Rental LED display professional guidance and practical tips

What is a rental LED display and how does it work?

Rental LED display screen is an advanced display device that is widely used in various activities and occasions. It uses light-emitting diodes (LEDs) as light sources and controls the light-emitting characteristics of LEDs through current to achieve high-quality display of images and videos

The working principle of rental LED display is based on LED array, which is a group of regularly arranged LED components. Each LED pixel can be controlled independently to achieve different brightness and color display effects by adjusting the current intensity and color combination

The working process of rental LED display is: the input signal is sent through the device connected to the controller. The controller processes and decodes the signals and generates corresponding control signals. These control signals are sent to the LED display module through the transceiver card. The LED display module controls the brightness and color of each LED pixel according to signal instructions, and ultimately forms an image or video

What types of rental LED display are there?

The following are commonly and less commonly used rental LED display types:

Commonly used rental LED display types:

Indoor rental LED display：high resolution and smaller pixel pitch, achieving clear and delicate image and video display effects
Outdoorrental LED display: high brightness, waterproof, dustproof, durable, suitable for long-term use under various weather conditions
Small-pitch rental LED display:high pixel density and high resolution, suitable for places with high requirements for display details and clarity
Splicing rental LED display:forming a large screen by splicing multiple modules, suitable for occasions requiring large-size display

Less commonly used rental LED display types:

Flexible rentalLED display: is composed of flexible LED modules and has a flexible and bendable design to adapt to different shapes and curved surface installation needs
Curved rental LED display: made into curved, concave-convex or other curved shapes as needed to suit specific occasions and special design needs
Cylindrical rental LED display:Multiple modules are freely spliced into a ring or cylindrical for displaying circular advertisements and wrap-around publicity
Detachable rental LED display:It consists of multiple modules that can be disassembled and assembled, and can be flexibly spliced and configured according to site and design requirements
Transparent rental LED display: Made of transparent materials, it can display content at the same time and the objects or landscape behind it are transparent and clearly visible. It is used for occasions where it is necessary to blend in with the environment or show a perspective effect

What are the main components of a rental LED display ?

The main components of a rental LED display include:

1.Module: includes LED lamp beads, circuit boards and driver chips, responsible for displaying images and video content, and can be combined into a large screen

2.Receiving card: receives the data signal from the control system, decodes and transmits it to the LED display module to display images and videos

3.Sending card: Convert and transmit the image and video data of the control system to the receiving card of the rental LED display

4.Power supply: Provide stable power supply for rental LED display, with overload protection, short circuit protection and temperature monitoring functions

5.video processor: processes and optimizes input signals to provide higher quality, more accurate, and more realistic image and video display

6.Outer frame box: Made of metal or other solid material to provide structural mounting support and protection for the rental LED display

7.Stacking bracket: Adjustable design supports the installation of multiple LED display modules in a large area

8.Cabinet-to-cabinet power cord: Used to connect the power supply required for the rental LED display, transmitting power from one cabinet to another

9.Cabinet-to-cabinet data cable: used for data transmission required to connect rental LED display, transmit data from one cabinet to another cabinet

10.Ribbon cable: used to connect various module of the rental LED display or to transmit power and signals between module

11.Power distribution box: a device that centrally manages and distributes power to provide stable power supply for rental LED display and related equipment

12.Hanging Beam：Specially designed device made of metal material that matches the mounting point of the rental LED display to simplify hanging installation

13.5V power cable:Provides the necessary 5V power supply for the rental LED display

14.Main power cable: connects and supplies power to the entire rental LED display system

15.Main signal cable: connects the control system and rental LED display, transmits video signals and control commands

16.Fixing plate with bolts：Securely fix rental LED display modules or modules

17.Module mask with screws：Installed in front of the module to protect and facilitate maintenance and replacement of LED display module

18.Flight case：Specially designed box for storage, protection and convenient transportation of LED display module and related equipment

What are the commonly used outer frame boxes for rental LED display?

The following are the main types of outer frame boxes commonly used in the rental LED display market:

1. Die-cast aluminum box: Boxes with complex shapes and excellent mechanical properties are formed by high-pressure injection of aluminum alloy. Lighter weight, excellent strength, good heat dissipation performance, corrosion resistance, suitable for indoor and outdoor rental LED display

2.Steel box: Made of steel, it has higher strength and durability, provides better protective performance, and is suitable for earthquake resistance, impact resistance and protection of outdoor rental LED display

What is the modular design principle of rental LED display screen?

