Company Gmini traces its history back to 2008, when the market was presented the first Full HD player Gmini MagicBox. Since that time, the range of the company’s products, of course, became much wider: today, this brand offers not only various audio and video devices, but also e-books, IP and action cameras, video recorders, chargers for various gadgets and mobile batteries (powerbank).
On the official website there is section “Health”, in which while there is a single device — infrared thermometer GM-IRT-860D. I will start a series of reviews on some products Gmini.
Overview pyrometers, IR thermometers and measurements with them
Thermometers (this is a class of measuring devices, infrared thermometers are one of its components) is designed for remote non-contact measurements of temperature of different objects.We will not hesitate to tell about their classification, physical principles of functioning and cites numerous examples of usage and focus only on the category that applies to Your model: cheap portable infrared thermometers, designed primarily for use in the home or other purposes that do not require neither high precision nor a very wide range of measurements, nor the collection and subsequent automated analysis of large volumes of data.
But even in these limits there’s a lot of options.
Some of these devices are designed to measure temperature of different objects or surfaces (for brevity, we will continue to call them multi-purpose), others — to work with the human body (medical), and still others combine both of these capabilities (let’s call them combo).
I have to explain the difference. For measurements related to the human body, requiring high accuracy (for the considered model Gmini stated ±0.2 °C), while the accuracy is similar for the price of multi-purpose thermometer is usually ±2% or normal body temperature was 36.6 °C, they can display and as of 35.9 °C, and as of 37.3 °C, both these values may indicate disease.And very often for low-cost models have a question, is there a limit of error of the current measurement or limit of the scale — for example, 200 °C (then the deviation at all can be plus or minus 4 degrees). Sometimes gracefully specifies “±2% or ±2 °C” and understand it as they want…
And do not confuse measurement accuracy with the bit mapping, that is, the number of digits on the display, including the decimal point. Very often, for example, a cheap household electronic scale is specified “accuracy: 0.1 g”, and an uninformed buyer quite believe, because the scoreboard really weight is displayed in tenths of grams. In fact, these figures can not be taken into account, and what about the first digit before the comma is questionable. The same applies to the IR thermometer.
To ensure high measurement accuracy over a wide temperature range is difficult, therefore, for combined IR thermometers, the error often indicates different: less for body temperature and more to work with objects, and in the second case it may differ for positive and negative temperatures (of course, if this model supports such values).
The difficulty is not only with range but with another parameter associated with the object of measurement. He is called the coefficient of emission depends on the reflectivity of the surface of the object (so it is also called the degree of blackness) and can be in the range from 0 to 1. The value can vary not only depending on the material of the object, but also on the state of its surface: copper with a rough (diffuse) surface coefficient of emission of about 0.2, oxidized copper — 0,7-0,8, polished — 0,02-0,07.
Accordingly, the readings of the pyrometer for two bodies of equal temperature, are made of different materials or differently treated surfaces, can vary greatly.
For human skin the average value of emission factor very close to unity and is 0.97, however, depending on conditions and individual characteristics can sometimes be from 0.84 to 1.
In advanced models, IR thermometers, you can manually enter the emissivity and the temperature will be displayed with the corresponding amendment. A specific value, often in the form of tables, can be found on the Internet, but the trouble is that for the item of interest in them is not always possible to find your desired numbers, and if they are in the form of a range.
The device allows easier to enter the correction in degrees (or fractions of degrees), that for non-professional purposes can be even more convenient. Well, in the cheapest thermometers the differences in reflectivity of objects, or not counted at all, or set emission factor of 0.95, and to change it it is impossible.
Another important factor that may affect the measurement, connected with optical resolution, which is understood as the ratio of the spot size on the surface of the inspected object, from which the thermometer takes readings, and the distance from that surface. If quite simply, imagine an ordinary flashlight: it is the light directed to the wall, with a distance of one meter and three meters will create spots with significantly different diameters, the degree of difference will depend on the optical system of the flashlight.
