An acronym for “Two-Sided Thermal”, 2ST™ is a patented technology that allows simultaneous printing on both sides of thermal paper. This provides numerous benefits, included improved environmental impact, (less paper is used because both sides are printed, making a shorter ticket); the ability to use the back of a receipt for coupons or advertising; the ability to get more information onto a certain-sized space (by printing on the back); reduced changeover and obsolescence costs (by printing terms and conditions on the back rather than preprinting, unused paper with the old information does not have to be destroyed); and less frequent paper replenishment (since less paper length is consumed with each receipt).
A black area that is preprinted on paper or tickets and is used by the printer (in conjunction with an appropriate sensor) to make sure that the paper or document advances to the same, known point after every printout. This is especially useful when using preprinted tickets where printed information must be located in a specific spot. Black mark printing is not needed when printing from a continual roll of white paper since it doesn’t matter exactly where the printing starts on the paper itself. Black mark detection requires the use of a reflective sensor. The sensor light will reflect off the white paper surface but stop reflecting when reaching the black mark. This signals to the printer that the black mark has been reached.
More accurately called “Print Buffer”, this is a memory area of the printer that stores commands and data sent to the printer until it can be printed. Once printed or executed, the commands/data are automatically deleted. The higher the print speed the faster the buffer gets cleared and available for further data. If the buffer get full the handshake of the data comms interface signals “stop sending” to the host in order to avoid a buffer overrun.
A bundler is a device that is located on the output side of a printer to collect pages as they are printed, and present multiple pages to the customer all together (as a bundle) rather than one at a time. Without a bundler, a five (5) page printout would require the user to first take page one, wait while page two is printed, take page two, wait while page three is printed, etc. With a bundler, all five pages would be printed, then all five pages would be presented to the user at once. A bundler is used instead of a presenter, and usually provides all the benefits of the presenter (preventing vandalism by preventing user contact with the paper before its cut, retract capability, etc.). Typically, a bundler is used in bank statement printers.
Thermal printers by HENGSTLER include a feature that will adjust burn time of the thermal printhead automatically depending upon ambient temperature, a reason why we also speak of Temperature Compensation. Burn Time Correction allows the adjustment of these burn times to “tune” the printer to maximum performance for any given paper, thereby improving print quality but having some effect on current consumption. If current draw is truly critical, reducing burn times will reduce current draw slightly at the cost of lower contrast in the printout.
Besides temperature, the print speed has a certain impact on burn time. A paradoxon allows to reduce the burn time at higher print speed because the dots have less time to cool down and will heat up faster on the next dotline.
The optional chute/jam sensor continually monitors whether there is paper in the chute and can be read via the Status function. This function is often used in conjunction with the host’s peripherals to signal the user when a printout is not taken.
Examples where this is important include when the information is confidential, or the printout can be redeemed for cash or items of value. This function can also be used to prevent the host from sending a new print job until the printout from the previous print job has been removed. As printing takes place, the printer also “knows” how many paper advance steps have been made, and if the paper does not reach the sensor when expected, the printer assumes that a paper jam has taken place and signals this fact via the Status command.
Dot history monitors previously burned dots and reheats them for a shorter time to prevent blooming and excessively black areas, thereby decreasing total current consumption. On the other hand, a previously white dot is heated for a longer time to comensate for the colder spot. Using dot history helps improving contrast and edge sharpness.
A dual-feed unit is a specific device that is added to the paper feed side of a printer. The dual-feed allows two paper rolls or fanfold stacks to be fed into it, then the dual-feed unit selects (under command of the print controller) which roll should be used. The dual-feed unit can be programmed to either select the paper roll based on a command sent to it by the printer, or to switch from one paper roll to the other when the first paper roll is exhausted. Advantages of using a dual-feed unit include the ability to double the paper supply (and therefore the time between changing paper rolls), and the ability to switch between two different types of paper. One typical use for the second capability is to use thicker stock to print tickets, and then switch to a standard paper stock to print a receipt.
When in this operating mode (which is the default after power up or reset), you have direct control over what the printer does using Escape Command sequences. The printer has two operation modes you can choose from. In variable page mode, the printer acts as a simple word processor, printing text that it receives. It can also print various types of barcodes as well as predefined images stored in the flash memory. The selection of fonts and barcode types is limited to what is stored in the flash and the firmware of the printer. In this mode, information is printed in the same sequence as it is received. In fixed page mode, you can place rotated text, barcodes, images, and ruled lines. This mode provides more flexibility than variable page mode, but may be limited by available printer memory. Printout elements can be specified in any order. You instruct the printer when your layout is complete, and it is all printed at once.