Modular design is a key principle in the rental LED display industry, which is based on the component structure of the LED display. rental LED display screen is composed of many modules, which can be easily disassembled and connected as needed to assemble into large screens of different sizes and resolutions

First of all, the modular design provides flexibility, and the size and shape of rental LED display can be adjusted as needed to adapt to different scene requirements

Secondly, the modular design ensures reliability. Each module is an independent unit and can be replaced separately in case of failure without affecting the normal operation of the entire rental LED display

In addition, the modular design provides efficiency, and standardized dimensions and interfaces make the installation and removal process faster and easier

In short, the modular design principle of rental LED display screens is based on component structure, providing flexibility, reliability and efficiency, bringing convenience and diverse choices

What about the detachable structure and portability of rental LED display?

The following are the key points of the detachable structure and portability of rental LED display:

Detachable structure: Rental LED display adopts a modular structure and is easy to disassemble and assemble. Each module is operated and maintained independently, making installation and disassembly more convenient and faster, saving time and costs

Portability: Rental LED display screen focuses on lightweight design and compact packaging, making it easy to carry and transport. The shell made of high-strength materials is lightweight and durable. Equipped with a portable stand and vehicle-mounted equipment, rental LED display can be flexibly arranged and moved at any time

How is the protection and heat dissipation design of rental LED display implemented?

The following reveals the secrets of rental LED display protection and heat dissipation design:

In terms of protective design, a solid metal shell or a waterproof and dustproof plastic shell is used to effectively protect rental LED display from dust, moisture and collision. Also use protective glass of appropriate thickness to protect the LED module from damage

In terms of heat dissipation design, advanced heat dissipation technology is adopted. The heat sink can efficiently absorb and disperse the heat generated by rental LED display and improve the heat conduction efficiency. For high-temperature environments, fans are equipped to enhance air flow and accelerate heat dissipation to ensure that the temperature of rental LED display is always within a safe range. In addition, heat pipes and thermal conductive glue are used to improve the heat dissipation effect and conduction efficiency

How to save energy and protect the environment when rental LED display screen?

Energy saving and environmental protection are important considerations when rental LED display. The following is an analysis of key technologies:

High-efficiency and energy-saving LED chips:Use high-efficiency, low-power LED chips to reduce energy consumption
Intelligent brightness adjustment: Equipped with intelligent brightness adjustment technology, it automatically adjusts the brightness of the rental LED display according to the ambient brightness
Energy management system: Apply energy management system for real-time monitoring and analysis to optimize energy use
Energy-saving control solution: Combined with the intelligent control system, it can effectively reduce energy consumption through functions such as timer switches and power-saving modes
Environmentallyfriendly materials and manufacturing: Use environmentally friendly materials and manufacturing processes to reduce environmental impact

What are the cost analysis and optimization strategies for Rental LED display screen?

The following are important contents of rental LED display cost analysis and optimization strategies:

Cost analysis: In addition to considering the price of rental LED display, you also need to consider related costs such as transportation, installation, and maintenance

Optimization Strategy:

Choose energy-saving LED technology to reduce energy consumption and save operating costs
Adopt flexible modular structure design to facilitate quick installation and disassembly, reducing time and labor costs
Maintain regular maintenance and responsive technical support to avoid long-term downtime and repair costs

Why choose to rental LED display ?

The following are the key reasons to choose to rental LED display:

Flexibility:Rental LED display screens are suitable for a variety of applications, and you can choose the appropriate rental LED display size and configuration according to your needs
detachable structure and portability: Rental LED display adopts each module is operated and maintained independentlya modular structure and is easy to disassemble and maintain. The packaging focuses on lightweight design and structure, making it easy to carry and transport
Latest technology, high quality: The most advanced display effects, high resolution, excellent color performance and reliable performance

How to choose a high-quality rental LED display?