The same with the thermometers. The larger the diameter of the “spot” at a given distance, the higher the probability that it will go not only to the examined object or its important part, but also something foreign, therefore, at large distances it is better to choose models with higher optical resolution (for example, 12:1) — they “beam” is more narrow.But if such a device is used at very small distances, the “spot” becomes very small and it can get only a component object with an emission factor, not characteristic of the subject as a whole (example: the head of the fastening screw), and temperature measurements will be incorrect; then it is better to use the optical resolution of smaller — say 4:1.
For some models not specified optical resolution, and the optimal working distance range, and that is what we see in specifications GM-IRT-860D.
Finally, the measurement modes. In simple models may provide only “one button start measurement — single value”, and in more advanced and even continuous scanning, sometimes not only display the current values, but also with a separate fixation of minimum and maximum. This is useful, for example, when examining the surface of a considerable size or if the object’s temperature is changing rapidly. Let’s see more detail info about one the best infrared thermometer.
Consider the above example on the Gmini GM-IRT-860D.
Characteristics, appearance package
The stated characteristics shown in the table.
|The range of measurement body temperature||35-43 °C|
|The accuracy of the measurement of body temperature||±0.2 °C|
|Measurement range surface temperature||0-100 °C|
|The accuracy of surface temperature measurements||±1 °C|
|Measurement time||0.5 sec|
|Distance measurement||5-15 cm|
|Working environment temperature||10-40 °C|
|Permissible ambient humidity||80%|
|Estimated price||20 usd|
The appearance is quite typical of hand-held tool device has the shape of a gun. On the handle there is a recess under the three fingers, making the grip more comfortable (up to size hand: settlement was clearly on women’s graceful brush, although larger men’s special inconveniences does not feel), and the measurement start button is pressed the index finger is a trigger (the details of which have not passed the military service of the citizens and especially citizen called “trigger”).
In the handle is located and a compartment for two AA batteries. The weight of the device together with the battery (according to our measurement) is only 140 grams.
On one end coupled with the handle unit of measurement is the LCD screen and the group of four buttons, on the other — hole IR sensor and laser emitter, the red beam is used for accurate guidance on “purpose”.
The details of the body have two colors: milky white and, depending on the delivery option, either pale green or blue.
Thermometer is Packed in a beautifully decorated box, included is also case-pouch of velvety material, two alkaline batteries, book manual in Russian and warranty card.
Work with IR thermometer
Like other similar devices, the measurement itself is very simple: click on “trigger” and get a reading on the indicator.
And then start the nuances. The text on the screen (they are few, but they are there) can be in English or Chinese. Don’t be alarmed, seeing the characters: you just click and hold the little yellow “Mode” button, then there will be English words. However, they are also not all may be familiar, so please explain. There are two modes of measurements: marked as a medical Body (“body”), it has an increased accuracy, but the range of measurement lies between 35 and 43 °C, lower or higher temperature simply are not displayed, the system displays only the letters Lo (Low, low) or Hi (High, high).
For measurements in this mode it is necessary to direct the pyrometer on the forehead or the ear, as other parts of the body even in a healthy person can have a temperature significantly different from the usual 36.6 in. It is theoretically possible to measure and in the armpits — remember familiar from childhood with the installation of a thermometer, but if you use a pyrometer such action will require the removal of clothing, and therefore sense it has no: guide to the forehead is much easier, and the result is the same (of course, if people didn’t come just from severe frost).
To attract attention in case of high temperature and changing the color of the backlight: up to 37.5 °C it is green (cause for concern) between a 37.5 and 37.9 orange (dangerous but not very), and above — red, but still hear five-times buzzer (serious danger!). Temperature is below 36 °C may also indicate some health problems, but found a similar much less, so the developers decided to do without a change of the backlight in such cases.
In the second mode, labeled Surface (surface), the range is much wider: from 0 to 100 °C (above and below will display Hi or Lo), but the error is greater. Naturally, the “color differentiation
pants temperatures” no: the light is always green.
