JPH0452883A - Bar code demodulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding a barcode demodulator that demodulates and converts a digital signal read from a barcode reader, it reads and demodulates barcodes in parallel and continuously converts barcodes into The sub-CPLI includes an edge detection circuit that receives a barcode data signal and outputs a timer value between edges, and a counter circuit that outputs a count value indicating the number of times the edge has been detected. and a common RAM that stores the timer value and the count value, a demodulation circuit serving as a main CPU that receives the output of the common RAM, and a code conversion circuit that receives the output of the demodulation circuit and converts the code. In the demodulation device, when the count value of the common RAM reaches a predetermined number, the demodulation circuit starts operating in parallel with the sub CPU and demodulates the timer value from the common RAM. , and is configured to perform code conversion in a code conversion circuit.

[Industrial application field]

The present invention relates to a barcode demodulation device that demodulates and converts a digital signal (barcode data signal) read from a barcode reader.

[Conventional technology]

Conventionally used bar code demodulation and code conversion will be explained with reference to FIGS. 5 and 6. Fifth
The barcode shown in the upper part of the figure (shaded areas are filled in black) is input to the barcode reader 10 as a barcode scanning signal (BS) by operating the barcode reader 10. The barcode reader 10 includes a photoelectric conversion circuit 11, an amplifier circuit 12, and a shaping circuit 13, and converts the barcode scanning signal into a digital signal (DS) as shown in the lower part of FIG.
Convert to

The digital signal is supplied to hand belt terminal 15. Hand belt terminal 15 is edge detection circuit 1
6. Equipped with a counter circuit 17, a RAM (Random Access Memo'J) 18, a demodulation circuit 19, and a code conversion circuit 20, the barcode data converted into a digital signal is detected by an edge detection circuit, and each pulse signal ( The timer value of the timer activated for the bar code (corresponding to the bar code space) is stored in the RAM, and counted up by a counter circuit for each pulse. When the timer value stored in the RAM detects a stop margin (blank that lasts for a certain period of time) provided after a series of barcodes as shown in the upper part of FIG. 5, demodulation is started in the demodulation circuit 19. The signal is converted into code data (CD) by the code conversion circuit 20.

[Problem to be solved by the invention]

As mentioned above, in conventional devices, when barcodes are successively read by a barcode reader in order to detect the stop margin and then start demodulation, the previous data is demodulated and the code data is output. There was a problem in that the process did not necessarily end, and the next barcode could not be read until a short interval had elapsed. This tendency became more pronounced as the amount of barcodes included between the stop margins increased.

Therefore, an object of the present invention is to read barcodes and demodulate them in parallel, thereby making it possible to read barcodes continuously.

[Means to solve the problem]

In the present invention, as illustrated in FIG. 1, a barcode demodulation device receives a barcode data signal from a barcode reader, demodulates the signal, and converts the code, comprising:
The barcode demodulation device includes an edge detection circuit 3 as a sub-CPII (central processing unit) 1 that receives the barcode data signal, detects edges, and outputs a timer value corresponding to the time between edges; A counter circuit 4 which receives the output of the circuit 3 and outputs a count value indicating the number of times of the edge, and a common RA which receives and stores the timer value from the edge detection circuit 3 and the count value from the counter circuit 4.
M (random access memory) 5, and main CP
The common RAM 50 includes a demodulation circuit 6 as U 2 that receives the output of the common RAM 5, and a code conversion circuit 7 that receives the output of the demodulation circuit 6 and performs code conversion.
When the count value reaches a predetermined number,
A bar code demodulation device is provided in which the demodulation circuit 6 starts operating in parallel with the sub CPU 1, demodulates the timer value from the common RAM 5, and converts the code in the code conversion circuit 7.

[For production]

As illustrated in FIG. 1, a barcode demodulator in a hand belt terminal is equipped with a sub-CPU 1 including an edge detection circuit 3, a counter circuit 4, and a common RAM 5 to detect digital signals, and a demodulation circuit 6. A main CPt12 including a code converter circuit 7 and a code conversion circuit 7 is provided to demodulate the barcode, so that these two functions can be performed separately. When the number of pulses detected by the edge detection circuit on the sub CPU l side reaches the value specified on the main CP0.2 side, the sub CPU
U sends a response to the main CPU. Main C
When the PU side confirms the response, it monitors the count value stored in the common RAM and, for example, advances demodulation every time the count increases by one character of the barcode.