The following are the key elements for choosing a quality rental LED display:

Pixel density: Choose a rental LED display with high pixel density to present higher-definition and more realistic images and videos
Brightness and contrast: With enough brightness and contrast, the rental LED display can be clearly seen in various environments
Color performance: Choose a rental LED display with wide color gamut and high color reproduction capabilities to present bright and vivid images
Flexible and easy to install: modular design and lightweight outer box make it easy to install and disassemble the rental LED display
Reliability and stability: Choose a rental LED display with high reliability and stability to reduce failure rate and maintenance costs and ensure smooth operation
Service and support: Choose a supplier with good after-sales service and technical support to ensure that the rental LED display is always in the best condition

How to install and debug the rental LED display?

The following are the installation and debugging steps for rental LED display:

Determine the installation plan: According to customer needs and site conditions, formulate a suitable installation plan, including installation location, power access, support structure, etc
Installation bracket or hanging frame: Choose the appropriate fixing method according to the actual conditions of the installation site
Splicing assembly: According to the installation method of the LED display module, the splicing assembly is firm, tight and smooth
Power access:follow safe operating procedures to connect the power cord
Signal input: Connect the signal source and select the appropriate signal input method according to your needs, such as HDMI, DVI, VGA, etc
Debugging settings: Perform basic debugging settings on the LED display, including adjustments to brightness, contrast, color and other parameters
System testing: System testing of display effects and functions of installed LED display
Adjustment and optimization:Make further adjustments and optimizations based on actual usage and needs
Safety inspection: Check whether the LED display installation complies with relevant safety standards and regulations

How to choose a rental LED display suitable for indoor and outdoor use?

When choosing a rental LED display suitable for indoor and outdoor use, you should consider the following points:

Brightness and contrast: Choose medium brightness and high contrast indoors. Higher brightness is needed outdoors
Pixel density: High pixel density is required indoors, and appropriate pixel density can be used outdoors
Protection level: No high protection level is required indoors. Outdoors need to be dustproof and waterproof
Viewing angle visibility:indoor viewing angle requirements are lower, outdoor viewing angle requirements are wider
Maintenance and ease of use: Consider the modular design, remote monitoring and fault diagnosis functions of the LED display to facilitate maintenance and operation
Energy-saving performance: Choose LED display with energy-saving technology to reduce energy consumption, operating costs and environmental impact

How to choose the appropriate rental LED display size, shape and aspect ratio?

There are the following key points in choosing the appropriate rental LED display size, shape and aspect ratio:

Consider the venue: Determine the appropriate LED display size based on the size and layout of the venue. Choose from a small size for indoors and a large size for outdoor use
Audience distance: Consider the distance between the audience and the LED display and choose the appropriate pixel density and size. Select a small size with high pixel density for short distances, and a large size with low pixel density for long distances
Content needs: Determine the shape and aspect ratio of the LED display to suit the content being displayed. The horizontal screen is suitable for playing wide landscape content, and the vertical screen is suitable for displaying vertical content
Market demand: Understand market trends and customer needs, choose popular sizes and aspect ratios, and meet the wider applicability and needs of LED display

What impact does the brightness and viewing angle of a rental LED display have on the display effect?

Brightness and viewing angle are important factors affecting the rental LED display screen, related to the display effect

Brightness impact: High-brightness LED display provide clarity and vivid colors indoors, while providing sufficient brightness when exposed to sunlight outdoors

Viewing angle impact: The large viewing angle ensures that viewers can get clear images from all angles, whether indoors or outdoors

What are the environmental and sustainable benefits of rental LED display?

Rental LED display screen has the following environmentally friendly and sustainable advantages:

Energy saving:LED technology saves up to 50% energy compared to traditional displays, reducing energy consumption and carbon emissions
Long life:The LED display screen has a long life, which can reach hundreds of thousands of hours, reducing the frequency of maintenance and replacement, and reducing the generation of electronic waste
Resource recycling:The leasing model can realize the recycling of equipment and reduce resource waste and waste generation
Environmentally friendly materials:LED display use environmentally friendly materials to reduce negative impacts on the environme

How does the protection level and waterproof performance of rental LED display meet the needs of outdoor environments?

The rental LED display has a strong protection level and excellent waterproof performance, which can ensure safe and reliable operation in outdoor environments, showing excellent visual effects whether it is sunny or rainy

Protection level: Adopt IP (International Protection) level standards, such as IP65, IP67, etc., which can effectively protect against the intrusion of dust, moisture and other external substances

Waterproof performance: All-weather waterproof, rainproof, moisture-proof and splash-proof

How to use the split function of the rental LED display?

