Compact billing device

Abstract

Provided is a portable billing device and method that enables electronic bill generation from calculator-style arithmetic expressions without requiring explicit product registration or mode switching. The device comprises a compact display, a calculator keyboard, a processing subsystem with memory, and optionally a printer and communication subsystem. During normal operation, the device functions as a standard four-function calculator, storing all key presses and corresponding operators in an operation history. When a user actuates a designated billing key, the device compiles a structured bill with calculated totals, which may be printed or electronically transmitted to customers. The device supports optional features including customer identification, credit sales tracking, change calculation, and cash balance reconciliation, all while maintaining the simplicity and familiarity of calculator operation.

Description

Compact Billing Device

[0001] The present invention relates to compact electronic devices for billing, electronic cash registers, inventory and point of sale devices for use in retail and wholesale industries.

[0002] Many small retailers still rely on manual billing processes, utilizing handheld calculators to perform calculations and issue handwritten receipts. This manual approach is time-consuming and prone to human error. Retailers must calculate totals, issue bills, and generate sales summaries, often relying on a combination of calculators and traditional pen-and-paper methods.

[0003] Thus, there is a significant need for an innovative electronic billing solution that is cost effective, portable and ease of use like handheld calculators.

[0004] The present invention provides a compact, portable billing device and associated methods that enable electronic bill generation directly from calculator-style arithmetic expressions, without requiring explicit product registration, mode switching, or changes to existing manual billing practices. The invention is particularly suited for small retailers, mobile vendors, and informal businesses that currently rely on handheld calculators and handwritten bills, and for whom conventional point-of-sale (POS) systems are too complex or expensive.

[0005] In one aspect, the invention provides a portable billing device comprising a compact display, a calculator keyboard including numeric keys and operation keys, a memory, and a processing subsystem. During normal operation, the device functions as a standard calculator; user inputs are received through the calculator keyboard, arithmetic expressions are evaluated, and intermediate or final results are displayed. Simultaneously, the device records each key press and corresponding operator in an operation history stored in memory.

[0006] In another aspect, the invention provides methods for operating such a portable billing device. The methods include receiving a sequence of key presses representing an arithmetic expression, storing this sequence as an operation history, and, upon detecting a designated billing key (such as an EQUAL key, PLUS key, SAVE key, CREDIT key, PRINT key, or similar), parsing the stored expression to generate line items and a bill total. If the designated billing key is never actuated, the device behaves entirely as a conventional calculator, thereby preserving the familiar user experience and avoiding the need for the user to change modes.

[0007] In certain embodiments, the portable billing device further includes an integrated or connected printer for printing physical bills, and / or a communication subsystem for electronically transmitting bills to customers via SMS, messaging applications, or other electronic channels. Additional features may include customer identification and credit sale registration using a phone number or other identifier, calculation of cash received and change due, and generation of daily, monthly, and yearly sales summaries stored in non-volatile memory.

[0008] By reusing familiar calculator keystrokes and retrospectively converting them into structured billing data only when a designated billing key is pressed, the invention significantly reduces cognitive load and the number of steps required for billing compared to conventional cash registers and POS systems that rely on modes, department keys, product look-up codes, or separate item registration operations. The invention thus provides a low-cost, robust, and user-friendly electronic billing solution that can be easily adopted by users already accustomed to simple calculators, without requiring major changes to existing workflows or infrastructure.

[0009] Many small retailers still rely on manual billing processes, utilizing handheld calculators to perform calculations and issue handwritten receipts. This manual approach is time-consuming and prone to human error. Retailers must calculate totals, issue bills, and generate sales summaries, often relying on a combination of calculators and traditional pen-and-paper methods.

[0010] Thus, there is a significant need for an innovative electronic billing solution that is cost effective, portable, and ease of use like handheld calculators.

[0011] A system and method for a compact billing device is described. The aim of the claimed invention is to enable electronic billing for businesses without changing their existing manual billing process and addressing the aforementioned problems.