Mode Body still shows the number in the lower right corner of the indicator marked “Log”. This number of memory devices that record the temperature readings taken during the previous measurements; they can be up to 34, and upon reaching cell number, the record will be continued with the 1st, erasing available there. Displaying the values is at least two black buttons.
In Surface mode the values are not remembered — apparently, the developers have decided that it is not too important, especially given the limited amount of memory; what is logical. However, for medical purposes it would be nice to record not only the temperature but the time of measurement, but to demand from such an inexpensive device it is impossible.
The modes differ not only this. For Body each press of the start button means obtaining one measurement, the value of which is stored in the memory; if you continue to hold the button, nothing happens. For Surface and holding the button will give a continuous scanning: when you send the thermometer to a different object or part of object with a different temperature, the readings will change and so will be until we release the button.
By the way, specified in the specification of the optimal measurement range of 5-15 cm, most likely, it refers to the mode of the Body, where increased accuracy is required. In Surface mode, the device works perfectly and from a greater distance, but it is necessary to take into account what was said about optical resolution.
After 7-8 seconds after pressing any of the buttons the screen turns off to conserve battery. Return to operating mode takes place only after pressing “trigger” (at the same time and froze), the other buttons such influence have not.
There is a menu of presets, in which only three points: the units — Celsius or Fahrenheit, and disable the alarm, as well as an amendment from -5 to +5 °C in increments of 0.1 °C.
Even without this menu by pressing the available buttons can not only change the language, but also to disable-enable lights, laser and sound, and erase the contents of memory cells is set to current or all at once; the details are in the instructions.
I should definitely say: the temperature is read not with the red dot generated by the laser emitter, and region, mostly located just below it (the size of this region depends on the distance to the subject, see said earlier about optical resolution). So even if you just will induce a laser beam on some small detail, it is not necessary to think that on the display will the temperature of this circuits.
And most importantly: the laser emitters are extremely dangerous for the vision — in contact of the beam in the eye of a human or animal can come tragic consequences, sometimes irreversible. Despite the presence of an appropriate warning in the instructions, we generally believe the presence of such a “pointer” is unnecessary in household IR thermometer, designed to work with distances not exceeding 15 cm; or the developers felt that the only sniper-Pro can’t miss with this range, and all other necessary “laser sight”?!And especially high risk medical measurement when measuring temperature the thermometer is directed to the face.
Of course, this emitter in the thermometer Gmini switchable, but not the fact that the user will not forget to do it before you send the device to the person themselves or their children. Moreover the laser can easily be included, and there is no guarantee that children will not play with such a interesting thing.
Perhaps someone will ask: and how guilty contact thermometers, especially for medical purposes, where they have higher accuracy? We’re not talking about unsafe mercury, and the mean e: a lot of models offered, and the prices are lower.
The answer is simple: remember how much you had to hold a mercury thermometer under the arm? That’s right: at least 3-4, but preferably 5-6 minutes. Modern electronic contact thermometer requires smaller 30-60 seconds. Well, the pyrometer measurement time — less than one second!
Besides, it is more hygienic: the body does not touch, and if they are different people, that there is no danger of infection transmission.
And all of this is especially critical if you need a short term to measure the temperature at a large number of people. For example, to monitor the condition of passengers who arrived by flight from the area where the identified dangerous disease, or children in multiple classrooms or groups in kindergarten during the epidemic of influenza. With contact thermometers, the problem becomes virtually unsolvable, but the IR thermometer, it is quite capable.
Finally, non-contact temperature measurements do not disturb the patient: a person may continue to sleep peacefully, and an attempt to use a contact thermometer will surely Wake him up. This is especially appreciated by parents of young children.
Some tests, recommendations
With the testing phase had problems: what to check? Is that accurate — so we do not have precision temperature meter.
Of course, some of the tests we did. First of all verification of declared functions, here there are no comments.