This term refers to how a paper cutter severs paper. A full cut means that the paper is completely separated from the paper roll when it is cut, so it can fall freely. The advantage of full cut is that the printout is completely free after cutting and can be dropped into a chute or bin for customer access. Full cut is always used when a presenter is used, because the presenter must move the separated printout via its own paper transport mechanism. If full cut is used, the paper not yet printed can be retracted back into the printer to save paper on the next printout. The disadvantage of full cut is that the printout can fall to the floor, causing clutter and possible slip hazards, if it is not caught in a bin or something similar. See also “Partial Cut”.
Printing graphic images rather than text consumes usually more current than printing only text. Typical text-only printing is considered to be 12.5% coverage, while graphic or barcode printing varies from 25% to 50%, consuming 2x to 4x the average current. Both should be avoided or minimized if current draw is critical.
Graphic Printing vs. Printing with Printer’s Fonts
One area that causes frequent confusion with regard to printers in general is that of graphic printing versus printing using the printer’s internal fonts or barcode commands.
When printing from the internal character sets (we’ll call that Unicode or “ASCII printing” here for convenience), characters are sent to the printer and the corresponding characters from a preselected character set are printed. This has both advantages and disadvantages. The biggest advantage is that the host need only send one character per printed character. So, for a text string of 40 letters, for example, only 40 bytes of data (plus some overhead for formatting, indenting, etc.) need be transmitted over the data interface. In other words, you can print a lot of text and need to send only a little data. The downside is a lack of flexibility. In today’s Windows® world, we are all used to printing exactly what appears on our computer screens, in the same font, size, etc. as we see it. With ASCII printing, what will be printed is based on the printer’s internal character set.
This leads to the other type of printing which wel call “Graphic printing”. You can compare this to what happens when you print to an ink jet or laser printer from your PC. The installed printer driver, which is unique for each printer, translates what is on the screen as a graphic into graphic commands to be sent to the printer. Everything printed through a print driver prints as graphics. It takes a lot more data to transmit graphics than to transmit ASCII. In our 40-character example, assuming a text string of 12 x 20-pixel characters, would require ~1000 bytes to print (Please note that these are estimates, and that various compression algorithms help reducing the amount of data).
The advantage of Graphic printing, then, is the ability to print anything; pictures, text, photos, etc. exactly as you see it on your screen. The disadvantage is that it generates typically 20 to 40 times more data that must be sent to the printer.
As a practical matter, then, it comes down to this. If you are doing ASCII printing, you can use USB or a serial interface. Even with lower baudrate settings, both are fast enough to handle the smaller amount of data. But if you are doing Graphic printing, USB is a far better choice due to its higher speed, and serial may increase the time to complete a printout to an unacceptably long period or may infavourably impact the print speed.
Handshaking
Sometimes referred to as “flow control”, “handshaking” can be defined as communication between a computer system and an external device, by which each tells the other that data is ready to be transferred, and that the receiver is ready to accept it. Handshaking comes in numerous forms. From a perspective of our printers, we are usually the external device. Some interfaces use only a single form of handshaking (e.g., USB) so there are no printer settings to adjust. Other interfaces (e.g., RS-232) have multiple handshaking options. Since this must be considered in our printers usually when dealing with RS-232, we will use that as the example.
In RS-232, there are three common types of handshaking; hardware, software and none. In hardware handshaking, physical wires go between the computer system and the printer and are used for handshaking. If the RTS (ready-to-send) line of the computer becomes “set”, the printer recognizes this and checks if it has space for data. If it does, it sets its CTS (clear-to-send) line. If at any point, the printer detects that it cannot accept more data, it will reset the CTS line. The computer will recognize this and stop sending data. This is the basic principle of hardware handshaking. The advantage is that this approach is very secure. If the data is damaged by electrical noise, the handshaking lines still continue to control the data flow. The disadvantage is that additional wires are needed in the interface cable.
Software handshaking uses two special characters to signal “OK to send” and “Stop sending”. These characters are, respectively, called “XON” and “XOFF”. If the printer sends an XOFF character, the host will stop transmitting. When it’s ready to accept data, the printer will send an XON character. The advantage of this system is that only three wires are needed in the interface cable; signal ground, “send data”, and “receive data”. The disadvantage of this system is that the XON and XOFF characters can be lost due to interference or electrical noise. If an XOFF is lost, the host will continue to send characters indefinitely, and the characters in excess of the printer’s buffer will be lost, resulting in a printout with gibberish. For this reason, XON/XOFF is usually used in lower data volume applications and with slower baud rates.