〔Example〕

A block diagram of a hand belt terminal including a bar code demodulator as an embodiment of the present invention is shown in FIG. This device is composed of a sub CPU 1 and a main CPU 2. The sub CPU 1 includes an edge detection circuit 3, a counter circuit 4, and a common RAM 5.
U2 includes a demodulation circuit 6 and a code conversion circuit 7.

The barcode scanning signal photoelectrically converted, amplified, and shaped by the barcode reader is supplied as a digital signal (DS) to the edge detection circuit 3, where the edge (rising or falling waveform) of the barcode data is detected and the edge is detected. The timer value corresponding to the time between is calculated and stored in the common RAM.
5.

The counter circuit 4 counts the edge signals from the edge detection circuit 3, and the count value is stored in the common RAM 5.

Figures 2 to 4 show the storage of data in the common RAM and the human output of data between a 16-bit main CPU and an 8-bit main CPU.
The case where pit sub CPU is used is shown. FIG. 2 shows only the sub CPU side, and the common RAM shows count value and timer value data in 2 bytes. FIG. 3 shows a case where the number of timer values reaches a specified value (for example, 30).

When the count value of the counter circuit 4 reaches the specified value indicated by the demodulation circuit, the response from the sub CPU is sent to the main CPU.
It is sent to the PU side (see Figure 3). The demodulation circuit 6 starts demodulating the 30 timer values, converts the code of the demodulated data, and outputs coded data (CD) (see FIG. 4).

For example, a binary level CDDE39 barcode requires 10 timer values to demodulate one character, and the specified value can be set to 30 on the main CPU side. Common RAM
When the count value reaches 30, the sub CPU side switches to the main C
A response is sent to the PU side, and the main CPU side confirms it and starts demodulation. By appropriately selecting the specified value in this way, the waiting time for processing can be reduced compared to the conventional method in which demodulation is not started until the stop margin is detected.

〔Effect of the invention〕

According to the present invention, barcode reading and demodulation are performed in parallel, making it possible to read barcodes continuously.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a hand belt terminal including a barcode demodulator as an embodiment of the present invention, FIGS. 2 and 3 are diagrams explaining data storage in a common RAM in the embodiment, and FIG. FIG. 5 is a diagram illustrating the input/output of data in the common RAM in the embodiment, FIG. 5 is a diagram showing the correspondence between barcode data and digital signals, and FIG. 6 is a block diagram of a barcode reader and a conventional demodulator. . In the figure: 1...Sub CPU. 2...Main CPU. 3... Edge detection circuit, 4... Counter circuit, 5... Common RAM. 6... Demodulation circuit, 7... Code conversion circuit, 10... Barcode reader, 11... Photoelectric conversion circuit, 12... Amplification circuit, 13... Shaping circuit, 15... Hand Belt terminal panel 16...edge detection circuit, 17...counter circuit, 18...RAM. 19... Demodulation circuit, 20... Code conversion circuit.

Claims (1)

[Claims] Receiving a barcode data signal from a barcode reader,
A barcode demodulation device that demodulates the signal and converts the code, the barcode demodulation device includes a sub-CPU (1),
an edge detection circuit (3) that receives the barcode data signal, detects an edge, and outputs a timer value corresponding to the time between edges; a count value that receives the output of the edge detection circuit (3) and indicates the number of times the edge occurs; Counter circuit (4) that outputs
, a common RAM (5) that receives and stores a timer value from the edge detection circuit (3) and a count value from the counter circuit (4), and a common RAM (5) serving as the main CPU (2). It is equipped with a demodulation circuit (6) that receives the output, and a code conversion circuit (7) that receives the output of the demodulation circuit (6) and converts the code, and the count value of the common RAM (5) is a predetermined regulation. When the demodulation circuit (6) reaches the sub-CPU (
A barcode demodulation device starts operation in parallel with step 1), demodulates a timer value from the common RAM (5), and converts the code in a code conversion circuit (7).