Quality Checklist for Custom Android Tablets (Functional Checks)

This month’s article lists out a few of the standard functionality tests Hatch performs on custom Android tablets.  These tests are part of a longer list which includes many kinds of inspections Hatch does to ensure the product meets Hatch’s basic quality standard.  Beyond the fundamental tests, when checking the functionality of a custom Android tablet, Hatch will add custom quality checks based on the product’s specific functionality requirements.  For example, if the product uses a wide angle camera lens, Hatch will check that the viewing angle meets the special requirements.  If an unforeseen problem gets found during the development process, Hatch will introduce a test into the quality control process to cover that specific issue.

The name of each check is followed by details of the inspection process.

Functional Defects

Functional tests ensure correct performance of the custom Android tablet. The proper functionality of a tablet starts with using good components. This is why there are different functionality tests for all the key components of the tablet.

  1. Plug Insertion Force

This test ensures that the ports of a custom Android properly fit with the plugs that go in them. Generally this applies to a USB, earphone, and charging port. Plug insertion force is the force required to insert the plug into a slot. The port shouldn’t be too loose, so the plug falls out unintentionally, and it shouldn’t be too tight, making it difficult to insert or withdraw the plug.

We measure this force using gram-force. Gram-force (gf) is a metric unit of force that is equal to the force of gravity on a one-gram mass.

The tolerance range for this test is Min 250gf and Max 1500gf.

  1. Button Activation Force 

This test makes sure that the buttons are working properly, and more specifically, that they respond to the right amount of force. It applies to physical buttons which ‘click’, rather than touch buttons which use other sensing methods.

Button activation force defines the amount of pressure required to apply to a button for it to function. It’s also measured using gf.

The tolerance range for this test is Min 200gf and Max 400gf.

  1. Speaker Audio Quality

This test ensures that the audio output from the Android tablet or smartphone is clear at the highest volume.

Speaker Audio Quality is evaluated using sound pressure level (SPL) and total harmonic distortion + noise (THD+N) at peak speaker loudness on 1kHz sine wave.

The tolerances are SPL as dBa and THD+N as a percentage. These are checked at a distance of 10cm from the speaker. An acceptable SPL, dBa is ≥72 and THD+N, % is ≤15. To put things into everyday terms 40dB is the volume of a quiet library. 60dB: ordinary spoken conversation. 85dB: a food blender. 88dB: heavy traffic. (source: rnid.org.uk)

  1. Display Quality

This test applies to the image shown on an Android tablet or smartphone screen. It ensures that the screen’s colors, brightness, and pixels appear correctly.

Display defects are defects which cause total or partial image loss, image distortion, or reduces display usability under bright ambient light.

The tolerances for this test include average brightness (in nits), brightness uniformity (as a percentage), color representation (CIE1931), bright dead sub-pixels (based on size and density), and dark dead sub-pixels (based on size and density).

Additional tests include:

Age testing, where the device runs a demanding workload, usually playing a video at high volume. This test lasts for between several hours to several weeks, depending on the product. The point is to ensure that the system functions properly over a longer period of time while under a high stress level.

Drop testing, where the device is dropped at a specified height onto a hard surface multiple times at different angles. The goal is to ensure the device can sustain violent impact and continue to function properly.

And there are tests for all the other major components such as camera, microphone, battery, and memory.

The list of functional testing covers all elements of the custom Android tablet or smartphone that could affect its performance. All custom devices also undergo tests which are specific to their unique requirements as well. These tests are initially based on the devices custom requirements and new tests are added during the development process as new issues are found.

Custom Tablet for Photographers – Case Study

Project Scope

Design a tablet for photographers to quickly review their shots and copy photos from the camera’s memory card to a spare card.

Use Cases

Photographers want to quickly review photos on a clear and large screen then move images off their camera’s memory card so they can get back to taking photos again.  Hatch’s client identified this unique market and turned to Hatch to manufacture a custom Android tablet tailored to serve it.

Hardware and Mechanical Requirements

  • 9” Screen
  • No Wireless Connectivity (mobile data, Wi-Fi, Bluetooth, etc)
  • Two Full Size SD Card Slots
  • Large 4000mAh Battery
  • Custom Protective Case

Hatch’s Responsibilities (Learn more about Android Development Service)

  • Custom Android firmware programming
  • Custom PCBA design
  • Reference design modification to add extra SD card slot
  • Assistance with Industrial Design
  • Mechanical Engineering
  • Creating prototypes
  • Tooling for device case
  • Manufacturing process optimization
  • Create finished product testing procedure
  • Trial and Mass Productions

Time Frame

This project moved fairly quickly from Hatch’s end.  Two months passed from kickoff to initial prototype.  The customer took a few months to thoroughly test the initial prototype, which is time well spent.  Another month was used to refine aspects of the firmware in parallel with producing the tooling for the tablet’s casing.  Trial production took a month and then the customer needed extra time to refine and debug their app.  The whole process took about 8 months, but most of this time was used for app related development and optimizations.

How it Happened 

The client initially approached Hatch about working together when they first started conceptualizing the project around 2017.  At that time, as a new company and concept, they couldn’t commit to Hatch’s minimum order quantity.  We wished them good luck and ended the discussion.  They came across another tablet supplier who said all the right things, won the business and then forced the client to place a large order (which they weren’t ready for) or lose their deposit.  If everything went well that’s where the story would have ended, but after deceptive business practices the other supplier also shipped bad products and were difficult to work with.  At that point the customer contacted Hatch again and asked for help with getting out of their dilemma.  Typically we don’t get involved with this kind of situation, but the client seemed like good people in a bad position.  We agreed to help them fix the problems and manage production for the rest of their order from the first supplier before redeveloping the product ourselves.

As the first order was coming to an end Hatch started to redevelop and improve the product.  Hatch had the benefit of learning from the mistakes of the first development, which helped our development go smoothly and make the customer experience even better.

The device had several custom hardware requirements that deviated from the standard reference design, the electronics design which ‘off the shelf’ Android tablets are based on.  For example, remove Wi-Fi, Bluetooth, cameras, headphone jack, unnecessary apps, and increase battery size.  Also Hatch needed to add a second memory card slot and make both memory cards full size SD, while the reference design calls for one MicroSD size memory card.  Most of these hardware customizations also required related firmware modifications.

Second SD memory card slot for copying photos.

Result

The results were great.  A large part of the success came from the lessons learned from the first generation of the product.  Our client was able to earn a reputation for higher customer satisfaction than the competition (in their niche) thanks to the great job they did with redesigning their app and the improvements Hatch made to the hardware and firmware.  This allowed them to raise the retail price, helpful in offsetting the high costs of fixing problems with their first generation product.

It’s hard to predict how things go in business, but some situations create good stories when told in retrospect.  Sometimes, for whatever reason, people don’t connect with potential friends/customers/whatever on the first interaction, but a relationship develops in the future.  This client has turned out to be a great company to work with and Hatch provided key value to them.  Often companies contact us who aren’t ready to work with Hatch when they first reach out.  I try to guide them in the best direction for them rather than sell them services they’re not ready for.  Hopefully my guidance or something else they did brought success.  It’s always a pleasure to see companies flourish and become able to help them.