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Tag Archives: LIthium Polymer Battery

ON CAMERA

CAM#A

 

After my grandson flew his newly purchased quadcopter a few weeks ago, I was stunned by the quality of video produced by its camera.  During the course of this blog, we will trace the development of compact cameras, as well as their effect upon the radio control models.

The evolution of drone cameras began in 1901, when renown photographer George Lawrence conceived the idea of attaching a camera to a balloon to take photos of banquet halls and outdoor ceremonies.  Lawrence developed a panoramic camera with a relatively slow shutter speed, which proved idea for area photographs.  While his first balloon pictures were a success, both he and the balloon crashed, with Lawrence surviving a 200 ft. fall without injury.  He then developed a camera platform using a series of kites connected by bamboo shafts to support the weight of the camera and ran a steel piano wire from the ground up to carry the electrical current that would trip the camera shutter.  The photos were retrieved by parachute.  This system was so successful, Lawrence used it to photograph San Francisco after the 1906 earthquake – from which he earned $ 15,000.

However, it wasn’t until the advent of digital technology in the 1970′s, which allowed photography to become more adaptable, that compact cameras became feasible.  A digital camera is a hardware device, which takes pictures like a conventional camera, but stores the image to data instead of printing it to film. Most digital cameras are now capable of recording video in addition to taking photos.  Perhaps the earliest precursor to digital photography occurred in 1957 in which Russell Kirsch, a pioneer of computer technology, developed an image scanning program utilizing a rotating drum to create images, the first scanned image a picture of Kirsch’s son.  By 1969 a charge-coupled semiconductor was created by ATT Bell Labs, in which a semiconductor was capable of gathering data from photoelectric sensors, then transferring that charge to a second storage capacitor.  Analog data could be transferred from a light sensitive chip, which could be converted into a digital grid, producing an image.  In 1974 Bell Laboratories developed a charge transfer system, which could store and transfer charge carriers containing pixel data in serial order. This system was further refined by Bell in 1978, in which a charge transfer imaging device was produced using solid state technologies. This system was both more cost-effective, as well as preventing smearing aberrations created by similar image capture devices.

In 1973 Eastman Kodak took a gamble and hired Steve Sasson, a young electrical engineer. Sasson was one of a small cadre of electrical engineers employed by Kodak, a company well known for its chemical and mechanical engineering projects.  Sasson was directed to capitalize on the capabilities of a charge-coupled device created by Fairchild Semiconductor, which could transmit and store images of 100 by 100 pixels.   In 1975 Sasson completed a prototype camera incorporating a charge-coupled device, adapting a lens from an eight millimeter film camera, an analog -to-digital converter from a Motorola digital voltmeter, and a digital-data cassette recorder for storing image data.  With this combination, Sasson and other Kodak technicians could capture an image and record it to a cassette in a mere 23 seconds.

By 1990 several companies began to enter the digital photography market, creating a new segment for consumer cameras.  The first digital camera ready for sale in the US market was the Dycam Model 1, which came out the same year.  The Model 1 was capable of recording images at a maximum resolution of 376 pixels by 240 pixels.  Two developments in the 1990′s further enhanced the marketability of digital cameras.  The first was a codec, utilized for image compression, the precursor to the JPEG image file format of today.  This system exponentially increased the storage capacity of digital cameras over prior magnetic tape and floppy disc storage systems.  By the mid 1990′s Apple began to market the Quick Take 100, the most widely marketed digital camera in the United States.  The Quick Take had a maximum resolution of 640 by 480 pixels and could store up to 24 images in 24 bit color.  In 1995 Casio released the QV-10, the first consumer digital camera to include a to include a liquid crystal display (LCD) screen, which quickly allowed camera owners to review newly photographed images.  Other developments in the 1990′s included a pocketable imaging device with an LCD screen capable of displaying images from a camera storage device, as well as a single- lens digital reflex camera, which could reproduce camera images in 35mm film quality.  By the end of the decade, digital cameras had a resolution of 2,000 pixels by 2,000 pixels.