[0012] The invention described herein seeks to incorporate the essential functionalities of billing into a compact, portable device similar to a calculator. This novel billing device aims to provide the functionality, flexibility and simplicity of traditional calculators while delivering the core capabilities necessary for effective sales transactions, such as billing and daily summaries. Notably, the device can function as both a calculator and a billing device without requiring any mode switch, allowing calculations to be performed seamlessly during the billing process or for non-billing-related calculations.

[0013] The invention aims to meet the need for a user-friendly, battery-operated billing device that facilitates seamless transactions in a variety of retail environments, allowing users to adopt modern electronic solutions within their existing process and constraints of small budget.

[0014] In certain embodiments, the compact billing device is configured to operate as a standard four-function calculator for all entered key sequences until a designated billing key is actuated. During this time, every key press, including numeric and operation keys, is stored as an operation history while the expression is evaluated in the same manner as a conventional calculator. When the designated billing key is pressed, the processing subsystem retrospectively analyzes the stored operation history to register one or more line item entries. The device then computes a bill total over all registered line item entries and may print or electronically transmit a bill based on these entries. If the billing key is never actuated, the device behaves purely as a calculator: no product registration or bill generation occurs. This allows users to continue using the device as a normal calculator and, only when desired, convert one or more calculator expressions into a structured bill with a single billing key press instead of equals key or as additional key press after equals key.

[0015] The device offers significant advantages by being easily set up and adopted without requiring any changes to the simple business processes commonly followed by small retailers. Users can replace traditional calculators with this invention to avoid the need for manual bill writing. Additionally, the device provides instant access to daily, monthly, and yearly sales summaries. With support for billing and on-the-fly custom calculations, the need for an additional calculator is substantially reduced.

[0016] In contrast to standard calculators, which require multiple steps to calculate a bill total, this invention streamlines the process. Standard calculators typically involve two rounds: first, calculating the amount for each line item by multiplying the quantity and price and writing down the results, and second, summing all the line items to obtain the total. This invention allows users to perform all calculations in a single round, eliminating the need to manually record intermediate results. Furthermore, because the compact billing device can interpret an entire calculator expression such as “120 × 3 + 200 × 4 + 50 × 2” as a sequence of line items when a billing key is actuated, users are not required to change modes or enter separate registration commands while performing their calculations. The same keystrokes that would be used on a simple calculator for checking a bill can therefore be reused, at the user’s discretion, to automatically generate a structured bill with individual line items and totals. This significantly reduces cognitive load and the number of keystrokes compared to conventional cash registers and POS systems that rely on separate department keys, PLU codes, or explicit registration keys for each product.

[0017] The presented method ensures seamless sales registration and bill generation within the constraints of a limited display size, enhancing user satisfaction and operational efficiency. Furthermore, the invention supports a more compact display compared to existing solutions, offering practical advantages for various use cases. For example, small retailers and mobile sellers can utilize this compact, portable, low-cost device to register sales and produce bills efficiently. The smaller form factor enables users to comfortably hold and operate the device with one hand, significantly improving usability and productivity, particularly when multitasking or handling other items simultaneously.

[0018] Unlike POS systems, this billing device is compact and lightweight, comparable in size to a typical desktop calculator or smartphone, offering true portability. The design ensures low power consumption, similar to calculators, allowing the device to operate on small rechargeable or standard alkaline batteries. Certain variations of the device can function for weeks or even months on a single recharge, making it highly convenient for on-the-go use.

[0019] Many existing portable solutions, while marketed as such, are often bulky and require a fixed surface for operation. In contrast, this device may be designed for handheld use, enabling seamless mobility within a business setting and providing added convenience.

[0020] Unlike touch-based devices, which rely heavily on visual cues, this device can be cost-effectively manufactured with physical keys that promote muscle memory, enabling users to operate it efficiently without relying on visual attention.

[0021] Compared to tablets or smartphones, which require complex electronics, this invention is built with simpler, cost effective components. This simplicity enhances durability, making the device suitable for rugged environments and harsh conditions. Additionally, the device is more robust than high-end devices that require frequent software updates and are vulnerable to security concerns.