The following points are included in using the split function of the rental LED display:

Split mode:Through the split function, the LED display screen is divided into multiple areas to realize the simultaneous display of multiple images or videos
Layout options:Choose a suitable layout, such as tiled, cascading, spliced, etc., and customize the size and position of each area as needed
Content management:Use professional software or control systems to flexibly manage divided areas and easily adjust the playback content of images or videos
Interactive control:Supports touch screen or external devices to realize interactive control between users and various areas, increasing participation and interactivity

What are the tips for rental LED display for event marketing?

There are the following key tips for using rental LED displays for event marketing:

HD Content: Create high-quality, engaging image and video content
Dynamic display: using animation and transition effects
Timing strategy:Precisely control the playback timing of content according to activity needs
Interactive elements: Incorporate touch screens or external devices

How to design attractive content to display rental LED display?

When presenting your rental LED display, use these tips to design engaging content:

HD Visuals: Create high-quality, clear images and video content
Dynamic elements: Use animation and transition effects
Concise and clear: The information should be concise and clear, highlighting the main information and avoiding overcrowded or complex content
Color Matching: Choose an attractive color combination that matches the event theme
Interactive experience:add interactive elements

How to customize a personalized rental LED display?

Key points of customized personalized rental LED display:

Size and shape: Choose the size and shape that suits the site and needs, such as curved, curved or custom shapes
Resolution and pixel density: The rental LED display screen is guaranteed to have high resolution and pixel density
Color and brightness:Customize the color and brightness of the rental LED display according to the environment
Convenience of installation and disassembly: Consider the convenience of installation and disassembly of the rental LED display
Content customization: Customize unique information content according to needs

How to select and design commercial and outdoor advertising rental LED display?

Key points for select and design of commercial and outdoor advertising rental LED display:

High brightness and protection: Choose a high-brightnessrentalLED display with waterproof, dustproof and shockproof protection functions
Good visibility: consider the audience’s long-distance viewing needs and choose appropriate pixel density and display size
Energy saving and environmental protection:Choose a rental LED display with high energy efficiency, energy saving and environmental protection to reduce energy consumption
Remote management: Make sure the monitor supports remote content management and monitoring
Content design: Design advertising content that is concise, clear, attractive, and contextual

How to choose and apply rental LED display for conferences, exhibitions and commercial activities?

Key points for selection and application of rental LED display for conferences, exhibitions and commercial activities:

Size and resolution:Choose the appropriate display size and high resolution according to the size of the venue and the distance between the audience and the audience
Flexible and portable:Choosing to rental LED display can be used flexibly in different venues and activities, and is easy to carry
Brightness and adjustability:Ensure that the rental LED display screen has sufficient brightness and the brightness is adjustable
Content customization and interaction:Customize personalized content according to event needs, highlight key information, and add interactive elements
Technical support and service:Choose reliable suppliers to provide professional technical support and after-sales service

How to create rental LED display performance and stage background effects?

Key points for create rental LED display performance and stage background effects：

Resolution and pixel density: Choose a rental LED display with high resolution and suitable pixel density
Color performance and contrast: Consider the color performance and contrast of the rental LED display
Easy installation and splicing: Choose a rental LED display that is easy to install and splice and supports flexible shape and size adjustment
Visual effects and motion design: Design attractive visual effects and animations to highlight the atmosphere and theme
Flexible control and interactivity: Ensure that the rental LED display supports flexible remote control and touch interaction

How can rental LED display be used in social entertainment activities?

Key points for the application of rental LED display screen in social entertainment activities:

Creative interactive experience: Create unique interactive experiences such as projection interactive games and real-time social media interaction
Multifunctional scene creation: create diverse atmospheres by projecting different scenes
Real-time content update: Update event information content in real time, maintain interaction and provide the latest information
High-definition picture quality and sound effects: Choose a rental LED display with high resolution and high-quality sound effects
Safe and stable operation: Choose a supplier with professional technical support and reliable after-sales service

How can rental LED displays work best at sports events?

Key points for rental LED display to achieve the work best at sports events：

Large-size high-definition: Choose a large-size, high-resolution rental LED display
Real-time data and statistics: real-time display of important data, scores and game progress statistics
Video playback and slow motion: video playback and slow motion playback at critical moments
Interactive highlights and special effects: display player introductions, celebration animations and other interactive highlights and special effects
Flexible scene switching: Flexibly switch between full scenes, single close-ups and other different scenes as needed

How to use rental LED display in urban facilities and public places?

