FAQs

How do mechanical day and night cameras work?

These cameras incorporate IR cut filters which automatically move over the CCD sensor for daytime(color) usuage, to prevent IR light to the CCD. At night time, the filter...

These cameras incorporate IR cut filters which automatically move over the CCD sensor for daytime(color) usuage, to prevent IR light to the CCD. At night time, the filter will be removed automatically to bring in IR right to the CCD, and maximize the low light sensitivity with black and white image.

What is an optical low-pass filter (OLPF)?

In high-quality digital maging systems, optical low-pass filters (OLPF) are used to eliminate color Moire fringes. An OLPF cuts off the lens MTF above the sampling freque...

In high-quality digital maging systems, optical low-pass filters (OLPF) are used to eliminate color Moire fringes. An OLPF cuts off the lens MTF above the sampling frequency of the imager resulting an overall MTF curve that approximates a step function in spatial domain. IR cut-off function is often incorporated into OLPF as well.

What is WDR?

Wide Dynamic Range (WDR) technology uses two shutter speeds in alternative video fields, high and normal, and combines these two fields into one frame. It allows every de...

Wide Dynamic Range (WDR) technology uses two shutter speeds in alternative video fields, high and normal, and combines these two fields into one frame. It allows every detail to be captured accurately even if one portion is bright while other portions are dark. As a result, combined fields yield a frame of high quality images. Below is a comparison of camera technologies with its video images of Regular, Backlight Compensation (BLC), and Wide Dynamic Range.

What is (IR)LED ?

A light-emitting diode (LED) is a semiconductor device that emits visible light when an electric current passes through it. The light is not particularly bright, but in m...

A light-emitting diode (LED) is a semiconductor device that emits visible light when an electric current passes through it. The light is not particularly bright, but in most LEDs it is monochromatic, occurring at a single wavelength. The output from an LED can range from red (at a wavelength of approximately 700 nanometers) to blue-violet (about 400 nanometers). Some LEDs emit infrared (IR) energy (830 nanometers or longer); such a device is known as an infrared-emitting diode (IRED).

An LED or IRED consists of two elements of processed material called P-type semiconductors and N-type semiconductors. These two elements are placed in direct contact, forming a region called the P-N junction. In this respect, the LED or IRED resembles most other diode types, but there are important differences. The LED or IRED has a transparent package, allowing visible or IR energy to pass through. Also, the LED or IRED has a large PN-junction area whose shape is tailored to the application.

Benefits of LEDs and IREDs, compared with incandescent and fluorescent illuminating devices, include:

  • Low power requirement: Most types can be operated with battery power supplies.
  • High efficiency: Most of the power supplied to an LED or IRED is converted into radiation in the desired form, with minimal heat production.
  • Long life: When properly installed, an LED or IRED can function for decades.

What is a CMOS camera. How is it different from a CCD camera?

A CMOS sensor is a kind of sensor that is normally 10 times less sensitive than a CCD sensor. A human eye can see objects under 1 lux illumination (a full moon night). A...

A CMOS sensor is a kind of sensor that is normally 10 times less sensitive than a CCD sensor. A human eye can see objects under 1 lux illumination (a full moon night). A CCD sensor normally will see better or as good as a human eye in the range of 0.1~3 lux and is 3 to 10 times more sensitive than a CMOS sensor.

Why is an IR filter in color cameras necessary?

An IR filter (IR cut filter), is a color filter blocking the infrared light. There are several good reasons for using an IR-cut filter. Using a color camera to achieve re...

An IR filter (IR cut filter), is a color filter blocking the infrared light. There are several good reasons for using an IR-cut filter. Using a color camera to achieve realistic colors in white light requires an IR-cut filter. The color spectrum seen by the human eye is quite limited compared to the spectrum seen by a CCD camera. In the near infrared region of the spectrum, the difference in sensitivity is significant. This is important to know since many light sources, including the sun, emit infrared light. A CCD color camera in daylight without an IR-cut filter will therefore see a significant amount of infrared light resulting in strange colors. Another reason for using an IR-cut filter is the limited color correction for many lenses. It is difficult to design imaging optics covering both the visible spectrum and the near infrared spectrum at the same time. Therefore, many lenses have different depths of focus for the visible and the infrared spectrum. The IR-cut filter blocks a significant amount of the overall collected light and thereby affects the sensitivity in a negative way. In general, color cameras are one factor less sensitive compared to monochrome (depending on the CCD chip). This is primarily due to the IR-cut filter.

What is super smear rejection?

The photo on the left shows an image of a back illuminated rectangular aperture with an exposure time of 1ms in a stretched scaling (48-100 counts correspond to 0-25...

The photo on the left shows an image of a back illuminated rectangular aperture with an exposure time of 1ms in a stretched scaling (48-100 counts correspond to 0-255 gray levels). The white line indicates the position of the readout pixel row shown in the next graph. The right photo shows an image of the same aperture with the same scaling at 100ms exposure time and reduced back illumination. The resulting right image has the same intensity values like the left image.

If an interline-transfer-CCD-image sensor is read out, the generated charge carriers are transferred from the light sensitive part (photodiode) of a pixel to the shift register, which is next to the photodiode and acts like a potential bucket. Because of the weak light sensitivity of these shift registers, they are shaded to prevent the additional generation of charge carriers. When the charge transfer to the shift registers is complete, they are shifted vertically row by row to the horizontal readout line, which is read out in a serial way. This vertical shift of row by row can be best compared with an endless conveyor belt process. With every shift step all registers are shifted by one register location including register rows that were already drained from the image.