[0022] The systems and methods implemented in this invention also allow for a reduced number of keys while enabling users to perform additional tasks in an intuitive and familiar manner

[0023] is a block diagram of an exemplary compact billing device that may incorporate the system and method described herein;

[0024] is a plan view of exemplary compact device shown in;

[0025] is a 3D view of exemplary compact device shown in;

[0026] is an exemplary bill printed by the compact device shown in;

[0027] is a sample flow diagram of a minimal method of billing products;

[0028] is a sample flow diagram of a method of billing products with credit sales;

[0029] is a sample flow diagram of a method of billing products with credit sales and sending the bill electronically to the customer;

[0030] Turning now to the drawing figures, which describe several examples of the invention described in this application,is a block diagram of an exemplary compact portable device that may incorporate the system and method described herein. The device is highly portable due to its compact and lightweight nature; however, it may be fixed in place when user prefer it. The compact device 100 includes a processing subsystem 140, a display 112, and a memory subsystem and software modules 106, and various other device subsystems 102. The compact device 100 may also include data storage 108, a barcode scanner 114, a card reader 116, a mini USB port 120, one or more external connectors 122, and a communication subsystem 104.

[0031] The processing subsystem 140 controls the overall operation of the compact portable device 100. System software executed by the processing subsystem 140 may be stored in a persistent store, such as a flash memory 106, but may also be stored in other types of memory devices in the memory subsystem, such as a read only memory (ROM) or similar storage element. In addition, system software, specific device applications, or parts thereof, may be temporarily loaded into a volatile store, such as a random access memory (RAM) 110. Communication signals received by the compact device 100 may also be stored to RAM 110.

[0032] The processing subsystem 140, in addition to its system functions, enables execution of software applications 106 on the device 100. A predetermined set of applications that control basic device operations may be installed on the device 100 during manufacturing or during a system update process.

[0033] The communications subsystem 104 enables communication between the compact device 100 and other proximity systems or devices, which need not necessarily be similar devices. In certain embodiments, communication subsystem may provide data backup and synchronization or SMS features.

[0034] In this exemplary device 100 the device contains only one compact display. Certain embodiments may have additional displays. For example, a customer facing display.

[0035] Turning to the, 200 is the plan view of the device 100. The keyboard 220 illustrates five columns and five rows. Certain embodiments may use alternative layouts, such as six rows with five columns or even a non-grid arrangement, depending on the design needs.

[0036] The keys of the calculator keyboard are divided into two groups. The group 222 is numeric keys which are used to input numeric values to the device 100. The group 224 is a set of operation keys used to perform operations on the provided input or perform other operations. Certain keys within this group may execute mathematical operations (e.g., 224h, 224f), while others may (e.g., 224a, 224b) be utilized for operations such as canceling ongoing sales, reset device, registering values to memory and printing a physical bill. Upon selection of operation keys, mathematic operation keys may display a character on the display 240 while other operation keys may not display any character but trigger the device to perform the associated operation. For example, selecting the key 224f may display “X” on the display area 240 but selecting the key 224a may cancel the current sales without displaying anything. It is also noted that, in certain embodiments, none of the operation keys may display anything.

[0037] illustrates a total of 14 operation keys. Certain embodiments may have more or less number of operation keys than 14. Certain embodiments may have additional numeric keys such as “00”.

[0038] As used herein, a “calculator keyboard” refers to a numeric input interface similar to that of a standard physical calculator, featuring keys for basic arithmetic operations such as addition, subtraction, multiplication, and division, and potentially additional keys designated for specific billing functions, for example CREDIT, SAVE. The keyboard is suited for entering complete arithmetic expressions in the same manner as a basic calculator, which expressions may later be interpreted as line items as described herein. The keyboard typically contains fewer than 30 keys, although the exact number may vary depending on the configuration.

