Data communication system, data carrier driving apparatus, and data carrier apparatus

摘要

In a data communication system according to one aspect of the present invention, a data carrier driving apparatus, which communicates with a data carrier apparatus using a rectification smoothing circuit for generating a power supply voltage, controls a pulse width of each pulse of a clock signal (pulse voltage) supplied to the data carrier apparatus. The data carrier driving apparatus sets the duration of each pulse of a pulse voltage generated by the data carrier driving apparatus, so as to suppress a decrease in the level of the pulse voltage caused by a charging operation for the rectification smoothing circuit, particularly, such that the duration in which the pulse voltage becomes a high-level voltage is longer than or equal to the duration in which the pulse voltage becomes a low-level voltage during one period.

主权项

1. A data communication system including a data carrier driving apparatus and a data carrier apparatus that perform data communication via a first contact and a second contact,
the data carrier apparatus comprising: a rectification smoothing circuit configured to include a rectification element and a capacitance element, and to rectify and smooth a pulse voltage input from the data carrier driving apparatus via the first contact, and outputs the rectified and smoothed pulse voltage, the rectification element and the capacitance element being connected in series between the first contact and the second contact; a pulse detection unit configured to detect the pulse voltage that is input from the data carrier driving apparatus and applied to the rectification smoothing circuit; and a first control unit, that is connected to the rectification smoothing circuit, configured to operate using a voltage output from the rectification smoothing circuit as a power supply voltage, and to identify downlink transmission data from the data carrier driving apparatus to the data carrier apparatus based on a pulse width of the pulse voltage detected by the pulse detection unit, the data carrier driving apparatus comprising: a current detection element configured to detect a current flowing from the data carrier driving apparatus to the data carrier apparatus via the first contact as an output current corresponding to uplink transmission data from the data carrier apparatus to the data carrier apparatus; a pulse generation circuit configured to generate a pulse voltage that periodically alternates between a high-level voltage and a low-level voltage using a voltage output to the data carrier apparatus via the second contact as a reference voltage, and to output the generated pulse voltage to the data carrier apparatus via the current detection element and the first contact; and a second control unit configured to control the pulse generation circuit to set a per-period pulse width of the pulse voltage accordance with the downlink transmission data, wherein the second control unit when transmitting first data to the data carrier apparatus as the downlink transmission data, controls the pulse generation circuit to set the per-period pulse width to a first pulse width with which a time frame of the high-level voltage is longer than or equal to a time frame of the low-level voltage, and when transmitting second data to the data carrier apparatus as the downlink transmission data, controls the pulse generation circuit to set the per-period pulse width to a second pulse width with which a time frame of the high-level voltage is longer than or equal to a time frame of the low-level voltage, the second pulse width being larger than the first pulse width Wherein the first data corresponds to a bit one and the second data corresponds to a bit zero or the first data corresponds to a bit zero and the second data corresponds to a bit one.