If an intense light source is imaged to the CCD-image sensor, this can generate unwanted charge carriers in the shadowed shift registers (mainly due to scattering of light on the CCD chip) in every line or row, which is shifted below the spot. This results in unwanted additional light signals, called “smear”, which can be recognized as bright vertical bands above and below the bright image spot. This phenomenon is more often seen at very short exposure times (because the light signal has to be intense to achieve a good image with a sufficient signal-to-noise ration) and is a characteristic of the corresponding CCD-image sensor.

What is RS422, RS485, and RS232?

RS 232 is well known due to the popularity of today’s PCs. These are used in industry for control systems and data transfers (small volumes, not hundreds of Mb...

RS 232 is well known due to the popularity of today’s PCs. These are used in industry for control systems and data transfers (small volumes, not hundreds of Mb/s).

So, what is the main difference between RS 232 and RS 422 & 485? The RS 232 signals are represented by voltage levels with respect to ground. There is a wire for each signal, together with the ground signal (reference for voltage levels). This interface is useful for point-to-point communication at slow speeds. For example, port COM1 in a PC can be used for a mouse, port COM2 for a modem, etc. This is an example of point-to-point communication: one port, one device. Due to the way the signals are connected, a common ground is required. This implies a limited cable length of about 30 to 60 meters maximum. The main problems are interference and resistance of the cable. Put simply, the RS 232 cable was designed for communication of local devices, and supports one transmitter and one receiver.

RS 422 & 485 uses a different principle: Each signal uses one TP line (two wires twisted around themselves). We’re talking balanced data transmission, or differential voltage transmission. Simply, let’s label one of the TP wires ‘A’ and the other one ‘B’. Then, the signal is inactive when the voltage at A is negative and the voltage at B is positive.

Otherwise, when the signal is active, A is positive and B is negative. Of course, the difference between the wires A and B matters. For RS 422 & 485 the cable can be up to 1200 meters (4000 feet) long, and commonly available circuits work at a 2.5 MB/s transfer rate.

What is the difference between RS 422 and RS 485? The electrical principle is the same: both use differential transmitters with alternating voltages 0 and 5V. However, RS is intended for point-to-point communications, like RS 232. RS 422 is intended to use two separate TP wires, so that data can be transferred in both directions simultaneously. RS 422 is often used to extend a RS 232 line, or in industrial environments.

RS 485 is used for multipoint communications: more devices may be connected to a single cable (similar to ethernet networks), which use coaxial cables. Most RS 485 systems use Master/Slave architecture, where each Slave unit has its unique address and responds only to packets addressed to this unit. These packets are generated by the Master unit, which periodically polls all connected Slave units.

What is a Super HAD CCD camera?

Super HAD CCD is a trademark of Sony Corporation. The Super HAD CCD is a version of Sony's high performance CCD HAD (Hole-Accumulation Diode) sensor with sharply improved...

Super HAD CCD is a trademark of Sony Corporation. The Super HAD CCD is a version of Sony's high performance CCD HAD (Hole-Accumulation Diode) sensor with sharply improved sensitivity by the incorporation of a new semiconductor technology developed by Sony Corporation.

Our various KT&C cameras come with SONY SUPER HAD CCD!

Efforts for more pixels and smaller CCD size have resulted in a smaller aperture area of sensor, presenting the problem of lower sensitivity. To improve this, a lens has been provided on the top of the sensor for focusing, which increases the virtual aperture area of the sensor for higher sensitivity. That is what is called the on-chip micro-lens. Sony, the first to adopt it for the CCD image sensor, has thus successfully achieved higher sensitivity.

The Super HAD CCD sensor optimizes the shape of on-chip micro-lenses in order to minimize the invalid area between micro-lenses on each pixel, which thereby minimizes the lost incident light. Doing this improves the sensitivity per unit of area in our products, despite reducing the unit pixels.

Comparison of Conventional CCD and Super HAD CCD Sensor Structure

On-chip Micro-lens of Conventional CCD Conventional CCD Sensor Structure
On-chip Micro-lens of Super HAD CCD Super HAD CCD Sensor Structure

 

What is an EX-View CCD camera and what's good or bad about it?

"EX-View" is a sensitivity-enhancement technology developed by SONY to improve light sensitivity of its CCD by a factor of two for visible light and a factor of four for...

"EX-View" is a sensitivity-enhancement technology developed by SONY to improve light sensitivity of its CCD by a factor of two for visible light and a factor of four for near-infrared wavelengths."

EX-View is a proprietary SONY technology in which the P/N junction of each photodiode in the CCD matrix is specially fabricated to have much better photon-to-electron conversion efficiency. In addition, each photodiode (representing one pixel in an image) has a microscopic lens fabricated over it to better capture and focus light onto the active semiconductor junction. This results in an improvement in light sensitivity of 2 times for visible light and 4 times for near-infrared (800 ~ 900 nm) compared to the conventional CCD versions offered by SONY. The lux rating of the EX-View CCD is two times better than the premium SONY “Super HAD” CCD for both visible and near-infrared wavelengths.