[0039] As used herein, a designated billing key refers to a calculator keyboard key configured to trigger parsing and line item registration. In certain embodiments, a designated billing key is selected from the EQUAL (=) key, the PLUS (+) key, a SAVE key, a CREDIT key, or a PRINT key. When an existing calculator key, such as the EQUAL key, is designated as a billing key, the key maintains dual functionality. In such embodiments, the key continues to perform its normal mathematical operation while also triggering parsing of the stored operation history and registration of one or more line items. The core inventive aspect resides in the configured function of triggering parsing and registration, rather than in the key’s name, symbol, or physical location on the device. Accordingly, alternative implementations may designate keys labeled TOTAL, SUM, CALCULATE, RESULT, or any other. Any such variation remains within the scope of the present invention.

[0040] Display 240 shows an exemplary display to show both inputs entered into the device 100 using the keyboard 220 and outputs generated by the device. It is a compact, rectangular display; however, certain embodiments may feature alternative shapes or arrangements suited for presenting inputs and outputs. The display may range from a simple calculator-style screen, such as a twisted nematic (TN) display, to a single-color dot matrix display or, in some embodiments, a fully functional color display with more advanced graphical capabilities. Regardless of the specific technology used, the display is compact and generally smaller than the screens typically found on standard smartphones, ensuring portability and ease of use. 242 is an example of input entered into the device 100 using the keyboard 220. 242 is a numeric input,

[0041] is a 3D view of exemplary compact device 100.

[0042] Turning to, 400 represents an exemplary bill printed by the compact device 100. The bill 400 contains three line items: 422, 424, and 426. Line item 422 includes a product name indication 422a for a product, the unit price of the product 422b, the quantity of the product 422c, and the amount 422d. In certain embodiments, a line item may contain additional information such as discount, discounted unit price, and product specific tax. The product name indication may not necessarily represent the actual product name or description, but merely serve as an indication. 412 is a phone number that identifies the customer. In certain embodiments, instead of a phone number, the customer's name, social security number, or other identifying information may be used.

[0043] In one class of embodiments, the compact device 100 supports a billing key that converts a complete calculator-style arithmetic expression into a bill without requiring the user to change modes or explicitly register each individual product while entering the expression. During normal operation, the user may enter an expression such as “120 × 3 + 200 × 4 + 50 × 2” using only the numeric keys and arithmetic operation keys on the calculator keyboard 220. While these keys are pressed, the processing subsystem 140 evaluates the expression and displays intermediate and final calculation results on display 240, just as a conventional calculator would. Simultaneously, the device stores the sequence of key presses and the corresponding operators in an internal operation history in the memory subsystem, for example in RAM 110. When the user subsequently actuates a designated billing key, the device accesses this operation history and parses the stored expression for creating line item entries. The device then maps one numeric value to a unit price and the other to a quantity. For example, it may assign the left operand as the price and the right operand as the quantity (or vice versa, depending on configuration). Next, it calculates the amount for each product and compiles these entries into a bill with a total amount. In this way, a user who is accustomed to performing manual calculations with a basic calculator can continue to input expressions in the same manner, and only when a designated billing key is pressed does the device interpret the expression as a set of line items. If the billing key is not pressed, the same sequence “120 × 3 + 200 × 4 + 50 × 2” remains a simple calculation and no line item or bill generation occurs. This retrospective parsing of calculator expressions into line items is independent of the particular key layout used on the calculator keyboard 220 and can be applied in combination with the various flow diagrams described below, for example allowing the user, after conversion, to optionally invoke keys for closing the bill, calculating change, printing the bill, or registering the bill as a credit sale as described with reference to FIGS. 5 to 7.

[0044] is a sample flow diagram 500 of billing products, a minimal billing process is illustrated as an example here. The method may be used with a compact device 100. At step 502, user selects a key from the calculator keyboard. At step 504, the device determines whether the selected key is the first designated billing key (e.g. SAVE) from 224. If yes, the device retrieves the recorded sequence of selected keys from memory, parses it, and registers one or more line item for the billing at step 506. Otherwise, the device determines whether the selected key is the second designated billing key (e.g. PRINT) at step 510. If no, the device functions as a calculator at step 508, allowing the user to perform various mathematical operations such as multiplication, addition, division, and subtraction until a designated billing key is selected.