Key points for the application of rental LED display in urban facilities and public places:

Information transmission and announcements: Deliver real-time, easy-to-read important information and announcements, such as weather forecasts, traffic tips, community announcements, etc
Advertising and promotion: conduct advertising and promotional activities
Event promotion and interaction: Promote city activities and community activities such as performances, exhibitions, competitions, etc
Art display and cultural exchange: art display, cultural content, historical and cultural introduction
Emergency notifications and safety tips:In case of emergency, issue emergency notifications and safety tips

How to use rental LED display in control center and monitoring applications?

Key points for the application of rental LED display in control centers and monitoring applications:

Real-time monitoring and data display: Real-time display of video footage and related data from surveillance cameras
Multi-screen display and segmentation: realize multi-screen display and segmentation, and display multiple monitoring images at the same time
Alarm and emergency notification: timely response to alarm information and emergency notification
Data visualization and analysis: visual display and analysis of monitoring data
Remote control and management: remote control and management monitoring system for screen adjustment, display content switching, etc

How can rental LED display be used in education and training?

Key points for the application of rental LED display screens in education and training:

Interactive teaching demonstration: vividly display teaching content and conduct interactive teaching demonstrations
Multimedia resource display: display multimedia resources in the form of teaching videos, experimental demonstrations, pictures and charts, etc
Remote teaching and collaboration: remote teaching and collaboration through real-time interaction and remote discussion
Intelligent assessment and feedback:Learning guidance and progress tracking assess students’ work and provide instant feedback
Information release and notification: timely release of important information, courses, notices, etc

How to use rental LED display in medical applications?

Key points for using rental LED display in medical applications:

Medical information display:display medical information services and guidelines such as hospital navigation, doctor scheduling, medical treatment instructions, etc
Medical record data display:display examination results, diagnosis reports and other medical record data
Medical education and training:Demonstrate surgical techniques, case discussions, etc. for medical education and training
Health education and prevention:Carry out health education and disseminate disease prevention knowledge
Medical equipment monitoring:real-time monitoring of medical equipment data

How to maintain and solve rental LED display faults?

Maintenance and troubleshooting points for rental LED display screens:

Check power and connections:

Make sure the power cord is firmly connected and not loose or disconnected. If damaged, it should be replaced in time

Check that the power outlet is working properly, try changing the outlet or testing with another power source

Adjust brightness and color:

Adjust brightness and color settings using the LED display menu or remote control

Appropriately adjust brightness and color saturation according to actual environment and requirements

Fix pixel issues:

Use a pixel repair tool or software to fix the affected pixels. If the repair fails, please consider replacing the LED display module where the faulty pixel is located

Handling signal issues:

Check that the signal source output is well connected and whether the cable is damaged or loose. Reconnect or replace the cable

Adjust the output settings of the signal source to ensure it matches the resolution and refresh rate of the LED display

Cleaning and dustproofing:

Use professional cleaning tools and methods to gently wipe the surface of the LED display . Clean the cooling system and vents regularly

Operation monitoring and prevention:

Regularly monitor the operating status of the LED display, including temperature, brightness, pixels and other parameters

Pay attention to abnormal situations and take prompt measures to clean the cooling system or adjust the brightness settings

Hotspot solutions:

Reduce hotspot effects by adjusting brightness and color balance, or fix them by adjusting pixel brightness and color using hotspot correction technology

Lamp bead replacement and repair:

Use appropriate tools and techniques to promptly replace faulty lamp beads and install new ones

Control system troubleshooting:

Check the controller and signal transmission line of the LED display, Repair or replace damaged controller or wiring

Regular maintenance and upkeep:

Develop a regular maintenance plan, including cleaning the LED display surface, checking connecting cables, updating software, etc Regularly check equipment health and perform timely maintenance and upkeep

How to deal with rental LED display faults through remote monitoring?

