# Early Automatic Cash Dispenser Using Credit Cards > This 1973 patent describes a machine that dispenses cash using a coded credit card, verifies the card's validity, and updates its code after each transaction to prevent fraud. - **Patent:** US 3761682 - **Original title:** Credit card automatic currency dispenser - **Owner:** Docutel Corp - **Granted:** 1973 - **Status:** Public domain (expired) - **Times cited:** 36 - **Field:** consumer_electronics, software, finance, semiconductors ## What it does This patent details a method for an automated machine to dispense cash based on a credit card. When a card is presented, the machine reads its coded data and compares it against stored verification codes to check for validity, such as bank code, expiration date, or number of uses. If the card is valid, the machine dispenses the requested currency. Crucially, after dispensing cash, the machine updates the card's coded data to reflect the transaction and then re-scrambles it with a changing key. This updated, scrambled code is then recorded onto a new document (presumably a replacement card or a receipt) that is removed from the machine. This process aims to prevent unauthorized use by ensuring the card's code is always current and unique after each transaction. ## What it does NOT cover - Dispensing cash without a coded document being presented - Dispensing cash using a document that has expired or exceeded its usage limit - Dispensing cash without verifying the coded data against stored codes - Updating the coded data on the document after a transaction - Scrambling the coded data after each transaction to prevent reuse ## The clever bit The innovation lies in updating and re-scrambling the credit card's code after every single transaction, effectively creating a unique, dynamic identifier that prevents the same card data from being used repeatedly to withdraw cash. ## Real-world examples 1. Docutel Automatic Teller Machine (ATM) prototypes ## Why it matters This patent represents an early attempt at creating an automated banking machine that could dispense cash using a credit card, a precursor to modern ATMs. It addresses the critical need for security in such machines by incorporating data verification and transaction-specific code updates to deter fraud. ## Frequently asked questions ### What does Early Automatic Cash Dispenser Using Credit Cards cover? This 1973 patent describes a machine that dispenses cash using a coded credit card, verifies the card's validity, and updates its code after each transaction to prevent fraud. ### Who owns patent US 3761682? Docutel Corp owns this patent, granted in 1973. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 3761682 cited by? This patent has been cited by 36 later patents that build on its ideas. ### What problem does this patent solve? This patent represents an early attempt at creating an automated banking machine that could dispense cash using a credit card, a precursor to modern ATMs. It addresses the critical need for security in such machines by incorporating data verification and transaction-specific code updates to deter fraud. ### What does this patent NOT cover? Dispensing cash without a coded document being presented **Full plain-English explainer:** https://patentbrief.org/patent/us/3761682/atm-cash-dispenser **Original patent:** https://patents.google.com/patent/US3761682 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Computers Use Hardware to Stop Software Piracy and Cracking](https://patentbrief.org/patent/us/4558176/computer-systems-to-inhibit-unauthorized-copying-unauthorized-usage-and-automated-cracking-of-protected-software) — A 1982 hardware-based security system that prevents software from being copied or cracked by destroying sensitive data if the computer detects unauthorized access or execution. - [How a Server Updates Smart Card Apps and Shows Ads](https://patentbrief.org/patent/us/9959544/updating-an-application-on-a-smart-card-and-displaying-an-advertisement) — This patent describes a system where a central server authenticates a smart card user, identifies the specific smart card, allows the user to update applications on it, and then sends an advertisement to the user's computer. - [How James Ritty's First Cash Register Tracked Sales](https://patentbrief.org/patent/us/271363/cash-register-ritty) — This 1883 patent describes an early mechanical cash register invented by James Ritty, designed to record sales transactions and display the total amount, helping businesses prevent employee theft and track daily income. - [The First Digital Camera's Core Technology](https://patentbrief.org/patent/us/4131919/digital-camera-electronic-still) — Kodak's 1978 patent on the fundamental technology for capturing, processing, and storing digital images using a CCD sensor and magnetic tape. - [How a Spring-Loaded Pocket Dispenser Works](https://patentbrief.org/patent/us/2620061/pez-dispenser) — A 1949 mechanical design for a pocket-sized container that uses a spring to push items like pills or candies to the top for easy access.