[0045] When line items are registered for billing at step 506, the device may compute amount, line discount, tax or other pertinent information and continues to function as a calculator at step 508. The additional inputs entered after the registration step 506 may be used to add more products or to perform cash balance or tax calculation to the bill.

[0046] For example, assume the device has already recorded the sequence “100 × 12 + 200.5”. When the user subsequently selects the first designated billing key (e.g., SAVE), the device registers two line items: one with a sales price of 100 and a quantity of 12, and another with a sales price of 200.5 and a quantity of 1. The input sequence data may be stored in a temporary data structure in RAM 110, or directly in permanent storage 106 or 108. In other embodiments, the data may be stored in a networked storage system or computer system.

[0047] In another example, assume the device has recorded the sequence “100 − 10 × 12 + 200.5”. The device may pass this sequence such that the first line item has a sales price of 100, a discount value of 10, and a quantity of 12 and the second line item has a sales price of 200.5 and quantity of 1.

[0048] In another example, assume the device has recorded the sequence “200 – 10% × 12 + 200.5”. The device may pass this sequence such that the first line item has a sales price of 200, a discount value of 10%, and a quantity of 12.

[0049] If the second designated billing key is selected at step 502, the device proceeds to step 512, where the device passes the recorded sequence of selected keys stored in memory and registers one or more line items for billing, closes the bill and prints it, and then continues to function as a calculator at step 508. In this case, the additional inputs entered after step 512 may be used for further calculations unrelated to the completed bill or as part of a new bill.

[0050] This printing function can be achieved through a connected or integrated bill printer. In certain embodiments, the device may only close the bill and ignore printing.

[0051] For example, assume the device has already recorded the sequence “100 × 12 + 200.5” and the user presses the first designated billing key, in this case equal (=). At step 504, the device determines that the user selected the first designated billing key. If yes, at step 506, register line items and displays the bill total “1400.50. At step 508, the user selects the minus (−) key and inputs the cash received from the customer, for example, the input sequence “2”, “0”, “0”, and “0”. During these key presses, the device functions as a calculator. The user then selects the second designated billing key (E.g. PRINT). This causes the device to display the change “599.50” on the display 240 at step 512 and print the bill with cash and balance information.

[0052] depicts a sample flow diagram 600 illustrating a billing process according to another embodiment. A credit-based billing process is demonstrated. At step 602, the user selects a key from the calculator keyboard. At step 604, the device determines whether the selected key is a first designated billing key from 224. If so, the device passes the recorded sequence of selected keys stored in memory and registers one or more line items for billing at step 606.

[0053] Otherwise, at step 610, the device determines whether the selected key is a second designated billing key. If the selected key is not the second designated billing key, the device functions as a calculator at step 608. If the second designated billing key is selected at step 610, the device proceeds to step 612, where the device passes the recorded sequence of selected keys stored in memory, registers one or more line items for billing, and closes the bill.

[0054] At step 614, the user selects a key. At step 616, the device determines whether the selected key is a SAVE key. If the selected key is not the SAVE key, the device accepts the input as part of customer identification at step 620. When the user later selects the SAVE key at step 614, the device registers the bill amount as a credit to the identified customer account at step 618. The SAVE key is described herein for ease of explanation, and any dedicated or contextual operation key may alternatively be used to trigger equivalent functionality.

[0055] For example, at step 610, the device determines whether the user selected the second designated billing key (e.g., CREDIT). If yes, the device closes the bill and displays the bill total (e.g., 1400.50) At step 614, the user selects a numeric key “7” and the user selects the SAVE key next time. It will save the bill and register a credit value of 1400.50 to the customer identified by “7” at step 618.