“None” handshaking (meaning that no handshaking is used) is always somewhat risky. It assumes that the printer will always be ready to receive data. From a practical standpoint, it is usable in applications where only a ASCII printing is used, and the print buffer is large in comparison. We generally recommend customers use hardware handshaking, since it is the safest, but customers sometimes prefer the other two choices.
Please note that it is important that the interface and handshake settings of the printer exactly match those of the appropriate COMs interface of the host computer! After changing the comms settings, the printer and in some cases the computer must be restarted.
An additional Head Status Sensor is used to determine whether the printhead is in the up (do not print) or down (ready to print) position. Normally, most of the heat generated by thermal printing is transferred to and absorbed by the thermal paper as the it advances. When the printhead is up with no paper contact, all dot heating energy would remain in the thermal print head leading to overheating. Because this may cause permanent damage to the printer, the firmware will prevent printing or paper loading if the head is up. The output of this sensor is also available from the query function.
An area of a ticket or printout that contains a hole, and that is used by the printer to make sure that the paper or document advances and gets cut at the same, known point after every printout. This is especially useful when using preprinted tickets where printed information must be located in a specific spot. Mark printing is normally not needed when printing from a continual roll of white paper since it doesn’t matter exactly where the printing starts on the paper itself. Hole mark detection generally requires the use of a through-beam sensor with a separate transmitter and receiver. The light is continually blocked by the ticket or paper until the hole is reached, at which time the light reaches the receiver, signaling that the hole has been located.
Often, fan-folded ISO tickets provide tags between them leaving a gap of 1 to 3 mm in length. This gap can easily be used as the hole mark.
One advantage of hole marks over black marks is the fact that the paper can have any kind of pre-printing on either side like customer logos or advertisements with no impact on the sensor performance.
Private, confidential information, or valuable printouts, are often generated with thermal printers. Examples of these are banking information, train tickets, medical data, credit card numbers, or vouchers to be redeemed for cash. When these printouts are not taken by the user, or are only partially printed because of a power failure, it is desirable to hide the information and render the printout unusable under certain conditions. These conditions include after loading paper; at the end of paper; when data has been lost; and on initialization. In all cases, the purpose of the feature is to prevent printouts that might be partially valid from being misused. For example, if a train ticket had been in the process of printing and the printer ran out of paper, the printer would stop printing and automatically invalidate the partially printed ticket. This process is called “invalidation”. One common way to invalidate a printout is to overprint it with a complex, random pattern so that the original printout cannot be discerned.
Another example: to avoid that “empty” valuable paper is dispensed and cut upon paper loading, the printer will print an invalidation pattern on any piece of paper that is used during the paper loading.
This feature is a feature that will reduce peak current during printing. When this feature is turned on, only one half of the printhead is fired at a time, reducing the peak current by a factor of typically two, but having virtually no effect on average current. This is very useful if your power supply has a restrictive maximum current but slows printing.
There is a sensor in the paper entrance area that serves several functions. First, it detects paper during paper loading and signals the printer to begin the paper autoloading function. When the paper runs out during printing or upon removal, this sensor detects it accordingly, too.
In many cases, the same sensor is also used to detect Black Marks or Hole Marks depending on sensor type. See also “Black Marks” and “Hole Marks”.
The most common sensor type is the reflex or reflective sensor, where the light source and detector are located on a single chip. Basically, the light strikes the white paper surface and reflects back into the sensor. If enough light reflects to activate the sensor, the printer concludes that paper is present. If there is not enough light reflected, the printer assumes that this area is black, meaning the printer is on a black mark or after some feeding distance the printer is out of paper.
A through-beam sensor has a light source on one side of the paper and the detector on the other side of the paper. When the light is blocked and cannot reach the detector, the printer
concludes that paper is present. When the light does reach the sensor, the printer concludes that there is no paper present. Usually, the through-beam sensor is located on the centerline of the paper path.
A sensor on the exit side of the print mechanism detects when paper has passed through the cutter assembly and reached the paper exit. This sensor serves different pruposes. It is used to monitor the paper movement upon paper loading and can detect if there is a paper jam. On the other hand, it also monitors if a printed receipt has been taken by the customer after it has been presented through the panel.
Paper Pre-End (Paper Low) Sensor
Paper Pre-End (often abbreviated by “PPE”) sensors are typically shipped to be mounted by the customer. The sensor is a reflex type, meaning that it senses paper by bouncing light off the paper and detecting its reflection. The sensor is equipped with a long cable to allow flexible mounting by the customer, and the sensor itself is mounted on a small printed circuit board with a hole to be used for mounting it. Simply mount the sensor where it will detect paper low (it is often mounted facing the side of the paper roll, so that as the diameter of the paper roll decreases, it eventually loses the reflection of the light and changes state). The PPE sensor cable plugs into the appropriate connector on the printer’s control board.