Key points in handling rental LED display failures through remote monitoring:

Real-time status monitoring: Real-time monitoring of LED display brightness, color, temperature and other parameters, as well as the working status of signal input and output conditions
Fault alarm and notification: Automatically detect LED display pixel faults, abnormal brightness, communication interruption, etc. and issue fault alarms and notifications
Remote fault diagnosis: access the LED display controller and settings to quickly locate and diagnose the cause of the fault
Remote restart and reset: Provide restart and reset functions to remotely restart the LED display through the network and try to solve some common faults
Remote parameter adjustment: adjust the brightness, color, contrast and other parameters of the display to optimize the LED display effect
Remote firmware upgrade:Upgrade the firmware of the LED display to ensure that the system has the latest functions and fix known problems
Data analysis and fault prediction: Collect and analyze the operating data of the LED display, predict faults through algorithms, and take maintenance measures in advance to avoid faults
Remote technical support:Provide professional real-time video conferencing, remote screen sharing, remote operation guidance and other technical support and troubleshooting
Security and privacy protection:It has security encryption and rights management mechanisms to ensure the security of data transmission while protecting user privacy
Maintenance records and reports:record maintenance operations and troubleshooting processes, and generate corresponding maintenance reports for subsequent analysis and reference

How to use the functions of the rental LED display through training?

To quickly master the functions of rental LED display screens, the following are concise and efficient training points:

Ensure basic operations: master the power switch and restart functions, Learn how to navigate menus and adjust settings
Signal input and output: Connect to the correct signal source, such as computer, media player, etc, adjust resolution and refresh rate
Brightness and color adjustment: Adjust brightness according to scene needs, and improve image saturation and contrast through color adjustment
Content playback and switching: Learn to use USB, HDMI and other playback software or devices, and master content switching and scheduling
Pixel fault handling: Learn how to detect and repair pixel faults, and master the use of pixel repair tools or software to repair them
Remote control and monitoring: Understand the use of remote control systems, learn to remotely adjust parameters, perform fault diagnosis and firmware upgrades
Common fault handling: Master the solutions to common faults such as signal interruptions and display abnormalities, and learn to quickly solve problems and take appropriate actions
Regular maintenance: Develop a regular maintenance plan and regularly check the operating status of connecting cables and equipment

How to provide technical support and training for rental LED display screens?

The key points of providing technical support and training for rental LED display screens are:

Remote technical support: Provide real-time video conferencing and remote screen sharing, solve problems and provide technical guidance, remotely access LED display controllers, quickly locate and diagnose faults
Basic operation training: teach basic operations such as power control, menu navigation, setting adjustment, etc.and provide guidance on the correct connection methods for signal input and output
Dimming and color adjustment: adjust brightness, saturation and contrast,Learn to use color adjustment tools
Content playback and switching: teach the usage skills of content playback software or equipment, Guide content switching and scheduling
Pixel troubleshooting: Learn how to detect and repair pixel failures, training on using pixel repair tools or software
Remote control and monitoring: Guide the use of remote control systems to achieve remote operation and monitoring. Remote parameter adjustment, fault diagnosis, firmware upgrade skills training
Common fault handling: Provide methods and techniques for solving common faults such as signal interruptions and display abnormalities, and provide training to quickly solve problems and take appropriate actions
Maintenance: guide the development of regular maintenance plans, and train how to clean and inspect connections and equipment

How to provide comprehensive after-sales warranty and extended warranty services for rental LED displays?

The key points of providing comprehensive after-sales warranty and extended warranty services for rental LED displays are:

Clear warranty policy: Provide detailed warranty policies and terms to ensure customers understand their rights and responsibilities.Explain warranty duration, coverage, and repair procedures
Rapidly responsive technical support: Establish a 24/7 technical support hotline to quickly respond to customer questions and needs. Provide remote technical support to resolve faults via video conferencing or remote access
Training and guidance: Provide operational training to enable customers to correctly use and maintain LED display. Provide user manuals and video tutorials so customers can get help at any time
Rapid repair and replacement: Establish a rapid maintenance service network to ensure that faults can be repaired in time. Provide spare parts and quick replacement services to reduce maintenance time
Extended warranty period: Provide extended warranty service options to extend the warranty period of the LED display. Explain the extended warranty policy and fees, and help customers choose a suitable extended warranty plan
Regular maintenance and inspection:Provide regular maintenance plans to keep the LED display running normally. Regularly check and clean the LED display to prevent potential failures and damage
Excellent customer service:Develop a professional customer service team to provide friendly and professional support. Continue to follow up on customer feedback and improve after-sales service quality