[0056] depicts a sample flow diagram 700 illustrating the process of billing in another embodiment. A credit-based billing process and sending the bill to the customer is demonstrated. At step 702, user selects a key from the calculator keyboard. At step 704, the device determines whether the selected key is a first designated billing key from 224. If yes, the device pass recorded sequence of selected keys in the memory and registers one or more line item for the billing at step 706. Otherwise, the device determines whether the selected key is a second designated billing key at step 710. If no, the device functions as a calculator at step 710. If the second designated billing key is selected at step 702, the device proceeds to step 712, where the device passes the recorded sequence of selected keys stored in memory and registers one or more line items for billing and closes the bill. At step 714, the user inputs customer identification. At step 716, the device registers the bill amount as a credit to the identified customer account. At step 718, the user actuates sending the bill, and the device sends the bill to the customer at step 720.

[0057] For example, at step 710, the device determines whether the user selected the second designated billing key (e.g., CREDIT). If yes, the device closes the bill and displays the total, (e.g., 1400.50). At step 714, the user inputs the customer's mobile number as identification (e.g., 7776724). The device registers a credit value of 1400.50 to the customer's account at step 716. At step 718, the user selects the send button, and the device sends a SMS with bill details at step 720.

[0058] The present invention is industrially applicable to various sectors where sales is conducted, particularly in retail, mobile sales, small vendors and related domains. The described system and method offer practical solutions for enhancing the efficiency and effectiveness of transactions conducted through compact devices, thereby improving overall operational workflows and user experiences.

Claims

A method of registering one or more line item entries for billing in a portable billing device comprising a compact display, a calculator keyboard with numeric keys and operation keys, and a processing subsystem with memory, the method comprising: the processing subsystem receiving a sequence of key presses consisting of numeric values and operators; storing in memory an operation history comprising the received key presses and corresponding operators; when a designated billing key is received, the processing subsystem accessing the stored operation history and parsing the stored sequence to create and register one or more line item entries.The method of claim 1, wherein the device then compiles the line item entries into a bill.The method of claim 1, further comprising generating a bill comprising the registered line items and a bill total.The method of claim 3, further comprising printing the bill via a connected or integrated bill printer.The method of claim 3, further comprising electronically transmitting the bill to a customer via a communication subsystem.The method of claim 1, wherein prior to actuation of the designated billing key, the processing subsystem evaluates the stored operation history as an arithmetic expression and displays a result on the compact display.The method of claim 1, further comprising, upon actuation of a designated billing key, the processing subsystem closing the bill and preventing further line item creation for the current bill.The method of claim 7, further comprising the device accepting input of customer identification data and registering the bill amount as a credit entry associated with the customer identification.The method of claim 7, further comprising the device accepting input of a cash amount received from a customer, calculating a change amount, and displaying the change amount on the display.A portable billing device comprising: a compact display; a calculator keyboard with numeric keys and operation keys; a memory; and a processing subsystem configured to: receive key presses from a user via the calculator keyboard and store in the memory an operation history comprising the received key presses and corresponding operators, when a designated billing key is actuated, accessing the stored operation history and parsing the stored sequence to register one or more line items.A portable billing device comprising: a compact display; an input interface including no more than 30 keys, including one or more designated billing keys; and a processing subsystem configured to transform a calculation history into one or more line items for billing upon activation of a designated billing key.The device of claim 10, further comprising a card reader for electronic card payments.The device of claim 10, wherein the device operates in dual mode: (a) as a standard calculator when no designated billing key is actuated, and (b) as a billing device when a designated billing key is actuated, without requiring explicit mode switching.A method of operating the portable billing device of claim 1 in both networked and offline conditions, comprising transmitting stored transaction records to a centralized computer system for synchronization of billing records for further processing.A transaction aggregation system comprising a plurality of portable billing devices according to claim 10, each associated with a unique device identifier and a location identifier, and a centralized computer system configured to receive billing records from the portable billing devices, store the billing records, and generate aggregated transaction reports.

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