In the early 2000′s a merging of digital camera and lithium polymer battery technologies took place.  In the latter case, the flexible polymer battery began to deliver near gas engine performance with the attributes of less weight and volume on the rc model frame.  Digital cameras were now both lightweight and efficient, capable of both still photos and video covering a relatively wide area.  By 2010 a number of drones and smaller quadcopters  carried flash drive units, which could be inserted into the rc model camera to record flight video.  Once on the ground, the rc pilot would then insert the drive unit into the USB connection of a personal computer, playing the video of the quadcopter flight on the computer monitor screen – a far cry from pulling piano wire to trip a camera shutter.

 

DIG#10

 

 

 

 

 

 

 

 

 

CHARGE EM UP

Within the past fifteen years there has been a revolution in both types and capabilities of rc model batteries.  During this blog, we will attempt to analyze current types of batteries on the market and their best uses.

The NICAD or nickel cadium  battery was the first battery in use for rc models and has served the radio control pilot for decades.  NICAD batteries were first developed in Sweden, with the first practical batteries produced in 1906.   Nickel cadium batteries were first produced in the United States in 1946 and radio control enthusiasts began to use them in the 1950s.  They were popular because they had a higher power to weight ratio than gasoline engines in use on rc models of the time, although they had a limited endurance.  Nickel cadium batteries offer the advantages of a low internal charge resistance, producing high currents.  These batteries also have a relatively low self discharge (retaining its charge while stored) and their performance is not drastically affected by fluctuations in temperature.  Some of the disadvantages of NICADS are they are both heavier and bulkier than newer technology batteries, are not environmentally friendly, as well as gradually losing their charge capacity if not periodically drained and recharged.  Despite the availability of newer battery types, some rc hobbyists continue to use them when extremely fast performance Is required.

BATTERIES#1

Nickel-metal hydride (NIMH) batteries are chemically similar to nickel cadium cells while utilizing a hydrogen-absorbing alloy instead of cadium.  An NIMH battery has two to three times the capacity of an NICAD battery.  Nickel-metal hydride batteries were first tested in 1967 using a lanthanum alloy, which was both expensive to produce in addition to having a limited charge life.  After extensive testing in the 1970s and 1980s a practical battery using  a mischmetal alloy was developed in 1987.  NIMH batteries have the advantages of a higher capacity than NICAD batteries, in addition to retaining more of their charge capacity over time and being more environmentally friendly.  Nickel-hydride batteries can lose their charge faster than other types, and require an outside charger for peak efficiency, unlike NICAD batteries.  NIMH batteries are lighter than nickel-cadium units and more subject to breakage with imported batteries often running below stated capacity.  NIMH batteries are most often used in transmitter and receiver packs of rc model units.

A lithium polymer or LIPO battery is a rechargeable battery of lithium-ion in a soft pouch type structure, unlike NICAD or NIMH batteries.  The cells of the LIPO batteries contain liquid electrolytes with the polymer barriers used to separate the battery cells.  The electrolytes may also be gelled by a polymer additive to conduct current.  Lithium polymer batteries have been in use since the mid 1990s  and have a very high power to weight ratio.  They retain much of their charge in storage and are resistant to temperature changes.  However, they are sensitive to overcharging and rapidly discharging, posing a fire hazard due to the polymer chemicals.  RC models such as quadcopters now routinely use LIPO batteries attaining performance and endurance greater than many gas powered units.  There are two recent variations of LIPO technology which overcome some of the basic LIPO battery limitations.  The LifePO4 is more resistant to overcharging and discharging than the basic LIPO battery, as well as being less flammable .  The LifePO4 has an ever higher power to weight ratio than a regular lithium polymer battery.  The A123 battery, a modified LifePO4 utilizing nano technology, is able to deliver current at an even faster rate than the LifePO4 with greater safety.  Such batteries give the rc pilot revolutionary advantages of weight, performance and safety.