Test accuracy is also conducted for mode Body, where a large error can not be called valid. Compared with a mercury thermometer in a standard place (in the armpits) he showed 36,6 °C, and at the same time froze on his forehead with GM-IRT-860D gave 36.8 °C, and in the ear to 36.7 °C. Even without the quite slight difference in temperature in these three locations, the deviation still fit him in the frame of ±0.2 °C (besides the thermometer and the error is also not zero). For the test we used several people, adults and children;the spread of readings were within specified limits.
The accuracy of measurements in the regime of Surface harder to judge, but it is possible to assess the impact of emission factor: in our laboratory we tested the device on different surfaces for a long period of time were practically the same temperature conditions (in the same room close to each other and at the same height, without heating — house and located next to heating appliances or electronic devices). So:
|the cupboard door (chipboard with laminate flooring in light wood)||24,6 °C|
|wall (plaster, painted in a light beige color)||24,0 °C|
|metal surface (painted in Matt white color)||24,3 °C|
|metal surface (smooth, unpainted)||25,9 °C|
|a vessel made of dark brown plastic||23,1 °C|
|a vessel made of white plastic||24,8 °C|
|white ceramic mug||24,1 °C|
As you can see, the scatter turned out noticeable. Of course, we have no guarantee that all these items had exactly the same temperature, but there is justifiable confidence that the main contribution to the difference reached almost 3 degrees made it the different emission factors. In very many cases it can be neglected, but if, for example, it is necessary to precisely measure the temperature of the liquid in some vessel, say, baby food for which a deviation of a few degrees can be critical — you’ll have to do better, “Tara”.Make it easy: once is enough to measure a contact thermometer, and then compare with readings of the thermometer and remember the difference.
Recommendations for the use of
We now give some General recommendations of the plan, which will help to ensure the normal operation of the device and acceptable measurement accuracy.
First of all, check the condition of the battery (on the LCD screen there is an item indicating a strong degree — when he appears, do not skimp and replace them). By the way, the laser “sight” consumes a lot of energy, so disabling it will not only protect your eyes but also extend the life of the batteries.
Keep clean the lens of the IR sensor.
Remember that the operation of the unit at certain temperatures, and above and below the specification range, it can begin to “lie”.
When measuring the temperature of the body (forehead) is also possible deviations of emission factor — for example, if the forehead is covered with perspiration, the thermometer can give erroneous readings.
Although the instructions mention a measurement in the ear, it is better to measure the temperature on the forehead, as the ear is the organ with difficult terrain and direct the IR thermometer at the right place is quite difficult: doctors recommend to be measured in the ear in General, and in the opening of the ear canal and send a sensor with a recommended minimum distance of 5 cm you are unlikely to succeed.
When in doubt it is better to make several measurements for one point and take the average value, and the time interval should be substantial — at least 15 seconds. And of course, don’t forget the recommended distance of 5-15 cm
In children, the heat transfer is somewhat different than in adults. Before measuring the temperature the child should not move actively, it is not necessary to do the measurement immediately after coming off the street and after taking hot or very cold food (drink). For babies, many pediatricians and is recommended to use only the contact thermometers.
Finally, all measuring instruments require periodic calibration after prolonged use or storage of their testimony can “float away”, so you need to adjust. In the case of the Gmini device can be recommended to carry out temperature measurements on the forehead (of course, you have to be sure that it is normal), and in the case of constant significant over or understatement of the amendment using the appropriate menu item.
The company Gmini infrared thermometer GM-IRT-860D is a simple and easy to use household device designed to measure body temperature in the range from 35 to 43 °C and surfaces of different items in a much more wide range — from 0 to 100 °C.
Testing confirmed its functionality, as well as the accuracy sufficient for medical purposes.
Of course, this is not the only IR thermometer of this class on the market, but you have to remember that they are just appliances, not precision laboratory instruments, and to treat their testimony should be appropriate, given what we have said above.