protection module includes: a first port, a second port, a third port, and a fourth port; the first port is used for being in communication connection with the OLT interface, and the second port is used for being in communication connection with the ONU interface; the third port is connected with an ONU optical module; the fourth port is connected with an OLT optical module; the data processing module is used for transmitting signals between the ONU optical module and the OLT optical module; the protection module switches a signal transmission link and a bypass link section thereof according to the abnormal condition of the equipment, so that the problem of network disconnection of a hung user end caused by the fault of the PON amplifying equipment in the prior art is solved; furthermore, the optical signal can be automatically adjusted to proper power through an automatic optical attenuation adjusting module capable of automatically adjusting the attenuation parameter and then enters the optical module, and the optical signal can be shielded by the bypass link section, so that the universality of the equipment to different environments is improved.

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.

Claims (9)

1. An optical signal amplification device is characterized in that the optical signal amplification device is connected in series in an optical communication link between OLT equipment and ONU equipment in a PON network; the optical signal amplifying apparatus includes:

the OLT interface is used for being connected to one side of the OLT equipment in a communication mode;

the ONU interface is used for connecting communication to one side of the ONU equipment;

a protection module comprising: a first port, a second port, a third port, and a fourth port; the first port is used for being in communication connection with the OLT interface, and the second port is used for being in communication connection with the ONU interface;

the ONU optical module is in communication connection with the third port;

the OLT optical module is in communication connection with the fourth port;

the data processing module is in communication connection with the ONU optical module and the OLT optical module and is used for signal transmission between the ONU optical module and the OLT optical module;

a signal transmission link is formed among the OLT interface, the first port, the third port, the ONU optical module, the data processing module, the OLT optical module, the fourth port, the second port and the ONU interface; the protection module is used for switching the signal transmission link to a bypass link section when the optical signal amplification equipment works abnormally, and the bypass link section is formed by connecting a first port and a second port in the protection module in a communication mode.

2. The optical signal amplification device of claim 1, further comprising: and the automatic optical attenuation adjusting module is integrated in the protection module, is connected between the first port and the third port in series, and is used for outputting an optical signal obtained from one of the first port and the third port to the other port after attenuation processing.

3. The optical signal amplification device of claim 2, wherein the optical attenuation automatic adjustment module is configured to attenuate the received optical signal to a pre-optical power normal value/normal range by an adjustable attenuation parameter.

4. The optical signal amplification apparatus of claim 2, wherein the bypass link segment does not include the optical attenuation autoregulating module therein.

5. The optical signal amplification device of claim 1, wherein the signal transmission link comprises: the uplink is used for transmitting signals to the OLT interface direction along the ONU interface; the optical signal amplifying apparatus further includes: and the uplink burst optical detection module is connected in series in a first link section from the OLT optical module to the data processing module.

6. The optical signal amplification device of claim 5, wherein the signal transmission link comprises: a downlink for transmitting signals along the OLT interface to the ONU interface; the downlink includes: and connecting the data processing module to a second link section of the OLT optical module, wherein the second link section is different from the first link section.

7. The optical signal amplification device of claim 1, wherein the OLT interface and/or the ONU interface are flanged to the outside.

8. A PON network system, comprising:

OLT equipment and ONU equipment;

the optical signal amplification device of any one of claims 1 to 7, connected in series in an optical communication link between the OLT device and the ONU device.

9. A PON network system as claimed in claim 8, wherein one or more stages of optical splitters are connected in the downlink from the OLT device to the ONU device in the PON network system, the optical signal amplification device is located at the lower stage of any one of the optical splitters, and its OLT interface is connected to the downstream interface of the optical splitter, and its ONU interface is connected to the next stage device in the downlink.