In some rare cases, a micro switch with an arm and roller is used to register the remaining diameter of a paper roll or stack.
This term refers to how a paper cutter severs paper. A partial cut means that a small portion of the paper is not cut, so the paper will not fall. A user must pull the paper to separate it, but it requires very little force to tear the small remaining tab. Partial cut is often used to prevent cut receipts from falling on the floor or leave multiple copies of printouts together for archiving or other legal purposes.
With partial cut, the paper hangs out of the front of the cutter waiting for someone to take it. Also, while very difficult, it might be possible for a vandal to pull paper out of the printer slowly until they can grip paper behind the partial cut, and then pull the entire paper roll out through the printer. HENGSTLER can offer a smart solution to prevent such. Please feel free to contact us for details.
Our partial cut cutters leave the small paper tab connection near the middle of the printout; some competitive cutters leave it at one of the edges. See also “Full Cut”.
The XPM 80™ and XPM 200™ use a “pizza-cutter” style paper cutter. A cutting disk moves from one side to the other to sever the paper from the roll against a stationary, fixed blade. A separate motor is used to control a helical cam that moves the “sled” holding the cutting disk. Sensors are located at the end of travel for this cutter, so the controller can detect where the cutter blade is and determine in which direction it should be moved to cut the paper.
A presenter is a device that is located on the output side of a printer and which prevents the user from touching the printout before the printout is printed completely and cut. After the printout is cut, the presenter will transport it out the front of the device to the user. In some versions, a Retract (sometimes called “Reject”) function will pull the printout back into the presenter and drop it in a recycle bin if it is not taken after a certain length of time.
Presenters generally have two primary functions; 1) to prevent vandalism by preventing the user from contacting the paper before it’s printed and cut. Without a presenter (or an alternate solution), vandals could grasp the paper and pull paper off the roll through the printer; 2) to prevent untaken printouts from falling on the floor accumulating, thereby causing a mess and a slip hazard to passersby. Because presenters add cost to a printer solution, other solutions are sometimes used to prevent vandalism. One common one is to locate the printer inside the kiosk or housing and have it drop the printout into a chute. By positioning the printer high enough and making the chute long enough, the user can’t touch the printout until after it’s cut and falls.
A printer driver is a special piece of software whose purpose it is to inform the operating system (for example, Windows 10 or Linux) about all important characteristics of the printer and to translate graphic images into proper format and commands specific printer attached to the computer system. Please note that, when a different operating system is used, (for example, Linux instead of Windows), a different driver is needed. Also, since printers generally have different native commands, each printer requires its own printer driver. Because printer drivers work by breaking down whatever needs to be printed into graphics, and sending that graphic information to the printer, they must send more data than sending the printer text and employing the printer’s internal character generators. It is important to remember that everything sent to the printer via a printer driver prints as graphics. See Graphic Printing.
Besides performing the graphic printing, the driver package also provides various APIs (application programmer’s interface, typically via DLLs) that help programmers to build printer functions into their runtime application and communicate to the printer direct in parallel to the operating system (when there is no active printing through the spooler). A typical example is the use of bidirectional communication to query the printer’s status before, during and after a transaction, like checking for the readiness status of the printer or success the recent transaction or query statistical information from the printer’s internal log file.
Further to this, the driver package (Windows) also provides a collection of tools for development, diagnosis, testing, configuration, firmware upload, font and image definition etc.
With print density we refer to the energy settings of the printer in terms of effective burn time (the length of time the dots are “fired” for each dotline). Increasing print density usually improves print quality, but at the same time will increase average current draw. Therefore, print density is always a trade-off between these two characteristics. Use the density settings according to “as little as possible but as much as necessary”
If the print density is set too high, the thermal paper may inversly react and generate an overburned image that will look grey instead of black. Excessively high print density settings can impact the life of the printhead.
Print Speed is a parameter that can be set in the printer’s configuration by command or tools provided with the driver packages or instructed by the driver of the operating system in conjunction with each graphic receipt to be printed.
Print speed is affected by various factors. First, the maximum print speed is dependent upon the operating version of the printer that you ordered. Even with the maximum print speed in the firmware set to 350 mm/sec, 12 Volt models will not exceed ~180 mm/sec. Other significant factors affecting print speed include:
A shutter is a physical barrier that will close the slot through which the paper is presented to the user in order to prevent vandals from spraying liquids into the slot. They are often used with presenters and bundlers.
